软性多孔材料圆柱降噪特性实验研究

由钝体绕流产生的气动噪声可以通过在物体表面覆盖软性多孔材料得到降低。为了证实这种方法的有效性，在北京航空航天大学D5气动声学风洞中，对不同直径圆柱表面覆盖软性多孔材料，在不同风速范围下开展了气动声学测量实验，并利用恒温热线测速仪对其后缘尾迹流场进行了测量。结果显示，通过在圆柱表面覆盖软性材料，可以降低由圆柱产生的气动噪声，流场结果表明软性材料延长了圆柱后缘尾迹，抑制圆柱后缘涡脱落。

Experimental inverstigation on Reduction of cylinder noise by soft porous material

In the field of aerodynamic noise, cavity noise is an important part, and acoustic liner. As an effective noise reduction measure, the principle of sound absorption is the principle of micro-perforated plate absorber, that is, multiple helmholtz resonators are connected in parallel to absorb sound energy by excitation resonance of the back cavity.The sound absorption was affected by various structure parameters of the lining. Aiming at the problem of aerodynamic noise in the low speed cavity, this paper makes a multi-parameter mix design of the sound liner through the principle of micro perforated plate sound absorber, and adds it to the cavity. The spectral characteristics of cavity noise before and after the installation with acoustic liner were compared, and the noise reduction effect of the sound liner in the cavity noise problem was evaluated. The influence of adding acoustic liner to the noise of the self-excited oscillation cavity and the effect of the acoustic resonance were analyzed.