Aerofoil Essay

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Chapter 1

Introduction

1.1 What is aerofoil?

Aerofoil is a large stucture which is attached to the airplane. It has curved surfaces designed to give required ratio of lift and drag. It helps to create different aeodynamic forces. The force perpendicular to the motion of aeofoil is lift force. The force parallel to the motion of aerofoil is drag force. 1.2 How it works?

Aerofoil consists of following components:

• Suction surface
• Pressure surface
• Leading edge
• Tailing edge
• Chord line Figure 1 Profile of Aerofoil
Source: (Wikipedia, 2017)
On suction surface high velocity of air and low static pressure is generated. On lower surface low velocity of air and high static pressure is generated. Due to the pressure difference in suction surface and lower surface lift is generated. The point on which maximum pressure is generated is known as leading edge. The trailing edge is the point having minimum curvature of he aerofoil. The line
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The experiments were performed in a closed-type subsonic wind tunnel of test section 0.15 m (width) 0.15 m (height) 1.8 m (length). The turbulence intensity of the empty wind tunnel was less 0.1% at 7 m/s. The NACA 0012 airfoil model made of acryl has a chord length of C ¼ 75 mm and a thickness of 9 mm. The airfoil model was mounted in the middle height of the test section at zero angle of attack. During the experiments, the Reynolds number based on the airfoil chord length was varied in the range of Re ¼ 1.03 104–5.14 104. The aerodynamic forces acting on the airfoil model were measured using a three-component load-cell with a nonlinearity of less than 70.5% in the full range of 2 kgf. The load-cell having temperature sensitivity of 0.05%/1C was coupled with a DC strain amplifier (DSA-100). The precision error is less than 2%. The drag coefficient based on the effective frontal area (A) of the airfoil model was defined as follows:
CD1/4=Drag/(0.5*ρ*U∞2

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