Aerofoil Experiment

Summary

In this laboratory, a NACA 2415 aerofoil was tested in a wind tunnel at various angles of attack, in order to investigate how this affects the amount of lift generated. It was found that at low angles of attack,  increased linearly by , though this stopped rather abrupty at the stall angle of attack, after which  drops sharply. The effect of adding a leading edge slat was also investigated, which was found to increase the stall angle of attack. Pressure distributions were also plotted at varying angles of attack, some including a leading edge slat, in order to better understand why lift is generated overall, and the fundamental effects of varying the angle of attack and adding a leading edge slat. This helped to understand why boundary layer separation explains why a stall angle of attack occurs. Comparisons were also made to experiments made in the 20th century by NACA, which included tests at higher Reynolds numbers.

 

Experimental Apparatus

The open-return wind tunnel used allowed for air to be channeled in at a velocity to the test section, allowing for the aerofoil dynamics to be analyzed. (Left: UIUC Applied Aerodynamics Group)

 

The experimental apparatus relevant to calculating the pressure and lift coefficients.

 

Results

Comparison between the same geometry no slat aerofoil (NACA 2415) at different Reynolds numbers. Note the sharp drop off in lift coefficient past a certain angle of attack. Using MATLAB analysis tools, the gradient of the linear region for the Bath data was found to be 5.93/rad, and the zero-lift angle of attack was around -2 degrees.

 

Comparison between the same geometry aerofoil (NACA 2415) at the same Reynolds number, but with one test run featuring a leading edge slat fitted.

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