加糙平板湍流边界层紊动特性

本文应用偏振差动式激光测速仪对加糙平板湍流边界层紊动特性进行了研究,得到了紊动强度、三阶矩、四阶矩、概率密度分布、功率谱、自相关等特征量。结果表明,可据高阶矩的符号来对湍流边界层沿垂向进行分区,并给出了分区标准,同时发现,加糙使边界层湍流趋于均匀、各向同性,即概率密度分布更接近于高斯分布。

CHARACTERISTICS OF TURBULENT BOUNDARY LAYER FLOW OVER A ROUGH FLAT PLATE

In this paper, the differential LDV system has been used to investigate the characteristics of the turbulent boundary layer flow over a rough flat plate. The characteristical quantities, such as turbulent intensity, third order moment, fourth order moment, probability distribution, auto-correlation and power spectrum, have been obtained. The experimental results expressed that the turbulent boundary layer can be divided into subregions in the vertical direction according to the sign of higher order moment, and the limits of divisions have been given. Meanwhile, it was found that the turbulent boundary layer flow tend t be homogeneous and isotropic owing to the roughness of the flat plate, i. e., the distribution of probability density is close to Gaussian distribution.