Integration of Turbo-Expander and Turbo-Ramjet Engines in Hypersonic Vehicles

Turbo-expander-ramjet and turbo-ramjet are two engine concepts considered for hypersonic aircraft designs with a flight regime between Mach 0 and 7. To establish any performance or integration aspects for these two combined-cycle engine types, an extended study of a variety of influence parameters is necessary, because the interaction between aircraft and propulsion system is even stronger than on conventional aircraft. In fact, the propulsion system is very sensitive to intake and nozzle/afterbody design at these high speeds. This paper presents the engine configurations chosen for comparison and describes the computer program used for the propulsion system performance simulation, including all relevant integration aspects. Furthermore, some results of propulsion system performance for a generic hypersonic aircraft and a typical ascent profile will be compared to indicate the special characteristics of the engines. Finally, some thoughts concerning the suitability and relevant technological requirements of the two engine types—seen from an aircraft manufacturer’s view—are included. The paper includes the results of two diploma theses, written by W. Sterr [1] and B. Zellner [2] at the Technical University of Munich, supervised by Prof. H. Rick (LFA) and O. Herrmann (MBB).