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What is the difference of design between a propeller designed to be powered by the wind (i.e. those huge wind power turbine blades) and those designed to be used to propel a plane that are powered by an engine (i.e. a Cessna 172's props)?
(To be clear, I'm talking about one that is powered by the air vs one that powers through the air.)
Blades of wind turbines, airplanes and helicopters are essentially the same. They are all wings, roughly to do the same job. However, each one is designed or enhanced to do their special job. The differences can be:
Turbine blades are designed to move in large volumes of rather slow moving air (usually 10-30 mph, 16-50 km/h) and not create turbulence that fouls the next blade. Aircraft propellers are designed to move high velocity air and avoid the turbulence by moving out of the way.
Wind turbines use blade pitch to adjust the rotation speed and the generated power. Wind turbine's control system adjusts the blade pitch to keep the rotor speed within operating limits as the wind speed changes. In aircraft, blade pitch is usually described as "coarse" for a coarser angle, and "fine" for a finer.
The airfoil profile is also slightly different since, in the case of propellers, the goal is to push the air through. Therefore, the lift produced by the wing and felt by the shaft will produce torque that opposes the rotation. In the other case, the goal is extract energy from the flow going through the turbine. Thus, the lift force is in the opposite direction and helps the shaft rotation. Furthermore, more specific energy (as in per unit mass) can be extracted from the flow than injected into it. This is because, in turbines, the flow is going down the pressure gradient which has a stabilising effect. With a propeller, you're trying to push the flow through an adverse pressure gradient and this tends to enhance flow separation on your blades. Therefore, turbines tend to have higher loads and require thicker profiles.
Airplane propeller has blade angle almost perpendicular to the rotor axis. It normally ranged 0-15 degree. 0 degree will not produce any thrust. More than 15 degree will produce more drag, compare to the trust.
Wind propeller has blade angle almost parallel to the axis. 0 degree mean the blades adjusted exactly parallel to the rotation axis. 15 degree mean, has 15 degree "discrepancy" from the axis.
Angle of Attack (AoA) of propeller and wind turbines are seen from different perspective. AoA of a propeller is seen from the axis itself parallel to the blade. It is just how the bolt corrugation. Meanwhile the AoA of wind turbine blades is seen from the frontal site, parallel to the axis.
This two kinds of bold. The single one is reflecting the AoA of propeller. The corrugation almost perpendicular to the bolt (axis) itself. While the smaller bold in the second picture, showing longer pitch. The longer the pitch until almost parallel to bolt (axis) itself, the more suitable to the wind turbine blade.
There is a BIG difference. The curve of the blades is reversed. On a propellor, the leading edge is close to the propellor disk, with the flatter surface towards the rear. In a turbine, the leading edge points forward (into the wind), with the flatter surface also forward.
