Precise measuring system for non-contact acquisition and analysis of the dynamic flow behaviour of wind turbine rotor blades

The boundary layer flow of aerodynamic profiles on wind turbine rotor blades is unsteady as the flow conditions such as the wind speed, the turbulence level and the angle of attack vary depending on the position of the rotor blade during one revolution of the rotor. This dynamic behaviour influences the aerodynamic properties of the profile and hence the efficiency of the energy production of the entire wind turbine.

The state of the art metrology for a non-invasive measurement of the boundary layer flow on rotor blades of wind turbines in operation is thermographic flow visualization. Compared to state-of-the-art methods that use invasive preparations of the blade surface, thermographic flow visualization uses the effect of different surface temperatures due to different heat transfer coefficients in the boundary layer for a contactless differentiation between the flow regimes. So far, the measurement system only visualizes static flow phenomena by taking single snap-shots of the rotor blade during operation. Therefore, an advancement of the existing metrology is necessary that enables studying dynamic flow behavior.

Therefore, the aim of project PreciWind is to develop a new co-rotating measurement system that allows the camera system to follow the rotor blade movement. This way, each radial section of the rotor blade is observed continuously during one revolution of the rotor. This allows a detailed measurement of the dynamic flow behaviour in the boundary layer flow as well as dynamic structural behaviour due to the changing flow conditions that also imply varying structural loads.

Funding authority:Federal Ministry for Economic Affairs and Climate Action
Funding ID:03EE3013A