A Kind of Shield Method Used to Suppress Supersonic Impinging Jet Discrete Frequency Noise
Han BiaoYao, ZhaohuiXu, Hongqing
(Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China)

Abstract: Based on understanding the feedback mechanism of discrete frequency noise supersonic impinging jet, a new kind of method is proposed to reduce the noise by destroying formation of the feedback loop effectively. The main idea is using a shield to prevent the feedback acoustic wave from arriving at the nozzle lip, which is required to be out of the jet boundary, so that no effect on the flow of impinging jet may occur. Experimental results show that the noise can be generally reduced by more than 5 dB at the right shield parameters. Moreover, measurements and analysis confirm that the method is helpful for the impinging jet to increase thrust and remove particles on the surface.
Keywords: Supersonic impinging jet, discrete frequency noise, feedback loop, shield.