Numerical simulation on heat transfer characteristics of rectangular vortex generators with a hole

Vortex generators (VGs) can enhance the heat transfer of the channel, but it can also cause a certain pressure loss. In order to decrease the flow resistance of VGs, the VGs with a punched hole was proposed. In this research, three-dimensional numerical simulations of VGs are performed to analyze the heat transfer enhancement and the flow resistance in a rectangular channel with two-row rectangular vortex generators with and without a hole at the Re from 214 to 10,703. The heat transfer enhancement and the pressure drop are described by using the dimensionless factors Colburn factor j, friction factor f, and thermohydraulic performance factor PEC = j/(f)1/3. Then, the effects of the hole diameter and the hole position were investigated. The results show that the values of PEC in the rectangular vortex generators with a hole are larger than those in the rectangular vortex generators without a hole. Through the analysis of the values of PEC, j and f, the optimal diameter of the hole is determined as d = 5 mm. In the vertical direction, the PEC increases with the increase of c and has the maximum value at c = 4.5 mm. In the lateral direction, the PEC first increases and then decreases slightly and has the maximum value at e = 18 mm.