Numerical analysis of flow interference on flat-plate-modeled aerodynamic brakes for high-speed railways

Abstract

An aerodynamic brake is a device that is aimed for increasing air drag to obtain brake force by expanding plates. As proposed by Takami (2013), multiple plates are distributed on the train roof. In this arrangement, many devices are installed in the wake of the most upstream device. In the wake, where the flow is slow, the devices are difficult to gain drag force. Thus, to obtain efficient drag force in this method, it is desirable to rearrange all the devices so that they are subjected to a higher velocity flow. For this purpose, it is important to understand the influence of the device arrangement on the obtained drag, and this drove us to perform a computational flow analysis on flat-plate-modeled aerodynamic braking devices. Specifically, the flat plates are placed in the staggered layout and the clearance between the flat plates (in the crossflow direction) was parametrically varied. Then, their impact on the magnitude of drag force and the flow field were investigated. As a result, by decreasing the clearance between the flat plates from 50 % to 0 % of its width, drag force increased by 11 % because the flow velocity behind the plates easily recovered so that faster flow hits the plates located downstream.