Pressure-based lift estimation and its application to feedforward load control employing trailing-edge flaps

Abstract

This experimental load control study presents results of an active trailing-edge flap feedforward controller for wind turbine applications. The controller input is derived from pressure-based lift estimation methods that rely either on a quasi-steady method, based on a three-hole probe, or on an unsteady method that is based on three selected surface pressure ports. Furthermore, a standard feedback controller, based on force balance measurements, is compared to the feedforward control. A Clark-Y airfoil is employed for the wing that is equipped with a trailing-edge flap of chordwise extension. Inflow disturbances are created by a two-dimensional active grid. The Reynolds number is Re=290 000, and reduced frequencies of k=0.07 up to k=0.32 are analyzed. Within the first part of the paper, the lift estimation methods are compared. The surface-pressure-based method shows generally more accurate results, whereas the three-hole probe estimate overpredicts the lift amplitudes with increasing frequencies. Nonetheless, employing the latter as input to the feedforward controller is more promising as a beneficial phase lead is introduced by this method. A successful load alleviation was achieved up to reduced frequencies of k=0.192.

Description
Keywords
Wind-Tunnel, Airfoil, Reduction, Thickness
Citation
Bartholomay, S., Wester, T. T. B., Perez-Becker, S., Konze, S., Menzel, C., Hölling, M., et al. (2021). Pressure-based lift estimation and its application to feedforward load control employing trailing-edge flaps. 6(1). https://doi.org//10.5194/wes-6-221-2021
License
CC BY 4.0 Unported