International Journal of Engineering Trends and Technology (IJETT) – Volume 35 Number 1- May 2016 ISSN: 2231-5381 http://www.ijettjournal.org Page 33 Numerical Analysis of Drag Reduction Method Using Vortex Generator on Symmetric Aerofoil 1 P Jennifer Vinodhini, 2 T Jebin Samuvel, 3 G Samuel Raj 1 Student, 2 Assistant Professor3Student Sri Shakthi Institute of engineering and technology Chinniyampalayam, Coimbatore, Tamil Nadu-641062, India Abstract—Design and analysis of vortex generator by using Computational Fluid Dynamic on Subsonic Aircraft model is carried out on this project. One of the main causes of aerodynamic drag is the separation of flow near the aircraft’s rear end. To control the flow separation, various shapes of vortex generator is tested for application on the roof of aircraft wing surface. A vortex generator is an aerodynamic device, consisting of a small vane that creates a vortex. It modifies the flow around the surfaces affecting boundary layer and controlling the flow separation. The objective of the project is introducing the delta wing shape vortex generator and determining the percentage of drag reduction, which is designed by Computer Aided Design in CATIA V5 software. Vortex generator reduce drag by preventing flow separation at downstream of the aircraft wing. Drag Force values can be obtained by using output of CFX Besides that, CFX simulation results of streamline flow at the rear end of symmetric Airfoil model is also obtained. Comparison of drag coefficient values of the model with Various Shapes of vortex generator must be done and the most efficient shape is important to achieve is the project objectives. Keywords—External flow, Boundary layer theory, Flow separation and Drag coefficient. INTRODUCTION A vortex generator is an aerodynamic device, consisting of a small vane usually attached to a lifting surface (such as an aircraft wing) or a rotor blade of a wind turbine. When the airfoil or the body is in motion relative to the air, the vortex generators creates a vortex, which, by removing some part of the slow-moving boundary layer in contact with the airfoil surface, delays local flow separation and aerodynamic stalling, thereby improving the effectiveness of wings and control surfaces, such as flaps, elevators, ailerons, and rudders. The effect of flow with and without vortex generator is shown below. Fig. 1 Function of vortex Generator A very effective yet simple solution to avoid separation is to use tabulators/Vortex generators. Each of these small elements creates a swirling wake that places an energy in the boundary layer of the wing. The result is a higher critical angle of attack, a lower stall speed, and gentle stall characteristics. The vortex generators affect boundary layer in the flow around the airfoil. Turbulent boundary layer is more resistant to separation. In this way it is possible to fly at a slower speed and higher angles of attack. Vortex Generators on stabilizers act similarly improving the effectiveness of control at low speeds and with high deflections of control surfaces. Proper location of vortex generators is very important. They should be positioned precisely in the transition region of the boundary layer. Situation is somewhat complicated by the fact that transition region, depending on the flow conditions and angle of attack, changes its position. If Vortex generators will be too close to the leading edge - will be in the laminar boundary layer and cause excessive drag during cruise, but if they are too far from the leading edge -their effectiveness at high angles of attack and low flight speed may be affected. The optimal mounting location can be determined by computer simulations, wind tunnel testing or during test flights.