Effect of windage heating on a micro high-speed rotor-stator cavity

The main objective of this work is to investigate the effect of windage heating on the micro high-speed rotor-stator cavity. The influences of centrifugal force and spacing on the windage heating are analyzed with and without the change of gap ratio respectively. The results demonstrate that there is no difference in the flow structure between micro and large-scale rotor-stator cavities at the same rotational Reynolds number and gap ratio. However, the windage heating induced by the larger centrifugal force and smaller spacing brings the different heat transfer laws for the micro rotor-stator cavity. The larger centrifugal force weakens the local heat transfer near the rotor periphery. Such influence can be strengthened at higher rotational Reynolds numbers and lower rotor excess temperatures. Besides, the smaller spacing further enhances the windage heating and reduces the average heat transfer especially under the condition of lower gap ratio. The findings of this work contribute to the design of rotor-stator cavity utilized in the micro rotating machinery.