Airfoil Selection for Wind Turbine Blades: Key Aerodynamic Considerations

One blade, several sections

A wind-turbine blade is not “an airfoil.” Structural bending moment is highest at the root, so root sections are thick — sometimes 30% of chord or more — and exist to house a spar. Mid-span sections carry most of the torque-producing lift and are drawn for a high lift-to-drag ratio at the design angle of attack. Tip sections are thinner, see the highest speed, and dominate noise. Each station has its own chord and its own rotational speed, so each station has its own Reynolds number. A single polar copied from root to tip is the wrong model.

What the outer-board section owes you

• High L/D at the design CL, because rotor torque comes from the tangential force, and profile drag subtracts from it. The design CL is chosen with the rotor design, not from a catalog’s favourite angle.
• A stall that the controller understands. Stall-regulated machines once used stall as the power limit. Pitch-regulated machines try to avoid a surprise stall during gusts. In both cases the section stall type and the post-stall behaviour matter, and steady attached-flow polars are only the start.
• Roughness insensitivity. Bugs and leading-edge erosion are normal, not a defect. Rank candidate sections on a tripped or eroded polar. A laminar bucket you lose in the first month is not an annual-energy feature.
• A usable Reynolds-number range. Outer boards on large rotors run at high Re. Small turbines and the inboard stations of any turbine run lower. Check the section at the Re of that station.
• Noise at the tip. Trailing-edge thickness, separation and tip speed set much of the broadband noise. A section choice that ignores a square trailing edge will show up in the acoustic survey.

Thickness schedule

A selection sequence

1. From the rotor design, take radial stations with chord, local speed and a target angle of attack or CL.
2. Compute Re and Mach at each station. They will not match.
3. Pick a thickness family that meets the structural thickness at that station.
4. Compare candidates clean and with a leading-edge trip, at that station’s Re.
5. Look at moment only insofar as twist and structure care; a turbine blade is not trimmed by a tail, but torsion still twists the section out of its design angle.
6. Keep the tip’s trailing edge and stall picture in the noise conversation. Do not promise a decibel number from a polar.

The section tools in HENFOIL are the right place to build those station polars and to keep Re, trip and method written on them. Annual energy and acoustic compliance are rotor-level calculations that consume those polars. They are not a property of the DAT file.

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Where this sits in the series

In simple words: what this page is for

A turbine blade is many airfoils. The root is a thick structure, the outer board is a high-lift machine, and the tip has to stay efficient when it is dirty and quiet enough to site.

This lesson exists because section decisions fail when geometry, method labels and selection reasons are scattered. Airfoil Selection for Wind Turbine Blades: Key Aerodynamic Considerations helps you keep a clean trail from shape to polar to choice.

Why the topic matters

Engineers lose time when a title sounds clear but the page only sketches the idea. This article expands Airfoil Selection for Wind Turbine Blades: Key Aerodynamic Considerations so you can answer three questions without jargon: what is the idea, when do you use it, and how do you check it in a HENDOI product.

Read the sections above for the core definitions. Use the steps below to move from reading into a real project trail you can share with a teammate.

How to apply this in HENDOI

In practice: create a HENDOI account or log in, open HENFOIL, bring a section in (create, import DAT, or digitize), pass the geometry gate, climb the analysis ladder only as far as the decision needs, then compare and archive. Every calculated number should keep its method label.

When the section choice is ready for the aircraft, continue in HENSYNTH for mission, compliance and trades. Same account. Same plans.

What this page will not claim: a teaching polar or geometry note is not a flight-Re certificate. HENFOIL labels methods so you know what you bought. Tunnel data and professional judgement still sit outside any single software run.

Checklist before you leave this page

• Can you state the idea of Airfoil Selection for Wind Turbine Blades: Key Aerodynamic Considerations in one sentence?
• Do you know which product owns the next action — HENFOIL or HENSYNTH?
• Will every number you keep carry a method label or a stored-run source?
• If you are new here, have you opened Register or Login?

Related reading on this site

• Airfoil Performance in Crosswind and Yawed Flow: What Engineers Should Know
• How to Evaluate Airfoils for Wind Tunnel Testing and Experimental Validation
• How to Measure Airfoil Lift and Drag in a Wind Tunnel
• Airfoil Wind Tunnel Testing: Instrumentation, Test Conditions and Data Reduction
• All HENDOI blog articles
• HENFOIL product page
• HENSYNTH product page
• Pricing — Student, Professional & Team
• FAQ
• Login · Register now

• Previous: How icing changes lift, drag and stall
• Next: Airfoils for electric aircraft and eVTOL
• Index: all HENFOIL airfoil lessons

These pages teach the ideas. They are not wind-tunnel data and not a certification analysis. When a number matters, compute it at a stated Reynolds number, Mach number and transition setting, and keep the method label on the result. In HENFOIL that production polar is a VIC polar — see the analysis ladder and the polar field guide.