Fluid core wind turbines?

[Titan]

I was thinking of the exotic D&D weapon, the mercurial greatsword, which houses a hollow shaft in the blade with mercury in the hilt, so when you swing it, the weight shifts to the tip of the blade casing more damage. I doubt this is practical, but is the genesis of my idea.

I know enough about rotational inertia and angular momentum to say that I would think it would be a good idea to create blades of wind turbines housing a shaft with some liquid, possibly under a certain pressure of choice, or maybe a partial vacuum. So when it spins faster, the rotational inertia increases and more power can be generated, if it is really windy. Conversely, on days with little to no wind, the blade won't stall and keep spinning from lower rotational inertia. In short, this would increase overall efficiency.

Of course, designing this has many obstacles including safety risks, but, simply put, would it work?

Do they already do it?

 

[firewolfsm]

http://www.smbc-comics.com/ind...b=comics&id=1371#comic

Think of the skater moving her arms in and out as she spins, as the liquid flows to the outside of the blades, the turbine will actually slow and will require more force to move. Conversely, it will be easier to start as more mass is concentrated around the center at the beginning. Also, you didn't account for gravity in this system, the blades at the bottom will experience different forces than the top.

Either way, there's no net effect in the end. This just produces a changing moment of inertia, which cannot increase energy output.

 

[BrownTown]

it doesn't actually produce any more energy but id DOES provide a way of keeping the fan blades going at a more constant speed despite large changed in wind velocity. However I would think there would be much easier ways. For example a simple gearbox does the same job. Also, there are things you can do electrically liek changing the generator excitation that should have the same results.

 

[PowerEngineer]

While it's true that the higher rotational inertia of moving weight out further on the blades would help reduce the fluctuations in rotating speed, it must also increase the mechanical stress that the blade must withstand at its root. I have to think a blade with extra mass towards the tips would not collect as much enegy as a similar blade that used that same extra mass to tack on another few feet of wind-catching length.

 

[silverpig]

Most wind turbines allow for changing the angle of attack on the blades.

 

[KIAman]

I don't think fluid inside the turbine blades will do anything to keep the blade from stalling when the wind dies down. Because of gravity, once the blades slow down where the rotational force does not cancel out gravity, the fluid will flow toward center when the blade is pointing up but the blades that are pointing down will continue to have the fluid at the tips. If anything, all that internal movement probably causes the turbine to LOSE energy.

Have you ever played with those toys that are spherical but has a mechanical movable mass inside (I got toddlers, so...), they are fun because when you roll the ball, it moves in a random pattern instead of a strait line. Rolling that ball and a normal ball with the same mass and dimensions, the normal ball rolls much further (I don't know if that's a good analogy).

Also, good ole' conservation of energy. If you are using the greatsword in a purely slashing movement, then it is no different than swinging an axe.