Active load alleviation potential of adaptive wind turbine blades using shape memory alloy actuators

Abstract

Upscaling of wind turbine blades calls for implementation of innovative active load control concepts that will facilitate the flawless operation of the machine and reduce the fatigue and ultimate loads that hinder its service life. Based on aeroelastic simulations that prove the enhanced capabilities of combined individual pitch and individual flap control at global wind turbine scale level, a shape adaptive concept that encompasses an articulated mechanism consisting of two subparts is presented. Shape memory alloy (SMA) actuators are investigated and assessed as means to control the shape adaptive mechanism at airfoil section level in order to alleviate the developed structural loads. The concept is embedded in the trailing edge region of the blade of a 10‐MW horizontal axis wind turbine and acts as a flap mechanism. Numerical simulations are performed considering various wind velocities and morphing target shapes and trajectories for both normal and extreme turbulence conditions. The results prove the potential of the concept, since the SMA controlled actuators can accurately follow the target trajectories. Power requirements are estimated at 0.22% of the AEP of the machine, while fatigue and ultimate load reduction of the flap‐wise bending moment at the blade root is 27.6% and 7.4%, respectively.

Effect of shape memory alloys partial transformation on the response of morphing structures encompassing shape memory alloy wire actuators

“…In this section, a case study where SMA actuators are configured in an antagonistic scheme to actively adapt the shape of a structure is presented. The chosen application refers to a camber adaptive airfoil rib intended for aerodynamic load alleviation in large horizontal axis wind turbine blades (Karakalas et al, 2019b). The particular application is chosen as a highly representative case where the consideration of PT behavior can drastically improve the response of the SMA actuators and robustly enhance the performance of the whole system.…”

“…The assessment of the modified PT model is subsequently conducted for a more demanding actuation scenario, which involves the controlled activation of two antagonistic SMA actuator pairs, rotating the parts P10 and P30, respectively, to actively adapt the shape of the camber line to follow a predefined target trajectory in time. The trajectory was calculated by aero-elastic analysis to alleviate the calculated unsteady aerodynamic loads on the blade, based on extreme turbulence modeling, assuming wind speeds of 25 m/s and for the case of an airfoil section located at 78.802 m from the blade root (Karakalas et al, 2019b).…”

Finite Strain Constitutive Modelling of Shape Memory Alloys Considering Partial Phase Transformation with Transformation-Induced Plasticity

“…Such unique behavioral characteristics make SMAs largely employed in a wide range of innovative applications [3]. Particularly, thanks to PE, good biocompatibility, and high corrosion resistance, SMAs are extensively used in the biomedical field, as stents, occluders, or surgical tools, while thanks to the SME and high output energy density, coupled with several advantages for system miniaturization (e.g., high power-to-mass ratio, maintainability, reliability, clean and silent actuation), SMAs are largely investigated as actuators in various engineering industries including, e.g., aerospace [4], civil [5], automotive [6], and recently wind energy [7][8][9][10].…”

Development of a frequency-dependent constitutive model for hysteresis of shape memory alloys

“…Due to high power density, high actuation strain, biocompatibility, high corrosion resistance, and adaptation in smart structures, shape memory alloys (SMAs) have been used in many applications including aerospace, 1–4 biomedical industry, 5 robotics, 6 wind energy, 7 and micro electro-mechanical systems (MEMS) devices. 8 Many researchers have tried to replace SMAs with traditional actuators in the past two decades.…”