Aerodynamic characteristics and braking distance of high-speed trains equipped with aerodynamic braking devices

To optimize the synergistic configuration of aerodynamic braking devices (ABDs) for high-speed trains operating at speeds exceeding 400 km/h, the overall braking gain and efficiency of aerodynamic braking systems are systematically analyzed. Using the body shape and fundamental braking system configuration of the CR400AF high-speed train as a reference, different quantities of “butterfly” braking devices are deployed, and the aerodynamic braking characteristics under various operating conditions are simulated and evaluated. A direct integral solution and a segmental cumulative solution are proposed to determine the braking distance and time of aerodynamic braking. The results indicate that ABD installation significantly enhances the aerodynamic drag of the train, thereby improving braking performance. A higher density of aerodynamic braking plate (ABP) arrangements intensifies airflow interference between the front and rear rows of adjacent ABPs. The combined braking system utilizing aerodynamic braking effectively compensates for the insufficient adhesion braking force at high speeds while addressing the low braking efficiency of aerodynamic braking at low speeds. The braking distance in compound braking is proportional to the square of the initial speed, while the braking time exhibits a linear relationship with speed. Combined aerodynamic braking reduces the emergency braking distance from an initial speed of 350 km/h to below 5500 m, thereby enhancing braking safety.