Research on the reasonable end shape of the windbreak wall model in the wind tunnel test via numerical simulation

The improved delayed detached-eddy simulation (IDDES) method was used in this study to explore the influence of windbreak wall end shape on the wind tunnel test of the high-speed train aerodynamic characteristics. Affected by three different types of windbreak walls (long-enough, rounded-end, and blunt-end), the aerodynamic force, pressure distributions on the train surface, and flow fields around the train were compared and analyised mainly under a yaw angle of 30 degrees. A wind tunnel test was carried out to verify the reliability of the numerical calculation method. Windbreak walls with different end shapes mainly exert an effect on the flow field in the region between the front end of the windbreak wall and the nose of the head car. However, the influence on the aerodynamic load and surface pressure distribution of the train is local, so the end of the windbreak wall can be blunt for convenience in the wind tunnel test. In addition, the length of the windbreak wall is an important factor affecting the accuracy of the wind tunnel test.