Simulation on Unsteady Crosswind Forces of a Moving Train in a Three-Dimensional Stochastic Wind Field

Abstract

Unsteady aerodynamic forces are significantly critical to the safety and stability of trains traveling in high winds. This paper describes a study into unsteady crosswind forces of a moving train subjected to a three-dimensional stochastic wind field with longitudinal, lateral, and vertical turbulences. Initially, a three-dimensional computational fluid dynamic (CFD) model is established to calculate the aerodynamic coefficient of a moving train, and then the wind velocity time histories at the position of the train are generated. Finally, the quasi-steady theory and weighting function method are used to model the unsteady crosswind forces of a moving train in a three-dimensional turbulence field. The results demonstrate that a generalized sine form is useful for predicting the aerodynamic coefficient that varies with the resultant wind yaw angle, and an adequate modeling of unsteady crosswind forces with complete wind turbulences can produce a greater force fluctuation and peak. Particularly when the flow direction of crosswind deviates from 90°, consideration of only a portion of the turbulence components may underestimate the dynamic response of trains.

Keywords

• unsteady force
• crosswind
• moving train
• CFD
• wind turbulence