Establishment of aerodynamic force model with varying wind yaw angles and its influences on the safety and comfort of the rail vehicle

Abstract

Taking the CRH2 rail vehicle as the case study and combined with the pressure measurement test method, the influences of different wind yaw angles (β) on the pressure distributions and aerodynamic coefficients of the rail vehicle were analyzed, and the contributions of each part of the rail vehicle surface (windward, top, leeward, and bottom) to the three-component coefficients of the rail vehicle were investigated. Significant differences in the aerodynamic coefficients of the rail vehicle between the results obtained from the traditional sine rule and those from the test results were found. Then, the expressions of modified sine rule model for the aerodynamic coefficient of the rail vehicle under the whole β of 0°–90° were proposed, and the buffeting force model of the running rail vehicle was established. Finally, the influences of the aerodynamic coefficients based on the modified sine rule and the traditional sine rule on the safety and comfort of the running rail vehicle were comparatively studied by using the SIMPACK multi-body dynamics software. The results showed that when the β∈[45°,50°], the curve-fitting expression for calculating the mean pressure coefficient (Cp_mean) on the rail vehicle surface has the same format as that for calculating the RMS values of fluctuating pressure coefficient (Cp_rms). The aerodynamic coefficients of the rail vehicle obtained by using the traditional sine rule are significantly smaller than the test values at the different β. The overall fitting accuracy of the drag coefficient of the rail vehicle by the modified sine rule model is the highest at the β of 0°–90°. It was found that wind loads of the rail vehicle are independent of the vehicle speed under the β of 0°–20°. The dynamic responses of the rail vehicle calculated by the modified sine rule are always greater than those calculated by the traditional sine rule at different wind speeds and vehicle speeds, and the traditional sine rule will lead to unconservative or unsafe conclusions on the operation safety of the rail vehicle.