الفهرس يوجد فقط 14 صفحة متاحة للعرض العام
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المستخلص
This thesis show the effect of active slat on the airfoil performance parameter and separation, throughout the simulation of clean airfoil and compare the results with forced blowing, clean slat and active slat In this study active flow control to delay separation over a NACA 4418 airfoil is investigated. The novel approach in this study is the use of an ”Active Slat” in which the slat is actively operated to enhance the mixing on the upper surface and delay separation. The concept of the active slat flow is realized using an oscillating blowing jet by four studies. First the simulation on a clean airfoil at Re=40,000 and angle of attack 10{u00BA} is performed. Second a harmonic blowing jet is added on the upper surface of the airfoil. The width of the jet is 1.5% of chord length. Investigations for different jet parameters (dimensionless frequency f+, jet amplitude Vjet, dimensionless distance X+) are considered. Numerical simulations are conducted over a range of parameters of jet locations (0.055, 0.074, 0.09 and 0.2 % of chord from leading edge); jet velocity ratios (0.1 and 0.01 times of free stream velocity) and dimensionless frequency f+ (0.1, 1 and 10) are investigated. Simulation results show that an increase in lift and reduction in drag is possible. Third the simulation of an airfoil with slat is investigated. The relative outlet flow angle is controlled by the geometry of the slat. Different slat geometries were selected to have exit flow angles of 10-15o relative to airfoil surface. The results show good effect on the performance with lift increase and drag reduction and separation delay. Finally the simulation of an active slat based on the previous study is investigated