Making a model wind pump for a science project challenges budding scientists and engineers to learn to create electrical power using wind turbines. By hooking the turbine to a miniature water pump, students can explore the practical uses of the green, clean wind energy that is present all around us.
Put on your safety goggles.
Insert four 6-inch straight PVC pipes into four separate 90° corner joins. Connect two of these assemblies with a T-join. Do the same with the other two, making sure that the corners are pointing the same direction, as these will be the feet of your tower.
Lay the footed assembly pieces across from each other with the open end of the T-joins pointing in. Insert a 6-inch straight PVC piece in the open T-join on both sides.
Drill a small hole at the centre top of another T-join. Insert each side of the footed assembly to this T-join with the open end pointing up.
Insert the 24-inch straight PVC into the open T-join to create the tower.
Attach a 90° corner join to the top of the tower. Insert the geared motor in the open end of this pipe with the rotor pointing out. Feed the wire down the inside of the tower and out the small hole in the centre T-join of the base. If the wires attached to the motor are not long enough, extend them with a length of insulated electrical wire. Strip wire ends at the base with a wire stripper and attach alligator clips.
Secure the motor in place by wrapping the motor in duct tape if it fits loosely. Alternatively, you can use epoxy to set it firmly in place. Slide the crimping hub onto the rotor.
Cut at least three 6-inch lengths of 1/4-inch dowel, depending on the number of arms you want your wind pump to have.
Cut blade shapes out of balsa or cardboard, 10 to 12 inches long and 3 to 4 inches wide. Glue or tape the blades to the dowel arms securely, leaving 1 to 2 inches of the dowel sticking out. Insert this end into the openings around edge of the hub, making sure to distribute them evenly around the hub for balance.
Hook the wires at the base to the multimeter and place your wind pump so that the centre of the box fan lines up with the centre of the turbine. Turn the fan on to set your wind pump spinning. Read the voltage output on the multimeter. Experiment with the number and angle of the blades until you get a minimum of 2 volts output and preferably 3 to 6 volts.
Connect the alligator clips at the base of the wind pump to the wires on the miniature water pump. Wrap the connections with electrical tape. Run a rubber tube between the water pump and a graduated cylinder.
Fill a small basin with water. Set the water pump into the water basin.
Turn on the fan and set the turbine spinning again.
Measure how much water your turbine pumps in 1 to 2 minutes. Make adjustments to the air speed, blade design and angles, if necessary, to increase the power output and make the water pump run more efficiently.
Adjust the diameter of the PVC to the size of your motor, as it should fit securely inside the pipe. Check with your local hobby shop or electronics store for electrical supplies. If possible, test the voltage output of your geared motor at the store using a multimeter. According to OtherPower, you will need at least 3 volts to run a miniature water pump.
Handle the motor and gear box with extreme care. Bent or damaged parts will prevent your wind pump from working properly. Kid Wind points out that this type of wind pump does not have a rotating head to allow for changes in wind direction, so watch it carefully if you try to test outside with real wind. It also states: "Efficient blades are a key part of generating power from a wind turbine. Sloppy or poorly-made blades will never make enough energy to power anything. It takes time and thought to make good blades!"