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Numerical investigation of flow control strategies on delta wings

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2019
Yıldırım, Alper
The use of Unmanned Aerial Vehicles (UAV), Unmanned Combat Aerial Vehicles (UCAV) and Micro Aerial Vehicles (MAV) have been increasing in recent years. The researchers aim to understand the complex flow structure around low sweep angle delta wings, which are frequently used in such vehicles.They are also interested in controlling the flight performance of these vehicles by various active and passive means. This study involves numerical simulations of flows around a delta wing with a sweep angle of 45oat high angles of attack. Passive bleeding, which is a method based on the idea of transferring momentum from the pressure side of the flow to the suctions side by allowing air to pass through the bleed holes, is used as a flow control technique. Various bleed hole configurations are studied and the effects of the dimensions, locations and orientations of the holes on the flow fields are examined. Four design alternatives are proposed and tested at attack angles of 16°, 17° and 18° and Reynolds number of 75000. Results show that the performance of the passive bleeding method is highly affected by the geometrical parameters of the holes. It is seen that the newly proposed idea of using yaw angle, i.e. positioning the holes not parallel to the leading edge but with an angle, gives promising results. With appropriate bleeding hole sizing and positioning, it is observed that three-dimensional vi flow separation is delayed and suction pressure is increased even at high angles of attack by the regeneration of vortical structures.