无剪切湍流混合层中被动标量扩散的实验研究

Experimental study on the passive scalar diffusion in shearless turbulent mixing layer

研究被动标量在无剪切湍流混合层中的扩散。实验在风洞中进行,用大小网格尺度比为2∶1的网格实现无剪切湍流混合层,用烟粒子作为测量用的示踪粒子同时作为被动标量形成浓度场,用PIV测量得到速度场同时用Mie散射测量得到高施密特数的浓度场,由此可以计算得到速度和浓度相关,并用实验数据直接检验大涡模拟中亚格子应力Smagorinsky模式和亚格子质量通量梯度模式。

In this paper, passive scalar diffusion in shearless turbulent mixing layer was studied.An experiment was carried out in a wind tunnel where a grid composed of two parts with a ratio of 2 in grid size produces a shearless mixing layer by the interactions of two scales of homogeneous isotropic turbulence at each side. The incense is added at the larger grid or smaller grid respectively both as tracer particles for PIV and as a passive scalar with high Schmidt number. PIV and Mie scattering diffusion are used to measure turbulence velocity and concentration simultaneously, thus correlation between velocity and concentration can be calculated. The comparison between the subgrid terms and models is made by use of the experimental data.