The airflow velocity experiments consisted of measurements taken with different holes in the airfoil. This was done in order to find the effects a hole had on the airflow over the airfoil. A grid was drawn on the airfoil, with points where airflow velocity measurements would be taken. There were 5 vertical x 10 horizontal points on each side of the airfoil; a total of 100 points. The objective of this experiment was to find the effects a hole in an airfoil had on the surrounding airflow. A chart was printed for writing down the airflow velocity at each of the 100 points. About 6-9 measurements were taken at each point to ensure an accurate measurement.
In total there were 9 experiments done. In the first experiment, the airfoil was at 0 degrees angle of attack, with no hole. This would provide the control for the next experiments, and something to compare the results with. For the second and third experiment there was an angle of attack of 7.5 and 15 degrees, with no hole. From these experiments the angle of attack at which the airfoil created the greatest lift was determined. It was found that the airfoil created the most lift at about 7.5 degrees angle of attack. For the rest of the experiments, an angle of attack of 7.5 degrees was used, and for each experiment, each of the 6 different holes was inserted into the airfoil. For all the experiments, the maximum voltage of 118 volts was used. The data collected from these experiments was collected and graphed.
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The graphs above show the airflow velocity in terms of the number of rotations the anemometer spun. That however, is not the actual velocity of the airflow. To find the actual airflow velocity, the conversion graph between the number of rotations of the anemometer and the actual airflow velocity has to be used.
A less precise method of converting is using the conversion formula (derived from the graph). It's a faster method, but because the relation is not perfectly linear, the answer might not be as accurate.
A=r/32
where A is the actual airflow velocity in m/s, and r is the number of rotations of the anemometer.
