EXPLORATORY INVESTIGATION OF AEROACOUSTIC OPTIMIZATION OF THE VARIABLE IMPEDANCE EDGE CONCEPT APPLIED TO UPPER SURFACE BLOWN CONFIGURATIONS

摘要

The noise generated by aircraft propulsive lift systems is a potential problem in both the community and inside the aircraft itself.This study investigates the feasibility of using porous surfaces on lift augmenting flaps to reduce the noise at the source, without adversely affecting aerodynamic performance.Numerous flap configurations were tested on a USB (upper surface blowing) type powered lift model (approximately 1/5 full scale).Significant reductions of far field noise and aeroacoustic pressures were found, and many configurations exhibited aerodynamic characteristics comparable to unmodified configurations of the nozzle/flap system.