Effect of Dimple Configuration on Heat Transfer Coefficient in a Rotating Channel

Abstract

The detailed distribution of heat transfer coefficients in a rotating dimpled rectangular channel (aspect ratio =6 and 12) was measured by the transient liquid crystal technique. The rotating speed of the channel was fixed at 500 rpm and the tested Reynolds number based on the channel hydraulic diameter was varied from 19,000 to 44,000. Four different dimple configurations were tested to investigate the effects of relative dimple depth, dimple center distance, and channel height on the heat transfer coefficient. A stationary case and two different rotating directions were tested so that the dimple fabricated surface became the trailing or leading surface. Results showed that the heat transfer coefficient on the dimpled surface was higher if the dimpled surface became a trailing surface. Also, with the same dimple diameter, higher heat transfer coefficients were observed for deeper dimple, narrower channel or densely distributed dimple cases.