2015 年 81 巻 822 号 p. 14-00307
Hydrodynamic structure and heat transfer characteristics in coaxial rotating cylinder simulating Electric Vehicle (EV) motor are experimentally and numerically investigated. Flow visualization experiment clarifies that Taylor-Vortex flow can be observed in low Reynolds number and transit to turbulent flow as increasing Reynolds number. Numerical results indicate that the flow transition from Taylor-Vortex flow to turbulent flow is caused by the changes of the balance between the centrifugal force and the differential pressure. The heat transfer experiment and the numerical calculation show that the heat transfers in the gap between the coaxial rotating cylinder and the motor end part are in good agreement with Nu = 0.21(TaPr)1/4 and Nu = 1.26Re0.385, respectively. Based on the results obtained, the thermal network model for the EV motor is developed. It is experimentally clarified that the present developed thermal network model can precisely predict the temperatures in each part of the EV motor in a wide range of the motor rotational speed.
