Heat Transfer Characteristics in Coaxial Cylinders simulating an Electrical Rotating Machine

Abstract

Toward the improvement of performance of an electrical rotating machine such as a motor and a generator, an appropriate design for heat removal is important. A typical motor is composed of the pair of coaxial cylinders with the fixed outer cylinder (i.e. stator) and rotating inner cylinder (i.e. rotor). The present study numerically clarifies the influence of inner shape on heat transfer characteristics in the electrical rotating machine. The heat transfer coefficient of the gap region between the rotor and stator was obtained. As a result, a vortex structure was observed in the slit on the stator wall, and the heat transfer coefficient of with-slit case in the high rotational speed was increased compared with that of without-slit case. Hence, it was implied that the heat flux was increased by the presence of the vortex of the internal slits.