Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

In this study, based on the shear-stress transport - turbulent model, the improved delayed detached eddy simulation method has been used to simulate the unsteady aerodynamic performance of trains with different obstacle deflectors at two yaw angles (0 degrees and 15 degrees). The numerical algorithm is used and some of the numerical results are verified through wind tunnel tests. By comparing and analysing the obtained results, the effects of the obstacle deflectors on the force of the trains as well as the pressure and flow structure around the trains are elucidated. The results show that the obstacle deflectors primarily affect the flow field at the bottom of the head car as well as the wake flow, and that the internal oblique-type obstacle deflector (IOOD) markedly improves the aerodynamic performance of the trains, by decreasing most of the aerodynamic forces of the train cars and minimising their fluctuations. Further, a nonzero yaw angle weakens or even changes the effect of the IOOD on the aerodynamic forces of the train cars. However, the effect of the IOOD is more on the tail car.