Smart Blades (Task 2.1.5)

Motivation

The loads on rotor blades of wind turbines are defined most significantly by the turbulent wind inflow. As a result, up to 10^8 load cycles are expected to take place during the 20-year long operational life time of a wind turbine. Until now, the possibilities of research on the precise temporal and spatial structure of turbulent near-rotor inflow were limited. Current measurement methods are restricted to point measurements, e.g. with cup anemometers or relatively slow scanning rates (5-20 Hz) with pulsed LiDAR systems.

Measurements in alpha ventus

In the frame of the Smart Blades project, which is funded by the Federal Ministery for Economic Affairs and Energy, a so-called „short-range WindScanner“ will be acquired, which will be mounted on a wind turbine in a wind farm in the scope of the RAVE project. With this system, it is possible to scan up to 400 measurement points per second at a focus distance of 200 m on a conical measurement surface. The spatial resolution in the line-of-sight direction is – depending on the focus distance – clearly smaller than that of currently used devices, whereas the temporal resolution is 10-40 times larger.

The short-range WindScanner will be operated for about six months either in the spinner or on the nacelle of a wind turbine. The goals of the measurement campaign are:

1. Derivation of turbulence characteristics and wind field properties in the rotor blockage region for the preparation of aerodynamic and aeroelastic analysis
2. Correlation of the measured turbulent wind flow with local wind turbine loads for validation of aeroelastic models
3. Preparation of reference data for the specification of simple, robust laser-optic systems for predictive control methods