ThermoStall2

Dynamic stall on wind turbines leads to unsteady loads, reduces the aerodynamic efficiency and increases the acoustic emissions of the rotor blades. Currently, there is a lack of in-process measurement technology for detecting and localizing dynamic stall on real wind turbines in order to investigate, understand and ultimately minimize the occurrence and underlying mechanisms of this phenomenon.

The aim of the project is therefore to enable non-contact, indirect detection of dynamic stall by identifying and using characteristic signatures of both surface temperature and acoustic emissions.

As an imaging measurement method, thermographic flow visualization offers a high spatial resolution, while the acoustics of the rotor blades react with a short time delay to the onset of flow separation. The evaluation of thermal and acoustic signals thus promises both spatially and temporally high-resolution detection and localization of dynamic stall on operating wind turbines.

Numerical and experimental studies will be used to develop a fundamental understanding of the thermal and acoustic signals when dynamic stall occurs and to clarify the resolution and measurability limits of the hybrid measurement approach. The experiments include wind tunnel investigations with idealized measurement conditions as well as free-field measurements on a rotating rotor blade on a real wind turbine.