中文摘要：

采用基于k-ε方程的湍流数值模拟方法，研究单层客车在不同路堤、桥梁以及路堑运行时的气动性能，得到气动力系数与侧滑角之间的关系；根据车辆倾覆稳定性计算模型，得到不同高度路堤、桥梁以及不同深度路堑条件下车速和，临界倾覆风速关系。研究结果表明：列车在路堤上运行时，气动力系数总体上随侧滑角的增大而增大，在侧滑角为15°-70°之间变化较为明显，之后变化缓慢；临界倾覆风速随着路堤高度的增加先增高后降低，其拐点在车速为120km／h的位置；桥梁高度越高，临界倾覆风速越低；路堑深度越深，临界倾覆风速越高；车速相对较低时，相同高度条件下，车辆在路堤上的临界倾覆风速大于在桥梁上的临界倾覆风速，当车速超过分界车速时，车辆在桥梁上的临界倾覆风速大于在路堤上的临界倾覆风速。

英文摘要：

Numerical simulation method based on k-ε turbulence equations was used to study the aerodynamic performance of a single - layer car running on different embankments, bridges and cuttings. The relationship be- tween the aerodynamic coefficients and the slip angle was gotten. According to the vehicle stability calculation model, the relationship between running speed and critical overturning wind speed was also gotten under the conditions of different heights of embankments, bridges and different depths of cuttings. Results show that： When the single -layer car runs on embankment, the aerodynamic coefficients generally increase with the increase of slip angle. The aerodynamic coefficients change obviously when the slip angle is from 15° to 70°, then they change slowly. The critical overturning wind speed increases with the increase of embankment height first, and then decreases. The inflection point of vehicle speed is found to be about 120 km/h. The critical overturning wind speed decreases with the increase of bridge height, and it increases with the increase of cutting depth. At relatively low speed, the vehicle critical overturning wind speed on the embankment is greater than that on the bridge at the same height. When the speed of vehicle exceeds the boundary speed, the vehicle critical overtur- ning wind speed on a bridge is greater than that on the embankment.