Influence of Rail Fastening System on the Aerodynamic Performance of Trains under Crosswind Conditions

The large number and dense layout of rail fastening can significantly affect the aerodynamic performance of trains. Utilizing the Improved Delayed Detached Eddy Simulation (IDDES) approach based on the SST (Shear Stress Transport) k-ω turbulent model, this study evaluates the effects of the rail fastening system on the aerodynamic force, slipstream and train wake under crosswind conditions. The results indicate that in such conditions, compared to the model without rails, the rail and the fastening system reduce the drag force coefficient of the train by 1.69%, while the lateral force coefficients increase by 1.16% and 0.87%, respectively. The aerodynamic force can be considered virtually unchanged within the error allowance. However, the rail and the fastening system cause an inward shift of the negative pressure center on the leeward side of the train. The peak slipstream velocity near the ground in the rail and rail fastening system model is significantly lower than that in the situation without rails. Additionally, the rail and the fastening system not only induce two displacements in the vortex structure of the train but also accelerate the dissipation of shedding vortex and the rapid decrease of turbulent kinetic energy.