湍流信号的三项分解

THE THREE PART DECOMPOSITION OF TURBULENT SIGNAL

利用数字滤波方法和子波（ｗａｖｅｌｅｔ）分析方法对用热线测得的湍流信号进行了三项分解．将湍流信号分解为近似各向同性的小尺度涡和各向异性的大尺度涡之后，再将大尺度涡分解为相干结构部分以及非相干结构部分．与目前检测相干结构常用的条件采样方法相比较后发现，本文的分解方法是可靠的．利用此方法不仅能确定相干结构的时间尺度，而且可以得到非条件平均的相干结构波形．

The turbulent signal measured by hot wire is decomposed into three parts with the digital filter and the wavelet analysis. First, the turbulent signal is decomposed into the small scale vortex that has approxmate isotropy and the large scale vortex. Then, the large scale vortex isdecomposed into the coherent and the non coherent parts. Compared with the conditional sampling, the decomposition is realiable. The time scale and non conditional mean profile of coherent structure can be obtained with this method.