A comparative study of an ATREX engine and a turbo jet engine

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The performance of an ATREX (Air-TurboRam Expander cycle) engine and a Pre-Cooled Turbo Jet (PCTJ) engine have been compared by cycle calculation along a flight trajectory of constant dynamic pressure. The results showed that the both engines produce approximately the same thrust at transonic condition, which is the critical condition to define the vehicle configuration. At low Mach number, PCTJ can produce larger specific thrust (Isp) than ATREX, but ATREX can produce larger Isp than PCTJat higher flight Mach number regime, when the turbine inlet temperature (TIT) is increased. Some technical issues on developing ATREX engine and PCTJ have been addressed, and shown to have no significant difference in the difficulty to be resolved. The most important issue would come from the transient total temperature change due to the rapid acceleration of the Two-Stage-ToOrbit (TSTO) space plane mission which flies from sea level static (SLS) condition (288K) to Mach 6 at 30km of altitude (1680K) in 6 minutes. The change of the rotor radius due to this large temperature change have been assessed to be 0.5% of the blade height, for the both engines. If this corresponds to the tip clearance, this will result in 1.5% of fan efficiency reduction per stage, and 7% * Manager, Aero-engine & Space Operation, Research & Engineering Division, t Aero-engine & Space Operation, Research & Engineering Division, Copyright© 2001 by the American Institute of Aeronautics and Astronautics Inc. All rights reserved. of the surge margin reduction. The reduction of the efficiency won't cause big problems, however, the reduction of the surge margin may be large enough to cause problems.