1、Best Practices Entry: Best Practice Info:a71 Committee Approval Date: 2000-04-04a71 Center Point of Contact: MSFCa71 Submitted by: Wilson HarkinsSubject: Computational Fluid Dynamics (CFD) In Launch Vehicle Applications Practice: Use high-speed, computer-based computational fluid dynamics analytical
2、 techniques, verified by test programs to establish propulsion and launch vehicle hardware designs for optimum performance and high reliability. These procedures will validate designs and provide an early assurance of operational viability.Programs that Certify Usage: This practice has been used on
3、the Space Shuttle, Space Shuttle Solid Rocket Motor (SRM); Space Shuttle Main Engine (SSME) programs.Center to Contact for Information: MSFCImplementation Method: This Lesson Learned is based on Reliability Practice Number PD-AP-1311, from NASA Technical Memorandum 4322A, Reliability Preferred Pract
4、ices for Design and Test.The use of computer-based computational fluid dynamics methods will accelerate the design process, reduce preliminary development testing, and help create reliable, high-performance designs of space launch vehicles and their components. In addition to design verification and
5、 optimization, CFD can be used to simulate anomalies that occur in actual space vehicle tests or flights to more fully understand the anomalies and how to correct them. The result is a more reliable and trouble-free space vehicle and propulsion system.Provided by IHSNot for ResaleNo reproduction or
6、networking permitted without license from IHS-,-,-Implementation Method:Accurate definition of flow-induced pressure and temperature loads can be achieved long before actual hardware testing through the use of high-speed, computer-based computational fluid dynamics analytical techniques. Designs can
7、 be constructed in electronic three-dimensional computer-aided design format, and the flows of fluids and gases can be accurately simulated using CFD techniques. Computer-based simulations of this type can be accomplished so rapidly that designs can be changed in real time even before hardware is fa
8、bricated. CFD techniques are being successfully used as diagnostic tools to provide insight into problems with existing rocket engine components and to develop optimum designs of liquid rocket engine pump components such as impellers, diffuser vanes, and shrouds; turbine components such as turbine b
9、lades, turbine staging, volutes, and turbine wheels; launch vehicle base thermal protection configurations; transpiration and conductive cooling methods for rocket nozzles; flow paths within solid rocket motors at various stages of combustion; and launch and reentry pressure and thermal loads on veh
10、icle configurations.The Team Approach to CFD Code and Data Base DevelopmentMSFC has found that a very effective way of developing and selecting CFD codes (the computer-based equations that control a CFD analysis) and CFD Data Bases (the empirically derived factors that fit the CFD codes to various s
11、pecific applications) is to form multi-organizational teams in specialized areas related to propulsion and to other space flight applications. These teams, which are part of a CFD Consortium for Applications in Propulsion Technology (CAPT) are comprised of individuals from within MSFC, other NASA ce
12、nters, prime and subcontractors, and the academic community, communicate frequently and meet periodically to exchange and disseminate information about the rapidly growing field of computational fluid dynamics as related to rocket propulsion and other related space flight applications. The teams tak
13、e into account the best available theory on CFD, the most advanced computer computational and graphic capabilities, and the latest test techniques and results of component, subsystem, subscale and full scale rocket engine tests. This information is used to continuously develop and improve the comput
14、er-based representation of the temperatures, pressures, and flow patterns (velocities, accelerations, and directions) in space vehicles and their propulsion systems.Implementation of CFD Into the Design of Rocket Engine PumpsThe implementation of CFD into the design process for rocket engine pumps h
15、as been aided by the activities of a Pump Stage Technology Team (PSTT) which is a part of the NASA/MSFC CFD Consortium for Applications in Propulsion Technology. The teams goals have included the assessment of the accuracy and efficiency of several CFD methodologies and application of the appropriat
16、e methodologies to understand and improve the flow inside fuel and oxidizer pumps for liquid propellant rocket engines. As an example of the type of CFD work that has been done under the cognizance of this team, subtle changes in the axial impeller length, blade count, and blade configurations of pu
17、mp impellers resulted in efficiencies of up to 98 percent. This resulted in head Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-coefficients (which are measures of pump power) increasing from 0.53 to 0.66 in experimental impeller designs.CFD Analysi
18、s of Base Flowfields in Clustered Nozzle ConfigurationsAs a launch vehicle proceeds up through the atmosphere into space from its near sea-level launch position, the rocket exhaust plumes expand to a point where a plume reverse flow is encountered. Where multiple nozzles are used, the closed impinge
19、ment of the exhaust plumes can cause a reverse jet. The reverse jet impinges on interior base surface areas, components, and base shields causing heating, contamination, and/or possible combustion in the launch vehicle base areas. Computational fluid dynamics has proven to be a useful tool in predic
20、ting the recirculating exhaust base flow patterns encountered in various launch vehicle configurations, and these patterns can be used as an input to the design and development of reliable vehicle configurations and thermal or pressure protection schemes. Figure 1 is a typical output from a CFD anal
21、ysis which shows velocity vectors indicating the flow patterns that are generated at high altitude (approximately 92,000 feet above sea level) when a launch vehicle has four exhaust nozzles. With the knowledge of the pressure, temperature, and flow profiles in the base region provided by a CFD analy
22、sis, components and insulation systems can be designed to withstand environments in the base region or insulated to protect them against the potentially hostile environment that occurs due to exhaust recirculation at high altitude.refer to D descriptionD Turbine Improvements Using CFDComputational f
23、luid dynamics techniques are being used in the advancement of turbine aerodynamic Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-design techniques as well as the development of a understanding and characterization of the unsteady aerodynamic environ
24、ments in existing rocket engine turbines. The CAPT Turbine Technology Team is addressing several areas of CFD application to existing and future liquid rocket engines. The techniques reduce developmental risk, decrease the amount of intermediate testing, improve performance and durability, and reduc
25、e cost. In one turbine improvement effort, gas turning angle in the turbine blades was increased from the traditional design limit of approximately 140 degrees to 160 degrees. The CFD analysis showed that this change, coupled with other minor improvements, would increase turbine efficiency by almost
26、 10 percent and reduce the required number of turbine blades by approximately one half. Maximum blade mach number was decreased dramatically from the 1.32 of the original design to 0.87 for the new design. The new configuration employed a single stage turbine rather than an originally planned two st
27、age configuration.CFD has also proven to be a useful tool in the evaluation of secondary losses and turbine blade tip loss control mechanisms such as endwall fences, blade fences, tip grooves, tip cavities, and mini-shrouds. This technique is also useful in the simulation and design of inlet and out
28、let turbine volutes. Cold flow testing of reduced scale and full scale turbines has verified many of the CFD simulations.Flow Fields, Flow Separation, Film Coolants, and Heat Transfer in Rocket Engine CombustorsComputational fluid dynamics analyses have been successfully applied in areas related to
29、the prediction and simulation of combustion flow behavior and heat transfer to the internal walls of rocket engine injectors, combustion chambers, and nozzles. These analyses have been used to optimize nozzle entrance geometries, evaluate new step nozzle exit configurations that adapt to altitude ch
30、anges, determine pressure and temperature profiles in rocket engine chambers and nozzles, and to study the effects of coolant flows in liquid rocket engine chambers on internal wall temperatures. These analytical procedures have helped to evaluate anomalies discovered in actual engine firings and to
31、 design reliable combustion chamber, nozzle, and coolant arrangements that result in high thrust coefficients under various atmospheric and space conditions. The CAPT Combustion Devices Technology Team has been instrumental in many of these investigations. Computational fluid dynamics simulations ha
32、ve also been useful in determining pressure, heating, and insulation requirements for launch vehicles during liftoff, ascent, and reentry into the atmosphere.Technical Rationale:NASA/MSFC has sponsored the CFD Consortium for Applications in Propulsion Technology since the early 1980s. Symposia have
33、been held for the past twelve years in which participants from MSFC, other centers, prime contractors, laboratories, other agencies, and the academic community have exchanged information in the development and application of CFD analytical techniques related to rocket engine propulsion systems. MSFC
34、 has also been involved in the other aerodynamic and fluid dynamics applications of CFD. Computational fluid dynamics is a discipline that has come of age in the concurrent engineering process that results in the design, development, and flight of highly reliable and cost effective launch vehicle sy
35、stems.Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-References1. “Proceedings of Workshop for Computational Fluid Dynamic (CFD) Applications in Rocket Propulsion,“ April 19-21, 1994, Marshall Space Flight Center, NASA.2. “Overview of the NASA/MSFC
36、CFD Consortium for Applications in Propulsion Technology,“ McConnaughey, P.K. and L.A. Schutzenhofer, AIAA, 92-3219, AIAA/SAE/ASME/ASEE 28th Joint Propulsion Conference, July 6-8, 1992, Nashville, TN.3. “Computational Fluid Dynamics Analysis for the Reduction of Impeller Discharge Flow Distortion,“
37、R. Garcia, et al, 32nd AIAA Aerospace Sciences Meeting, January 10-13, 1994, Reno, NV.4. “Numerical Analysis of Base Flowfield at High Altitude for a Four-Engine Clustered Nozzle Configuration,“ T.S. Wang, 29th AIAA Joint Propulsion Conference, June 28-30, 1993, Monterey, CA.5. “Analytical Investiga
38、tion of the Unsteady Aerodynamic Environments in Space Shuttle Main Engine (SSME) Turbines,“ Lisa W. Griffin, et al, May 24-27, 1993, ASME, New York, NY.6. “Advancement of Turbine Aerodynamic Design Techniques,“ Lisa W. Griffin, et al, May 24-27, 1993, ASME, New York, NY.7. “Advanced Technology Low
39、Cost Engine (ATLCE) 50K Testbed Combustion Chamber Film Coolant Parametrics,“ Joe Ruf, November 5, 1993, MSFC, AL.8. “Unified Navier-Stokes Flowfield and Performance Analysis of Liquid Rocket Engines,“ T.S. Wang, et al, Journal of Propulsion and Power, September 1993, AIAA, New York, NY.9. “Numerica
40、l Analysis of the Hot-Gas-Side and Coolant-Side Heat Transfer for Liquid Rocket Engine Combustors,“ T.S. Wang, et al, 28th AIAA Joint Propulsion Conference, July 6-8, 1992, Nashville, TN.10. “Numerical Study of the Transient Nozzle Flow Separation of Liquid Rocket Engines,“ T.S. Wang, CFD Journal, O
41、ctober 1992, MSFC, AL.11. Reliability Preferred Practice PT-TE-1427, “Rocket Engine Technology Test Bed Practice.“Impact of Non-Practice: Failure to thoroughly analyze the pressures, temperatures, and flow rates of gases and fluids in propulsion systems using Computational Fluid Dynamics (CFD) techn
42、iques prior to design and manufacture could result in inadequate strength, thermal protection, and operational control of liquid rocket propulsion systems and related launch vehicles and components. The ultimate result of inadequate designs could be excessive redesign and testing, increased costs, a
43、nd the potential for launch vehicle, engine, system, or component failure.Related Practices: N/AProvided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Additional Info: Approval Info: a71 Approval Date: 2000-04-04a71 Approval Name: Eric Raynora71 Approval Organization: QSa71 Approval Phone Number: 202-358-4738Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
