Unsteady Aerodynamic Loads of High-speed Trains under Stochastic Winds

Abstract

To study the unsteady aerodynamic forces of high-speed trains under stochastic winds,the fluctuating winds of a moving point shifting with high-speed trains are calculated in this paper based on COOPER theory and harmonic superposition method.The effects of train speeds and average wind speeds on the dimensionless power spectral density are analyzed.The computational fluid dynamics method is used to obtain the aerodynamic load coefficients at different slip angles.The unsteady aerodynamic load calculation methods for high-speed trains under fluctuating winds are studied and the probability distribution of unsteady aerodynamic loads is derived.The fluctuating winds and the unsteady aerodynamic loads of high-speed trains under train speeds of 200-400 km/h,and average wind speeds of 10-35 m/s are calculated and the results show that the dimensionless power spectral density is moving to a higher frequency range with the increase of train speeds,while the average wind speeds have little effect on it.The average wind speeds have a more significant impact on fluctuating winds than the average train speeds do.When considering fluctuation of the slip angles,fluctuation of the unsteady aerodynamic loads increases.The unsteady aerodynamic loads obtained using the quasi-steady method and the modified quasi-steady method have the characteristic of ergodicity of random processes.While the ones obtained using the weighting function method and the modified weighting function method do not have this characteristic.