Effects of STOL Thrust Reversers and Powered Lift on Inlet Flow Quality

An experimental test program was conducted to determine the engine environment which results from STOL operation with blown flaps and thrust reversers. Testing was conducted in a low speed wind tunnel with a 1/11 scale model of a STOL transport consisting of a fuselage and high-lift wing with triple-slotted externally blown flaps, leading edge slats, and powered model engines. Steady-state and dynamic total pressure distortion were moderate at takeoff and approach conditions with blown flaps. The cascade type STOL thrust reversers tested produced severe dynamic distortion due to unstable interactions of the reversed streams with the oncoming flow and vortex ingestion. Comments on methods to alleviate these problems are presented.