不同雷诺数下空腔流的流动特性

Characteristics of Cavity Flows at Different Reynolds Numbers

利用PIV测量空腔中垂面流场,研究雷诺数对空腔流流动特性的影响。时均结构在不同雷诺数下都具有相似的主流区及回流旋涡区。涡量的最大值位于进口角点处,高值区集中在边界层分离区。紊动强度及雷诺应力的高值区位于主流与出口角点的冲撞处,随着雷诺数的增大,参数高值区沿流向的长度不断变大,而进口角区低值区的范围不断缩小。纵、垂向能谱特征参数在相同雷诺数下的空间分布规律基本一致;调整雷诺数将导致回流区的掺混范围及来流自身的紊动特性发生改变,从而影响空腔流能谱的空间分布规律。

The influence of Reynolds number on characteristics of cavity flows was studied using particle image velocimetry( PIV). Results showed that time-mean velocity fields display same structures at different Reynolds numbers,namely,the main flow and backflow vortex structures. The maximum vorticity locates at the entrance corner,and high value vorticities gather in the boundary separation zone. At the impinging corner,values of turbulent intensities and Reynolds stress reach maximum. The stream-wise lengths of high value zone of turbulent intensities and Reynolds stress increase with the increase of Reynolds number,but it is opposite to low value zone in the entrance corner. Distribution forms of the characteristic parameter of longitudinal and vertical spectrum resemble each other at different Reynolds numbers. Variation of Reynolds number results into mixing range changes of backflow and characteristic changes of the incoming flow,which will influence the spatial distribution of spectrum in the cavity.