Study on aerodynamic characteristics of a two-dimensional high-speed train/bridge model under a turbulent wind profile
The strong turbulent environmental wind aggravates the instantaneous characteristics of the flow field around a high-speed train,which then causes strong fluctuating aerodynamic loads of the train and directly poses a risk to the running safety. When the train runs on a viaduct,the aerodynamic load of the train would change more greatly under the coupling condition of the environmental wind,train,and bridge. Therefore,it is particularly important to adopt a more real turbulent wind profile to simulate the aerodynamic characteristics of high-speed trains running on bridges under crosswinds and clarify the flow structures' characteristics around trains under different wind field profiles. Based on the large eddy simulation method,the aerodynamic characteristics of a two-dimensional car body standing on a 10 m high bridge under the constant uniform wind profile,exponential average wind profile and exponential turbulent wind profile (based on the harmonic synthesis method and using Kaimal wind speed spectral density model to generate the time history data of wind speed) were studied. The results show that there are great differences in the flow structure around and the aerodynamic performance of the car body under different wind field profiles. Compared with the exponential average wind profile,a pair of more fully developed vortex structures is produced on the leeward side of the car body under the constant uniform wind profile. The lateral force coefficient of the car body decreases by 16.4％,the lift coefficient increases by 59.7％ and the overturning moment coefficient decreases by 23.6％. Thus,there is a significant difference in the aerodynamic characteristics of the trains under the two time-averaged wind fields corresponding to different wind profiles. However,when the exponential turbulent wind profile is adopted,the surface pressure distribution of the car body shows a differential change. The lateral force coefficient of the car body increases by 9.0％,the lift coefficient decreases by 13.4％ and the overturning moment coefficient increases by 9.5％,which shows that the turbulent wind profile has a significant impact on the aerodynamic performance of the high-speed train on bridges. The research results of this paper can provide technical support for the operational safety and the speed-limit control system of high-speed trains running on bridges under crosswinds.
万方数据
维普
