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Forum Index : Windmills : Torque vs RPM from wind turbine blades

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DaveP68

Senior Member

Joined: 25/11/2014
Location: New Zealand
Posts: 292

Posted: 02:12am 13 Jan 2018

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For those interested plotted 3 graphs of projected Torque vs RPM for 2, 3 & 4 bladed wind turbines all with a TSR of 5.7, so wind speed will directly proportional to RPM if TSR is kept constant. Wind speed range is from just under 2.5 m/s to just over 10 m/s.

The power output from each set of blades will be considered the same. Power = Torque x RPM divided by 9.5493. Power is in Watts and Torque Nm.

First is 2 bladed wind turbine graph.

Second is 3 bladed wind turbine graph.

Third is 4 bladed wind turbine graph.

These graphs show how the torque interacts with the RPM over the same wind speed range.

The torque data can be used to evaluated the type of PMA(s) to use as it becomes a compromise. Higher RPM but lower torque which most PMA's prefer vs having lower RPM & more torque making start up easier in low wind conditions. Having more torque is great, but the PMA must be able to take it at higher RPM or it may result in blade run away in strong wind conditions.

There are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)

SparWeb

Senior Member

Joined: 17/04/2008
Location: Canada
Posts: 196

Posted: 10:44pm 14 Jan 2018

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Hi Dave,
What diameter did you use?

Steven T. Fahey

DaveP68

Senior Member

Joined: 25/11/2014
Location: New Zealand
Posts: 292

Posted: 11:09pm 14 Jan 2018

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Thought I'd missed something important out. It's for 2.8 m diameter using GOE 222 profile as they are high torque blades.

There are realities if you do not accept, will lead to frustration because you will be spending time on wrong assumptions and the results cannot follow! The Dunning Kruger Effect :)

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