The different aspects of overall performance of three variable cycle engines (VCE) candidates for future supersonic civil transport are analysed in this work. These aspects concern the design and off-design points performance, the airframe engine integration and variable geometry compressor and turbine design and performance. The three engines are compared to a traditional turbojet. The variable compressor maps were obtained with their running lines for the whole mission profile including the transition mode from medium býpass ratio to a lower bypass ratio turbofan. The specific fuel consumption (SFC) of the VCEs showed a significant improvement, especially at subsonic cruise, relative to a Turbojet engine. The extent of the variable geometry on the compressor stator angles, mixing area and the nozzle throat and exit areas is evaluated. The Fuel bill is estimated for two standard mission profiles. The effect of installation is estimated on an isolated nacelle. A sizing calculation is carried out for the whole nacelle including the intake and the nozzle. The drag due to the friction, pre-entry, afterbody and the shock waves is calculated in order to estimated the installed performance of the three engines. In the search of improving the VCE performance at subsonic cruise, the use of variable geometry at the low pressure turbine for the Turbofan-Turbojet engine is investigated. The effects of varying the LP turbine guide vanes stagger angle on the engine performance and component parameters are analysed. The turbine efficiency and non-dimensional mass flow changes due to the use of variable geometry are estimated. An updated version of the Turbornatch program was corrected and tested in order to study variable cycle engines, especially to simulate the transition from one mode to another.

The different aspects of overall performance of three variable cycle engines(VCE) candidates for future supersonic civil transport are analysed in this work. Theseaspects concern the design and off-design points performance, the airframe engineintegration and variable geometry compressor and turbine design and performance. The three engines are compared to a traditional turbojet. The variablecompressor maps were obtained with their running lines for the whole mission profileincluding the transition mode from medium b?pass ratio to a lower bypass ratio turbofan. The specific fuel consumption (SFC) of the VCEs showed a significant improvement, especially at subsonic cruise, relative to a Turbojet engine. The extent of the variablegeometry on the compressor stator angles, mixing area and the nozzle throat and exitareas is evaluated. The Fuel bill is estimated for two standard mission profiles. The effect of installation is estimated on an isolated nacelle. A sizing calculationis carried out for the whole nacelle including the intake and the nozzle. The drag due tothe friction, pre-entry, afterbody and the shock waves is calculated in order to estimatedthe installed performance of the three engines. In the search of improving the VCE performance at subsonic cruise, the use ofvariable geometry at the low pressure turbine for the Turbofan-Turbojet engine isinvestigated. The effects of varying the LP turbine guide vanes stagger angle on theengine performance and component parameters are analysed. The turbine efficiency andnon-dimensional mass flow changes due to the use of variable geometry are estimated. An updated version of the Turbornatch program was corrected and tested inorder to study variable cycle engines, especially to simulate the transition from one modeto another.

Six of the candidate propulsion systems for the High-Speed Civil Transport are the turbojet, turbine bypass engine, mixed flow turbofan, variable cycle engine, Flade engine, and the inverting flow valve engine. A comparison of these propulsion systems by NASA's Glenn Research Center, paralleling studies within the aircraft industry, is presented. This report describes the Glenn Aeropropulsion Analysis Office's contribution to the High-Speed Research Program's 1993 and 1994 propulsion system selections. A parametric investigation of each propulsion cycle's primary design variables is analytically performed. Performance, weight, and geometric data are calculated for each engine. The resulting engines are then evaluated on two airframer-derived supersonic commercial aircraft for a 5000 nautical mile, Mach 2.4 cruise design mission. The effects of takeoff noise, cruise emissions, and cycle design rules are examined. Berton, Jeffrey J. and Haller, William J. and Senick, Paul F. and Jones, Scott M. and Seidel, Jonathan A. Glenn Research Center NAS3-26617; NAS3-6618; NAS3-25965; NAS3-25963; WBS 22-714-09-46

High-speed flight is a major technological challenge for both commercial and business aviation. As a first step in revitalizing efforts by the National Aeronautics and Space Administration (NASA) to achieve the technology objective of high-speed air travel, NASA requested the National Research Council (NRC) to conduct a study that would identify approaches for achieving breakthroughs in research and technology for commercial supersonic aircraft. Commercial Supersonic Technology documents the results of that effort. This report describes technical areas where ongoing work should be continued and new focused research initiated to enable operational deployment of an environmentally acceptable, economically viable commercial aircraft capable of sustained supersonic flight, including flight over land, at speeds up to approximately Mach 2 in the next 25 years or less.