micro turbine iii_pdr

Microturbine III Senior Design 05002

Micro Turbine III

Senior Design Project 05002

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Preliminary Design Report

Design Team:

Lincoln Cummings

Joseph Calkins

Mark Fazzio

Allison Studley

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Executive Summary:

This report discusses in detail the work done by the Micro Turbine III design team

throughout the design process thus far. The objective of the design project is to scale

down the size of the system for implementation onto a Micro Air Vehicle (MAV). The

parameters are that the micro turbine generator is to produce 5 watts of continuous

power, have a system weight under 45 grams, and sized to fit within a MAV. The goals,

procedures, analysis and other aspects of the design process are discussed throughout this

technical paper. Much of the research and development of a feasible Micro Turbine

design has been previously completed by the 04013 senior design team from last year. A

Miniature Turbine is a feasible replacement for the current battery power on the RIT -

MAV. Although last year’s design proved to provide enough power for all of the

electronics on the MAV, the overall design was much too large to be implemented into

the MAV airframe. By creating a Micro Turbine system which has advantages over the

current battery power supply such as higher power to weight density, and decreased

costs, the capabilities of the MAV can substantially increase.

In order to provide as many possible improvements upon the previous design,

new concepts were brainstormed, developed, and investigated further. Comparisons

between the previous research and these concepts were made in several dimensions.

Aspects such as weight, size, cost, availability, and ease of production were used to

compare the different concepts and determine their feasibility. As a result of these

comparisons, it was determined that the previous turbine design was most feasible due to

time constraints, limited man power and a fixed budget. Other aspects of the design such

as the fuel canisters, housing, fuel supply system, and also use of exhaust gases for

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reducing the drag on the plane were either newly designed or modified from last year’s

design.

The design of the Micro Turbine III was done through the use of the Engineering

Design Process which consists of twelve different facets. Only six of the facets were

used in the development of the preliminary design and are discussed throughout this

document. Each of these facets is contained in its own chapter, which discusses the facet

in detail.

Through the use of the Engineering Design Process, a new Micro Turbine design

was developed that allows the system to be implemented into the MAV airframe. By

using aspects of the previous designs along with some newly developed concepts, the

system was not only made more compact, but may also possibly decrease the drag on the

MAV. These designs and concepts must now be validated through the development of

prototype systems which can be tested and analytically compared to the theory.

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Table of Contents

Executive Summary:........................................................................................................................31.0 Recognize and Quantify the Needs............................................................................................7

1.1 Mission Statement....................................................................................71.2 Project Description...................................................................................71.3 Scope Limitations....................................................................................81.4 Stakeholders.............................................................................................81.5 Key Business Goals.................................................................................91.6 Top Level Critical Financial Parameters.................................................91.7 Financial Analysis..................................................................................101.8 Preliminary Market................................................................................101.9 Secondary Market..................................................................................111.10 Order Qualifiers...................................................................................111.11 Order Winners......................................................................................121.12 Innovation Opportunities.....................................................................121.13 Background Research..........................................................................121.14 Formal Statement of Work...................................................................151.15 Organizational Chart............................................................................17

2.0 Concept Development......................................................................................172.1 Subgroups..............................................................................................17

2.1.1 Housing Team...........................................................................182.1.2 Turbine Team............................................................................182.1.3 Fuel System Team.....................................................................18

2.2 Housing Concepts..................................................................................192.2.1 Bearings....................................................................................19

2.3 Turbine Concepts...................................................................................202.4 Fuel System Concepts............................................................................20

2.4.1 Fuel...........................................................................................212.4.2 Tubing & Connectors................................................................212.4.3 Flow Regulation........................................................................22

2.5 Generator ...............................................................................................233.0 Feasibility ...............................................................................................24

3.1 Turbine Feasibility.................................................................................243.2 Housing Feasibility................................................................................253.3 Bearing Feasibility.................................................................................263.4 Fuel System Feasibility..........................................................................27

3.4.1 Fuel Feasibility..........................................................................273.4.2 Tubing Feasibility.....................................................................283.4.3 Flow Regulation Feasibility......................................................28

4.0 Objectives and Specifications..........................................................................294.1 Objectives..............................................................................................294.2 Performance Specifications...................................................................294.3 Design Practices.....................................................................................304.4 Safety Issues...........................................................................................31

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5.0 Design Analysis & Synthesis...........................................................................325.1 Turbine Analysis & Synthesis...............................................................325.2 Housing Analysis & Synthesis...............................................................34

5.2.1 Housing FEA Analysis.............................................................355.2.2 Shaft Selection & Analysis.......................................................365.2.3 Bearing Selection......................................................................375.2.4 Coupling Selection....................................................................37

5.3 Fuel System Selection & Analysis.........................................................385.3.1 Fuel Selection............................................................................385.3.2 Tubing & Connectors Selection................................................385.3.3 Flow Regulation........................................................................395.3.4 Fuel System Analysis................................................................39

6.0 Future Plans ...............................................................................................416.1 Test Setup...................................................................................................

416.2 Schedule ...............................................................................................426.3 Budget ...............................................................................................43

7.0 Conclusion .............................................................................................414A. Appendix A – Turbine Performance Graphs...............................................46B. Appendix B – Turbine Performance Data...................................................49C. Appendix C – Mass Flow Calculation D. Appendix D – Finite Element

Analysis On Housing / Cap..........................................................................57D. Appendix D – Finite Element Analysis On Housing / Cap.........................58E. Appendix E – Turbine Performance Data....................................................63

Figures, Tables, and EquationsPage Title

13 Fig 1-1: Capstone Micro Turbine14 Fig 1-2: MIT's Micro Turbine & Test Stand17 Fig 1-3: Organizational Chart19 Fig 2-1: Housing Concept20 Fig 2-2: 3-D Pelton Wheel Turbine33 Fig 5-1: Blade33 Fig 5-2: Turbine Design35 Fig 5-3: Cap FEA36 Fig 5-4: Housing FEA42 Fig 6-1: Schedule43 Fig 6-2: Budget

25 Table 3-1: Housing Feasibility26 Table 3-2: Bearing Feasibility

33 Eqn 5-1: Blade Calculation34 Eqn 5-2: Torque34 Eqn 5-3: Efficiency40 Eqn 5-4: Density40 Eqn 5-5: Velocity40 Eqn 5-6: Mass Flow

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1.0 Recognize and Quantify the Needs

1.1 Mission Statement

The purpose of the 05002 Senior Design team is to design and build a working

prototype of a micro-turbine generator that can be integrated into a MAV airframe and

power the vehicles electrical accessories. The micro-turbine design is to be a

continuation and improvement upon the previous design team’s project through the use of

much of the previous research and design along with new research and design to create a

baseline for integration into the MAV airframe.

1.2 Project Description

The current RIT MAV vehicle’s motor and electronics are powered by a heavy

and expensive Lithium Ion battery. Although these batteries supply the proper electrical

capabilities, it has been proven through previous research and senior design teams that a

more lightweight and compact power supply is feasible. The scope of the current project

is to improve upon the previous year’s designs and to implement the design into the

MAV airframe, which has not been done by previous teams.

As a result of last year’s senior design team, there is an existing Pelton wheel

turbine design which can be used in this years design. Other turbine designs, as well as

other Pelton wheel designs will be investigated and their feasibility will be determined

compared to the current design. Last year’s design produced the necessary power

requirements, however was much too large to be implemented into the MAV airframe.

This year’s team will research different turbine designs, propellants, and other

components and evaluate their feasibility and advantages/disadvantages over the current

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design. One of the major goals is to make a smaller housing which will be able to fit into

the MAV airframe as well as be lightweight, robust, and fulfill the required power and

flight requirements. The MAV requires a minimum of 5 watts of power for use by the

onboard electronics. In order to achieve these power requirements, the turbine must

rotate at high speeds, which last year’s team determined to be around 100,000 rpm.

While designing the new system, the overall weight goal of 45 grams must be considered.

1.3 Scope Limitations

Through previous senior design research, it has been determined that a minimum

of 5 watts of power is needed in the flight of the RIT MAV. This requirement sets a

limitation on the micro turbine to produce a minimum of 5 watts of power for sustainable

flight. As mentioned previously, the weight of the system is also an issue to improve

upon the current battery power. A goal of an overall weight including propellant tanks is

a reasonable 45 grams.

Many of the limitations to research and design parameters are due to the limited

amount of time as well as a project budget of $1000 - $1500. The budget is to be

supplied by the Kate Gleason College of Engineering.

1.4 Stakeholders

The primary stakeholders in this design project are the members of the design

team. In addition to these persons is the faculty of RIT’s Mechanical Engineering

Department. Dr. Jeff Kozak, the teams advisor and contact, is the dominate member of

the faculty who will benefit from this year’s project in advancing the design onto future

micro turbine design teams along with MAV teams.

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Secondary stakeholders include the outside venders sought for the manufacture of

intricate parts. Also on this list are faculty and staff of other RIT departments including

the Microelectronics Department and those in the Brinkman Laboratory. Stakeholders

extend onto member of other current and future MAV design teams at RIT and other

schools involved in micro turbine research.

1.5 Key Business Goals

A successful project will be defined by the evidence of a working micro turbine

prototype producing five watts of power, weighing less than 45 grams, and sized to be

implemented onto a MAV. If the design team is capable of completing the task, then

much will have been accomplished. Not only will the core objective of the project be

achieved, the students on the team will have also gained a valuable experience in working

with a multidisciplinary team. The results of this project will serve as a stepping stone

for further development in this field. Success of this project will bring future research a

step closer to replacing the power source on MAVs, which is the ultimate goal.

1.6 Top Level Critical Financial Parameters

Almost all of the budget will be used for purchasing of raw materials or sub-

assemblies. The goal is to have the micro-turbine design be within a reasonable amount

of a battery powered system. The prototype will use nitrogen gas in large canisters, the

goal for future micro-turbine teams is to shrink the weight and size of the nitrogen

canisters and piercing components so that they can be incorporated onto an MAV

airframe.

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1.7 Financial Analysis

The project has a tentative budget of $1000 from the Mechanical Engineering

department at RIT. This will be used to fund purchases of all the components listed in

the Bill of Materials (see appendix XXX). The major components that will be ordered

are the following:

Housing material

Fuel canisters

Puncture system for the fuel canisters

Turbine

Internal components: shaft, bearings, couplings

Machining costs: housing

1.8 Preliminary Market

The project team two years ago conducted a proof of concept project, while last

year’s team designed a functioning prototype. That project initiated a host of long-term

research projects. Therefore, the work being done is still set in the research realm while

concern for actual implementation onto an MAV is under heavy scrutiny. The primary

customer for this year’s project remains academia. Eventually these efforts and research

will develop into a feasible energy source that the RIT MAV team can utilize for efficient

flight.

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1.9 Secondary Market

Through added time and research, this design could be developed into a reliable

source of lightweight energy production. There are numerous applications for such

products. The Department of Defense (DoD) and the Forest Service are currently

interested in utilizing MAVs for their particular needs. The DoD is interested in using

MAVs in military conflicts for ground personnel to utilize as scouts or forward observers.

The Forest Service would like MAVs to fly into and around forest fires and monitor their

status to help better direct fire fighting efforts. However, the product is not limited to

MAVs. This lightweight energy production is open to a host of other applications.

Micro robots that could be made lighter and smaller using micro turbines are a good

example of this. The micro turbine is open to numerous applications in the future.

1.10 Order Qualifiers

The purpose of this research design is to improve upon the technology that has

already been produced at RIT. Therefore, the senior design team must produce a

prototype micro turbine/generator system that is sized to be more suitable for MAV

application than last year’s design in addition to including the fuel system into the design.

To be more useful, the power produced shall be reduced from 18 W to 5 W. This is the

power required by a MAV flight production. The weight must also be held to less than

45 grams. This will make the product more feasible for MAV application.

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1.11 Order Winners

If time and money permit the team will work to complete the following goals:

Implement the fuel system into the design.

Optimize turbine efficiency.

Maintain the ease of assembly and disassembly of the turbine/generator system.

Improve bearing setup and design.

Improve the housing design to better fit an MAV.

Be safe to users and environment.

Validate data using Computational Fluid Dynamics modeling.

Design and test all components for form and function.

1.12 Innovation Opportunities

In this day and age, persons in all industries are looking to maximize efficiency

while minimizing the materials required. Micro turbines strive to achieve the same goal

in providing an alternate power source. Since everything is on the micro scale, the

complete package will be light in weight and compact in sized. Research in these

turbines will aid any electrical required applications limited by space and weight.

1.13 Background Research

The term micro turbine has become undefined as its definition changes from field

to field. It can be used to describe a stand-alone unit producing hundreds of kilowatts in

industry to a Micro Electrical Mechanical System (MEMS) producing milliwatts of

power in academic institutions. A wide range of applications in industry see the potential

for micro turbine generators for electricity. The primary use for micro turbines is in the

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Fig 1-1: Capstone Micro Turbine


growing Unmanned Aerial Vehicle (UAV) and model airplane markets. Institutions

throughout the country are currently designing micro turbines on the micrometer scale.

The high efficiency of micro turbines has led

industry to scale down power producing turbines from

thousands of megawatts to tens of kilowatts. Capstone

Turbine Corporation remains the world leader in the

micro turbine market since introducing their products in

1998. These highly efficient turbines are used for

everything from hybrid electric vehicles (HEVs) to

providing power to hotels and office buildings. By

utilizing a wide variety of fuels, these generators are able to be used in remote locations.

In the commercial market, micro turbines are generally aircraft turbines scaled

down to be sized appropriately. These turbines produce just a few pounds of thrust

sufficient for UAVs, Missiles, and remote controlled aircraft. The continuous growth in

the autonomous missile and UAV markets is being pushed by the military. NASA and

the defense department hold numerous contracts for research and production of micro

turbines. Unfortunately, these micro turbines are too large for MAV applications.

Research is being conducted at universities throughout the nation and around the

world. This research is on the scale in which RIT has been performing its work on the

topic. A number of institutions are furthering research in the realm of power production

on the milliwatt scale to a few watts. MIT is the currently leader in this field. Other

work is being done at Stanford and Simon Fraser University. The work being done at

each of these institutions is of a different nature.

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Fig 1-2: MIT’s Micro Turbine & Test Stand


MIT is leading the micro turbine research market due to their heavy funding

provided by the Defense Advanced Research Projects (DARPA) along with other defense

agencies. Due to this fact, much of their work remains unpublished while it is in the

development stages. Figure 1-3 represents the radial flow reactive compressor,

combustor and turbine system being developed by MIT. The greatest difficulty with this

design is in the bearings, which are unable to withstand the high rotations per minute.

The goal of this project is to produce approximately ten to twenty watts of power based

on liquid hydrogen fuel. Alternative fuels such as hydrocarbons could produce up to a

hundred watts of power.

Stanford and Simon Fraser University are focusing their work on new

manufacturing techniques to be used to produce highly specialized turbines. Stanford is

developing a Mold Shape Deposition Manufacturing (Mold SDM) process to produce

complex silicon nitride parts. While they have not testing a compressor and turbine

system, compressed gas testing has proven the turbine to be successful up to 456,000

rpm. Figure 1-4 shows an example of some of the Stanford’s designs. Simon Fraser

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University is using a design already tested in nuclear magnetic resonance (NMR)

spectroscopy of solid samples. Using this technology, impulse radial inflow turbines

were produced in sizes ranging from 10-2.2 millimeters in diameter. Samples of these

spun by compressed nitrogen have shown to function up to 1,000,000 rpm.

The research and development at RIT began just three years ago with a proof of

concept senior design project. During this project, headed by Dan Holt, a dentist drill

was used to spin a generator. Holt continued the project on with his master’s thesis, in

which he expanded into the realm of using a compressed gas to drive a turbine which in

turn spins the generator. Last year’s design team continued the efforts of Holt by

designing and producing a functioning micro turbine generator. This design was a great

achievement for RIT in developing a usable design for Micro Air Vehicle (MAV)

applications. However, the prototype from last year remained too large and heavy for use

on a MAV. In addition, the fuel system was not included in the design. The current

project described within this report aims to reduce the size and weight of the system, as

well as implementing the fuel storage and delivery system into the overall design.

1.14 Formal Statement of Work

The Micro Turbine III Design Team shall produce a micro turbine/generator

system fitted for implementation onto a MAV. This system will be centered on a micro

turbine and self contained fuel source. The micro turbine will be attached to a rotor that is

coupled to a generator. The design must also be contained in a housing that supports the

turbine and necessary flow paths.

The generator of this system shall output a minimum of 5 Watts of power. To be

useful in the application of MAV power production, the system must output at least 5

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Watts of power for onboard electrical equipment. In addition, if necessary, addition

power produced could be used for propulsion.

The micro turbine system shall weigh less than 45 grams. The prototype designed

and built by the previous senior design team was within this weight limit, however did

not include the fuel system and remained relatively large in size for MAV uses. To get

closer to the goal of MAV application, the system must undergo weight and size

reductions, along with design of the fuel system. This is why the design must undergo a

drastic redesign of many components, time permitting. The micro turbine system

includes the turbine, shaft, bearings, housing, seals, couple, fuel canisters, fuel delivery,

choked flow nozzle and all hardware required for the housing to remain closed. It does

not include the controls sensors, power converters, signal modifiers, and the generator.

Currently the sizes of the components not included are due to the test set-up, our limited

budget, and available resources within the team. For a practical application on MAVs,

the generator must be incorporated as part of the turbine/housing. This would require

tremendous research and is outside the scope of this project.

The design should maintain ease of assembly and disassembly of the

fuel/turbine/generator system. In thinking of eventual application, the system must be

versatile and simple. Assembly and alignment should be quick and sure. Parts should

also be easily replaceable in case of part malfunction.

The Design Team should design the onboard fuel system. Last years design used

an unlimited source of fuel for the turbine power. This year’s team shall design and

produce a fuel system suited to fit our needs.

The generator selection should be optimized for our application. Previous

generators were selected primarily because of size. This created a loss of efficiencies at

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certain power levels and operating speeds. The generator should be chosen to best fit all

of our design parameters.

1.15 Organizational Chart

2.0 Concept Development

This chapter will cover the different concepts the team investigated and redsigned.

The first few sections discuss the break down of the team. Since there are several

different aspects to the project, the team of four engineers broke up into subgroups.

From the subgroups, ideas were generated and brought together to aid in concept

development on housing, turbine, and fuel system designs.

2.1 Subgroups

We found it necessary to split the design project into smaller subgroups headed up

by individual members of the design team. The small group of four team members led to

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05002 Micro-Turbine ProjectLeader – Cliff CummingsMentor – Prof. Jeff Kozak

Fuel SystemsLead – Mark

Cliff

PDR/CDR

PaperLead – Mark

PresentationLead - Joe

Turbine and HousingLead – Joe

Allison

Fig 1-3: Organizational Chart


overlapping of members involved in each subgroup. The purpose of the subgroups is to

investigate, research, and design concepts to be brought forth and implemented into the

overall design. The subgroups created are Housing, Turbine, and Fuel System.

2.1.1 Housing Team

The housing subgroup’s main task was to reduce the size and weight of the

turbine and flow housing. This subgroup was headed by Joe Calkins, with the assistance

of Allison Studley. The main focus of their research was on scaling down the outer

dimensions of the housing to be more appropriate for MAV applications. Further thought

was placed on the bearing and seals to be used within the design and the flow path at both

the inlet and outlet.

2.1.2 Turbine Team

Allison Studley led the research into alternative turbine designs. With the support

of Joe Calkins, the subgroup investigated numerous proven high efficiency turbine

designs and their possible inclusion into our concept. The limited source of persons

available prevented a full redesign of the turbine.

2.1.3 Fuel System Team

The fuel system required the primary initial attention as it had to be completely

designed with no current benchmark. Heading up this subgroup was Mark Fazzio with

the assistance of Lincoln Cummings. The main focus of research and design was placed

on the fuel canisters to be used. Additional attention was spent on the fuel delivery to the

turbine including tubing, connectors, and nozzles.

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2.2 Housing Concepts

A major requirement of this year’s housing design is the implementation of the

housing into the current MAV airframe. In order to meet this requirement, the new

housing must be more compact than the previous design. After a session of housing

concept brainstorming, it was determined

that the circular design was the most

compact, durable, and easily manufactured

design.

One improvement made upon last

year’s design was the implementation of two

separate inlet ports, which was able to

eliminate the large inlet channel. The

removal of this inlet channel allowed the diameter of the housing to be shrunk from

1.875” to 1.25”. This allows for a much lighter, smaller housing design which is still

capable of withstanding the high pressures of the system.

2.2.1 Bearings

There are a few major design concerns when it comes to bearing selection in a

design such as this. The high nominal rotational speed of 100,000 RPM requires a

bearing which is rated for such high speeds. One design concern, which was experienced

by previous teams, is the high pressures in the system. Previous teams had trouble with

the high pressure blowing the grease out of the shielded bearings. From this, it was

determined that sealed bearings were necessary. Other bearings were investigated,

including air and magnetic bearings, but no bearings of a small enough size were found.

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Fig 2-1: Housing Concept


2.3 Turbine Concepts

The axial impulse and Francis turbines are impulse turbines that provide high

efficiency. They are 3 dimensional designs and are very costly to produce. The axial

impulse uses axial flow and the Francis uses a combination of radial and axial flow.

The Pelton wheel is a design that developed in the 1870’s by Lester Pelton. It

uses cups that are pushed by the moving fluid. It will hit the turbine in the center of two

adjacent cups and the fluid will flow around the sides. The impulse causes the wheel to

move. A 3-D Pelton wheel is

highly efficient. A 2-D Pelton

wheel uses a similar concept,

however does not have the cup

shape. They are concave blades that will

turn the wheel around its axis. Its

efficiency is nowhere near that of the 3-D but is much easier to produce.

2.4 Fuel System Concepts

The fuel system is the truly new component to the microturbine design. The task

at hand is to move from the general source of fuel provided by external tanks to a fully

integrated system. This system is to include the fuel itself, a canister, tubing, and flow

regulation. These components are to be made a part of the overall system and be

included into the airframe of the MAV.

Methods in which this could be done were contrived as a group. Stemming from

the single inlet housing of the previous design would lead to the use of a single canister to

hold the compressed gas. This method became obsolete as a single canister would not fit

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Fig 2-2: 3-D Pelton Wheel Turbine


along the center of the MAV, and placing the canister to one side would cause severe

imbalance of the MAV.

The design would thus incorporate two canisters of fuel to be placed equally on

either side of the fuselage and be ducted into a duel inlet housing design. Placement of

the canisters then had two options. The first was to place the canisters along side the

fuselage, while the second was to incorporate them along the leading edges of wings of

the MAV.

2.4.1 Fuel

The options for the fuel to be used were kept to those which are most easily

available. Brainstorming let to a choice between compressed air, Nitrogen, and Carbon

Dioxide. Due to weight being a key issue in the design parameters, Nitrogen was chosen

as the optimal gas to be used to propelling the turbine. A second advantage for the use of

Nitrogen is that it acts as an ideal gas under our conditions.

The required amount of fuel needed to operate the generator for a time of three

minutes would be determined in order to find the necessary quantity of Nitrogen to be

stored. This calculation would be performed based on the properties of the Nitrogen, and

characteristics of the flow. Once this quantity is known, a supplier of customized

compressed gas canisters will be used for purchasing the fuel.

2.4.2 Tubing & Connectors

Transporting the fuel from the canisters to the housing was the next step in the

fuel system design. Tubing to duct the fuel would be used, and two options presented

themselves. Tubing to be used could be made of plastic, such as surgical tubing, or

metal, either aluminum or copper. The positive aspects of surgical tubing being light-

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weight and flexible led to this as the optimal choice. However, once the gas pressure to

be used within the tubing was determined, it was concluded that metal tubing would have

to be used to withstand the pressures.

Once this choice had been made, thoughts turned to the connections at the

canisters as well as at the housing. Several options were brainstormed including threaded

fittings, epoxy, and compression fittings. As each of these were researched and analyzed,

an alternative to the tubing/connector component presented itself.

The eventual supplier of the compressed gas also provides puncturing devices to

be used to pierce the canister and duct the gas out through a threaded hole. A male-to-

male brass coupler could then be threaded into the puncture device and the housing.

Thus no additional tubing or connectors are needed.

2.4.3 Flow Regulation

Due to the concept of a high pressure gas canister to be used for storage of the

fuel onboard the MAV, the flow out of the regulator and into the housing must be

regulated to an efficient and effective pressure. Since a redesign of the turbine would not

be performed, the pressure values from last year’s data would be used to determine an

inlet pressure to the turbine.

Based on this information, several concepts of regulation were brainstormed. The

use of a spring regulator is commonplace for such flow regulation. The size and weight

of this, however, would be too large for our needs. A bellows spring had potential as it is

generally lighter and smaller than a standard spring regulator. While this appeared to be

a feasible option, it was still larger than we would prefer.

The final concept would be the simplest of the three. By choking the flow of the

gas and thus achieving a flow speed of Mach 1, by fluid dynamics this would provide a 22


constant mass flow. Once this method was determined, options presented themselves on

how this could be done. An inline small diameter throat could be placed in the tubing

between the canister and housing. This option would merely add components to the

system as well as additional connections which serve as a greater number of leakage

points.

The other concept for choking the flow is to incorporate the narrow diameter

throat with the nozzle within the housing. To achieve the required mass flow, a simple

standard nozzle would be insufficient. The use of a micro-nozzle available from the RIT

Microelectonic Engineering department would be optimal for the requirements.

2.5 Generator

Without any previous electrical engineering background, Dr. Kozak suggested to

us to speak with Dr. Lyshevski of the electrical engineering department. We know we

need a 3-phase motor that will generate a target speed of 100,000 RPM and 5W of power.

The size needs to be a 1.5mm diameter shaft, about 1” total diameter, and obviously as

light as possible.

In speaking with Dr. Lyshevski, he informed us that it needs to be a brushless dc

motor and pointed us to two companies online that we may be able to find what we need.

In researching these companies, it was found that the highest speed for this size motor is

about 65,000 RPM. This may be able to be used, however we would like something

faster. Last year’s electrical engineer, Ream Kidane, will try to be contacted in order to

see where their motor was from.

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3.0 Feasibility

Two different assessment methods were used to decide on the actual designs for

fabrication. The feasibility of all concepts centered on the overall objectives and goals of

the project. The key aspects which were considered in the assessments were weight, size,

cost, availability, and manufacturability. For concepts which involved only two options,

a direct comparison was used, while a weighted Pugh’s comparison was used on

components with more than two concepts. Feasibility assessments were performed on

the housing, turbine, bearings, fuel system, tubing, and flow regulation. A brief

discussion and procedure of the assessment are found in the following sections. Final

decisions and selections will be discussed in the conclusion segment of this chapter.

3.1 Turbine Feasibility

The feasibility attributes considered in the turbine selection are cost and

availability, cost being the more weighted of the two. Francis and axial impulse are very

difficult to manufacture. To do this would cost a lot and take a long time. These designs

are not practical for our application.

Of the Pelton wheel designs, the 3-dimensional is more costly due to the added

machining, however may not be out of possibility. For time and cost considerations, the

2-dimensional design was chosen. We will be using the same design from last year. This

will obviously not add to efficiency but this was chosen as the best option so we could

focus on other aspects. If there is time, we may have a 3-dimensional design option

available for quoting.

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3.2 Housing Feasibility

Through our process of housing concept development, we determined that

the most appropriate concept was similar to last year’s design. The new design would

have 2 inlets and 2 outlets, as opposed to last year’s 1 inlet 2 outlet design. The

feasibility of this concept is shown below as compared to last year’s design. Through this

feasibility test, it was determined that the new concept is more feasible than last year’s

design and will be used as the baseline for further design.

Co

st

Siz

e

Wei

gh

t

Ava

ilab

ility

Man

ufa

ctu

rab

ility

Ro

w T

ota

l

To

tals

Wei

gh

tin

g

Cost \ | \ | 1 1 0.1Size \ - \ 2 2.5 0.25Weight - \ 1.5 3 0.3Availability | 0 0.5 0.05Manufacturability 0 3 0.3

Column Total 0 0.5 1.5 0.5 3

Wei

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tin

g

Las

t Y

ear'

s D

esig

n

2 In

let

2 O

utl

et C

on

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t

Cost 0.1 3 2Size 0.25 3 2Weight 0.3 3 3Availability 0.05 3 3Manufacturability 0.3 3 2

Weighted Average 3.00 2.35Normalized Average 1.00 0.78

Housing Feasibility

25

Table 3.1: Housing Feasibility


3.3 Bearing Feasibility

Through our research of available bearings, our findings were very similar to last

year’s bearings. There are no air or magnetic bearings small enough for our application.

This causes them to be unfeasible. This leaves the axial and radial bearings. Due to the

low loads and thrust on the bearings, the radial bearings are the most feasible bearings for

our application. They are of lower cost, similar RPM rating and availability to the axial

thrust bearings.

Co

st

Siz

e

Wei

gh

t

Ava

ilab

ility

RP

M R

atin

g

Ro

w T

ota

l

To

tals

Wei

gh

tin

g

Cost - - | | 2 2 0.2Size - | | 1 1 0.1Weight | | 0 0 0Availability \ 0.5 3.5 0.35RPM Rating 0 3.5 0.35

Column Total 0 0 0 3 3.5

Wei

gh

tin

g

Air

Bea

rin

gs

Mag

net

ic B

eari

ng

s

Axi

al B

eari

ng

s

Rad

ial B

eari

ng

s

Cost 0.2 4 4 3 2Size 0.1 5 5 2 2Weight 0 3 3 3 3Availability 0.35 5 5 2 2RPM Rating 0.35 2 2 3 3

Weighted Average 3.40 3.40 2.70 2.60Normalized Average 1.13 1.13 0.90 0.87

Bearing Feasibility

26

Table 3.2: Bearing Feasibility


3.4 Fuel System Feasibility

The fuel system is composed to three components, the fuel canister, tubing, and

flow regulator. Each of these were assessed from a feasibility standpoint separately, as

outlined below. Since each is a direct comparison, a Pugh’s comparison was not needed.

The critical features of each were the weight, size, and availability of the components.

As a collective group, determining the layout of the fuel system itself provided

several concepts. The three main concepts were:

Single fuel tank with a split flow duct

Duel fuel tanks positioned within the leading edge of the MAV

Duel fuel tanks positioned along the fuselage of the MAV

It was quickly decided that a single fuel tank would be a poor option as it could

not be centered properly on the MAV, thus disrupting the stability and control of the

aircraft. The positioning of the duel fuel tanks was not of real concern until the size of

the tanks was known. Once we calculated the amount of nitrogen required and pressure

in which it must be stored, it became infeasible to place the canisters within the leading

edge. This decision was supported by the design of the MAV in which the leading edge

is not straight off of the fuselage. The final decision was made to align the fuel canisters

along side of the turbine and generator within the fuselage.

3.4.1 Fuel Feasibility

The nature of the project kept the fuel options to a minimum. The use of a

compressed gas to be used to drive a turbine was already known; therefore the selection

of gases to be used was left. Due to availability, cost, and environmental issues, the list

was quickly condensed down to compressed air, nitrogen, and carbon dioxide. The

27


weight became the separating characteristic of the choices. Nitrogen was chosen due to

its very low density, and high compressibility. In addition to these properties, the flow

characteristics proved to be favorable as nitrogen would act as an ideal gas within our

system.

3.4.2 Tubing Feasibility

The next step in the fuel system is the delivery from the fuel canisters to the

housing. To do this, two choices presented themselves, plastic or metal tubing. The

plastic tubing would likely be surgical tubing which is easily available. Aluminum or

copper would be used in the instances of metal tubing.

Due to the high pressures the tubing would be experiencing, surgical tubing was

determined to be infeasible as a result of connection issues. The choice was made for use

of metal tubing and connectors. However, as the design began to come together it was

realized that a male-to-male threaded elbow coupler would reduce the number of

connections and act as the tubing directly from the puncture device to the housing.

3.4.3 Flow Regulation Feasibility

Since the fuel will be stored at a high pressure, the mass flow must be regulated.

In order to do this, and maintain a light weight compact design, two concepts were made.

The first was the use of a spring operated regulator, likely using a bellows spring. The

bellows regulator would require additional connections to tubing as well as using more

space in the fuselage. The second is to choke the flow using a mirco-nozzle, thus

providing a constant mass flow. The micro-nozzle was chosen on the basis that it is

lighter in weight, smaller, and can be an added piece to the housing.

28


4.0 Objectives and Specifications

4.1 Objectives

The objectives of the Microturbine Generator Senior Design project were

presented prior to work being performed. The objectives were laid out by the RIT

Mechanical Engineering department in collaboration with MAV project teams and goals.

The key objectives are listed as follows.

Design a micro-turbine system

Build the micro-turbine system

Produce 5 watts of power

Overall system weight less than 45 grams

Integrate into a MAV airframe

Complete project by May 2005

Drive the propeller

4.2 Performance Specifications

The objectives we are set out to achieve are established based on previous work

performed, and the goal of producing a lighter and battery power alternative. During this

design process, we are likely to encounter a number of issues which may not have been

foreseen. While every attempt to work through these obstacles will be made, limiting

factors due to time and budget will inhibit us to do so. By understanding the performance

specifications, the team will be guided toward the appropriate tasks intended to be

achieved by the conclusion of the project. With this thorough understanding of the

29


performance specifications, the team will be able to justify those issues that must be dealt

with and those which can be left for future design teams.

The key objective of the project is to scale down the current micro turbine

generator design as well as include the fuel system into the design. The specifications

established were to produce 5 watts of continuous power, size the system to fit within the

MAV, and keep the weight of the system less than 45 grams. Since the turbine has been

proven to produce sufficient power, heavy consideration this year was on the size and

weight of the overall system.

4.3 Design Practices

To help the team achieve the objectives and specifications that was established, a

list of design practices were kept in mind when team members were developing designs.

A list of these practices is as follows:

1) Design for Manufacturability – One achievement in the new design of the housing is

a more simplified flow path. This design has basic geometric shapes which can be

easily manufactured at RIT. This improvement will save both money and time in

manufacturing as opposed to seeking an outside vendor.

2) Design for Assembly – The initial design is intended to be assembled and

disassembled with ease. This allows for streamlined testing as little time will be

required between tests for maintenance. In addition, should certain aspects of the

design require modification; any piece can be removed and interchanged with

simplicity.

30


4.4 Safety Issues

To ensure the safety of all members on the team, a set of safety precautions were

established. Since the testing of the design will undergo high pressures and components

will be spinning at high speeds, it is imperative that the members of the team follow these

guidelines.

1) To avoid any flying objects from hurting the engineers and whoever may come in

contact with it, all testing will be conducted in a contained area. The container will

be made out of plexiglass. The plexiglass is transparent so the engineers can see the

process, and it is strong enough to compensate for any accidents involving the design.

2) Engineers must wear goggles while testing. Despite the fact that there is a layer of

plexiglass between the engineer and the micro turbine, there is always room for the

unexpected. By wearing goggles, this will preserve the well being of the engineer.

3) If team members are to machine any parts in the machine shop, the machine shop

safety guidelines must be followed strictly.

4) The team ought to be careful when working with the electronics. There is a chance of

minor electrical shocks caused by the generation of electrical power by the turbine.

5) Due to the high speed the components of the turbine will be spinning at, there may be

a slight raise in temperature. When handling the turbine after testing, team members

must be careful and make sure all parts are at handling temperature.

31


5.0 Design Analysis & Synthesis

5.1 Turbine Analysis & Synthesis

Initial research into turbine designs led the team to use last year’s turbine design.

This was done because of two major factors, first the amount of resources and time that

would be required to design a new turbine, as well as the lack of technological

advancements in the last year.

The 5/16 in turbine design was chosen because of the previous RIT micro-turbine

teams. The first design was 1/2 an inch and produced 18 W, the second design was a 1/4

of an inch and produced 0.6 W. Much of the power loss was attributed to housing design

problems, which lead last year’s team to develop a turbine within that size range. Last

year’s turbine produced 19 W.

The tip speed of the turbine blades was calculated to be optimal at approximately

400,000 rpm, this is much larger than the generator and more importantly the bearing can

handle. The maximum practical velocity for the turbine is about 100,000 rpm. Research

into the blade size, based on Flockhart’s paper “Experimental and Simulation Analysis of

Microturbines” states that the smaller the blade thickness the greater the torque

performance.

The length and number of blades also follow Flockhart’s logic. The pitch

diameter of the blade should be as large as possible so that the pitch diameter is in the

middle of the blade. The number of blades should be maximized to the point that the jet

is not being impinging by the next blade. If the next blade impinges the current blade

then it would greatly decrease the turbine efficiency.

32


The major limiting factors on turbine design are the machining cost and lead time.

Three dimensional turbine designs are more efficient but cost much more. The pelton

type turbine is one of these three dimensional turbine designs; it has a ridge that follows

the edge of the blade radially. The pelton type turbine would cost well over our entire

budget. Our budget and practicality of having an easily machined and replaceable turbine

greatly limits the turbine designs that can be considered.

Last year’s team designed their own turbine using two set parameters, 100,000 rpm and

5/16 in outer diameter. These parameters lead the team to design 0.052 in high blades

with a pitch diameter of 0.27 in. Using equation 5-1 they calculated that there should be

8 blades:

(Equation 5-1)

n is the number of blades; r is the pitch radius; d is the jet diameter; and R is the overall

turbine radius. A range of 0.01 and 0.03 inches was used for the jet diameter. The blade

thickness was set at 5 degrees and the tip angle was determined to be 39 degrees. To

decrease the chance of the back of the blade hitting the jet flow a low profile design was

used. The final turbine design is shown below in figure XXXX.

Fig 5-1: Blade Fig 5-2: Turbine Design

33


The previous team used Engineering Fluid Mechanics to validate the design. The

mass flow rates were calculated using the following equation:

(Equation 5-2)

Where T is torque; r is pitch diameter; ρ is working fluid density β a correction factor; Q

is volumetric flow rate; vjet is the velocity of the jet; and Ω is the turbine’s rotational

velocity. The efficiency of the turbine was also calculated using another equation:

(Equation 5-3)

Where the efficiency is equal to the power output divided by the incoming kinetic energy.

This equation, however, is limited as the efficiency is also dependant on the other

components of the micro-turbine system.

5.2 Housing Analysis & Synthesis

Through the feasibility assessment, a similar design to last year’s microturbine

housing was developed. The major difference in this year’s design is the implementation

of two individual inlets to the turbine passage. This allows the previously designed flow

channel to be eliminated from the design. The elimination of this flow channel allows for

less complex geometry for ease of machining, as well as smaller diameter housing for a

more compact and lighter weight design.

Very similar to last year’s design, this year’s housing is focused around the

turbine passage. The bearings in the housing, as well as the housing cap, will help to

align the turbine concentrically in the housing. Since last year’s turbine design is being

implemented into this year’s design, the turbine passage will be the same dimensions as

last year with a diameter of 0.333” and a depth of 0.115”.

34

Fig 5-3: Cap FEA


In order to cut down on the head losses in the housing, the inlet and outlet ducts

are straight through. This will eliminate the losses which occurred in last year’s design

with the 90 degree outlet channel. Pressure losses from the cap will be contained by an

o-ring that is fitted into the housing cap. The cap will be held into place with two bolts,

which will also align the generator and it’s bracket on the opposite side of the housing.

Since the housing cap concentric with the housing, it is self aligning and will provide for

a more precise alignment of the turbine and it’s shaft.

5.2.1 Housing FEA Analysis

Through the use of Finite Element Analysis of the housing, it was determined that

the 30% fiberglass reinforced Nylon 6/6 would withstand the high pressures under our

current design. The Nylon 6/6 30% Fiberglass Reinforced has a tensile strength of

23,206 psi, along with a density of 1.38 g/cm^3. The target pressure inside of the

housing for our design is 100psi, however a safety factor of 3.0 was added for this case

since there are such high pressures as well as human interaction during testing. With this

in mind, the housing was

tested at 300psi, assuming

that there is not leakage past

the o-ring seal. The above

analysis showed the

maximum stress in the

housing under a 300psi load

to be 780psi.

35

Fig 5-4: Housing FEA


After completion of this analysis it was determined that the smaller design would

withstand the high pressures with the use of lightweight Nylon 6/6. Due to its light

weight and ease of machining, and inexpensive price, Nylon 6/6 was determined to be the

best choice of material for the housing. Alternative materials were then researched for

36


the housing. A lighter weight alternative is Nylon 6/6 with 10% Carbon Fiber Reinforced

providing 18,855 psi of tensile strength and a density of 1.18 g/cm^3.

5.2.2 Shaft Selection & Analysis

At the current time, we are in the process of locating a generator to integrate into

our design. Since a generator has not yet been found, our shaft selection cannot be

determined at this time. The current design is based around the 1.5 mm shaft that was

used on the previous design. Minor changes to the design may be made for a different

size shaft, since the shaft size will be determined by the generator shaft size. The shaft

will be of the same diameter as that of the generator, for ease of coupling the two shafts

together.

5.2.3 Bearing Selection

After researching all of the different options for bearings, it was determined that

radial sealed bearings were the best fit for this application. The seals are necessary due to

the high pressures, as previous teams had problems with shielded bearings losing their

lubrication. The final bearing selection will be determined by the shaft size once a

generator is found. At the current time, the bearing selection has been based upon the

previous shaft size of 1.5 mm.

The other major issue for bearing selection was the high rotational speeds

of the system. The bearings for this system must be rated for a minimum of 100,000

RPM. It was found that sealed bearings of 1.5 mm ID were attainable at a relatively

inexpensive price. The final bearing selection will be determined upon the selection of a

generator and shaft size.

37


5.2.4 Coupling Selection

One of the major issues experienced by the previous microturbine design was the

selection of a coupling to connect the turbine shaft to the generator shaft. Through much

research, it was determined that their best selection for a coupling was a small piece of

shrink tubing. The main reason for this was the fact that all of the micro couplings

researched were not rated for the high rotational speeds or did not have the necessary

rigidity.

A bit of research was done this year to search for any new technologies which

may allow for a more rigid and high speed coupling, however no couplings were found.

This leads us back to the previous team’s use of the shrink tubing as a coupling between

the two shafts. It was estimated previously that there is approximately 1% loss in the

shrink tubing coupling.

5.3 Fuel System Selection & Analysis

The fuel system became the critical aspect of this years Microturbine Senior

Design project. The fuel system in the past used laboratory gas cylinders in conjunction

with flow regulation equipment. This laboratory setup was used to as a result of the

previous generation’s goals: design a turbine and housing to be placed on a MAV,

without consideration of the fuel system. The goal this year is to include the fuel system

into the MAV, thus requiring it to be lightweight and miniature.

5.3.1 Fuel Selection

The fuel to be used for the microturbine had to meet three main criteria to be

selected. Those criteria were its weight, its flow properties, and the availability of the

38


gas. As a result of these conditions, and based on the feasibility assessment of the gases,

Nitrogen was chosen as the optimal gas to be used. Nitrogen has a lower molecular

weight than either compressed air or carbon dioxide. Under our storage and flow

conditions, the nitrogen acts as an ideal gas, thus simplifying the flow regulation.

Finally, nitrogen is a widely used and easily available gas.

5.3.2 Tubing & Connectors Selection

As the housing and fuel canisters were designed and selected, the tubing and

connections remained a secondary thought to be determined once other aspects of the

design were known. Throughout the process, the general concept to be used was a

connection at the fuel canister, tubing, and another connection at the housing.

Consideration into the puncture of the fuel canister presented additional connections that

would be required.

As the method of puncture was determined, which would be a supplied puncture

device available from the fuel supplier, the tubing and connection issue took a turn. It

was decided that the number of connections and size of the system could be reduced by

use of a straight male-to-male threaded coupler connecting the puncture device directly to

the housing.

5.3.3 Flow Regulation

Flow regulation was a fairly simple component of the system to select. Due to the

primary requirements of light weight and small size, a simple choked flow would be

optimal for our design. A micro-nozzle fabricated in the RIT Microelectronics laboratory

is the desired method for regulating the mass flow of the nitrogen. The micro-nozzles are

fabricated out of a silicone wafer through simple means and require minimal 39


manufacturing time. Due to the molecular structures of the silicone, a tapered jet nozzle

is formed. This is a desired feature as it increases the efficiency of the nozzle.

5.3.4 Fuel System Analysis

The most critical piece to the fuel system to be determined was the quantity of gas

required. The first step in analyzing this is to determine the type of flow which the

system will be experiencing. Based on criteria from thermodynamics, an ideal gas is

assumed when operating temperature is greater than twice the critical temperature, and

operating pressure is less than five times the critical pressure of the gas. Based on

thermodynamic properties of nitrogen, our system is within this criterion, therefore

allowing for ideal gas flow calculations.

The quantity of fuel required is dependent on the desired runtime of the system.

The goal of the design is for a runtime of three minutes. The use of the choked flow

nozzle results in a constant exit velocity of Mach 1 of the fuel along with a constant exit

area. Determination of the density of fuel within the canister is derived by

(Equation 5-4)

where is the density, M is mass, and V is volume.

Based on the chemical characteristics of the chosen gas, nitrogen, and the

assumption of constant room temperature exit flow, the exit velocity is calculated by

(Equation 5-5)

where is the exit velocity, M is the mach number, is the specific gas ratio, R is the

ideal gas constant, and T is the temperature.

Based on the equation of mass flow,

40


(Equation 5-6)

the variable we are left with is the density of the nitrogen in the flow. Determination of

the exit area of the nozzle to be 100 micrometers resulted in a mass flow rate of 1.53x10 -4

lbs/sec. In a choked flow system, this mass flow will remain constant, thus through

simple calculation an initial required mass for the three minute runtime is determined.

Based on this information, an initial mass of 13.6 grams of nitrogen in each of the two

fuel canisters is required.

41


6.0 Future Plans

6.1 Test Setup

To save the nitrogen in the fuel canisters, the turbine and housing will be tested

first with large tanks of laboratory nitrogen. After the design concept is proven, we will

test our fuel canister system.

In order to test the system to find the desired outputs, the previously designed test

setup will be used. This system uses pressure sensors, a flow meter, and thermocouples,

as well as current and voltage sensors to aquire the data through LabView. The open

loop control system reads the incoming pressure then is regulated by a servo valve

located on the inlet air pipe to the stagnation plenum. The system is able to read the inlet

temperature T, pressure P, and volumetric flow rate V to calculate mass flow rate, as well

as current and voltage to find power and efficiency.

The pressure sensor is rated to 200 psi and the turbine should operate at 100 psi.

The flow meter has a range of 10 L/min – 120 L/min, and the airflow is expected to be

between 40 L/min – 90 L/min. The analog data of the sensors will be converted to digital

for Labview to be able to compute everything. The Labview setup allows us to see the

power output graphically as it runs and see the best conditions for the micro turbine to

run.

42

Fig 6-1: Schedule


6.2 Schedule

The attached Gantt chart displays the proposed schedule for the design

development of our project. Key events are shown to give the team goals for timely

completion of project components as well as the overall project. The start and

completion dates are listed by each component; the vertical arrows indicate task

dependencies.

43

Fig 6-2: Budget


6.3 Budget

The micro-turbine project team has a $1000 budget via a RIT grant that is

intended to cover all expenditures associated with the project. The team plans on

spending $676.83 of that budget for parts and machining.

05002 Micro-Turbine III Project

Component Description Price per Qty Line PriceHousing Turbine $96.00 1 2 $192.00

Nylon rod $5.97 foot 1 $5.97machining $10.00 1 1 $10.00fittings $1.00 1 4 $4.00bearings $40.00 10 10 $40.00coupling $14.09 10 10 $14.09Mini Stainless Steel Shaft $3.93 1 1 $3.93O-Ring $4.00 100 100 $4.00Nylon cheese head screw $5.60 100 100 $5.60black nylon 6/6 nut $10.00 100 10 $1.00

Fuel Systems Ni Canisters $20.00 1 2 $40.00Connector $0.62 1 2 $1.24O-Ring $7.50 1 2 $15.00Puncture components $20.00 1 2 $40.00Jets $100.00 50 50 $100.00

Electrical Generator $200.00 1 1 $200.00

Overall Cost $676.83

44


7.0 ConclusionsThe Micro Turbine Generator III team has successfully completed the first six

aspect of the design process. These six facets includes: Recognize and Quantify Needs,

Concept Development, Feasibility Assessment, Design Objectives and Performance

Specifications, Synthesis and Analysis, and finally Preliminary Design Documents.

The eventual goal of the micro turbine is to provide Micro Air Vehicles with a

dependable and reliable power source that is also light in weight. By utilizing

compressed gases, the micro turbine will drive a generator, thus providing the electrical

power to onboard equipment. The micro turbine must withstand 100,000 rpm and be

capable of remaining intact and functioning at a pressure of 100 psi. The design must

maintain the integrity of all the components especially the generator. The generator shall

be reusable.

The main task of this project has been achieved. That task was to design a fuel

system to be incorporated with the turbine system, as well as scale the overall concept

down to be implemented onto an MAV. The design includes a duel high pressure

nitrogen fuel canister system ducted directly into the housing and regulated by a micro

nozzle prior to turbine impulse. The housing was fully redesigned to be smaller and have

a lighter weight than the previous design. Ease of manufacture has been considered in

the overall design as well as use of easily acquired components. A finite element analysis

performed on the housing and cap proved the design is sufficient to withstand the high

pressure it will experience.

At this point, the design is ready to move onto the parts acquisition,

manufacturing, and testing stages. These aspects of the development will occur in the

following quarter.

45


References

Anderson, John D., Jr. Fundamentals of Aerodynamics. 3rd ed. New York: McGraw-Hill Companies, Inc. 2001

Callister, William D. Jr. Introduction to Materials Science and Engineering, 4 th Edition. New York: John Wiley & Sons, 2000

Desai, V. R. and N. M. Aziz. “Parametric Evaluation of Cross-Flow Turbine Performance.” Journal of Energy Engineering, Vol. 120, No. 1, April 1994. 17 – 34.

Doty, F.D., B.L. Miller, and G.S. Hosford. “High Efficiency Microturbine Technology.” 26 th

Intersociety Energy Conversion Engineering Conference. Boston. August 1991.

Fox, Robert W. and Alan T. McDonald. Introduction to Fluid Mechanics. 5th ed. New York: John Wiley & Sons, Inc., 1998.

Hibbeler, R.C. Mechanics of Materials, 4 th Edition. New Jersey: Prentice Hall, 2000

Holt, Dan. et. al. “Design of a Miniature Turbine for Power Generation on Micro Air Vehicles.” Kate Gleason College of Engineering Multi-Disciplinary Engineering Design Conference. Rochester, New York, May 2003

Kang, Sangkyun, Jurgen Stampfl, Alexander G. Cooper, Fritz B. Prinz. “Application of the Mold SDM Process to the Fabrication of Ceramic Parts for a Micro Gas Turbine Engine.” Ceramic Materials and Components for Engineers. Germany. June 2000.

Lin, Simien. Et.al. Micro Turbine Senior Design Team: Preliminary Design Report. RIT, 2004.

Mehra, A., S. A. Jacobson, and C.S. Tan. “Aerodynamic Design Considerations for the Turbomachinery of a Micro Gas Turbine Engine.” 25 th National and 1st International Conferency on Fluid Mechanics and Power, ASME. New Dehli. June 2003.

46


Appendix

A. Appendix A – Turbine Performance Graphs(Based on 04013 Design)

47


48


49


B. Appendix B – Turbine Performance Data(Based on 04013 Design)

Max Power Output (nozzle .115 X .02)

Pitch Radius rpitch = 0.13 in 0.0033 mTurbine Vel. Omega = 100000 rpm 10472 rad/s

Beta = 84.5 deg 1.475 rad

Stagnation Pressure P

psigkPa

(abs) kPa (abs)20 239 12625 274 14530 308 163

Temperature M=1 35 343 181°C u (m/s) 40 377 19910 337 45 412 21715 340 50 446 23620 343 55 481 25425 346 60 515 272

65 550 29070 584 30875 618 32780 653 34585 687 36390 722 381

R= 287 95 756 400

A= .115*.02*2 0.0046 in2 100 791 418

3.01E-06 m2 105 825 436110 860 454115 894 472120 929 491

T= 10°C T= 15°C

50


P (psig) (kg/m3)mdot (kg/s)

Power (W)

P (psig) (kg/m3)

mdot (kg/s)

Power (W)

20 1.56 1.58E-03 15 20 1.53 1.56E-03 1525 1.78 1.81E-03 17 25 1.75 1.79E-03 1730 2.00 2.03E-03 19 30 1.97 2.02E-03 1935 2.23 2.26E-03 21 35 2.19 2.24E-03 2140 2.45 2.49E-03 24 40 2.41 2.47E-03 2445 2.68 2.72E-03 26 45 2.63 2.69E-03 2650 2.90 2.94E-03 28 50 2.85 2.92E-03 2855 3.13 3.17E-03 30 55 3.07 3.14E-03 3060 3.35 3.40E-03 32 60 3.29 3.37E-03 3265 3.57 3.63E-03 34 65 3.51 3.59E-03 3470 3.80 3.85E-03 36 70 3.73 3.82E-03 3675 4.02 4.08E-03 39 75 3.95 4.05E-03 3980 4.25 4.31E-03 41 80 4.17 4.27E-03 4185 4.47 4.54E-03 43 85 4.39 4.50E-03 4390 4.70 4.76E-03 45 90 4.61 4.72E-03 4595 4.92 4.99E-03 47 95 4.83 4.95E-03 47

100 5.14 5.22E-03 49 100 5.05 5.17E-03 49105 5.37 5.45E-03 52 105 5.27 5.40E-03 52110 5.59 5.67E-03 54 110 5.49 5.62E-03 54115 5.82 5.90E-03 56 115 5.72 5.85E-03 56120 6.04 6.13E-03 58 120 5.94 6.07E-03 58

T= 20°C T= 25°C

P (psig) (kg/m3)mdot (kg/s)

Power (W)

P (psig) (kg/m3)

mdot (kg/s)

Power (W)


100 4.97 5.13E-03 49 100 4.88 5.08E-03 50105 5.18 5.35E-03 52 105 5.10 5.31E-03 52110 5.40 5.58E-03 54 110 5.31 5.53E-03 54115 5.62 5.80E-03 56 115 5.52 5.75E-03 56120 5.83 6.02E-03 58 120 5.74 5.97E-03 58

51


Max Power Output (nozzle .115 X .02) v. Omega

T=20 deg C

=20,000 rpm =40,000 rpm

P (psig)

(kg/m3)mdot (kg/s)

Power (W)

P (psig)

(kg/m3)

mdot (kg/s)

Power (W)


100 4.97 5.13E-03 11 100 4.97 5.13E-03 21105 5.18 5.35E-03 11 105 5.18 5.35E-03 22110 5.40 5.58E-03 12 110 5.40 5.58E-03 23115 5.62 5.80E-03 12 115 5.62 5.80E-03 24120 5.83 6.02E-03 13 120 5.83 6.02E-03 25

=60,000 rpm =80,000 rpm

52


P (psig)

(kg/m3)mdot (kg/s)

Power (W)

P (psig)

(kg/m3)

mdot (kg/s)

Power (W)


100 4.97 5.13E-03 31 100 4.97 5.13E-03 40105 5.18 5.35E-03 32 105 5.18 5.35E-03 42110 5.40 5.58E-03 34 110 5.40 5.58E-03 44115 5.62 5.80E-03 35 115 5.62 5.80E-03 46120 5.83 6.02E-03 36 120 5.83 6.02E-03 48

=100,000 rpm =120,000 rpm

P (psig)

(kg/m3)mdot (kg/s)

Power (W)

P (psig)

(kg/m3)

mdot (kg/s)

Power (W)


100 4.97 5.13E-03 49 100 4.97 5.13E-03 58105 5.18 5.35E-03 52 105 5.18 5.35E-03 61110 5.40 5.58E-03 54 110 5.40 5.58E-03 63115 5.62 5.80E-03 56 115 5.62 5.80E-03 66120 5.83 6.02E-03 58 120 5.83 6.02E-03 68

=140,000 rpm

P (psig)

(kg/m3)mdot (kg/s)

Power (W)

53


20 1.50 1.55E-03 2025 1.72 1.77E-03 2330 1.94 2.00E-03 2635 2.15 2.22E-03 2940 2.37 2.45E-03 3245 2.59 2.67E-03 3450 2.80 2.89E-03 3755 3.02 3.12E-03 4060 3.24 3.34E-03 4365 3.45 3.56E-03 4670 3.67 3.79E-03 4975 3.89 4.01E-03 5280 4.10 4.23E-03 5585 4.32 4.46E-03 5790 4.53 4.68E-03 6095 4.75 4.90E-03 63

100 4.97 5.13E-03 66105 5.18 5.35E-03 69110 5.40 5.58E-03 72115 5.62 5.80E-03 75120 5.83 6.02E-03 78

Max Power Output Efficiency v.

T=20 deg C

v.

54


P (psig) (kg/m3) mdot (kg/s) Power (W) 20 1.50 1.55E-03 3 3.57 20,00020 1.50 1.55E-03 4 4.44 25,00020 1.50 1.55E-03 5 5.30 30,00020 1.50 1.55E-03 6 6.15 35,00020 1.50 1.55E-03 6 7.00 40,00020 1.50 1.55E-03 7 7.83 45,00020 1.50 1.55E-03 8 8.65 50,00020 1.50 1.55E-03 9 9.47 55,00020 1.50 1.55E-03 9 10.27 60,00020 1.50 1.55E-03 10 11.07 65,00020 1.50 1.55E-03 11 11.86 70,00020 1.50 1.55E-03 12 12.63 75,00020 1.50 1.55E-03 12 13.40 80,00020 1.50 1.55E-03 13 14.16 85,00020 1.50 1.55E-03 14 14.91 90,00020 1.50 1.55E-03 14 15.66 95,00020 1.50 1.55E-03 15 16.39 100,00020 1.50 1.55E-03 16 17.11 105,00020 1.50 1.55E-03 16 17.82 110,00020 1.50 1.55E-03 17 18.53 115,00020 1.50 1.55E-03 18 19.22 120,00020 1.50 1.55E-03 18 19.91 125,00020 1.50 1.55E-03 19 20.59 130,00020 1.50 1.55E-03 19 21.26 135,00020 1.50 1.55E-03 20 21.91 140,000

55


Efficiency v. Pressure (5 W Output)

T=20 deg C

=20,000 rpm

P (psig) (kg/m3) mdot (kg/s) 20 1.50 1.55E-03 5.4825 1.72 1.77E-03 4.7930 1.94 2.00E-03 4.2535 2.15 2.22E-03 3.8240 2.37 2.45E-03 3.4745 2.59 2.67E-03 3.1850 2.80 2.89E-03 2.9455 3.02 3.12E-03 2.7360 3.24 3.34E-03 2.5465 3.45 3.56E-03 2.3870 3.67 3.79E-03 2.2475 3.89 4.01E-03 2.1280 4.10 4.23E-03 2.0185 4.32 4.46E-03 1.9190 4.53 4.68E-03 1.8195 4.75 4.90E-03 1.73

100 4.97 5.13E-03 1.66105 5.18 5.35E-03 1.59110 5.40 5.58E-03 1.52115 5.62 5.80E-03 1.46120 5.83 6.02E-03 1.41

56


C. Appendix C – Mass Flow Calculation

Inputs: Pressure 800R 661.92T 537mass 0.03Volume 13.32941density 0.002251mass flow rate 0.000153

Time (s) Mass (lbs) Density Po (psi) To ®

Mass Flow Rate

0 0.03 0.002250662 800 537 0.0001529930.1 0.029984701 0.002249514 799.5920185 537 0.0001529930.2 0.029969401 0.002248366 799.1840369 537 0.0001529930.3 0.029954102 0.002247218 798.7760554 537 0.0001529930.4 0.029938803 0.00224607 798.3680739 537 0.0001529930.5 0.029923503 0.002244923 797.9600924 537 0.0001529930.6 0.029908204 0.002243775 797.5521108 537 0.0001529930.7 0.029892905 0.002242627 797.1441293 537 0.0001529930.8 0.029877606 0.002241479 796.7361478 537 0.0001529930.9 0.029862306 0.002240332 796.3281662 537 0.0001529931 0.029847007 0.002239184 795.9201847 537 0.000152993

1.1 0.029831708 0.002238036 795.5122032 537 0.0001529931.2 0.029816408 0.002236888 795.1042217 537 0.0001529931.3 0.029801109 0.00223574 794.6962401 537 0.0001529931.4 0.02978581 0.002234593 794.2882586 537 0.0001529931.5 0.02977051 0.002233445 793.8802771 537 0.0001529931.6 0.029755211 0.002232297 793.4722955 537 0.0001529931.7 0.029739912 0.002231149 793.064314 537 0.000152993

160.7 0.005414013 0.00040617 144.3736836 537 0.000152993160.8 0.005398714 0.000405023 143.965702 537 0.000152993160.9 0.005383415 0.000403875 143.5577205 537 0.000152993161 0.005368115 0.000402727 143.149739 537 0.000152993179 0.00261424 0.000196126 69.71306384 537 0.000152993

179.1 0.002598941 0.000194978 69.30508231 537 0.000152993179.2 0.002583641 0.00019383 68.89710079 537 0.000152993179.3 0.002568342 0.000192682 68.48911926 537 0.000152993179.4 0.002553043 0.000191535 68.08113773 537 0.000152993179.5 0.002537743 0.000190387 67.6731562 537 0.000152993179.6 0.002522444 0.000189239 67.26517467 537 0.000152993179.7 0.002507145 0.000188091 66.85719314 537 0.000152993179.8 0.002491845 0.000186943 66.44921161 537 0.000152993179.9 0.002476546 0.000185796 66.04123009 537 0.000152993180 0.002461247 0.000184648 65.63324856 537 0.000152993

57


D. Appendix D – Finite Element Analysis On Housing / Cap

58


59


The above seen boundary conditions were set upon the housing cap in order to test for

failure under the worst case scenario of 300 psi. A 300 psi pressure was placed on the contacting

face, side below the o-ring, and also the contact area for the bearing due to a pressure on the

bearing. Boundary conditions on the cap were placed such that the sides of the cap as well as the

bearing hole were constrained from moving in the radial direction due to the fact that the housing

and bearing will help to hold these constraints. The holes for the retaining bolts were

constrained to simulate the bolts holding the cap into the housing, which is visible in the

deflection under loading. The maximum stress seen under these conditions was determined to be

3740 psi, which falls within the maximum tensile strength of the reinforced nylon of 11,500 psi.

60


61


62


E. Appendix E – Turbine Performance Data

63


64

micro turbine iii_pdr

Automotive

years design

overall design

previous turbine design

senior design team

senior design project

feasible micro turbine

new micro turbine design

engineering design process