Hello, There's something of an engineering competition between a group of my friends against another group which is mostly for bragging rights. Basically its to make a blade for a wind power generator. The limit is that the base of it has to be a CD (you can make cuts on it to allow for the airflow except for the center hole) and the blades cannot extend further then 14 cm from the center. It will be attacked to the spindle on a CD player and that is how it will generate power. Then there is a 20 cm box fan set up either in front or above this setup that will blow air onto it. There is no vertical limit but it cannot extend further then 2 cm below the CD. Whomever can create the highest voltage across a circuit that the teacher will make. We can use anything we like to build it. The normal approach would be a fan type approach, to build a fan with a radius of 14 cm and make it as efficient as possible. My current opinion of this is that it will be pretty inefficient. Since the CD player sits right below the actual fan the air that exits the fan closer to the center can only excape out the sides which will create an area of high pressure at the bottom. This area of high pressure will drastically decrease the efficiency of the fan the closer to the center you get. My current idea is to take lamp shades and to cut them into strips and then glue them into 'L' shapes with the horizontal part around two to three centimeters wide and 6-8 cm long. They will be attached to the center of the assembly which is just a short light cylinder 4 cm in diameter. The vertical part of the L will be 6-8 cm tall and 2-4 cm wide. And they will be assembled into a cylinder with the tall part of the "L" on the outside and attached by the horizontal of the 'L' to the center cylinder and then glued to the CD and then a smaller CD or even a cut out a thick piece of paper into a circle to cover the horizontal "struts". It should look something like a centrifugal air fan or similar to an impeller. The idea is that when the air hits the bottom of the turbine it will create a high pressure point. Since there is nothing there other then the smooth surface that rests above the struts the air won't cause any major sort of friction. The air will then try and exit out the sides and in the process hit the vertical blades thus causing the turbine to spin. And since nothing will be covering the sides of the turbine there is little to no risk of large pockets of high pressure cutting the efficiency of the turbine. What do you guys think?
