Abnormal separated flow intensification and heat transfer enhancement in single-row inclined oval-trench dimples on the narrow channel wall

Abstract

Intensification of turbulent separated air flow and heat transfer enhancement at the hydrodynamic stabilization length on the periodic section of the narrow channel with inclined one-row oval-trench dimples (OTDs) is analyzed. The periodic section of the channel of height equal to 1, length – 8, and width – 9 is considered at Re=104. The inclined OTD 0.5 in width, 7.05 in length, and 0.25 in depth is located in the center of the heated isothermal wall. The rounding radius of the dimple edge is 0.21. The OTD inclination angle varies from 0° to 52.5°. It is found that the optimal inclination angles in terms of thermal and hydraulic performance (THP) are equal to 45° and 30°. It is observed that at large inclination angles the minimum value of relative friction decreases many times (up to-3.5).