Abstract
The aerodynamic features of a train and flat closed-box bridge system may be highly sensitive to train-bridge aero interactions. For the generally utilized railway bridge-deck with two tracks (the upstream and downstream ones), the aero interactions above are occupied-track-dependent. The present paper thus aims to reveal the aero interactions stated above via a series of wind tunnel tests. The results showed that the aero interactions of the present train-bridge system display four typical behaviors, namely, the underbody flow restraining effect, bridge deck shielding effect, flow transition promoting effect, and the flow separation intensifying effect. The above four aero interactions result in obvious reductions in the aerodynamic forces of the train in wind angle of attack α of [−4°, 12°] and in the static stall angle of the bridge-deck, and leads to sensible increases in the absolute values of the bridge aerodynamic forces in α of [−4°, 12°]. Upon comparing the results with the same train and bridge system but with the train model mounted on the downstream track, the quasi-Reynolds number effect was non-detectable when the train model was moved to the upstream track. Thus, no drag crisis and other saltatory aerodynamic behaviors were observed in the present study in α of [0°, 12°].
Highlights
Railway vehicles need to run on or through long-span bridges, i.e., HutongYangtze river railway bridge, Jinshajiang railway bridge, and Strait of PingTan Bridge [1].The serviceability of trains running on such long-span railway bridges is of major concern around the world [2,3,4]
The above quasi-Reynolds number effect governs the main flow features of the train-bridge system with the train model mounted on the downstream track in α = [0◦, 12◦ ]
The aerodynamic features of a train and flat closed-box bridge system with a train model mounted on the upstream track was investigated via wind tunnel tests
Summary
Railway vehicles need to run on or through long-span bridges, i.e., Hutong. To assess the dynamic responses of the long-span railway bridge induced by crosswinds, the aerodynamic properties of the bridge deck need to be measured, analyzed, and classified. The relative spatial position of two objects (i.e., circular cylinders, square and rectangular prisms) plays a determining role in their aerodynamic forces, flow structures, pressure distributions, velocity fields, and near wakes [30,31,32] When it comes to the train-infrastructure system, the change of the relative spatial position of the train and infrastructure is mainly influenced by the variations of the occupied track the train is running on. The present research carried out a series of wind tunnel tests to study the crosswind aerodynamic characteristics of a train and flat closed-box bridge system with the train model mounted on the upstream track, as well as the underlying flow physics.
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