Promising dimple technologies of vortex heat and mass transfer enhancement in energy and microelectronics

Abstract

Turbulent separated air flow and heat transfer at the starting hydrodynamic length of the longitudinal section of the dimpled narrow channel (1 in height, 4 in width, and 84 in length) with inclined one-row oval-trench dimples (OTD) are calculated. Packages of 20 and 31 dimples are compared. Each dimple has a length of 4.5, a width of 1, a depth of 0.2, an edge rounding radius of 0.2, and an inclination angle of 45°. Re=6000 and is determined in terms of the flow velocity at the channel entrance. The effect of abnormal separated flow intensification and heat transfer enhancement in OTDs due to the dimple density is confirmed. (fx/fxpl)min=−4 and (Nu/Nupl)max=7.2. Relative heat transfer grows by a factor of 1.9 and relative hydraulic losses – by a factor of 1.6.