I am planning to design a wind turbine that is has rotor blade radius of 0.915m and is connected to a generator. The generators specifications are, it is an ac generator with 5000 coil turnings and a 0.050 tesla magnet with area being \$1 m^2\$. The generator rotating at 135rpm producers 3534.29 V. The fan has 6 blades and when the wind velocity is 10m/s, the rotor will be going at 36.53 rpm (counting the efficiency of 35%). So, to get to the 135 rpm, gears will be used.

My question is, will the wind velocity be able to move the fan to 36 rpm when the gears will be attached to turn the generator at speed of 135 rpm?

Also, how can you figure out the theoretical yield of current that can be produced by the generated or is the current only found experimentally by attaching a load?

  • \$\begingroup\$ What is "1 m2 2"? Is the open circuit voltage really 3.5 kV? \$\endgroup\$
    – Transistor
    Commented Mar 28, 2016 at 4:56
  • \$\begingroup\$ that's theoretical. I used the equation NBAwsin(wt) to find that \$\endgroup\$
    – user510
    Commented Mar 28, 2016 at 5:06
  • \$\begingroup\$ Why are you designing for a tip speed ratio less than 1? TSR of about 4 or 5 would be more typical, and could give you 135rpm directly. See links here... electronics.stackexchange.com/questions/177513/… \$\endgroup\$
    – user16324
    Commented Mar 28, 2016 at 13:19
  • \$\begingroup\$ because I am assuming that the tip speed ratio is the only factor controlling the efficiency of the wind turbine (assuming the pitch angle has no effect). And since the coefficient value is limited to 0.59, and most wind turbines can only achieve 0.35, assuming that tip speed ratio had everything to do with the coefficient value, I chose 0.35. Is this a wrong assumption? \$\endgroup\$
    – user510
    Commented Mar 28, 2016 at 14:38

1 Answer 1


The torque needed to move the generator shaft depends on the electrical load it has to supply. The higher the electric load, the harder to move. It will likely move with no load (supposing it is able to overcome static friction), when you start to increase the electrical load, the speed will start to go down (assuming constant wind).

The exact manner in which this happens depends on the speed vs. torque curves of the generator and the characteristics of the turbine. If you lack this information, then you will have to make some experimental tests.


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