Study of aerodynamic coefficients used to estimate critical wind speed for vehicle overturning

Strong cross wind is one of the most important problems to consider for ensuring the safety of railway vehicles during operation. The critical wind speed for vehicle overturning or wheel unloading ratio is one of the indices used to evaluate the safety of railway vehicles under strong cross wind. The critical wind speed is calculated by the Detailed Equation. The Detailed Equation is an equation that describes the equilibrium of the forces acting on a railway vehicle and has many parameters. In this paper, the influence of each aerodynamic coefficient on the critical wind speed is examined by calculating the critical wind speed for given amounts of change in the aerodynamic force coefficients. The aerodynamic force coefficients used in this study were obtained from wind tunnel experiments (atmospheric boundary layer flow and uniform flow) and a full-scale model field test. We compare the aerodynamic force coefficients obtained by the respective experiments, and we evaluate the effects of the aerodynamic force coefficients by using the critical wind speed determined from the aerodynamic force coefficients. (C) 2015 Elsevier Ltd. All rights reserved.