NASA Technical Reports Server (NTRS) 19910011919: Large liquid rocket engine transient performance simulation system

218 Pages·8.4 MB·English

by  NASA Technical Reports Server (NTRS)

LARGE LIQUID ROCKET ENGINE
TRANSIENT PERFORMANCE
SIMULATION SYSTEM
FINAL REPORT
Prepared for
NASA-George C. Marshall Space Flight Center
Marshall Space Flight Center, Alabama 35812
Prepared Under
United Technologies Corporation
Pratt & Whitney
Government Engine Business
P.O. Box 109600,
West Palm Beach, FL 33410-9600
J. R. Mason R. D. Southwick
P&W Program Manager Propulsion Systems
Technology Manager

FOREWORD
Pratt
& Whitney, Government Engine Business of United Technologies Corporation
conducted this program for the National Aeronautics and Space Administration, George C.
Marshall Space Flight Center under contract NAS8-36994. The NASA project manager for
this contract was Mr. W.A. Adams, Jr. of the MSFC, mechanical systems control branch.
The P&W program manager was Mr. J.R. Mason with technical contributions of Mr. D.L.
Baker, Mr. C.R. Byrd, Mr. T.F. Denman, Mr. H. P. Frankl, Mr. S.M. Mericle, Mr. R.W.
Parham, Mr. J.W. Park, Mr. J.E. Pollard, Mr. T.J. Roadinger, Mr. RoS. Rosson, Mr. M.H.
Sabatella, Mr. D.H.Spear, Mr. J.P. Spinn, and Mr. P.W. McLaughlin of "The Simulation and
Modeling Workshop".
CONTENTS
Paae
1.0 SUMMARY .............................................................. 1
2.0 INTRODUCTION .......................................................... 3
3.0 SYSTEM DESCRIPTION .................................................... 7
4.0 TTBE MODEL ............................................................ 27
5.0 SYSTEM TESTING AND VERIFICATION ....................................... 49
6.0 CONTRACT END ITEMS ................................................... 107
7.0 CONCLUSIONS .......................................................... 113
8.0 RECOMMENDATIONS ........... . ......................................... 115
9.0 REFERENCES ........................................................... 117
APPENDIX A - USER'S MANUAL .................................................. 119
APPENDIX B - EXAMPLE PUMP MODULE ........................................... 151
APPENDIX C - INTERFACED NASA CONTROL MODEL ................................. 163
APPENDIX D - TTBE MODEL CONFIGURATION INPUT ................................. 177
SECTION I
SUMMARY
A new simulation system, ROCETS, was designed and developed to allow cost-effective
computer predictions of liquid rocket engine transient performance. The system allows a user to
generate a simulation of any rocket engine configuration using component modules stored in a
library thru high-level input commands. The system library currently contains 24 component
modules, 57 sub-modules and maps, and 33 system routines and utilities. FORTRAN models from
other sources can be operated in the system upon inclusion of interface information on comment
cards. Operation of the simulation Is simplified for the user by Run, Execution and Output
Processors. The simulation system makes available steady-state trim balance, transient operation,
and linear partial generation. The system utilizes a modern equation solver for efficient operation
of the simulations. Transient integration methods include integral and differential forms for the
trapezoidal, first order Gear, and second order Gear corrector equations.
A detailed technology test bed engine (TTBE) model was generated to be used as the
acceptance test of the simulation system. The general level of detail of the model was that
reflected in the SSME DTM (Reference 2). The model sucessfully obtained stady-state balance in
main stage operation and simulated throttle transients including engine start and shutdown. A
NASA fortran control model was obtained, ROCETS interface installed in comment cards, and
operated with the ]-IBE model in closed-loop transient mode.
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SECTION II
INTRODUCTION
The National Aeronautics and Space Administration (NASA) Facilities such as the George C.
Marshall Space Flight Center (MSFC) require analysis and simulation of pump fed liquid rocket
engine transient performance. The types of analysis and simulation include control design and
analysis, design parametric studies, research and development, failure investigation, real-time
simulation, feasibility studies, and software design, development, and testing. Therefore, multiple
simulations representing different engine configurations with various levels of fidelity and transient
response ranges are needed to support these studies. An analytical tool to meet these needs in a
cost-effective manner is a digital computer simulation system.
A computer simulation system named ROCket Engine Transient Simulation (ROCETS) was
designed and developed under this program. An engine transient performance simulation normally
consists of mathematical representations of the engine components interfaced together to describe
the engine system performance. These component-by-component engine simulations (Figure
2-1) require interfacing the component models together in a computer program, with appropriate
program controls to interpret user commands, execute the program, and provide outputs to the
user. All of this can be accomplished with in-line computer code that is a free-standing
simulation. However, a simulation system provides many benefits relative to individual,
free-standing simulations.
PUMP PRigURNER TURBINE MAIN CHAMIII_
ORIGINAL PAGE IS
OF POOR OUALI'W
USER ENGINE
ROCKET
ENGINE
SIMULATION
COMMANDS PREDICTIONS
Figure 2-1. A Rocket Performance Simulation Consist of
Component-By-Component Models
A simulation system (Figure 2-2) allows generation of simulations representing different engine
configurations without expensive new computer code production and verification. The system acts
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as a repository so that the same engineering methodology representing the components is utilized
in different simulations to ensure prediction consistency. In addition, the system provides the
latest modeling technology of verified numerical techniques and utilities; new advances placed in
the system can easily be shared by all simulations operating in the system. A simulation system
also provides a common operating base for all users to minimize required operational training after
the initial start-up experience is obtained.
• Re-Use Of Developed/Verified Model Codes
• Repository For Methodology
• Advanced Modeling Technology & Techniques Easily Adaptable
• Reduces Required User Training
/7 MODULES
s_ .ONI
Figure 2-2. Simulation Systems Are Effective Tools
The ROCETS program to design and develop a simulation system consisted of nine (9)
technical tasks:
1. Architecture
2. System Requirements
3. Component and Submodel Requirements
4. Submodel Implementation
5. Component Implementation
6. Submodel Testing and Verification
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7. Subsystem Testing and Verification
8. TTBE Model Data Generation
9. System Testing & Verification
The Architecture definition determined there would be five major components of the ROCETS
system:
1. Library System
2. Executive programs (or Processors)
3. Simulation Input and Output
4. Documentation
5. Maintenance Procedures
The requirements were developed and documented inthe System Requirements Specification
(SRS) of P&W FR-20283, 25 November 1988 (Reference 3). The component and submodel
implementation and testing/verification is contained inthe System Design Specification (SDS) of
P&W FR-20284, 25 July 1990 (Reference 4). The Technology Test Bed Engine (TTBE) Model
description and system testing/verification are contained in this report.
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