A Reality Check

Discussion in 'Start here' started by Minnesota, Aug 16, 2011.

  1. Minnesota

    Minnesota WindyNation Engineer

    The author wrote "15mph and still not going."

    Well, it matches their power chart. 0 rpm =0 amps. :cool:

    Stay away from these type turbines, please.
  2. windyguru

    windyguru WindyNation Expert

    That sucks for the owner of that car alternator wind turbine :(
    bluejay likes this.
  3. rinconwind

    rinconwind WindyNation Engineer

    The video needs some music in the background. Suggest the following:
    Hope you can get a refund.
  4. bluejay

    bluejay WindyNation Engineer

    Blades are everything to determine efficiency....Bigger is always better fo doin it in the wind :p:D
  5. windyguru

    windyguru WindyNation Expert

    Not necessarily. The circumference of a circle scales linearly with its radius. Double the radius and you double the circumference of that circle. Thus, if you double the length of a wind turbine blade, you double the distance (circumference) the blade has to travel to make one revolution.

    For a blade to be "perfect", it must be matched to the PMA/generator that it is going to be used on. A few things to consider:

    1. Longer blades give more start-up torque and overall torque but spin slower than shorter blades. The faster a generator spins, the more power it makes. So you do not necessarily make more power if you make the blades longer. There are, however, exceptions to this rule. If you mount a 2 foot blade on a wind turbine that needs an 8 foot blade, then in 15 mph wind that wind turbine will not spin at all with the 2 foot blade (not enough torque). When the 8 ft blade is put on the wind turbine, the wind turbine will spin and make power. In this case, increasing the blade length, increases the rpm.

    2. Adding more blades increases start-up torque but will slow down the rpm of the blades. Of course, the exception above in #1 applies here too. It is better to have 3 blades that are optimally matched to the PMA/generator then to have 13 blades that are poorly matched to the PMA/generator. Having three blades will give you more power because the blades are collecting cleaner wind:


    When you do not have access to a longer blade that is more suitable to a PMA/generator, some sellers will add more blades. This will get the PMA spinning because it produces more torque. But, the power output of the wind turbine will go down and down and down if you add more blades (That is if you using three blades that are very well matched to the PMA/generator).

    At the end of the day, to match a blade to generator takes lots of calculations and after the calculations are finished it takes lots and lots of real world testing.
  6. Minnesota

    Minnesota WindyNation Engineer

    The guy finally got this POS Raider 1600 to spin and it only produced 4-5 amps in heavy winds he says. He demanded his money back. He was getting up to 20A from an Air-X 400 on the same 25-foot tower in the same wind.
  7. bluejay

    bluejay WindyNation Engineer

    Torque is King and will produce better than just speed as it will push thru the drag of resistance..Yes you are correct in the technicals Windy.. but blade width verse lenth will give you speed and torque..

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