A kind of shield method for reducing supersonic gas impinging jet noise
一种超声速气体冲击射流噪声的屏蔽抑制方法

Based on understanding the feedback mechanism of discrete frequency noise in impinging jet,a new kind of method is proposed to reduce the noise by destroying the 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.At the same time the shield is required to be out of the jet boundary and keep no touch with the flow of impinging jet.Experimental results showed that generally the noise can be reduced by more than 5 dB at the right shield parameters.Moreover,measurements and analysis confirmed that the method is helpful for the impinging jet to increase thrust and remove particles on the surface.