Savonius wind turbines are a type of turbines which are used for catching wind power. The Savonius wind turbines are drag-type consisting of either 2 or 3 scoops. The turbines curvature makes the machine to experience little drag when the machine is moving in the opposite direction to that of the wind. Much of the Savonius rotor is placed very near the ground and this in turn reduces the overall energy produced. For this reason Savonius wind turbines are more useful in situations that reliability or cost is more important than energy efficiency.
Uses of Savonius wind turbines
In many occasions, larger Savonius wind turbines are used as Flettner Ventilators which are cooling devices on buses and vans. These ventilators use the Savonius wind turbines in driving extractor vans. Smaller Savonius wind turbines are used on some advertising signs to draw attention. When used as such, the Savonius wind turbines feature a two frame animation.
Simple Savonius Wind Turbine
How to build cardboard Savonius wind turbines?
It is relatively easy to make a simple cardboard Savonius wind turbine. Some of the materials you will need to come up with this include a cardboard box, rubber bands, an axis rod: you can use a 14-inch knitting needle or 14-inch dowel, electrical tape or duct tape and some hot glue.
Step 1: First, cut the cardboard into four strips of 4*10. These pieces will act as the vertical paddles which are used in catching the wind. On each piece, cut rectangular notches (2) each of 3 inches in length. Next, you will be required to cut the bottom and top turbine disks. You will need to come up with 2, 10 inch diameter disks.
Step 2: Then, cut out the circle. If you find it hard to come up with a clear circle then this will help you. Cut out a 10*10 of the cardboard and then on every corner of the square make a mark at about the 5th inch.
Step 3: Then with a ruler create lines to connect opposite marks (the lines must cut through the center of the square). The two lines will intersect on the center of the square. Then use a compass to draw a large circle. A school compass will not be of much help, a ten inch bowl will be more useful in tracing the circle. Then with that cut out the circle.
Step 4: Next, create angle lines on each disk. After this, you will need to attach the pieces. To do this you will need to do the following. Get one of the rubber bands and push it up the knitting needle or dowel to about 2 inch from the very top. The main reason for this is to hold disk to the needle through friction. The band will also help in keeping the turbine from slipping. Next push the dowel or needle through the disk's center with the angles facing up for easy alignment. Get the second disk and repeat the procedure with the angles facing down.
Step 5: Then get another rubber band and push it to within an inch from the bottom disk. Get the paddle pieces and one at a time push them onto the lower and upper disks ensuring that the notches on the paddles are pushed onto the disks angled notches. You may consider temporarily securing the paddle before placing another. Next, push the rubber band below the bottom disk further until it firmly sits against the disk.
Savonius Wind Turbine Direction Schematic
Final Step: Finally tape all the paddles on the lower disk to secure them onto the disks. With this, your cardboard Savonius wind turbine will be ready for testing. Then after testing your wind turbine, you may want to secure the paddles more firmly. To do this you can use a glue gun to firmly attach the paddles.
It is relatively easy to build cardboard Savonius wind turbines. If you have the right materials and tools it may take you as little time as only an hour to come up with a functional cardboard Savonius wind turbine.