A new method to measure the aerodynamic drag of high-speed trains passing through tunnels

摘要

AbstractDue to the infeasibility of using a wind tunnel to measure the aerodynamic drag coefficient of a high-speed train entering and passing a tunnel, a new moving model test method is proposed. A photoelectric sensor is fixed at the bottom of the train to scan the printed zebra stripes which are pasted along the track, from which the train displacement is obtained and the speed and acceleration can be calculated. The train aerodynamic drag coefficient before entering the tunnel and the drag coefficient of a train running inside the tunnel can be obtained based on Newton's Second Law. The results show that the aerodynamic drag coefficient of the train before entering the tunnel barely changes at different positions which can be considered as constant, but the value decreases as the train passes through the tunnel. This phenomenon is caused primarily by the transient airflow inside the tunnel. Comparisons with the verified numerical simulations are performed and good agreement with difference less than 7% is reached, which implies that the moving model method proposed in this paper is feasible and reliable.]]>