Aerodynamics of a scale model of a high-speed train on a streamlined deck in cross winds

Abstract

The cross wind aerodynamics of a high-speed train (HST) on a streamlined deck was investigated using sectional models in a wind tunnel. Aerodynamics of the HST-only model was also measured as a benchmark under similar conditions. The experimental results indicate that when the HST is on the downstream track of the deck it experiences significant changes in its aerodynamics depending on the angle of attack (α) of the oncoming flow. With an increase in α beyond zero, the mean drag and mean lift forces on HST begin to decrease or increase rapidly. This observation is attributed to the variation in the flow regime around HST from subcritical to critical although the approaching flow Reynolds number (based on the free-stream oncoming flow velocity U∞ and the height of train d) remains unchanged. The separated shear flow from the leading edge of the bridge impinges on the upstream shoulder of the HST on the downstream track at a critical orientation of the approach flow angle. The resulting accelerated flow in the shear layer, characterized by higher turbulence intensity, prompts the flow regime transition near the upstream shoulder of the HST without a change in the inflow Reynolds number. This change in the pressure field over the upstream shoulder of HST when it is on the downstream track on the bridge bears strong similarity to the changes experienced by circular cross-sections or cross-sections with rounded corners with a change in the inflow Reynolds number.