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

Highlights • Heat transfer enhancement in a channel with VGs with and without a hole. • The rectangular VGs with a hole can effectively decrease the flow resistance. • Effect of the hole diameter and position of the rectangular VGs with a hole. • Simulated results were validated based on the experimental date and formula data. Abstract 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. [ABSTRACT FROM AUTHOR]