Parametric study and optimization of flow and heat transfer characteristics in microgaps with longitudinal vortex generators array

In this paper, a three-dimensional numerical model of the microgaps with longitudinal vortex generators array is developed. In order to improve the the flow and heat transfer characteristics, the Taguchi method is employed to optimize the configuration of the model. The influence of seven geometric parameters, including the structure and arrangement of the longitudinal vortex generators and the height of microgaps is investigated numerically. Three evaluation indexes including heat transfer performance, flow resistance performance and overall performance, were selected to evaluate the optimized results. With the same uniform heat load of 10⁶W/m², 18 orthogonal tests have been carried out to established the optimum combination of different influence factors. The results show that the height of microgaps and the spacing of the longitudinal vortex generators pairs have significant influence on the Nusselt number. And the longitudinal spacing of two longitudinal vortex generators and spacing of two longitudinal vortex generators pairs have the high contribution ratio for the friction factor. In addition, the cooling capabilities of longitudinal vortex generators arrays and circular pin fin arrays were compared. The longitudinal vortex generators pin fin arrays show lower pressure losses in spite of reducing heat transfer performance.