小口径轴对称收缩喷嘴射流冲击大平板噪声特性的实验研究

为研究小口径喷嘴冲击射流的噪声特性，测定了3mm口径的轴对称收缩喷嘴在各种压比情况下产生的亚音速和超音速射流冲击坚固大平板产生的噪声。发现噪声在空间呈近似四瓣分布，当喷嘴与平板距离减小时，噪声指向壁射流下游的瓣到增强，反之，噪声指向喷嘴上游的瓣得到增强。噪声随喷嘴距平板距离的增加呈增强的趋势，在距平板一定距离内有锯齿现象。噪声随喷嘴压比的增加而增强，相应于各种工况，存在一不同的压比值，此压比之前，噪声随压比的增大而迅速提高，但有起伏现象，在此压比之后，噪声平缓地随压比的增大而增强。

Noise Characterastics of the Impinging Jet from a Small Diameter Axisymmetric Convergent Nozzle Acting to a Large Flat Plate

To investigate the noise characteristics of the impinging jet from a small nozzle, measurement of far field sound pressure level was performed for the aerodynamic noise generated by subsonic and supersonic jet from a 3mm-diameter axisymmetric convergent nozzle normally or obliquely impacting on a large rigid flat plate. The noise directivity pattern was found to be quadrupolelike. It was also found that the total noise intensity was enhanced as the nozzle-to-plate distance increased, and its distribution had a saw-teeth behaviour within the distance less than 20 nozzle-diameters.