Wind Tunnel Investigation of a Double Stacked Wagon in Free-Stream

The surface flow structure and pressure distribution of a model representative of a 48ft, double-stacked container wagon of an intermodal freight train is characterized. The model used is 1: 14.6 in scale, and all experiments are conducted in Monash University’s 450kW closed loop wind tunnel. The model employs 474 pressure taps in total, and data is logged with two dynamic pressure-measuring systems. Flow visualizations are carried out on the top and side surfaces using fluorescent Kaolin china clay with kerosene as a carrier. Testing is performed under three different floor boundary-layer profiles in order to assess the sensitivity of the surface flow variation in the floor boundary-layer. It is shown that in a time-averaged sense, the shear-layer separating off the leading edges of the wagon roll up to form three recirculating bubbles on the top and side surfaces. The consequent surface pressure profile matches closely to that of a surface-mounted cube where top and side pressure recovery occurs. For the three boundary-layer profile tested, pressure distribution displays very minor changes. A Karman like left-right wake shedding is observed in the wake with a shedding frequency of St = 0.195.