NOISE REDUCTION TESTS OF LARGE-SCALE-MODEL EXTERNALLY BLOWN FLAP USING TRAILING-EDGE BLOWING AND PARTIAL FLAP SLOT COVERING

摘要

Noise data were obtained with a large-scale cold-flow model of a two-flap, under-the-wing, externally blown flap proposed for use on future STOL aircraft. The noise suppression effec¬tiveness of locating a slot nozzle at the trailing edge of the second flap and of applying partial covers to the slots between the wing and flaps was evaluated. Overall-sound-pressure-level reductions of 5 dB occurred below the wing in the flyover plane. Existing models of several noise sources were applied to the test results. The resulting analytical relation compared favorably with the test data.