project 3, cea exercise - webmae-nas.eng.usu.edu/.../section7/project3_2019.pdfmae 5450 - propulsion...

MAE 5450 - Propulsion Systems

Project 3, CEA Exercise• This Programing Assignment is due on Beginning of Final Exam Period-- 11:30 AM MDT, Wednesday May 3.

• We are going to build a chemistry table for an AP-composite rocketPropellant, and investigate the effects due to increasing metallization of the grain.

• Look at important effects on flame temperature, molecular weights, andC* (infinitely expanded nozzle)

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Download and Build CEA Code

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• Down Load the CEAGUI from the NASA Glenn Research center Web site- Recommend you use the windows GIU as it seems to be bug free …- Linix code has a bunch of compile errors that need to be fixed- Special Setup Procedure for MAC User ..

http://www.neng.usu.edu/classes/mae/6530/propulsion_systems/section7/ceagui_FAQ_g77MacPC.pdf

• See … http://www.grc.nasa.gov/WWW/CEAWeb/ceaRequestForm.htm1)Update your comuter’s Java Runtime Environment, Reboot Computer

• Java SE Runtime Environment 8 Downloads

Works for most of you


• FCEA2.exe … built code for PC processor • Download all three(3) .zip files and save into the installation directory

• Extract (unzip) the CEAgui JAR file (CEAgui-jar.zip) • Extract (unzip)the CEA+ Fortran Package (CEA+Fortran.zip) for CEA files • Extract (unzip) the CEAexec Package (CEAexec-win.zip)

Download and Build CEA Code (2)

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• You must have the 6! Unzipped files installed in the installation directory

à 1) CEAgui.jar, 2) thermo.lib, 3) trans.lib, 4) b1b2b3.exe, 5) syntax.exe, and 6) FCEA2.exe in the installation directory.)


Download and Build CEA Code (3)

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• Directory Structure

Command Line (DOS) Interface

JAVA GUI Interface


Project Background

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Need atLeast 15% minimumtotal HTPB binder by mass for “cake” to stick together

0.150≤MHTPB

MAl + MAP+ MHTPB( )Adiabatic Flame Temperature of AP/HTPB/Al Composite Propellant as function of Mass


Project Background (2)

• Investigate Mixture effects

Plot T0,g ,C* for both Chamber & Throat vs O/F for increasing aluminization levels

6

• Using equilibrium properties at Throat, plot data for various mixture ratios and determine optimal operating mixture ratio (based on C*) .. Assume T0 is constant through out motor• Based on flow properties from nozzle throat … Update AMW L-700 model for “Best case” Formulation Properties

Assume that St. Roberts burn /erosive burn/Bates Grain parameters are same as previously used

O/F


Required Project Elements• 1) Set up input file to run as “Rocket” Problem with a combustion pressure

of 3000 kPa (30 bars)

•2) Look AP Composite propellant with Mixture ratio of AP/HTPB/AL

• 3) Run code in “equilibrium”, with “infinite” combustor contraction ratio

• 4) Use results for molecular weight(Mw), ratio of specific heats (g), and combustion temperature to calculate and C*

1) Based on Chamber, g, Mw.2) Based on Throat (*), g, Mw. …. Assume that T0chamber = T0

*

• 5) Plot properties for chamber and throat (g, Mw,T0, C*) as a function of O/F ratio and degree of metalization

• 6) Draw “85%” constrain ln on C* plot

7


Project Overview (2)

8

• Apply what we learn to AMW-L700 Motor Analysis

.. Look at both Cylindrical Port with both erosive burn and Bates grain .. Compare original and “improved” propellant” formulation (be sure to re-evaluate the propellant density based on formulation using Optimal allowable O/F and metallization fraction) Using new g, Rg, Mw, T0 ….......

• 7) Compare time history plots of chamber pressure thrustregression rate

• 8) Calculate and compare … total impulse .. effective Isp’s

… assume that Saint Robert’s burn parameters (a, n} and the erosionparameters (k, Mcrit) remain unchanged for new propellant


Project Overview (3)

9

• Based on Equilibrium flow “Frozen” at nozzle throat …

• 9) Compare to project 2 solution including erosive burn model for cylindrical grainand /Bates grain model

• 10) Based on Throat Properties, Calculate parameters for minimum length conical nozzle • 11) Plot Minimum length contour over actual nozzle contour

• Using equilibrium combustor properties from CEA

… See Next page


Project 3• 11) Plot Minimum length contour over actual nozzle contour

Original L700 Nozzle • Use nexit/2 rule

• What is the L-700 factor of safety ….

• Overlay Nozzle Contour Using

F.O.S =θwallmax −θexitactualθexitactual

θnozzle =23θwallmax

Rule


Equilibrium Properties at Chamber and Throat (example)

10

CHAMBER THROAT

P0/Pstatic 1.0000 1.7428P, BAR 31.000 17.787T, K 2925.58 2744.19RHO, KG/CU M 3.65500 2.2555 0H, KJ/KG 0.00000 -454.46U, KJ/KG -848.15 -1243.08G, KJ/KG -26683. 9 -25484.0S, KJ/(KG)(K) 9.1209 9.1209

MW, (1/n) 28.680 28.932(dLV/dLP)t -1.01044 -1.00776(dLV/dLT)p 1.2400 1.1912Cp, KJ/(KG)(K) 3.1727 2.9098GAMMAs 1.1495 1.1526SON VEL,M/SEC 987.4 953.4MACH NUMBER 0.000 1.000

Assume P0, T0 constant throughout motorCalculate C* based on local g (throat), Mw (throat) , T0 (chamber)


Chamber Pressure Ballistic Equation

11

• 11) Show that when “shifting equilibrium” from chamber to throat and then properties frozen at throat is used … the chamber pressure equation for solid motor must be modified as …

*, Mw* -> properties at throat

Rg -> based on molecular weight at chamber conditions, MwP0, T0 Chamber stagnation Pressure, temperature

Use modified chamber pressure ballistic equation in follow-on analysis

• 12)


Hint: Characteristic Velocity, C*• The characteristic velocity is a figure of thermo-chemical merit for a particular propellant and may be considered to beIndicative of the combustion efficiency.

• Lower Molecular Weight Propellants Produce Higher C*

• For this calculation based value on g, Mw

at the nozzle throat …

*

**

*

*

*


Hints: Mass Fraction Relationships

13

Relate O F to %( )NH4ClO4

→

O / F ≡MNH4ClO4

MHTPB+ MAL

%( )NH4ClO4

≡100%×MNH4ClO4

MNH4ClO4+ MHTPB+ MAL

⎛

⎝

⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟⎟

⎧

⎨

⎪⎪⎪⎪⎪⎪⎪⎪⎪

⎩

⎪⎪⎪⎪⎪⎪⎪⎪⎪

⎫

⎬

⎪⎪⎪⎪⎪⎪⎪⎪⎪

⎭

⎪⎪⎪⎪⎪⎪⎪⎪⎪

→ %( )NH4ClO4

=100%×MNH4ClO4


⎛

⎝

⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟⎟=100%× 1

1+MHTPB+ MAL

MNH4ClO4

⎛

⎝

⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟

=100%× 1

1+ 1O / F

⎛

⎝

⎜⎜⎜⎜⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟⎟⎟⎟⎟⎟

=100%× O / FO / F+1⎛

⎝⎜⎜⎜

⎞

⎠⎟⎟⎟⎟

Inverse→O / F =

%( )NH4ClO4

100%

1−%( )

NH4ClO4

100%


Hint: Mass Fraction Relationships (2)

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…i.e. Mass Constraint Rsolid on terms of O/F and fal

Rsolid ≡MNH4ClO4

+ MAL


fAl ≡MAL

MHTPB+ MAL

MNH4ClO4= O / F( )⋅ MHTPB+ MAL( )

→ Rsolid =

MAL

MNH4ClO4

+1

MAL+ MHTPB

MNH4ClO4

+1

MAL

O / F( )⋅ MHTPB+ MAL( )+1

MAL+ MHTPB

O / F( )⋅ MHTPB+ MAL( )+1=

MAL


1O / F( )

+1

Rsolid =

MAL


1O / F( )

+1⋅O / F( )O / F( )

=

MAL

MHTPB+ MAL( )+ O / F( )

O / F( )+1=fAl + O / F( )O / F( )+1

Inverse→ O / F( )= Rsolid − fAl1−Rsolid

=


Mass Fraction Relationships (3)

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…Summary

%( )NH4ClO4

=100%×MNH4ClO4


⎛

⎝

⎜⎜⎜⎜⎜

⎞

⎠

⎟⎟⎟⎟⎟⎟

O / F( )=MNH4ClO4

MHTPB+ MAL( )

Rsolid ≡MNH4ClO4

+ MAL


fAl ≡MAL

MHTPB+ MAL

→

Mass Constraint

Rsolid =O / F( )+ fAlO / F( )+1

O / F( )= Rsolid − fAl1−Rsolid


Mass Fraction Relationships (4)

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…i.e. Mass Constraint on terms of O/F and fal

O / FMax =

MAl + MAP

MHTPB+ MAl + MAP

⎛

⎝⎜⎜⎜⎜

⎞

⎠⎟⎟⎟⎟− fAl

1−MAl + MAP

MHTPB+ MAl + MAP

⎛

⎝⎜⎜⎜⎜

⎞

⎠⎟⎟⎟⎟

=0.85( )− fAl1− 0.85( )

fAl =MAl

MHTPB+ MAl

MAl

MHTPB

=fAl

1− fAl

Required .... MAl + MAP

MHTPB+ MAl + MAP

≤0.85

project 3, cea exercise - webmae-nas.eng.usu.edu/.../section7/project3_2019.pdfmae 5450 - propulsion...

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