1 avc gollege of engineering. mannampandal. department of mechanical engineering

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AVC GOLLEGE OF ENGINEERING.MANNAMPANDAL.

DEPARTMENT OF MECHANICAL ENGINEERING

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VIBRATION ANALYSIS OF DOUBLE IMPELLER MARINE PUMP USING FEA METHOD

GUIDED BY PRESENTED BY Mr.S.VIJAYARAJ.M.E., P.J SENTHIL KUMARASST.PROFESSOR, R.NATARAJANDEPT OF MECHANICAL ENGG T.BALAKRISHNAN K.JEGADESH

COMPANY PROFILE COMPANY NAME : MACRO ENGINEERING

PVT LTD PLACE : CHENNAI.

YEAR OF ESTABLISHED: 2003

PRODUCT DESCRIPTION :DESIGN & ANALYSIS

PUMPS

On the basis of transfer of mechanical energy, the pumps can be broadly classified as,

Positive displacement Pumps Roto dynamic Pumps The centrifugal pump of today is made by

250 years old evolution. It has now attained a new degree of

perfection It is widely used as it can be coupled directly to electric motors, steam turbines etc.

DOUBLE IMPELLER MARINE PUMP

It is a contrivance to boost up liquids in the pipe line by creating the required pressure with the help of centrifugal action.

In general it can be defined as a machine which increases the pressure energy of a fluid, as a pump may not be used to lift water at all, but just to boost the pressure in a pipe line

MARINE PUMP

APPLICATIONS To pump the salt water from sea to ship

for process. To boost up the working fluid between

two tanks To pump the back water in the seashore. To pump the water in power plant

industries.

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PROBLEM DESCRIPTION Vibration is the major problems of all machines

and rotating components. In marine pumps It affects the over all efficiency of the pump. Prevention and control of vibrations in pumps is more important point to increase the efficiency of the marine pumps. So it is necessary to find out the vibrations during its operating condition.

Determination of the stress and deformation of the already designed double impeller marine pump due to vibrations in the pump if any as prevention control of vibration of machines structure is an important design consideration.

For this reason, capacity, head, power consumption are the essential points in double impeller marine pump design.

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METHODOLOGY

MODELLING – PRO-E WILD FIRE 3.0

MESHING - HYPERMESH 9.0

ANALYSIS - ANSYS 10.0

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HARDWARE AND SOFTWARE DESCRIPTION:

The following virtual validation is carried on the following hard ware

Hardware: HP xw8200 Workstation Processor-Two 64-bit Intel® Xeon™

processor(s) with Hyper-Threading Technology

Memory-7 GB of ECC DDR2 400 MHz SDRAM

Graphics-NVIDIA Quadro FX 1400 (PCIe)

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Software: Preprocessing : Hypermesh9.0 Solver : ANSYS 10.0 Post processing : ANSYS 10.0

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INTRODUCTION OF FEA Finite element analysis is a process, which can be

used to predict deflection and stress on a structure. In finite element model, the structure is divided in to

number of grids, which is called as elements. Each of the elements has a simple shape (such as

square or triangle) for which the finite element program has information to write the governing equations in the form of stiffness matrix for the entire model.

This stiffness matrix is solved for the unknown displacements at the nodes, the stresses in each element can be calculated.

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INTRODUCTION OF FEA

The finite element is derived by assuming a form of the equation for the internal strains.

The equilibrium equation between the external forces and the nodal displacements can be written.

There will be one equation for each degree of freedom for each node of the element.

The equation is [K] [U] = [F]

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OBJCTIVE OF THE PROJECT

Build a detailed finite element model of the impeller assembly

Carry out a static Analysis with a single time step

Dynamic analysis with response spectrum behavior using corrugated load case.

INPUT DATA

CAD data: 3D Models of pump impeller and the assembly files of ProE wildfire3.0

Loading, boundary conditions and material properties as available in FIAT-GM Power train Italia standards.

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METHODOLOGY The model of marine pump was designed

by using pro-E software . The designed part assembly is saved as in

IGES format The IGES file was imported to hyper mesh . Now the assembled model is ready to be

used with hyper mesh for meshing The IGES format meshed model is

imported to ansys for taking analysis.(static & Dynamic

PRO-E MODEL PUMP

SIDE VIEW OF MARINE PUMP

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SPECIFICATIONS OF MARINE PUMP

Pump size 6”

Pump type Radial flow

Pump speed (n) 1470 rpm

No. of stages (N) 2 stages

Discharge (Q) 114 kg/s

Actual head (H) 105 m

Motor rating 200 KW

Motor type Wet

Voltage 415v

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Shaft And Impeller Assembly

STEPS INVOLVED IN MESHING Model input Problem definition Geometry cleanup Element shape No. of nodes and elements Meshing Preview of meshing Checking of quality index

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Material & Loads:

MaterialYoung’s Modulus

DensityPoisson

Ratio

Yield stressσy

Kgf/mm2 g/cc Kgf/mm2

YST310 21000 7.85 0.3 45.0

LOAD Speed = 1470rpmAngular Velocity = 2x3.14x1470/60

= 153.86 rad/sec

STATIC ANALYSYS

Deformation-mm

Usum - Shaft Ux – Impeller and Shaft

Deformation-mm

Uz – Impeller and ShaftUy – Impeller and Shaft

Deformation-mm

Ux – ImpellerUsum – Impeller

Deformation-mm

Uz – ImpellerUy – Impeller

Deformation-mm

Usum – Shaft Ux – Shaft

Deformation-mm

Uy – Shaft Uz – Shaft

Stress-Kgf/mm^2

Principle Stress – Shaft

Stress-Kgf/mm^2

Von Mises Stress – ImpellerVon Mises Stress – Impeller

Part Deformation-mmUsum Ux Uy Uz

Shaft 0.06861

0.264e-3

0.06861

0.926e-3

Impeller

3.94 0.1277 3.939 3.872Note: Usum, Ux, Uy, Uz are

Resultant deformation & deformation in X, Y & Z direction.

DYNAMIC ANALYSYS

MODAL ANALYSIS Frequency - Hz

1st Freq – Hz - Shaft 2nd Freq - Hz- Shaft

Vertical Bend - Shaft Vertical Bend - Shaft

2nd Freq – Hz - Shaft 3rd Freq - Hz- Shaft

Z- Bend - Shaft Vertical Bend - Shaft

4th Freq – Hz - Shaft 5th Freq - Hz- Shaft

Z- Bend - Shaft Local Bend - Shaft

6th Freq – Hz - Shaft 1st Freq – Hz- Impeller & Shaft

Local Bend - Shaft Vertical Bend - Shaft

4th Freq – Hz- Impeller & Shaft 5th Freq – Hz- Impeller & Shaft

Vertical Bend - Shaft Z Bend - Impeller

6th Freq - Hz

Twist - Impeller

MODAL ANALYSIS RESULTS FOR 6 MODES

FREQUENCY HZ Deformation mm minimum

Deformation mm maximum

162.796 1.878 mm 16.904

162.796 1.878 mm 16.904

435.475 -11.466 15.34

435.475 -11.466 15.34

775.88 8.765 78.885

775.88 8.765 78.885

MODAL ANALYSIS RESULTS

In modal analysis results the above following we find, various set of frequencies for shaft with impeller at a speed of 1470 rpm. The frequency ranges from 162.796 to775.88. It does not exceed 1KH .

The deformation value is not getting increased beyond

78.885mm with higher frequencies than 775.88Hz Hence the obtained range of vibrations is lesser

So that, the performance of the pump will not affected by vibrations.

Deformation – Usum Deformation – Ux

HARMONIC RESPONSE ANALYSIS Deformation Plot

Deformation – Uy Deformation – Uz

HARMONIC RESPONSE ANALYSIS Deformation Plot

Deformation – Usum - Shaft Deformation – Uy - Shaft

HARMONIC RESPONSE ANALYSIS Deformation Plot

Equivalent Stress - Shaft Equivalent Stress - Shaft

HARMONIC RESPONSE ANALYSIS Stress Plot

Equivalent Stress - Impeller Equivalent Stress - Impeller

HARMONIC RESPONSE ANALYSIS Stress Plot

Part Stress- kgf/mm^2

Shaft 0.0072

Impeller 0.01712

Yield Stress 45

FOS 2.628

Part Deformation-mm

Usum Ux Uy Uz

Impeller + Shaft

0.411e-3 0.845e-4 0.411e-3 0.206e-5

Note: Usum, Ux, Uy, Uz are Resultant deformation & deformation in X, Y & Z direction.

Note: σe – Stress Based on Energy theory (Von Misses Theory);

FOS = σy / σeDesign FOS 2.00< 2.628

Hence the design is safe in Dynamic load

RESPONSE ANALYSIS

0.00E+00

1.00E-03

2.00E-03

3.00E-03

4.00E-03

5.00E-03

6.00E-03

7.00E-03

8.00E-03

9.00E-03

1.00E-02

0 50 100 150 200 250 300 350

FREQ

AM

PL

ITU

DE

MASS-1

MASS-2

HARMONIC RESPONSE ANALYSIS Frequency – Hz Vs Amplitude -mm

Conclusions:

From the foregoing FE analyses & results, the following conclusions are

drawn.

The result of static analysis under the self weight + speed (1470rpm) are tabulated. It is seen that maximum

stresses in the impeller notch.Maximum stresses are within material yield, Design FOS = 2.0, Minimum

factor of safety is 2.14.

In the dynamic analysis the frequencies ranges from 124.42Hz to 775.88Hz. It does not exceed 1 kHz. So the Obtained frequencies during the analysis are within the limit.

Hence the obtained range frequency of vibrations is less. So that, the performance of the pump will not be affected by vibrations.

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Finally the design is found to be safe from the static and dynamic conditions are well

within material yield and meet the design requirements. The analysis is carried out using

ANSYS software.

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THANK YOU