냉각유로 내 곡관부 및 유로의 회전이 압력강하에 미치는 영향

Abstract

The present study investigated local pressure drop in a rotating smooth square duct with turning region. The duct has a hydraulic diameter (D<SUB>h</SUB>) of 26.7 ㎜ and a divider wall of 6.0 ㎜ or 0.225 D<SUB>h</SUB>. The distance between the tip of the divider and the outer wall of the duct is 1.0 D<SUB>h</SUB>. The Reynolds number (Re) based on the hydraulic diameter is kept constant at 10,000, and the rotation number (Ro) is varied from 0.0 to 0.20. The pressure coefficient distribution (C<SUB>p</SUB>), the friction factor (f) and the thermal performance (ŋ) are presented on the leading, the trailing and the outer surfaces. It is found that the curvature of the 180°-turn produces Dean vortices that cause the high pressure drop in the turning region. The duct rotation results in the pressure coefficient discrepancy between the leading and trailing surfaces. That is, the high pressure values appear on the trailing surface in the first-pass and on the leading and side surfaces in the second-pass. As the rotation number increases, the pressure discrepancy enlarges. In the turning region, a pair of the Dean vortices in the stationary case transform into one large asymmetric vortex cell, and then the pressure drop characteristics also change.