School of Engineering and Materials Science

Den233

Low Speed Aerodynamics

Pressure Distribution and Lift on a Piercy Aerofoil

Abstract

In this experiment in a low speed flow the static pressure around an aerofoil will be observed and discussed. The lift on the aerofoil will also be calculated and compared with the theoretical value. The aerofoil being used in this particular experiment is symmetrical and is taking place in a wind tunnel with a speed of 18.5m/s, therefore the flow is assumed to be incompressible. The different pressures along the surface of the aerofoil will be measured at an angle of attack of 4.1 degrees and 6.2

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This was done by using 13600 as , 9.807 as g and converting 761.5 mmHg to N/.

=101565.2 N/

Having a temperature of 23.5the absolute temperature was calculated using which gives a value of 296.66 K.

The value of is calculated using . By using R as 287.3, and the values above for P and T, it can be calculated as being 1.1917.

By using the equation

,

Where = 288.2 K, S =110.4 K, and , can be calculated to give a value of

The tunnel speed is calculated by

Where This gives a value of 198.59 and when put into the equation equals 18.53 m/s, where k = 1.03.

The critical Reynolds number is calculated using . It works out at 306464.6

By using the equation

The pressure coefficient will be found for each of the pressure tappings. is used to get the local chordwise loading where is the lower surface and is the upper surface at a given chord position.

The values used will be from pressure tappings 2 and 3 at an angle of incidence of 4.1, which are values of 11.7 and 9.8 inches, from the lower and upper surface respectively. These values are first converted from inches to millimetres by doing . This gives a value of 297.18 mm. The same is done