Countermeasures for Reducing Unsteady Aerodynamic Force Acting on High-Speed Train in Tunnel by Use of Modifications of Train Shapes

As the maximum speed of high-speed trains increases, flow-induced vibration of trains in tunnels has become a subject of discussion in Japan. In this paper, the authors report the results of a study on use of modifications of train shapes as a countermeasure for reducing an unsteady aerodynamic force by on-track tests and a wind tunnel test. First, a statistical analysis of on-track test data is conducted to identify exterior parts of a train which cause the unsteady aerodynamic force. Next, a wind tunnel test is carried out to measure the unsteady aerodynamic force acting on a train in a tunnel and train shapes are examined with a particular emphasis on the exterior parts identified by the statistical analysis. The wind tunnel test shows that fins under the car body are effective in reducing the unsteady aerodynamic force. Lastly, the fins are tested by an on-track test and its effectiveness is confirmed.