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I'm currently having a bit of an issue selecting the type of aerofoil I would want to use in my ridge mounted wind turbine honours project. I want to select a high lift generating aerofoil at low speeds, but I am overwhelmed with the options.

The blade will be fixed and have no moving flaps, the wind speeds will be controlled with a variable stator upstream of the blades in order to provide a wind speed as close as possible to the optimal speed for maximum lift generation which would allow for a higher rpm and thus more power generation.

I know the parameters of the wind tunnel I will be testing in and the wind speeds I could encounter in real world applications. Through my research it seems that liebeck aerofoils are the way to go, if I'm right which one? If I'm wrong, what questions should I be asking and what should I be doing differently?

Are there any online sources I should read through before I make my choice or should i just pick a standard blade with a high CL/CD? I would have liked to have two choices in order to evaluate which would be the preferred design.

In real world application wind speeds will range from 1 m/s to 25 m/s. Therefore, I will replicate these speeds in the wind tunnel.

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  • $\begingroup$ An essential information is missing: At which Reynolds number (speed and size are the important parameters here) will the airfoil be operated? $\endgroup$
    – Peter Kämpf
    Jul 11 at 11:48
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    $\begingroup$ Does this answer your question? airfoil choice for wind turbine $\endgroup$
    – sophit
    Jul 11 at 11:48
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    $\begingroup$ You need to consider your manufacturing technique. Many of the extreme high lift airfoils end up with a concave bottom surface. This can be a challenge for several manufacturing techniques. You need to size your blades to achieve high Cl/Cd at your expected operating point -- it isn't enough to have a high max L/D, you have to be able to achieve it. $\endgroup$
    – Rob McDonald
    Jul 11 at 14:41
  • $\begingroup$ @PeterKämpf ive added the wind speeds expected with the Reynolds numbers being quite low. $\endgroup$
    – Henry
    Jul 12 at 10:03
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    $\begingroup$ @RobMcDonald: at those low Re numbers, the laminar boundary layer is so sensitive that, as soon as the pressure starts to recover over the rear part of the airfoil, it separates from the surface making the rear part of the airfoil virtually stall and causing a big increase in pressure drag. So, depending on the needs, sometimes it's better to trade skin friction with pressure drag i.e. sometimes it's better to trip a earlier turbulent boundary layer (increasing the skin friction) but retarding the stall on the rear part (decreasing even more the pressure drag)... $\endgroup$
    – sophit
    Jul 12 at 18:13

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Given the low end of your very wide speed range, your airfoil should have very low thickness and high camber, similar to a bird wing's airfoil.

Thickness helps when a wide range of angle of attack needs to be tolerated and of course when structural strength is required.

The SG6043 in the answer linked to by @sophit checks those marks. The S807 also mentioned is a root airfoil for the blade of a wind turbine and has its high thickness for structural reasons.

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