Fluid-structure Coupling Analysis Of Wind Turbine Blade Flutter Suppression Based On Shape Memory Alloy

Wind turbine blade is the most critical component of wind turbine system to capture wind energy,and is the decisive factor to ensure the normal operation of the unit.With the development of modern technology,wind turbine blades are becoming more and more large-scale.The increase of blade length leads to the increase of its flexibility,which makes it more vulnerable to wind load and other loads in operation to generate flutter.Flutter is one of the main reasons for the damage of wind turbine blades,and suppressing the occurrence of blade flutter will significantly improve the economic benefits of the unit.In the study of flutter suppression of wind turbine blades,shape memory alloy materials have attracted some scholars’ attention due to their unique superelasticity,which can generate hysteresis effects and dissipate energy under alternating loads.The main beam is an important structure that maintains the strength characteristics of wind turbine blades.The web plate and main beam are connected in an I-shaped shape to support the main beam structure,mainly bearing the bending shear stress of wind turbine blades.The wind turbine blades have infinite bending stiffness in multiple directions,and the web plate will deform with the bending of the main beam.The connection between the root of the web plate and the main beam usually needs to be strengthened and laid.In order to study the suppression effect of memory alloy design on the flutter of wind turbine blades at the connection between the main beam and the web,memory alloy was used to strengthen the connection between the main beam and the root of the web of the wind turbine blades.The unidirectional fluid structure coupling method was used to analyze its flutter suppression effect on the wind turbine blades.The research content and conclusions of this article are as follows:(1)The Aurichio constitutive model describing the phase transformation process of memory alloys is introduced.Based on ANSYS Workbench,the hyperelastic energy dissipation characteristics of memory alloy springs during tension compression cyclic loading were simulated.The results show that memory alloy springs exhibit hysteretic cyclic characteristics during tension compression loading,and with the increase of deformation,the larger the area of the hysteretic loop generated during tension compression,the more energy dissipated.(2)The wind turbine blades were simplified as double closed hollow beams,and memory alloy was laid at the connection between the root of the beam web and the wall.Three types of beam models were established,including memory alloy laid,aluminum laid,and non laid,at the root of the web.Modal analysis and displacement response analysis were conducted on the three types of beams.The research results indicate that aluminum laying causes the natural frequency of the beam to shift higher than memory alloy laying in the austenitic state.Under static pressure,the displacement of the beam in the Y-Z and X-Y planes is significantly reduced,and the effect of memory alloy laying is better than that of aluminum laying.The displacement response analysis of the beam under harmonic load shows that the laying of memory alloy significantly reduces the displacement amplitude of the beam in the Z and X directions,and the laying effect of memory alloy is better than that of aluminum.(3)Select airfoil coordinate points based on Profili,use Solidworks to establish single web and non-web wind turbine blade models,select GRP as the wind turbine blade material,calculate the aerodynamic forces on the wind turbine blades under different wind speeds through Fluent,and load the calculated aerodynamic forces on the blades of the two structures respectively,and study the impact of the web structure on the vibration displacement of the wind turbine blades.The research results show that the web structure can significantly inhibit the vibration displacement of wind turbine blades,and with the increase of wind speed,the effect of the web is more obvious.(4)Based on the binary classical profile theory of wind turbine blades,the causes of wind turbine blade flutter were analyzed,and the established blade parts were selected for modal analysis and unidirectional fluid structure coupling analysis.The research results indicate that due to the enhancement of memory alloy,the vibration amplitude of the blade in the direction of swing and oscillation is significantly reduced,and the damping performance of the blade in suppressing flutter is improved,which can increase the critical speed of flutter occurrence.