F-15 inlet/engine test techniques and distortion methodologies studies. Volume 1: Technical discussion

Abstract

Peak distortion data taken from a subscale inlet model were studied to determine if the data can be used to predict peak distortion levels for a full scale flight test vehicle, and to provide a better understanding of the time variant total pressure distortion and the attendant effects of Reynolds number/scale and frequency content. The data base used to accomplish this goal covered a range from Mach 0.4 to 2.5 and an angle of attack range from -10 degrees to +12 degrees. Data are presented which show that: (1) increasing the Reynolds number increases total pressure recovery, decreases peak distortion, and decreases turbulence, (2) increasing the filter cutoff frequency increases both peak distortion and turbulence, and (3) the effect of engine presence on total pressure recovery, peak distortion, and turbulence is small but favorable.