Combined Influence of Free-Stream Turbulence and Favorable Pressure Gradients on Boundary Layer Transition and Heat Transfer
Combined Influence of Free-Stream Turbulence and Favorable Pressure Gradients on Boundary Layer Transition and Heat Transfer
复制标题
自由流湍流和有利压力梯度对边界层转变和传热的综合影响
DOI：
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发表时间：
1981
期刊：
影响因子：
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通讯作者：
M. Werle
中科院分区：
文献类型：
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作者：
M. F. Blair;M. Werle
文摘：对自由流湍流和流向加速对过渡边界层流动的综合影响进行了实验研究。在此期间，获得了流向加速度和自由流湍流强度四种组合下的对流换热系数、边界层平均速度和温度分布数据以及壁面静压分布数据。获得了四个试验工况的自由流多组分湍流强度、纵向积分长度尺度和谱分布数据。廓线计算结果表明，实验数据准确、一致，实验边界层高度二维。这些试验所产生的自由流湍流分布既是均匀的，又是近乎各向同性的。预计这些结果将提供所需的一组基本的、记录良好的实验测试用例，以便与分析预测进行比较。对过渡剖面形状因子和壁面换热分布数据的检验表明，在完全湍流壁面换热速率的上游，得到了全湍流平均速度剖面。目前的数据表明，建立的湍流平均速度剖面的长度比发展平衡湍流分布所需的长度要短。在本程序中获得的过渡位置数据与其他平壁研究中的数据非常吻合。给出了在自由流湍流和流向加速共同作用下预测平壁转折位置的建议关联曲线。
Abstract : Experimental research was conducted to examine the combined effects of free-stream turbulence and streamwise acceleration on transitional boundary layer flows. During this period convective heat transfer coefficients, boundary layer mean velocity and temperature profile data, and wall static pressure distribution data were obtained for four combinations of streamwise acceleration and free-stream turbulence intensity. Free-stream multicomponent turbulence intensity, longitudinal integral length scale, and spectral distribution data were obtained for the four test cases. The profile results indicate that the data are accurate and consistent and that the experimental boundary layers were highly two-dimensional. The freestream turbulence distributions generated for these tests have been shown to be both homogeneous and nearly isotropic. It is anticipated that these results will provide a needed set of fundamental, well documented experimental test cases to which analytical predictions can be compared. Examinations of the transitional profile shape factors and wall heat transfer distribution data indicate that fully turbulent mean velocity profiles are achieved upstream of fully turbulent wall heat transfer rates. The present data suggest that the turbulent mean velocity profile is established in a shorter length than is required for the development of the equilibrium turbulence distribution. Transition location data obtained in the present program agree very well with data from other flat wall studies. Suggested correlation curves are given for predicting flat wall transition locations with the combined effects of free-stream turbulence and streamwise acceleration.