Crosswind stability of high-speed trains in special cuts

Analysis of the aerodynamic performance of high-speed trains in special cuts would provide references for the critical overturning velocity and complement the operation safety management under strong winds. This work was conducted to investigate the flow structure around trains under different cut depths, slope angles using computational fluid dynamics (CFD). The high-speed train was considered with bogies and inter-carriage gaps. And the accuracy of the numerical method was validated by combining with the experimental data of wind tunnel tests. Then, the variations of aerodynamic forces and surface pressure distribution of the train were mainly analyzed. The results show that the surroundings of cuts along the railway line have a great effect on the crosswind stability of trains. With the slope angle and depth of the cut increasing, the coefficients of aerodynamic forces tend to reduce. An angle of 75° is chosen as the optimum one for the follow-up research. Under different depth conditions, the reasonable cut depth for high-speed trains to run safely is 3 m lower than that of the conventional cut whose slope ratio is 1:1.5. Furthermore, the windward slope angle is more important than the leeward one for the train aerodynamic performance. Due to the shield of appropriate cuts, the train body is in a minor positive pressure environment. Thus, designing a suitable cut can contribute to improving the operation safety of high-speed trains.