Effect of car-body lower-center rolling on aerodynamic performance of a high-speed train

The interaction between the car-body vibration and aerodynamic performance of the train becomes more prominent motivated by the vehicle’s light-weighting design. To address this topic, this study firstly analyzes the posture characteristics of the car-body based on the previous full-scale test results. And then the aerodynamic performance under different vibration cases (different car-body roll angles) is studied with an improved delayed detached eddy simulation (IDDES). The results revealed that car-body rolling had a significant impact on the aerodynamic behavior of bogies, which significantly increased the lateral force and yaw moment of a bogie and further may have aggravated the operational instability of the train. The unbalanced distribution of the longitudinal pressure on both sides of the bogie caused by the car-body rolling motion was the primary cause for the bogie yaw moment increase. The tail vortex of the train was also affected by the car-body rolling, resulting in vertical jitter.