CFD-BASED AERODYNAMIC ANALYSIS OF THE FLOW PAST AN AIRFOIL WITH PASSIVE TRAPEZOIDAL AND PERFORATED VORTEX GENERATORS

摘要

Passive vortex generators are widely used for heat and mass transfer enhancement in static mixers and heat exchangers. Trapezoidal vortex generators are used in the high efficiency vortex static mixer (HEV) because they generate a complex flow structure enhancing the transport phenomena. Moreover, vortex generators are used on airfoils and cars to delay or suppress flow separation. The flow past triangular and rectangular winglets was studied in the open literature showing good performance in enhancing the lift and drag coefficients. In the present study, a non-conventional vortex generator is proposed consisting on an inclined trapezoidal tab similar to that used in the HEV static mixer. In addition, the tab is perforated at its center (circular perforation). Inline array of several vortex generators are fixed on an airfoil and the drag and lift coefficients are analyzed for different geometries using computational fluid dynamics. Different cases are analyzed where the inclination angles of the vortex generators are changed and their effect is investigated. Furthermore, the effect of changing the size of the vortex generator is also assessed. The results are then compared to conventional vortex generators, mainly triangular winglets. The present results are validated against experimental and numerical data from the literature. The results show that the drag coefficient can be reduced with such vortex generators. They also show good agreement with experimental results for the lift coefficient.