COMPARATIVE CFD ANALYSIS OF AIRFOILS FOR UNMANNED AERIAL VEHICLES

Abstract

In recent years, Unmanned Aerial Vehicles (UAVs) have become an important constituent of the defence aircraft industry internationally. They are even preferred over conventional fighter aircraft in certain circumstances as they can be controlled remotely and have an endurance of approximately 24 to 48 hours. As in the case for most aircraft, wing profiles or airfoils have a large influence on the lift and efficiency of UAV wing structures too. Most current research focuses on comparison and analysis of various airfoils. Our study deals with the selection of a suitable airfoil for use in a UAV wing structure. We will accomplish this by selecting an available airfoil and then comparing it to an airfoil currently employed in a successful UAV. Cambered airfoils which provide lift even at low or zero angles of attack are usually used in UAV wing structures. Based on this and other basic requirements for UAV wing structures, weused NACA 4415 airfoil for comparison with NASA LRN 1015 airfoil currently employed in the Northrop Grumman RQ-4 Global Hawk. Using Computational Fluid Analysis (CFD) we simulated the airflow about the aforementioned airfoils at Mach numbers and altitudes typical to UAVs. We thenobtained the values and trends of values for the coefficients of lift, drag and pitching moment for both airfoils. Key similarities were found between the lift drag and pitching coefficient characteristics and trends of these characteristics leading us to preliminarily conclude that NACA 4415 may be used in a UAV. Hereupon, further 3D CFD analysis or wind tunnel experimentation with a 3D wing model may be undertaken to confirm this choice.