DESIGN AND DEVELOPMENT OF AERODYNAMIC BRAKING SYSTEM FOR HIGH SPEED TRAINS

Abstract

The train system is the most convenient means of transport in terms of cost and comfort. Recent advance have made possible to run the trains at higher speeds and the train speed in some of the countries has already reached beyond 300 km/hr. Now, when the train is running at very high speed it's not economical to use only mechanical brakes. Hence, aerodynamic braking may be used to slowdown the speed of the train. Mechanical brakes will be used along with aerodynamic brake on the railway trains to accelerate the deceleration or to keep them standing when parked. This report is concerned with the problem of aerodynamic brake by increasing the drag to control the forward speed. Aerodynamic brakes reduce the speed of the train without any mechanical or material losses. Once the speed of the train is reduced form high speed to low speed through aerodynamic brake, then conventional brakes can be used to stop the train. Time required for reducing :the speed of the train from higher speed to around 10 m/s has been calculated. A numerical investigation has been done in order to analyze the performance of aerodynamic brakes with the help of FLUENT at different speeds of 25 m/s, 50 m/s, 75 m/s and 95 m/s. The increase in drag force that results from the use of aerodynamic brake has been estimated numerically using FLUENT. To generate this drag force two mechanisms have been used here: 1. Side flap at the front of the engine. 2. The air jet developed due to high running speed of the train. Aerodynamic brakes enable decrease in speed during the operation of braking at high speed, make possible deceleration in train speed and allow a considerable braking of train. The drag on a moving vehicle can be increased by ejecting transverse air jets which in turn can be generated through the relative velocity between the vehicle and atmospheric air. A vehicle can be designed to hive holes/flaps which remain close during sailing and may get open to enhance the drag force. As we open the flaps and holes, drag force generated is around 60-70% more than that of drag force on train with closed flaps and holes.