How to connect a wind car alternator

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darwenn
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by darwenn » 30/07/09, 17:16

Good, here it is all finished, painting etc. But there is a big problem and I think you're right Elephant, it must be a blade problem.

Already some corrections, the wind turbine is at a height of 4, M 50 (and not 7 meters, I had drunk I think saying that). Then tilt the blades and 35 °. This afternoon it was a super wind, result: plums, the wind turbine almost did not turn or very little. I tried to disengage it from the motor, alone on its ball bearings, same observation, it hardly turned.

However, the wind vane is oriented very well, we had a south / west wind and the wind turbine was positioned well facing the wind, so on this side no worries. It is also not a problem of generating torque because even disengaged, nada!

You will tell me it is not high, yes certainly, but the wind was there. It has roofs around which could create swirling winds, but if it did it would rotate everywhere, which is not the case. When the propeller how to turn it looks like it is almost immediately braked. The shape chosen already might not be suitable, wider at the top than at the bottom must cause a problem with the centrifugal force, right?

I give my tongue to the cat and conlue to a bad propeller. What do you think ? where can i find the best advice for making a good 10mm plywood propeller? dimensions, inclination etc. Thank you, I am starting to despair after all this work.

PS: I checked, 1 pulley revolution is equal to 18 motor revolutions.

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loop
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by loop » 30/07/09, 23:08

Hi Darwen

Given the pitch angle you have chosen for your blades, the TSR (speed coefficient at the tip of the blade relative to the wind speed) will level off around 2 or 3.
It is insufficient to reach the right speed of start of production.
Your blades are not profiled and in addition when the relative wind component has the same angle as the incidence, your blades no longer provide torque, and the speed is capped.
I therefore advise you to reduce the pitch angle, in other words to place the blades at a position close to the plane of rotation.
As you did not twist your blades, the wedging angle seems good at the bottom (near the hub) but it is too strong at the blade tip (where it is most important to have the right angle)
A good blade is rather wide at the base and tapered at the end (because of the Reynolds number, and that is calculated with a given aerodynamic profile)

Give me some elements and I will look at the best compromise.

Good luck for the rest of your development

A+
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darwenn
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by darwenn » 31/07/09, 05:45

Thank you looping, I suspected that the angle at the tip was too large, because before making these blades I had made others of less inclined tests and it turned better, and I said to myself that it was wrong will turn even better more inclined.

This is what I am going to do today. I will correct the inclination of my 5-blade propeller and try to reverse them (by plugging the drilling holes with a wood paste) and make a test and then make a tri-blade, still in 10mm plywood, I will cut new blades according to the indications given on the Ebonys site and according to this drawing (I will defer the measurements to scale for blades of length 80cm). After looking at pictures of propellers, I chose this form of propeller because I deduced that it should have worked, like what, being clever didn't help me either. : Cheesy:

So these will already have a better shape, then I will tilt them by around 20 ° to the setting, so much less than what I currently have and I will keep you informed by giving you the ratings that I would have followed At scale. When it turns out well (hopefully), I will make blades sculpted and profiled to the same measures, with the plane in a more suitable wood.

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darwenn
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by darwenn » 31/07/09, 11:56

Voila, I used the blades to recut the news. So reduced inclination of almost half, there about 20 to 25 °. Largest part 14,5 cm and tip 6cm, length 70 cm per blade or 1 m wingspan. Your opinion ? it's better ?. The blades are bevelled / cut on the angle of attack over the entire length of the active part, that is to say about 40 cm and about half the width of each blade. I'm waiting to see if it will work better, there is no wind :x then if it works I will do a tri-blade to test. But I would already like it to turn this time ....

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Alain G
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by Alain G » 31/07/09, 19:24

Hello Darwenn!

The big problem is at the level of the drive between the pulley and the motor, you must use 2 pulleys, you chose the worst possible way of coupling, too much friction and sliding.

>> Fix this problem before you think about getting watts from your wind turbine.
:D
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darwenn
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by darwenn » 31/07/09, 19:53

Hi Alain, you confirm my doubt, yes I have thought about it, side floating it goes by turning by hand, but yes I think that at high speed I will have it, but the concern is that my large pulley is for a flat belt with washing machine grooves, except I don't have a small pulley for flat belt to put on the rotor of the generator, finally if, but I can not disassemble it from the axis of the engine the machine, but I'm not giving up :) , I will then need a belt of the right size, it is not won because the washing machine belts that I have are large, but I will go for a ride soon in a repair shop and spare parts washing machine to see what I can find, so while waiting to find the solution with pulley and belt, I train by friction. There for now I await the return of the wind to already see if my propeller turns well and then advise the training of the generator, I think I will find something well.
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Alain G
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by Alain G » 31/07/09, 20:12

Darwenn

why not go to a pulley dealer with your belt and your motor, they will provide you with the right pulley for the dimension of the motor axis, otherwise if your motor pulley is the right dimension you only have to heat it with a small plumber's torch and it will come out very easily.
:D
Last edited by Alain G the 31 / 07 / 09, 20: 36, 1 edited once.
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Alain G
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by Alain G » 31/07/09, 20:15

I forgot, nice job!

You are persistent, your blades are much better on the last photo.

Do not let go!
:D
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darwenn
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by darwenn » 31/07/09, 20:19

I will try tomorrow to extract it by heating, if I get there it is nikel because it is also 15mm in diameter, and I could mount it on the generator (with a small adaptation that I will find). But I will also go to the convenience store or revandeur in case
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darwenn
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by darwenn » 01/08/09, 11:04

Good news, well almost. Already my propeller works perfectly with a very weak wind, it is already a good point.

Then I managed to dismantle the small pulley and cut a strap to the right size then glued each end to the cyano with a rubber reinforcement on 8 cm. In short, no worries. The belt is neither too tight nor not enough, without any slippage. Thank you Alain for your advice : Lol:

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we do not see well on the photo

This morning, very light wind, barely 10 km / h at most and again the weather forecast was 0, in short a light breeze. I disengaged the propeller of the generator and the ohh wonder, it turns out right away, regular, without stopping, I estimated the speed of rotation of the propeller of around 240 RPM with a light breeze , so an estimated generator speed of 14400 rpm (multiple pulley by 18) !! oulha I'm scared there !! : Shock: but there I must remind you, that it was disengaged, so only on the ball bearings of the bearing. As soon as I put the generator back on the belt the propeller stopped.

it hurt my stomach to see it spinning so quickly freely and stop as soon as I plugged in the strap, however the torque requested by the generator is very low, I know that with a 20km wind it should still turn better, but there I wondered if I could not find a solution to drive the generator with a wind as weak as this morning, it would be the foot to see how it turned out well. You have an idea ? I have already lubricated the inside of the generator, limited the pressure spring of the coals on the rotor, it is better but not yet enough, the effort is caused because of the permanent magnets on the rotor, it feels light Suddenly. I know it's all normal, but I really wanted to find a trick to train it in very weak winds.

Anyway, this story of the 14400 revolutions a minute scares me, I'm going to get out of 40 volts or burn the generator at this speed, right? I will see if not I will change the ratio of the pulleys.
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