Monday, November 09, 2009

Wind generator yaw

Wind generator yawThis weird looking contraption is an easily reproducible experiment, to clearly demonstrate the issue I've been having with my wind generator.

The issue has been the wind generator turning out of the wind, reducing it's power output.

After an anonymous comment suggesting I try stopping the generator, then watching how it performs, I figured out that the generator was not turning out of the wind, but was, in effect, too sensitive to changes in the wind.

I've now tied a piece of rope around the mounting pole, using a clove hitch, then tying the other ends around the generator. This effectively dampens the yaw.

This had an immediate effect, with the generator now consistently pointing into the wind, yet still turning as the wind shifts over time.

As a conservative estimate, I'd say that I've doubled the overall power I'm now getting from the wind generator, as the blades no longer stop then have to run up again due to being pointed out of the wind.

I can only estimate the power output as, due to the nature of the wind, it's impossible to say definitively.

By way of a demonstration of the improved performance I'm now getting, I thought I'd setup an experiment so that anybody interested could get an idea of what I'm talking about.

I took a ballpoint pen, round, and using bungee chord attached a 2.5mm welding rod to it. If you are in the UK and have no bungee chord, just follow a postie for a while and you will soon collect yourself a rubber band you can use.

If you have no 2.5mm welding rods to hand, simply use squish a wire coat hanger to achieve the same effect. With the welding rod, I wanted to simulate the mass of the wind generator as it swung round, so the cross piece needs to be a reasonable weight and length.

The tail piece of the demonstration is simply a few pieces of duct tape stuck onto one end of the welding rod.

The whole construction I then put into a convenient piece of pipe I found, and taped that to the work table on board.

Because the ballpoint pen has virtually no resistance to turning, on account of it standing on the ball, it turns freely in the wind. Perfectly demonstrating the over-correction I see on the wind generator to tiny changes in wind direction.

For the second part of the experiment, I stuck some duct tape on the other end of the ballpoint pen, such that the duct tape gives some friction inside the tube (no sticky bits showing though), slid the welding rod to the other end of the pen and put the whole thing into the tube the other way round.

In the second position, the welding rod now consistently points into the prevailing wind without swinging wildly around, emulating the damping force the rope now gives the wind generator.

Rough and ready, I know, but it does the job.

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