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I am getting involved in an outreach project where I can modify a small wind turbine with different wing geometries. Are there examples of standard airfoil designs with particularly poor Cl/Cd performance? This way I am hoping to demonstrate the impact of airfoil design (by comparison with better blade profiles).

Edit: Just to be clear, I am looking for something that looks like an airfoil - flat plates and round trailing edges obviously work but "look" wrong, hence the need for a "standard" airfoil design.

Many thanks!

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  • $\begingroup$ Which level of fidelity has your model? $\endgroup$
    – sophit
    Commented Sep 16, 2022 at 11:45
  • $\begingroup$ @sophit Thank you for your reply. If by fidelity you mean CFD then DNS :). This project will be experimental - I will be 3-D printing the blades. Fairly low Reynolds number though $\endgroup$
    – Tom Waits
    Commented Sep 16, 2022 at 11:47
  • $\begingroup$ Use a ordinary airfoil but backwards? $\endgroup$
    – user3528438
    Commented Sep 16, 2022 at 11:48
  • $\begingroup$ Uh, then you also have to consider stall characteristics, unsteady characteristics and surface finishing (dirt) of the leading edge... I suppose you'd better read some appropriate book like Leishman, which also contain a section about wind turbine aerodynamics $\endgroup$
    – sophit
    Commented Sep 16, 2022 at 11:53
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    $\begingroup$ So basically you are looking for a legitimate airfoil that will be operating in wrong regime (reynolds) when put into a windmill? $\endgroup$
    – Jpe61
    Commented Sep 16, 2022 at 13:09

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Deisigning a wind turbine was actually my senior capstone for aerospace engineering at UMCP (I was on a team that competed in the USDOE Collegiate Wind Competition). We used an open source program called QBlade to help inform our blade design (I actually took point on this). What we found was quite interesting. We tested a couple standard wing airfoils including the Clark-Y and NACA 0012. These airfoils produced very poor power curves for a conventional horizontal axis wind turbine (HAWT).

Separately, there are airfoils out there designed specifically for HAWT applications. NREL has designed the S807, which is reasonable, but for small scale applications actually doesn't work very well. Then there's the SG6043, which my team ultimately settled on. This airfoil is very good in small scale applications. In our design work, the SG6043 produced a pretty stable power curve across a wide range of TSRs and windspeeds.

Overall, you'll notice that one key difference between the conventional wing airfoils and the wind turbine airfoils is that the L/D curves in the wind turbine foils is more symmetric about alpha == 0.

The 2021 UMCP design report is available from the USDOE, and goes into more detail about how we came to these conclusions.

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  • $\begingroup$ Bravo for a good choice. By chance, did you get around to trying a jib sail? $\endgroup$
    – Robert DiGiovanni
    Commented Jan 30, 2023 at 22:29

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