Huoyue Xiang

Numerical Simulation of the Protective Effect of Railway Wind Barriers Under Crosswinds

Computational fluid dynamics (CFD) was employed for the simulation of a train model subjected to crosswinds. The numerical model was validated by comparing the flow structures and aerodynamic coefficients. A discussion of the protective effects of wind barriers at yaw angles in the range 0 < β ≤ π/4 is provided, along with an analysis of the flow distribution, and a proposal for a transformation of aerodynamic coefficients in the presence of wind barriers. The results show that the protective effect of a wind barrier for end nose are different for various yaw angle; the separation lines of the end nose at the leeward side of the vehicle bottom shift to windward in the presence of a wind barrier. The coefficients obtained through this transformation are found to be applicable for the side drag and lift coefficients of the head nose, which were obtained through numerical simulation, and are larger than the coefficients of the end nose at a majority of yaw angles. The yaw angle has a little effect on the absolute errors of the transformation for the end nose. The wind-reduction factor and absolute errors can be used to evaluate the protective effects of railway wind barriers to avoid the appearance of the different protective effect in a wind barrier.

Improved Spectral Representation Method for the Simulation of Stochastic Wind Velocity Field Based on FFT Algorithm and Polynomial Decomposition

AbstractFor the simulation of fluctuating wind velocity field with n processes, the existing spectral representation method requires a total of n(n+1)/2 executions of the fast Fourier transform (FF...

Advance in Coupling Vibration of Wind-Vehicle-Bridge Systems

Lateral wind is one of the most important influencing factors on train running performance. In process of high speed train running along the flexible bridge under lateral wind, there is the interaction among wind, vehicle, and bridge, which represents the coupling vibration of wind-vehicle-bridge system. There was some existing research was reviewed, the latest advance in the field of wind-vehicle-bridge system is presented. Firstly, aerodynamic characteristics, A new test rig with moving vehicle model is developed in a large wind tunnel to respectively measure the aerodynamic force on bridge deck and vehicles while vehicles are running along the bridge deck under cross wind. The effects of vehicle speed, rail position of vehicle on the aerodynamic characteristics of vehicle and bridge are studied. The sudden change of vehicle aerodynamic forces are measured by wind tunnel test when vehicle is passing through the bridge tower and two vehicles are passing each other. Aerodynamic coefficients of CRH2 are also measured in wind tunnel. In addition, train induced wind is simulated by CFD. Second, coupling and failure mechanism, with engineering examples, many parameter studies are carried out to explore coupling mechanism of wind-vehicle-bridge system, including wind field, stiffness of bridge, vibration of bridge, the effect of sudden change of wind load and so on. The control factors in wind-vehicle-bridge system are analyzed for different bridge types. Meanwhile, the above-mentioned research findings and conclusions have been applied in Anqing Yangtze River Bridge, Hanjiatuo Yangtze River Bridge, Tongling Yangtze River Bridge, Shanghai Yangtze River Bridge, etc.