The Correlation Between a Propeller's Chord Length and the Electricity It Produces in Voltage

Overview

Objectives/Goals The objective of this experiment was to determine a propeller's efficiency when altering the chord length of the propeller. In an airfoil, which is a cross section of a propeller wing, the chord length is basically the entire length of the airfoil. When looked at as an entire wing or blade, it is basically the width of the wing/blade. My objective was to determine which propeller was efficient in producing the most amount of electricity meeting the changes of the chord length. This project shows the efficiency of a simple tool kit propeller against regular home use fan with all other variables constant, such as pitch angle, radius, shape, and airspeed from a fan. When air moves over a surface of a rotating propeller, like one on an airplane, the air pressure in front of the propeller is reduced and the air pressure behind the propeller is increased. This pressure imbalance is what then pushes the airplane forward. In this project however, instead of a propeller being attached to an airplane, it is stationary and is instead moving to the air being blown at it from a conventional fan. Here the wing is specifically producing induced drag, which is related to how the wing creates lift. Methods/Materials The materials used were a simple propeller making tool kit, wood, DC motor, digital multimeter, a simple wire resistor, and small jumper cords. I attached each propeller to a DC motor. This was placed on a wood plank, against the airflow of conventional fan to test for efficiency. The propeller chord lengths were, 37 mm, 35, mm, 31 mm, and 27 mm. Results Through this experiment, the average results produced were, 39.63 mV for the 37 mm, 47.97 mV for the 35 mm, 42.78 mV for the 31 mm, and 29.16 mV for 27 mm propeller. Conclusions/Discussion In all, the 35 mm propeller produced the most efficient amount of electricity. In regards to the 37 mm propeller, there was a critical point where the propeller was simply to big to spin against the airflow of a conventional fan. On the other hand, because of a shorter chord length, the 35 mm propeller produced less induced drag then the 37 mm and thus had better effect. The 31 mm also had great efficiency. Nevertheless, it was not on par with the 35 mm propeller because the 35 mm propeller deemed to be the best fit for the airflow produced by the conventional fan. The 27 mm propeller was simply too small against the airflow from the fan to generate much electricity.

Competition history

• CSEF 2010 Applied Mechanics & Structures · Entry S0212

Resources

• CSEF project summary ↗

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