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Comparison of Engine Cycle Codes for Rocket-Based Combined Cycle EnginesThis paper summarizes the results from a one day workshop on Rocket-Based Combined Cycle (RBCC) Engine Cycle Codes held in Monterey CA in November of 2000 at the 2000 JANNAF JPM with the authors as primary participants. The objectives of the workshop were to discuss and compare the merits of existing Rocket-Based Combined Cycle (RBCC) engine cycle codes being used by government and industry to predict RBCC engine performance and interpret experimental results. These merits included physical and chemical modeling, accuracy and user friendliness. The ultimate purpose of the workshop was to identify the best codes for analyzing RBCC engines and to document any potential shortcomings, not to demonstrate the merits or deficiencies of any particular engine design. Five cases representative of the operating regimes of typical RBCC engines were used as the basis of these comparisons. These included Mach 0 sea level static and Mach 1.0 and Mach 2.5 Air-Augmented-Rocket (AAR), Mach 4 subsonic combustion ramjet or dual-mode scramjet, and Mach 8 scramjet operating modes. Specification of a generic RBCC engine geometry and concomitant component operating efficiencies, bypass ratios, fuel/oxidizer/air equivalence ratios and flight dynamic pressures were provided. The engine included an air inlet, isolator duct, axial rocket motor/injector, axial wall fuel injectors, diverging combustor, and exit nozzle. Gaseous hydrogen was used as the fuel with the rocket portion of the system using a gaseous H2/O2 propellant system to avoid cryogenic issues. The results of the workshop, even after post-workshop adjudication of differences, were surprising. They showed that the codes predicted essentially the same performance at the Mach 0 and I conditions, but progressively diverged from a common value (for example, for fuel specific impulse, Isp) as the flight Mach number increased, with the largest differences at Mach 8. The example cases and results are compared and discussed in this paper.
Document ID
Document Type
Conference Paper
Waltrup, Paul J.
(Johns Hopkins Univ. Laurel, MD United States)
Auslender, Aaron H.
(NASA Langley Research Center Hampton, VA United States)
Bradford, John E.
(Georgia Inst. of Tech. Atlanta, GA United States)
Carreiro, Louis R.
(Air Force Research Lab. Eglin AFB, FL United States)
Gettinger, Christopher
(Pratt and Whitney Aircraft West Palm Beach, FL United States)
Komar, D. R.
(NASA Marshall Space Flight Center Huntsville, AL United States)
McDonald, J.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Snyder, Christopher A.
(NASA Glenn Research Center Cleveland, OH United States)
Date Acquired
August 20, 2013
Publication Date
April 1, 2002
Publication Information
Publication: 26th JANNAF Airbreathing Propulsion Subcommittee Meeting
Volume: 1
Subject Category
Spacecraft Propulsion And Power
Funding Number(s)
Distribution Limits
Work of the US Gov. Public Use Permitted.

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