Study in Reduction of Vortex Drag at Low Cruising Aircraft Speeds
Aerodynamic characteristics of plain wing designed for Light Sport Aircraft has been studied. The fluid characteristics include induced drag and lift to drag ratio. Then, winglets are added to reduce the induced drag and increase the lift to drag ratio which are affected by the wing tip vortices. The theoretical, and numerical approaches are used to verify the results. A rectangular untwisted 9.528 m wing spans with an Airfoil NACA 4412 was used for the basic design. Winglets are added with a tip airfoil of NACA 0012, side angle of 65o and new projected area of 10.328 m2. Lift and drag coefficients are used as means to measure the improvement of the aerodynamic characteristics. The wing tip vortices increase the induced drag and spoil the lift over the wing's surface. The winglets design main objectives are to decrease the induced drag, decrease fuel consumption, and increase flight safety, especially in take-off condition.
The wing with winglets model was simulated first using 3-D Fluent ANSYS version 14 at 50 m/s velocity and (0o, 5o, and 10o) angles of attack with laminar flow and standard atmospheric conditions at 15oC, and 101 kPa and all other flow parameters as well. The second verification method was to simulate the 3-D model using the 3-D Foil Multi-Surfaces code again with the same flow parameters. Finally, the last verification method was to solve the problem theoretically using the theoretical governing equations. The theoretical solutions were used as a base line for all other results. The total drag reduction observed from the calculations with winglets is about 7.4% during the takeoff regime using theoretical calculations, where the induced drag contributes about 77% of total drag of the plain wings. The lift to drag ratio improved also in our designed model wing with winglets by 14% from the plain wing design.
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