Experimental Study Of The Convection Heat Transfer Of The Surface Of The Rolling Wheel

In recent years, the development of high-speed train and heavy-duty train in our countryis fast. Friction heat produced when trains move and in train braking process. The effect offriction heat is extended to the safety and cost of train running. As the base data of frictionheat transfer in the wheel, heat transfer coefficient decides the friction heat transfer process.The coefficient directly affects the reliability and safety of the train. Due to the influence ofheat transfer, the present study the train wheels are modeled by the rolling wheels. Theconvection heat transfer characteristics of the rolling wheels are studied in specialexperimental system.The contents of present experimental study include: design rolling wheel with differentdiameter; obtain the local and average convection mass transfer characteristics on the rollingwheel surface by using naphthalene sublimation technology; get local and average heattransfer characteristics according to the mass/heat transfer analogy relationship; find a methodto obtain characteristic length which determine the heat/mass transfer of the rolling wheel.The following conclusions can be drawn:(1) the local and average Nusselt number of therolling wheel (surface and tread) increases with increasing rotating Reynolds number;(2)under the same rotating Reynolds number, local Nusselt number of the rolling wheel surfacedecreases along the radial direction;(3) under the same rotating Reynolds number, along theaxis direction of the wheel, the variation trend of local Nusselt number on the rolling wheeltread reduces at beginning, then keeps constant, and then increases;(4) compared with theconvection heat transfer characteristics of a rotating disk, Nusselt number of the rolling wheelobviously lower;(5) the characteristic length determining the heat/mass transfer of a rollingwheel is provided, and then, the correlations of average Nusselt number and Reynolds numberare obtained, the characteristic length provides the foundation of using the experimental datain real applications.