Aerodynamic Charactristics And Dynamic Performance Of High-speed Train On Viaduct Under Crosswind Condition

At present, the operation length of new high-speed railway is more than6000km in China, and6000km-length high-speed railway will come into service in2012. Then, Chinese high-speed railway backbone network will be completed basically and pass through vast region. The length of railway line on bridges covers more than80%of new high-speed railway in China. Affected by different geological and climatic condition, the running safety of high-speed train passing through the bridge is rather complex, which is a crucial issue during the running operation of Chinese high-speed railway. In particular, the running safety of high-speed train on the bridges, under crosswind, is quite important. However, the corresponding investigation is still not comprehensive in China, more detailed research work is required. On the other hand, the research work on aerodynamic performance and running safety of the high-speed maglev train on bridges, under crosswind, is rare in the world. Although the Shanghai maglev train has running for almost9years, so the research on running safety of maglev train under crosswind is also demanded to develop maglev transport technology. Under this background, the thesis studied the aerodynamic performance of the wheel-on-rail high-speed train and the high-speed maglev train on bridges, under crosswind, are investigated, as well as the running safety of high-speed train. The conclusions drawn from the numerical analysis will provide some reference to the design, construction and operation of Chinese high-speed railway.Firstly, aerodynamic models of the wheel-on-rail train and bridge system, the maglev train and bridge system under crosswind are set up. Then, the corresponding train dynamic models are built. The flow structure around the train and the pressure distribution on the surface of train are discussed. Influences of train speed, crosswind velocity and height of viaduct on aerodynamic performance of the wheel-on-rail train and maglev train are analyzed. Aerodynamic performances and the running safety of the wheel-on-rail train, under natural wind and even wind, on the windward and leeward side of a double-track viaduct, are compared. The critical safety running speed of the wheel-on-rail train in crosswind is determined based on a plenty of numerical analysis. In the same way, the impact of crosswind on the levitation and guidance gap of maglev train are studied considering flat ground track and viaduct track respectively. The effect of crosswind speed on levitation and guidance gap of maglev train is discussed. Dynamic performances of maglev train are studied in detailed considering the crosswind and track irregularity etc.Some conclusions are drawn from the numerical analysis. Aerodynamic performances and the running safety of the wheel-on-rail train in crosswind are mainly determined by the head car, while the maglev train’s aerodynamic performance is decided by both head car and tail car. With the increase of train velocity, crosswind speed and height of viaduct, both aerodynamic performances of the wheel-on-rail train and maglev train become worse and worse, as well as the running safety of the high-speed train. The changing rules of aerodynamic forces of high-speed train on viaduct is almost same as that on embankment when the crosswind speed and running speed of train increases. But, the aerodynamic performances of the high-speed train on viaduct is slightly better than that on embankment. When the wheel-on-rail train runs in natural wind, aerodynamic performances and running safety of high-speed train are worse than those in even wind. When the wheel-on-rail train travels on the leeward track, aerodynamic performances and running safety of the train are better than those on the windward track. Generally, the ratio of wheel-road reduction always exceeds its safety limit value firstly when the crosswind speed or the train speed increases, while the vertical wheel/rail force surpasses its limit value at last. Due to crosswind/aerodynamic effects, the static offset of levitation and lateral gap of maglev train occurs, and the amplitude of gap fluctuation increases slightly with the crosswind speed. The crosswing aerodynamic effects have little influence on vibration acceleration responses of the maglev train, the vertical mid-span deflection and vibration acceleration of the elevated-guideway.