AN EXPERIMENTAL-STUDY OF THE FLOW OVER A TRAIN IN A CROSSWIND AT LARGE YAW ANGLES UP TO 90-DEGREES

Experimental studies and numerical modelling of the flow over a train in a crosswind have, until recently, focused on the cases of yaw angles up to about 40-degrees, in which use was often made of the slender body analogy. As the yaw angle is increased above 40-degrees it is generally agreed that the flow changes from that associated with a slender body to unsteady vortex shedding. The mechanism of this transition between these two types of flow and its effects on the aerodynamic forces on the train, however, have not been investigated in. detail. The present paper reports a series of experiments of the flow at yaw angles above 60-degrees, which reveal details of the wake structure. The transition mechanism and its effects on the aerodynamic loads are hence deduced. The present observations complete the understanding of the flow over the entire yaw angle range from 0-degrees to 90-degrees.