Experimental Study of Measurement for Dissipation Rate Scaling Exponent in Heated Wall Turbulence
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摘要: 对中等雷诺数下壁面常温和壁面加热的平板湍流边界层中速度和温度粗粒化的耗散率结构函数标度指数进行了实验测量.用热线风速仪测量了风洞中壁面常温和加热的平板湍流边界层中不同法向位置的流向速度分量和温度的时间序列信号,研究了由于湍流边界层近壁区域相干结构的存在而导致的非各向同性、非均匀性对湍流耗散率结构函数标度指数的影响,研究发现,中等雷诺数下壁面加热的边界条件和剪切湍流的平均速度梯度对速度和温度耗散率结构函数的标度指数没有影响,均匀各向同性湍流的耗散率结构函数标度指数的层次结构模型对壁面加热平板湍流边界层的速度和温度耗散率结构函数的标度指数也是适用的.Abstract: Experimental investigations were devoted to the study of scaling exponent of coarse grained dissipation rate structure function for velocity and temperature fluctuation in a turbulent boundary layer at moderate Reynolds number. Longitudinal velocity and temperature were measured at different vertical positions in turbulent boundary layer over a heated and unheated flat plate in a wind tunnel using hot wire anemometer. The effect of non-isotropy and inhomogeneity on scaling exponent of dissipation rate was studied because of the existence of organized coherent structure burst process in the near wall region. The scaling law of coarse-grained dissipation rate structure function is found to be independent of the mean velocity shear strain and the heating wall boundary condition. The scaling exponent of the dissipation rate structure function is verified to be in agreement with the hierarchical structure model which has been valid for isotropic and homogeneous turbulence.
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Key words:
- heating /
- wall turbulence /
- dissipation rate /
- scaling exponent /
- hierarchical structure model
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