自然风下大比例模型的雷诺数效应

Reynolds number effect of large-scale model in natural wind

为了分析阻塞度和洞壁效应对大比例模型风洞试验结果精度的影响,通过制作缩尺比为1∶9的大比例尺流线型桥梁断面模型,安装到高速移动的汽车上,形成不同风速的自然风场。测量了不同车速下(即不同雷诺数)模型的表面压力,拟合了试验数据,研究了自然风作用下高雷诺数区的流线型断面的三分力系数的变化规律以及表面压力分布的特点,并将自然风场数据与风洞试验数据进行了对比。研究结果表明:阻塞度和洞壁效应将对大比例模型的雷诺数效应产生较大影响,其中,当Re<3×105时,随着雷诺数Re的增加,考虑阻塞度和洞壁效应影响的阻力系数呈不断减小的变化趋势,而不考虑其影响的阻力系数呈上升的变化趋势;阻塞度和洞壁效应使得升力系数数值变小,而升力矩系数数值却变大;阻塞度和洞壁效应不会改变模型表面最小压力点出现的位置,但是会使模型表面压力系数数值变小。

In order to analyze the effect of wall interference and blockage on the accuracy of wind tunnel test, a streamlined model of bridge deck in 1 ： 9 ratio was made to do the experiment on a high speed ve- hicle in natural wind. After measuring the surface pressures under different speeds different Reynolds numbers, and fitting the data, the test data between natural wind and wind tunnel were compared to fig- ure out the varying pattern of the mean aerodynamic force coefficient and the distribution characteristics of surface pressure on streamlined section in high Reynolds number under natural wind. The results show that there exist differences between the experiment under wind tunnel test and that under natural wind in mean aerodynamic force coefficient. When Reynolds number〈3 × 10^5, wall interference and blockage make the tendency of drag coefficient decrease, however, the tendency increases without the effect of wall interference and blockage; wall interference and blockage make lift coefficient decrease and torsion coefficient increase. They won＇t change the position of the lowest pressure point, but diminish the value of surface pressures. 1 tab, 10 figs, 16 refs.