Detached Eddy Simulation of the Flow around a Simplified Train under Crosswind Conditions
- 作者：Gao GuangjunWang XiaoyaHassan Hernida
- 会议时间：2012-12-05
- 关键词：Train ; Wind angle ; DES ; Aerodynamic performance ; Personal safety from running train
- 作者单位：Gao Guangjun,Wang Xiaoya(School of Traffic&Transportation Engineering,Central South University,Changsha 410075,China)Hassan Hernida(School of Civil Engineering,University of Birmingham,B15 2TT,UK)
- 母体文献：2012年全国环境风工程学术会议论文集
- 会议名称：2012年全国环境风工程学术会议
- 会议地点：厦门
- 主办单位：中国空气动力学会
- 语种：chi
摘要
There is a growing concern on stability of high-speed trains in strong crosswinds.In this paper, the influence of wind yaw angle on train aerodynamic performance is investigated using Detached Eddy Simulation (DES) combined with the method of dual-time step LU-SGS for transient iteration.The Reynolds number of the flow is 4.027× 106 based on the wind speed and height of the train.The computations are performed on a 1/10th scale model of the CRH1 train using seven different wind yaw angles: 0°, 15°, 30°, 45°, 60°, 75° and 90°.The results show a great effect of the yaw angle on the train aerodynamic performance.The trends of side and lift force coefficients and overturning moment coefficient of the head car are similar to these of the end car in the range of wind angles from 0° to 90°, rising linearly with the increase of wind angle.However, the coefficients of the end car are almost double the values of the corresponding coefficients of the head car.High pressure is observed on windward surface of train while a relatively low pressure is obtained on the other surfaces.The maximum pressure appears nearby the centre of windward surface of the front ear and the minimum pressure appears in windward edge of the roof of the train.With the increase of wind angle, the pressure of windward side of first and second cars increases gradually and an area of a lower pressure is built up on the leeward side.Streamlines on the streamwise face are divided into two directions; towards the roof of the train and towards the bottom face.The DES results show some diverse vortices distributing in the windward and leeward sides of carbody, and with the increase of wind angle these vortices increase in number and size.At 90° yaw angle, the flow field around the head and end cars is basically symmetrical.The aerodynamic forces experienced by a person in the track side of a passing train at speed of 250 km/h were also determined.A significant effect of the pressure and airflow are noticed if a person is within 7 m from the side of the train.The effects of pressure and induced airflow are, however, decreasing with the increasing the distance from the side of the train.It is found also that if the distance between the person and the side of the train is more than 7 m, the effects are almost small and independent of the distance of the train.