Linear Generaters

For what it's worth: rotating machinery is in a steady state when rotating. It is stressed by the thermal and mechanical stress of accerating from standstill. Reciprocating machinery is designed to well - reciprocate - so actual hours of operation are more likely to measure the consumption of its life.

Brian Whatcott Altus OK

Yes I understand those concerns too. Good points to ponder.

But with regards to generating electricity and the cycles, a linear generater would operate some what differant than a rotaing one?

From the aspect of reliability, rotaries win, so there has to be good reason to step backwards to recips.

Brian Whatcott Altus OK

Electrically, yes. Mechanically, no.

A rotating magnet is accelerating continuosly. The acceleration of any point on the magnet along any particular axis is a sine-wave, just like a linear generator. If you superimpose two orthogonal sine-waves that are out of phase by 90-degrees (aka a rotatating magnet) you get a circle.

Tom.

Is the system you are reffering to set up in a way where you can just convert the linear motion into rotation so you can use a normal rotary generator?

No unfortunately. It's a look into a wave energy converter and all possibilities must be considered.

Dear sugna41:

Like those flashlights that never need batteries...

Yes, but rotating generators / alternators can add multiple poles for smoother output. And as Brian points out, the reciprocating action carries its own lifespan constraints. That-which-reciprocates should have as little mass as possible.

Think of a piston in a car. This can move up and down, and rotary motion can be created. The flywheel provides some smoothness to the motion.

What is the problem you see? Getting electricity out, or what?

David A. Smith

In a car piston, isn't there already rotary motion, i.e. the piece actually moving the piston?

Dear Avi Schwartz:

In a car piston, will there continue to be rotary motion if the piston doesn't go up and down? Seriously, it is a four-bar mechanism, ascribing more meaning to one link over another is simply silly.

Actually, the flywheel does help get the piston+connecting rod past the statically-locked positions of top and bottom dead center. This does require the starter (or something) to get the "ball" rolling.

The OP is considering how to get energy from wave motion. Wave motion is inherently "up and down".

David A. Smith

David the problem is converting wave motion into electricity. The method deployed would depend on a combination of factors such as corrosion, strength and efficiency. all avenues must be investigated and a linear generater is one.

If I am visualizing the problem corectly, a problem with converting linear motion to rotaional in a wave-to-energy device is that the amplitde of real world waves is not constant. To maximize the amount of energy being converted, you would want your device to be able to span the full height of varying incoming wave heights...I can see why a linear generator would make sense. I had played with the same idea, but I think I had said it would use direct inductance....I think the setup would be pretty much the same...

I think the rate at which a wave rises and falls is part of the problem. The energy may have to be temperarly stored as compressed air/gas untill it can pass through a turbine. In this way the varying action of the waves compensated for.