The Vortex Generator Control Of Supercritical Wing Boundary Layer Separation

The paper investigates the problem on vortex generator control boundary layer's separation of supercritical airfoil and wing for body configuration wing. According to research on the boundary layer characteristics of airfoil and wing body configuration in wind tunnel test, the characteristics of boundary layer's separation on supercritical airfoil and wing body configuration are clearly understand. The flow mechanism of vortex generator is investigated, to control the boundary layer's separation and improve the lift - drag force performance for airfoil and wing, and the influence of vortex generator's shape, geometry parameter and position is also explored.Many techniques of wind tunnel experiment measure and diagnoses are applied in this paper in low speed large scale wind tunnel. The description of many factors as vortex generator's shape, geometry parameter and position etc. influence the effect on controlling boundary layer separation are presented comprehensively in this paper. The conclusion as follows:1) Supercritical airfoil demonstrates better form of high angle boundary layer separation and bad capacity of resistant stall because of the plainness on upper airfoil and the characteristic of mild separation on boundary layer.2) The control of supercritical airfoil boundary layer separation is adapted using micro-vortex generators. The micro-vortex generators not only can decrease drag during working state, but also produce very small addition drag during non-working state. The best position of micro-vortex generator is located in boundary layer separation line up between vortex generator 's height with 2H to 5H.3) Most part of the supercritical wing with equal chord and high aspect ratio is provided with 2-D flow characteristics approximately except wing tip.4) The supercritical wing with mild separation of boundary layer, which fit for applying micro-vortex generator with small height. It not only has better effect on decreasing drag, but also decreasing the loss of lift. The conclusion is the same as the control of airfoil's boundary layer separation. The high of vortex generators have their best chord position with an outstanding effect on controlling boundary layer separation. The span space of vortex generator has clear effect on controlling boundary layer separation: the small space is not benefit to decreasing resistance, vortex generator's ability to control flow is not sufficient to the beyond with biggish space. The suitable space is △Z = 25mm. The vortex generator's deflection has important effect on controlling of boundary layer separation. The best install angle is β = 25°.5) The mechanism of the vortex generators controlling the separationof the boundary layer is that, they increase the momentum of the bottom boundary layer. This kind change of the momentum affects the pressure gradient of the wing surface, which increases the velocity of the boundary layer upstream of the vertex generators. The technology of oil flow and silk thread can reflect effect of the vertex generators controlling the boundary layer separation of the wing truly.6) The single hot line doesn't fit for the measure of the three-dimensional boundary layer downstream of the vertex generators, according to the result of the flow visualization.