The Bridge-Windbreak Influence On The Operational Sfaety Of Vehicle Under Cross Wind

Nowadays, the construction of high-speed railway in China is placed in the great developing period. The bridge and tunnel take a rather high percentage in the high-speed railway. Meanwhile, because of the great distance between the bridge and ground, the natural wind speed seems relatively higher. So the safety of the operating vehicle under cross wind has becomes a severe problem, especially when passing through a bridge. In addition, with the increasing speed of the vehicle, the safety problem will be even tougher. By setting windbreak on bridges, the wind load acted on vehicle will be reduced and the overturning critical wind speed will be improved. Therefore, in engineering, windbreak is a typical measure to enhance the safety of the vehicle when passing through bridges in strong wind area.In this paper, CFD numerical simulation and wind tunnel model test are used to research the aerodynamic characteristics of the vehicle under cross wind when the style of windbreak changes. The main research work is carried out as follows:Firstly, based on the finite volume method, the flow equations are spatially discretized space domains and code FLUENT is used to build multi-layer hybrid grid. After a great number of trial calculation, the size of solution region is determined. SSTκ-ωeddy viscosity coefficient model is chosen to model turbulent flow in Reynalds time-averaged equations.Secondly, models in two-dimension space of vehicle-bridge-windbreak are established to analyze the relations of the height and ventilation rate of windbreak to the aerodynamic characteristics of the vehicle.Furthermore, wind tunnel model test is used to study and verify the relations between parameters of windbreak and aerodynamic characteristics of the vehicle.At last, a model in three-dimension space is built. The results draw a relationship how the aerodynamic coefficients vary with the velocity of vehicle with the given working condition. Accordingly, the overturning critical wind speed of vehicle is calculated.By CFD and wind tunnel model test, appropriate windbreak parameters for engineering application can be obtained. The research shows that the height and ventilation rate have important effect to the wind protection effect of windbreak. The research conclusion certainly guides significance and reference value to select the concrete windbreak parameters.