Super efficient energy using infinite forced induction?

[tehschifter]

I'd like to start off with saying that i am no expert in engineering or physics, or anything. i am a 20 year old community college student that is intrigued by concepts of things. if at any point I'm wrong feel free to correct and enlighten me.

as many of you may know, a ramjet (and subsequently a scramjet) operate by using their momentum through whatever fluid (air) as a power source for their engines. jet engines are similar to this, at least from my understanding. both of these expel force through their exhaust systems which provides the thrust for said engine. i also realize these use fuel to achieve the actual propulsion and the incoming airflow just serves as a "multiplier" if you will.

recently i was in my room with one of my fans going next to a fan that was off. i noticed that the fan that was off still produced airflow from the momentum generated by the fan that was on when it blew air towards the dead fan.

what would happen if someone were to construct a ring, as in just a basic circuit, of fans and jet engines, or whatever would be the ideal engine, that continuously blew into the next one? i know that the laws of thermodynamics and the principles of friction wouldn't allow for a 100% efficient circuit of these, but would it be relatively super efficient?

ive thought of two scenarios, one being a stationary track, where the engines and propulsion sources were stationary and the air being blown would be the moving part. alternatively i can think of a separate system in which the engines or whatever source of propulsion or energy is the moving entity. think of ball bearings on a skateboard wheel, and the engines would be allowed to move with something similar to that, a guided but not transport system.

/end rant. any thoughts on this? keep in mind that i have ultimately no knowledge on any of this. any feedback would be nice, thanks!

 

[mpaige1]

That's not going to work. Just think for a moment about what you just posted about not being 100% efficient. If one fan is not 100% efficient, that means that as you propel the other fans with your one fan the amount of energy received at the end of your line of fans will not be equal to the amount of power needed to run your first fan. That's why wind is considered a free energy. Since we don't need to propel a windmill, it creates power through wind only. This way it doesn't have to be 100% efficient to still produce power. You're system would defy the laws of physics.

 

[S_Happens]

It's certainly not very efficient to use exhaust gases to supply any combustion engine. Your ring of jet engines fails for this reason as well as a few others, but that one should be clear enough. No Oxygen = No burn.

Your ring of fans is nothing special either. By making it a ring, or by keeping all the fans the same size as well as the ring itself, you prevent it from becoming an axial compressor. Instead it's just a ring of air movers. Then, each fan is powered by an electric motor, which is going to run at a certain rpm, period. That means that there is a theoretical maximum speed that the air traveling in this ring could attain based on that rpm. The short answer is that it won't take as much current to drive each fan to that rpm when the air coming into it is already very close to the same speed that it will be at the discharge. It might be more efficient to use more of these "smaller" fans to move the air in this ring at that rate, than it would to use one single fan to do the job. This sort of principle is applied a lot in compressors, although your example may be slightly different (if we had to keep the size of the ring the same it might change things). Typically you can use a series of smaller "fans" instead of one larger one to do the same thing more efficiently.

Note: If you need to think of it simply, use your ball bearing wheel analogy with the fans. Think of the fans through the air as screws through wood. If the fans can only turn a certain rpm, then they can only travel so fast. If you didn't have to worry about friction with the air or slippage, then it wouldn't matter how many fans you had. The speed would be the same for any number of fans.

If you reduced the volume of the fans and didn't have them in a ring, you'd be making an axial compressor. You can look up multi-stage axial compressors (almost all axial compressors are multi-stage) to find out more.

That's all I can muster at 3:55 AM...