风洞试验中不同厚度挡风墙合理长度的数值研究

Numerical study on reasonable lengths of wind barriers with different thicknesses in wind tunnel tests

在风洞中,挡风墙的特性对列车的空气动力学特性有重要影响。利用改进的延迟分离涡模拟(IDDES)方法和剪切应力传输(SST)k-ω湍流模型,研究了不同挡风墙厚度下列车气动特性随挡风墙长度的变化。风洞试验结果用于侧滑角为30°时的验证。当挡风墙超过一定长度时,列车的空气动力载荷没有显著变化,可以认为达到了临界长度。通过拟合列车空气动力学系数与挡风墙长度之间的关系,确定了挡风墙的临界长度。挡风墙厚度与临界长度之间的关系满足二次函数y=-57.106x2+10.85x+28.822。当挡风墙厚度大于0.5 m(全尺寸)时,可通过将风洞试验中挡风墙的厚度代入上述函数来获得临界长度,以研究列车的空气动力学特性。

In a wind tunnel,the characteristics of wind barrier have a significant effect on the aerodynamic characteristics of a train.Using the improved delayed detached eddy simulation(IDDES)method and the shear stress transport(SST)k-ωturbulence model,the variations of the aerodynamic characteristics of the train with the length of the wind barrier were studied for different wind barrier thicknesses.The wind tunnel test results were used for comparison at a yaw angle of 30°.When the wind barrier exceeded a certain length,the aerodynamic load of the train did not change significantly,and it can be considered to have reached a critical length.The critical length of the wind barrier was determined by fitting the relationship between the aerodynamic coefficient of the train and the length of the wind barrier.The relationship between the thickness of the wind barrier and the critical length satisfied the quadratic function y=−51.235x2+8.659x+29.014.When the thickness of the wind barrier was more than 0.5 m(full-size),the critical length could be obtained by substituting the thickness of the wind barrier into the above function during a wind tunnel test to study the aerodynamic characteristics of the train.