中文摘要：

冲击射流的噪声抑制对于研究短程起飞和垂直起降飞行器（STOVL）是极其重要的．为了研究冲击射流噪声尤其是冲击单音与涡结构尺度之间的关系以及反馈声波的上传方向，采用小波分析技术和“声类比”方法来分析冲击单音的传播方向．研究中用到的冲击射流的速度场由PIV技术给出，冲击单音的频率通过噪声场的测量获得．利用双正交小波变换来提取冲击射流速度场中含有的波动信息，结合冲击单音的频率特性对噪声场进行研究．研究结果表明大尺度结构是冲击单音的“拟声源”．此外，还可以看出大尺度涡结构产生的反馈声波一部分向喷嘴出口处传播，形成反馈环；另一部分反馈声波向四周传播．

英文摘要：

It is important to take noise control of impinging jets in many engineering fields, such as a short take-off and vertical landing （SVTOL） aircraft as well as air nozzle. In general, the impinging jet noise is associated with the relationship between the impinging tone and the scale of vortex structure, and the propagating direction of feedback waves. In the present study, the propagation direction of impinging tone was investigated with wavelet analysis and acoustic analogy. The velocity field of impinging jet was obtained by Particle Image Velocimetry （PIV） technique and decomposed by means of biorthogonal wavelet transform. The frequency distribution of discrete tone was obtained from its noise field. The results show that large-scale structure can be viewed as ＂coustic source＂ of discrete tone. Moreover, the direction of upstream-propagating feedback waves is about 60° oriented from the impinging plane and agrees with Ho＇s experimental results.