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This paper presents the overall scope of the NASA Lewis High Performance Aircraft Propulsion Research Program. High performance fighter aircraft of interest include supersonic fighters with such capabilities as short takeoff and vertical landing (STOVL) and/or high maneuverability. The NASA Lewis effort involving STOVL propulsion systems is focused primarily on component-level experimental and analytical research. The high- maneuverability portion of this effort, called the High Alpha Technology Program (HATP), is part of a cooperative program among NASA's Lewis, Langley, Ames, and Dryden facilities. The overall objective of the NASA Inlet Experiments portion of the HATP, which NASA Lewis leads, is to develop and enhance inlet technology that will ensure high performance and stability of the propulsion system during aircraft maneuvers at high angles of attack.

The procedures and unique hardware used to conduct an experimental investigation into the response of a small turboshaft engine compression system to various hot gas ingestion patterns are presented. The temperature distortion generator described herein was capable of creating both steady-state and time-variant, or transient, temperature distortion at the engine inlet by using gaseous hydrogen. The transient temperature ramps produced by the distortion generator during the engine tests ranged from less than 111 deg K/sec (200 deg R/sec) to above 611 deg K/sec (1100 deg R/sec) and generated instantaneous temperatures to 422 K (760° R) above ambient. The distortion generator was used to document the maximum inlet temperatures and temperature rise rates that the compression system could tolerate before the onset of stall for various circumferential distortions and the compressor system response during stall.

Several unique techniques and related devices are in use at the Lewis Research Center for off-design testing of fan and compressor sections in full-scale jet engines. The devices presented not only permit a wide range of experimental conditions but also minimize downtime for hardware changes. The techniques involve use of such devices as inlet pressure distortion jets, a hydrogen burner for inlet temperature distortions, fan back pressure jets to simulate a variable area nozzle, and either an inflow-outflow bleed system or a fuel spurt system to alter compressor discharge pressure.