jester_s1

I'll try to explain this in a new way that maybe you'll understand. A fan's job is to move air, right? So we're starting with air that is not moving. The task is to move the air from one place to another as efficiently as possible ie, with the least amount of electrical (of whatever turns the fan) energy consumed per mass of air moved. When the fan turns a given number of times at a given speed, it moves a given amount of air. Work is done on the back end to create high pressure and move air in that direction, and work is done at the front to create low pressure to also move air in that direction. So essentially what a fan does is create a pressure differential that causes air to move. I think we agree on that point, right?

Now here's the kicker for your idea. If you do anything at all to make it harder to create that pressure differential on either end of the fan, you reduce the efficiency of the fan. Such things would include putting turns in the duct, narrowing the nozzle area or the intake, placing a turbine in front of the fan or behind it to tap some energy from the air movement, or putting any mechanism that reduces pressure in front or increases it in back. All of these things will reduce the efficiency of your fan. Obviously the opposite is true as well; if you can reduce the back pressure or increase the front pressure or if you can reduce the resistance to airflow (which is what a duct basically does if it's designed right) you will make your fan more efficient. I think that's what you are trying to do, but there is a major flaw in your thinking.

The error you are making is that there is no such thing as free energy. In order to plan out your project, you have to start with non-moving air. Using the example you love to tout so much, you must start with a ball that is on the ground, not on top of a mountain. When you start with non-moving air you'll find that there is simply no way to get more output than input. It can't be done anymore than you can make a ball deliver more energy to the ground than what was put into it to lift it off the ground and then drop it. If there was a way to get air moving through your device without having to spend any energy getting it to do so then you would be on to something, but there isn't. What you are describing in, in fact, a perpetual motion machine which is impossible according to the very laws of physics which govern the universe. If you still don't believe me stop posting stuff about dropping balls off a cliff and go build your machine. I'll be waiting to see your results.