ISSN : 2319–3182, Volume-2, Issue-4, 201338 Airfoil Selection of MAV (Miniature Air Vehicle) for Low Reynolds Numbe r Mayur S. Marathe & S. N. Bansode K.J Somaiya College of Engineering, Mumbai University E-mail : [email protected] sangitabansode@ya hoo.com Abstract –This paper discusses issues and practical requirements of Airfoil for MAV. Here considering the MAV which travel with the speed range between 9-20 m/s. The Airfoil which is been selected on various criteria, i.e. - stable flight, cover maximum distance with minimum force. So here the NACA 2204 is been selected for MAV. The Fluent analysis is done on the airfoil for lift to drag ratio. These MAV are having some purpose i.e.:- they can be use as a spy in enemy area, inspection of hazardous area, where human resource can’t reach. Aerodynamic performance and stability should be considered in the context of the airfoil structural integrity. Particular attention should be paid to the unsteady nature of the flow. Keywords –MAV, NACA 2204, Lift to Drag ratio, Flu ent analysis. I. INTRODUCTION Airfoil for MAV is very important, as it has to travel comparatively more distance & stable flight for the given forces. Here NACA 2204 is been selected as it’s a low camber airfoil. The lower surface of airfoil is somewhat flat, so it doesn’t allow the air flow away from it when it glides down to the surface. The air that hits to the lower surface of an airfoil try to push or lift the MAV, as the MAV is coming down the forces the resultant force will be in downward direction, so it will glide down to surface comparatively at slow speed, which will cause minimum damage. At the same time the airfoil also has to be good lifting coefficient i.e. Lift to drag ratio has to be high. As the MAV has to attain the height within in short range of distance, the stalling angle of airfoil also has to be high. Fig. 1: Airfoil with angle of attack II. DEVELOPMENT CONSIDERATIONS Several areas need to be carefully considered for the selection of a practical airfoil, including aerodynamics. These will be covered in turn, following a discussion of the benefits of airfoil. Consider the simple wing geometry as shown in figure 1 [1] This geometry will be used throughout the remainder of this paper as a baseline. Here the airfoil is at α angle of attack with relative wind (V ∞). III. EFFICIENCY For a selected airfoil, we are principally interested in maximizing lift L and minimizing the drag D, or alternatively, maximizing the lift-to-drag ratio, L_D (also written as the ratio of lift coefficient (C_l) to drag coefficient (C_d) or C_l /C_d, defined below). It is also necessary to look out on the overall efficiency of a wi ng. This ratio depends on wing geometry & air flow condition. These flow conditions are expressed as dimensionless parameters such as the Reynolds number Re and Mach number M. A selected airfoil profile will have vastly different lift and drag characteristics over the possible ranges of Re and M for a profile selected. Thus, airfoils are typically designed for a narrow range of flow conditions for optimum performance. Alternatively, one could design an airfoil that will operate over a wide range of air flow conditions. Lift capability & drag capability of an airfoil is depended on Lift & Drag coefficient, which is given as follows [1] L=0.5*ρ*V^2*S*C_lD=0.5*ρ*V^2*S*C_dFurthermore, the total drag is further subdivide into number of drag, such as, form, pressure, skin friction, parasitic, induced & wave drag. The induced drag can be estimated in terms of wing geometry by
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7/18/2019 Airfoil Selection of MAV (Miniature Air Vehicle)