The materials used include: DC motor and stand, 18V battery, a fan, multimeter, wires, wooden craft sticks and plastic cups (for blades), drill and glue. More than 14 different types of wind blades were made using craft sticks. The blades were attached to a generator, and a multimeter was used to measure the current and voltage. For each blade different conditions including wind speed and distance of a wind source were tested. The blades varied from 6 cm to 25 cm in length. For each blade, several tests were conducted, but two conditions (low & high wind speed) were used for final tests where low, high and average amps and volts were recorded for each test.
The electricity produced by each blade (watt) was calculated by multiplying the volts and the amps measured during the experiments. The highest electricity producing blade was a small horizontal blade with a variable blade angle at high wind speed. Approximately 160 mW of power was produced from this design. This provided about 100 times more electricity than the worst blades. For the low wind speed however, vertical blades produced more energy as some horizontal blades did not even turn at low wind speed. The general formula for estimating the wind energy is based on the blade area where the wind is exerted. However, the experiments demonstrated that area is not necessarily the most important factor in power production for wind blades. In fact, the largest blade, 5 times more area than the most efficient one, produced less than 1% of the power from the smaller blade.
The horizontal blade was the most efficient at the high wind speed; however for low speeds, the vertical blades produced more in power by harnessing the low wind. Based on the tests, how the blade harnesses the wind is more important in producing more electricity as it is related to efficient spinning of blades.
Science Fair Project done By Peter S. Min