Validation of aeroelastic dynamic model of active trailing edge flap system tested on a 4.3 MW wind turbine

Abstract

Active trailing edge flap (ATEF) is a promising technology for controlling wind turbine loads and enhancing energy production. The integration of this technology in the design of commercial wind turbines requires dedicated flap aeroelastic models, as aeroelastic simulations have an essential role in the wind turbine design process. Several aeroelastic codes developed specific flap modules. However, these models were only partially validated, with the risk of incorrect performance prediction that could jeopardize the development of commercial wind turbines equipped with ATEFs. This article describes the validation of the flap aeroelastic models developed by two aeroelastic codes, HAWC2 and BHawC, aiming to reduce the uncertainty of the dynamic response of the two flap aeroelastic models. The validation relies on field data from a 4.3 MW wind turbine equipped with an ATEF on one blade and operating in normal power production. The validation consists of three steps. At first, the actuator models of the flap are tuned based on the video recording of the flap deflections. The aerodynamic flap models are tuned and validated in the second step through the mean lift coefficient transient response. The lift coefficient is obtained with an innovative autonomous add-on measurement system placed on the blade in the middle of the spanwise extension of the flap. Finally, the aeroelastic ATEF models are validated based on the mean blade-to-blade moment transient response obtained from 3 months of field data under varying weather conditions. The validations show a good agreement between the simulated and measured mean transient responses. Furthermore, additional measurements are suggested to improve the flap model tuning. The validation confirms that the studied aeroelastic models provide a reliable and precise estimation of the dynamic impact of the flap actuation on the wind turbine aerodynamics and loading, a fundamental step in the safe implementation of the active flap in the design of commercial wind turbines.