一种超声速气体冲击射流噪声的屏蔽抑制方法

根据对冲击射流离散频率噪声产生的反馈机理的认识，提出了一种能够有效地破坏反馈环的形成，从而抑制冲击射流离散频率噪声的喷嘴屏蔽方法。这种方法是通过阻隔反馈声波使其不能到达喷嘴唇口、同时屏蔽物不与射流接触来实现降噪的目的，实验结果表明，对于合适的屏蔽罩参数，正常降噪效果达5dB以上。分析表明这种降噪方法对射流冲击平板的推力和除尘除水效率的提高有帮助。

A kind of shield method for reducing supersonic gas impinging jet noise

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.