Parametric Effect of Roughness Over an Airfoil

Introduction

The wing sectional view is called an airfoil which can be obtained along any cross-sectional plane of the three-dimensional wing. Airfoil is designed to allow flow over the top and bottom of the wing. The design of Airfoils has allowed the broad laminar stream, like the National Advisory Committee for Aeronautics (NACA) 4, 5, 6, and 7 series, of which NACA 6 and 7 series are called explicitly as Laminar airfoils have significantly less drag at average lift coefficients than different types of airfoils (Srivastav, 2012), (Howe, 2010),(Lambert, 2006). Before the National Advisory Committee for Aeronautics (NACA) fostering these series, airfoil configuration was somewhat subjective w,ith nothing to direct the designer besides previous involvement in known shapes and trial and error with adjustments to those shapes. The Advisory Committee has proposed the design of airfoils with the same curvature on the top and bottom, which are called symmetric airfoils. The curvatures are not the same on the top and bottom of the airfoil are called Unsymmetrical airfoils.

As per the NACA, symmetrical airfoils of four series are designated as NACA 00XX, where the XX is represented as the thickness of the airfoil, and the first two digits indicate that the curve is symmetric about the midline joining the leading and trailing edge called as chord line. Be that as it may, the symmetric airfoil delivers less lift than a nonsymmetrical airfoil and generally has bothersome slow-down qualities. The helicopter’s cutting edge (airfoil) should adjust to a broad scope of velocities and approaches during every insurgency of the rotor. The even airfoil conveys satisfactory execution under those exchanging conditions. Different advantages are lower cost and simplicity of development than the nonsymmetrical airfoil. Nonsymmetrical (cambered) airfoils might have a wide assortment of upper and lower surface plans. The benefits of the nonsymmetrical airfoil are expanded lift-drag proportions and more beneficial slow-down qualities. Nonsymmetrical airfoils were not utilized before in helicopters as the focal point of the pressure area moved a lot when the approach was changed. When the focus of strain moves, a bending power is applietoon the rotor edges. Rotor framework parts must be planned that would endure the bending power. Ongoing plan processes and new materials used to fabricate rotor frameworks have conquered the issues of using nonsymmetrical airfoils.