计算网格对列车空气动力学不确定性的影响

为评价计算网格对明线列车空气动力学数值仿真计算结果的影响，基于计算流体力学，研究了计算网格对列车气动特性的不确定性. 首先根据3种不同尺寸的计算网格及其计算结果，提出了计算网格对列车气动力和表面压力不确定性的计算方法；其次以ICE2列车为研究对象，划分了3种不同尺寸的计算网格，数值仿真得到了列车气动力和典型截面的压力；最后研究了该列车头车气动力和典型截面压力的不确定性. 研究结果表明:数值仿真得到的气动侧力系数与试验数据的误差仅为0.31%；车身迎风侧表面压力的不确定性接近于0；车身表面压力不确定性较大的位置主要位于车体底部，其最大不确定度达到1.42；头车侧力系数的不确定度为0.002 6，而头车升力系数的不确定度为0.509 3. 

Effect of Computational Grid on Uncertainty in Train Aerodynamics

To evaluate the effect of computational grid on the numerical simulation results of train aerodynamics in open air, the uncertainty of the computational grid on train aerodynamic characteristics is studied based on computational fluid dynamics. First, according to the grids of three sizes and the corresponding calculation results, the calculation method for the uncertainty of the train aerodynamic forces and surface pressure is proposed. Second, the ICE2 (inter-city express) train is taken as an object, three different grids are generated, and the pressure on typical cross-sections and aerodynamic forces are obtained by numerical simulation. Finally, the uncertainty of the aerodynamic forces and pressure on typical cross-sections of this train is studied. The results show that the error in aerodynamic side force coefficient between the numerical simulation and experiment is only 0.31%; the uncertainty of the surface pressure on the windward side of vehicle body is close to 0. The position with a higher uncertainty of the surface pressure is mainly located at the bottom of car body, and its maximum uncertainty is 1.42. As for the head car, the uncertainty of the side force coefficient is 0.002 6, and the uncertainty of the lift force coefficient is 0.509 3.