The wind-turbine wake-imaging system being developed at Sandia, a novel system capable of measuring the velocity of 3D coherent wake structures (e.g., tip vortices) over relevant time scales, will be deployed at an outdoor scaled facility as a final risk-reduction experiment. The data collected will improve the physical understanding and modeling of wind-turbine wake impacts on the power production and loads of down-wind turbines in a wind plant.

Schematic of the scaling experiment for the wake imaging system.

Schematic of the scaling experiment for the wake imaging system.

The system uses Doppler global velocimetry (DGV) or planar Doppler velocimetry (PDV) techniques on a larger scale and at lower velocities than previously demonstrated in other applications. Currently, Doppler measurements have been performed on a well-characterized target (spinning wheel) in a laboratory environment.

The project’s next-stage objective is to transition the system outdoors to determine how the method scales to larger viewing areas and to begin incorporating particle seeding to enhance the signal, two key issues that cannot be determined in a laboratory. Parameters such as the seeding concentration will be varied to determine DGV system capabilities, including the signal-to-noise ratio and measurement uncertainty, that are needed as inputs to the design/deploy the final system at the Scaled Wind Farm Technology (SWiFT) facility.

Read more in the April/May edition of Wind/Water Power News.