二维矩形截面柱体气动力系数雷诺数效应

Reynolds Number Effects on Aerodynamic Force Coefficients of 2D Rectangular Prisms

摘要:

在TJ 2风洞中，测量了5种截面宽厚比（B/D为2.0，2.5，3.0，3.5和4.0）的二维矩形截面柱体的表面风压时程，雷诺数（Re）的变化范围为1.1×105~6.8×105，然后通过风压时程积分的方法获得了模型的气动力系数时程.研究了各模型气动力系数的雷诺数效应，分析了模型的平均阻力系数随截面宽厚比的变化规律，并与以往的研究成果进行了对比，最后分析了各模型的气动力系数功率谱随雷诺数的变化规律.研究表明，宽厚比2≤B/D≤4的二维矩形截面柱体的气动特性受雷诺数的影响，且随着截面宽厚比的增大，二维矩形截面柱体模型的气动特性对雷诺数越来越敏感.尾流区的旋涡脱落对模型顺风向脉动风荷载有一定程度的贡献，但横风向升力主要来源于尾流的漩涡脱落.

Abstract:

Experiments on 2D rectangular prisms with side ratios of 2.0, 2.5, 3.0, 3.5 and 4.0 are reported in this study. The tests were conducted in TJ 2 wind tunnel to measure the wind pressures on the surfaces of 5 models for the testing Reynolds numbers ranging from 1.1×105 to 6.8×105. Aerodynamic forces were obtained by integrating the wind pressures around the model surface. The Reynolds number effects on the aerodynamic force coefficients and the power spectrums of aerodynamic force coefficients are presented, and the influence of side ratio on the drag force coefficients is analyzed. The results show that the aerodynamic characteristics of rectangular prisms with side ratio between 2 and 4 are Reynolds number dependent, and the rectangular prisms appear to be more sensitive to the Reynolds number with increasing side ratio. The along fluctuating wind force is produced mostly by the along fluctuating wind speed, and the vortex shedding plays a second role, whereas the crosswind lift force is mainly from the vortex shedding.