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Forum Index : Windmills : Number of Blades To Install In a Wind Turbine - Three or SIX? (!)

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Technophiliac

Regular Member

Joined: 18/12/2020
Location: New Zealand
Posts: 92

Posted: 05:04am 12 Jul 2022

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I've been pondering the optimal number of blades for my micro wind turbine. In my case it is easy to have 3, 5 or 6, so which is best? 3 is frequently promoted.

https://www.thebackshed.com/Windmill/articles/SweptAreaofHAWT.asp is a useful resource on this site, but it does not address the number of blades question.

My googling came across this article which seems very relevant:

https://www.researchgate.net/publication/306077949_The_Performance_Evaluation_of_Horizontal_Axis_Wind_Turbine_Torque_and_Mechanical_Power_Generation_Affected_by_the_Number_of_Blade

As I read it the data presented supports not 3 (contrary to the authors) but actually 6 blades for a micro turbine, particularly when one considers the wind flow distribution is likely to be around 50% of the time less than 6 m/s (in a site experiencing an average of 6 m/s per annum). I am not sure there is much downside when the wind is > ~ 6m/s (above mean levels) and indeed may be some benefit when the gusts get very large - the higher number of blades will effectively start to brake sooner on account of blade turbulence not exhausting before flowing onto the following blades - at high speeds disrupting laminar flow and then reducing torque.

Not sure how to run the app they developed, which seems relevant to run micro turbine sized scenarios to consider, rather than the much larger example shown. I hope but do not know if the principles exemplified scale down.

Might be worth linking the reference? Any comments?

Davo, Wellington. You can have it perfect, on time, and at the best price. Choose any two.

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