Water Turbine Project Science Experiment

This Water Turbine Project hydroelectric power generator has many possibilities for a school science fair project. Here are a few independent variables that can be adjusted in an experiment

• Gear ratio — I have included four different gears for the generator and turbine to try
• Load resistance — Drive a set of resistors ranging from 1 Ohm to 1 kOhm
• Water flow rate
• Water height

As a science fair project, the experiment plan and procedure is left open ended, to be designed by the student. A typical experiment might be to hypothesize on the power generated as a function of water bucket height, and then measure the relationship. A 3W LED is suggested as a power load, but this can also be left to the student. If choosing a different load, it is suggested that the load be sized to consume no more than a few Watts of power, and have at least 3 ohms of resistance. Higher resistance and lower power loads can also be used, and can be helpful in studying power transfer. Once the turbine parts are printed and other materials acquired, the turbine can be assembled (as pictured) in less than an hour. Accurate measurement is key to a successful experiment. Generator current and voltage can be measured with a set of two multimeters (one used in series to measure current, and the other measuring voltage across the generator leads). A more accurate measurement can be made with an oscilloscope if one is readily available, as modern oscilloscopes typically are capable of calculating average voltage over a fixed period of time (e.g., 10 seconds). ** Caution:** This experiment combines both water and electricity, and while the electricity generated is not enough to cause physical harm, the water is certainly capable of damaging the motor or test equipment. Protect the motor by wrapping it in plastic held in place with duct tape or rubber bands. Also, keep multimeters and oscilloscope away from the turbine by using long lead wires. An example load circuit and measurement locations are shown in the schematic below. Using either a multimeter or oscilloscope, measure voltage at locations V1 and V2. Current is then measured as I = (V1-V2)/R, where R = 3.3 Ohms, and power is measured as V1 x I. An example screen shot from an oscilloscope measurement is shown below. For this example, V1 = 2.94 Volts, V2 = 2.05 Volts, I = (2.94-2.05)/3.3 = 0.27 Amps, so power = 2.94 x 0.27 = 0.79 Watts. This was powering the red LED, and although this example does not show the full power capability of the LED or turbine, the 3W LED is extremely bright in this scenario.