Heavy-Haul Train Braking Simulation With Fluid Dynamics-Based Air Braking System

The dynamics of heavy-haul trains during braking are highly intricate, directly impacting their operational safety. A heavy-haul train longitudinal-vertical coupled dynamics model (HTLVDM) considering the air braking system is established in this paper. Based on the fluid dynamics theory, a detailed air braking system is established, which considers the characteristics of brake pipes, reservoirs and brake waves. The HTLVDM in-corporates locomotive and wagon components, along with nonlinear hysteresis characteristics of the coupler draft gear. Thus, the air braking system, which delivers pressure signals from the brake pipe to the brake cylinder via a control valve, is coupled to the locomotive and wagon dynamics system through a brake shoe. This model facilitates studying the dynamic performance of the entire system under varied train formations and braking strategies. Using this model, we compare and analyze the impacts of the fluid dynamics model (FDM) and empirical model (EM) of the air braking system on train dynamics behavior. Results reveal significant differences in train dynamic behavior between FDM and EM simulations, highlighting the necessity of employing the FDM for evaluating train operation safety.