Analysis of wind and rain load characteristics on high-speed train in heavy rainfall environment based on different rain load calculation models

To investigate the rain load characteristics on high-speed trains in a heavy rainfall environment, a numerical calculation model for aerodynamic characteristics of a three-car high-speed train under heavy rainfall was built with the Euler-Lagrange method, and the interaction between raindrops and airflow was established using an interphase coupling approach. Wind tunnel tests were conducted to validate the accuracy of the airflow field model, while raindrop falling tests were performed to verify the accuracy of the rain field model. The Lagrange method was employed to capture the state information of each raindrop impacting the train body within a unit time, including the impact velocity between raindrops and the train as well as the raindrop mass flow rate. The impulse of raindrops was converted into impact loads on the train by utilizing the conservation of momentum, and the impact loads of all raindrops on the train body within a unit time were integrated to establish rain load calculation model A. Based on raindrop impact tests, a normalized time-history curve of raindrop impact force was plotted. Integration was performed for the impact forces of all raindrops striking the train body within a unit time to establish rain load calculation model B. The wind and rain loads on the train were analyzed using the established numerical calculation model for aerodynamic characteristics and rain load calculation models. The results indicate that under the same rainfall intensity, the mass of raindrops falling onto the head train is the largest, followed by that onto the middle train, and the tail train receives the smallest raindrop mass. The aerodynamic drag, longitudinal total load, and the longitudinal rain-wind load ratio of the three cars all increase with the increasing rainfall intensity. When the train speed is 350 km·h^-1 and the rainfall intensity is 500 mm·h^-1, the mass flow rates of raindrops falling onto the head train, middle train, and tail train is 19.43, 9.08, and 5.94 kg·s^-1, respectively. Compared with that in the condition without rain, the aerodynamic drag of the head train, middle train, and tail train increases by 7.39%, 7.69%, and 5.43%, respectively. The longitudinal total loads on the head train, middle train, and tail train are 16 695.07, 7 463.84, and 7 591.44 N, respectively, and their longitudinal rain-wind load ratios are 0.37, 0.38, and 0.22, respectively. This study can provide a reference for the operational safety assessment of high-speed trains under heavy rainfall conditions.