電気自動車用モータ構造を模擬した回転二重円筒内の流動可視化観測

抄録

Heat removal in the exothermal of electric vehicle (EV) motors has been studied. Improvement of efficiency of EV with arranging thermal-hydraulic characteristics in the motor is required. However, the flow field in EV motor is not clarified. The aim of the present work is to clarify the flow characteristics of the narrow gap between an inner high speed rotating cylinder and a stationary concentric cylinder. In the present study, the gap between the inner rotating cylinder and the stationary concentric cylinder is visualized with experimental apparatus which simulates the geometry of an EV motor. Water is adopted in order to simulate the actual status of flow characteristic in the EV, where air flows as working fluid, by the Reynolds analogy. In addition, Reynolds number is applied as one of the experimental parameters and is changed in the range of 247 ≤ Re ≤ 2510 at intervals of about 65. The flow structures in the gap and the rotor end part are observed with mixing Kalliroscope flakes and nylon particles in the water. As a result, distinguishing stripe pattern which seems to be the Taylor vortex was observed. Furthermore, the flow regimes changed to different way such as azimuthally waves appear to stripe pattern by changing Reynolds number, finally it transited to complicated flow. The flow field of the rotor edge part observed from the stator end face also transited to complicated flow with increase of Reynolds number. However, flow direction turned from the circle of stator edge face to the central shaft and it does not change with increase of Reynolds number. The fluid in the gap did not actively move over to rotor edge part before Re = 383, but it moves obviously beyond Re = 584.