Abstract:

To study the unsteady aerodynamic characteristics of pantographs in different positions of high-speed trains, the aerodynamic models of high-speed trains are established based on the theory of computational fluid dynamics. A train with eight coaches is adopted as the train model, which includes a head coach, six middle coaches and a tail coach. The pantograph model has two pantographs, which includes a lifted pantograph and a folded pantograph. The pantographs are fixed on the front end or the rear end of the first middle car, or fixed on the front end or the rear end of the sixth middle car. The flow fields around high-speed trains running in the open air without crosswinds are numerically simulated by the detached eddy simulation (DES) method. The train running speed is 350 km/h. The characteristics of the unsteady aerodynamic forces acting on the pantographs fixed in different positions of high-speed trains are presented from the numerical results, which include the characteristics of the time domain, the frequency domain, and the unsteady flow structures around the pantographs. The results show that the time-average values of the aerodynamic drag force and lift force of the pantographs tend to decrease as the fixing position of pantographs moves backward along the longitudinal direction of the high-speed train. When the lifted pantograph is in the knuckle-downstream direction, the time-average values of the aerodynamic lift forces of the pantographs are smaller than those with the lifted pantograph in the knuckle-upstream direction, and the amplitudes in the aerodynamic lift force and side force of the sliding plate of the lifted pantograph are also smaller than those with the lifted pantograph in the knuckle-upstream direction. The fluctuations of the lift force and side force of the sliding plate of the lifted pantograph have broad frequency distributions, and their main frequencies range from 0 Hz to 300 Hz.

Key words: computational fluid dynamics, pantograph, power spectral density, unsteady aerodynamic forces, high-speed train