The effect of atmospheric turbulence on trains

Abstract British Rail have performed experiments to investigate the probability of new designs of light-weigth trains overturning in high winds. The results show that the aerodynamic force and moment coefficients of model trains are sensitive to the nature of the simulated atmospheric boundary layer used in the experiment. This paper describes an experiment in which a model train has been placed in different free stream turbulance conditions and the force and moment coefficients and the flow on and around the model have been measured. A theoretical approach enabling the prediction of the side force coefficient of the model train in different turbulance conditions is also described. Results are presented for the side and lift force coefficients and the points of action for the leading car of an idealised train model in different turbulence conditions as well as flow field measurements. Theoretical curves for the side force coefficient in the same turbulence conditions are also shown.