Aerodynamic phenomena and drag of a maglev train running dynamically in a vacuum tube

Abstract

A maglev train can run at supersonic speed in a vacuum tube, and its transient state makes the airflow around it more complex. Therefore, to assist vacuum tube train studies, a flying model test platform is under construction. Using a model flying at the same speed as a real train, this test platform ensures that the airflow around the model is more consistent with the real state. Based on the test platform, a vacuum tube train model is established. Then, aerodynamic characteristics of the vacuum tube train during the acceleration, uniform motion, and deceleration processes are studied, and the variation of shock waves, choked flow, and aerodynamic drag during each process is analyzed. The results indicate that the aerodynamic drag obtained under the instantaneous startup condition is acceptable, but the aerodynamic phenomena afforded are different from those under the normal startup condition. During the acceleration process, the generation of shock waves causes the aerodynamic drag of each part to take a sudden leap and chokes the flow in front of the train. During a uniform motion process, a normal shock wave generated in front of the choked flow enhances the choked flow, aggravating the aerodynamic drag of the head train. Moreover, the high-pressure region expands to the rear, reducing the pressure drag of the tail train. During the deceleration process, the disappearance of shock waves and expansion waves in the rear causes the aerodynamic drag to suddenly decrease.