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Preliminary Evaluation of a Turbine/Rotary Combustion Compound Engine for a Subsonic TransportThe fuel consumption of a modern compound engine with that of an advanced high pressure ratio turbofan was compared. The compound engine was derived from a turbofan engine by replacing the combustor with a rotary combustion (RC) engine. A number of boost pressure ratios and compression ratios were examined. Cooling of the RC engine was accomplished by heat exchanging to the fan duct. Performance was estimated with an Otto-cycle for two levels of energy lost to cooling. The effects of added complexity on cost and maintainability were not examined and the comparison was solely in terms of cruise performance and weight. Assuming a 25 percent Otto-cycle cooling loss (representative of current experience), the best compound engine gave a 1.2 percent improvement in cruise. Engine weight increased by 23 percent. For a 10 percent Otto-cycle cooling loss (representing advanced insulation/high temperature materials technology), a compound engine with a boost PR of 10 and a compression ratio of 10 gave an 8.1 percent lower cruise than the reference turbofan.
Document ID
19760014112
Document Type
Technical Memorandum (TM)
Authors
Civinskas, K. C. (NASA Lewis Research Center Cleveland, OH, United States)
Kraft, G. A. (NASA Lewis Research Center Cleveland, OH, United States)
Date Acquired
September 3, 2013
Publication Date
March 1, 1976
Subject Category
AIRCRAFT PROPULSION AND POWER
Report/Patent Number
NASA-TM-X-71906
E-8695
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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