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 Topic: Torque vs RPM from wind turbine blades
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DaveP68
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Joined: 25 November 2014
Location: New Zealand
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Posts: 289
 Posted: 13 January 2018 at 12:12pm | IP Logged
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.

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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
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Joined: 17 April 2008
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Posts: 193
 Posted: 15 January 2018 at 8:44am | IP Logged
Hi Dave,
What diameter did you use?

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Steven T. Fahey

DaveP68
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Joined: 25 November 2014
Location: New Zealand
Online Status: Offline
Posts: 289
 Posted: 15 January 2018 at 9:09am | IP Logged
Thought I'd missed something important out. It's for 2.8 m diameter using GOE 222 profile as they are high torque blades.

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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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