Research On Aerodynamic And Noise Characteristics Of Wind Turbine Blades Based On Coupled Bionic Design

The current research on wind turbine blades is not limited to the study of the aerodynamic properties of wind turbine blades.The noise generated by wind turbine blades during operation will have a significant impact on th e health and life of residents,so it is urgent to develop a wind turbine blade with good aerodynamic performance and certain noise reduction characteristics.Inspired by the excellent aerodynamic properties of seagulls and the silent flight characteristics of owls,this paper systematically studies the aerodynamic and acoustic characteristics of different bionic optimized blades,which provides strong technical support and theoretical basis for the design and development of efficient and low-noise wind turbine blades.The work content and main research results of this paper are as follows:(1)The SST k-ω turbulence model based on RANS method was used to verify the excellent aerodynamic performance of the seagull airfoil at different cross-sections at different angles of attack,and compared with the S1223 standard airfoil.The seagull airfoil at the tip of the small angle of attack has a higher lift-to-drag ratio,and the highest lift-to-drag ratio gradually moves to the middle of the wing with the increase of the angle of attack.At α=5°,the lift-to-drag ratio of the seagull airfoil was increased by 22.9%compared with the standard airfoil.At α=13°,the lift-to-drag ratio of the seagull airfoil is increased by 90.8%compared with the standard airfoil.Under the three typical angles of attack,it is found that compared with the standard airfoil,the seagull airfoil has thinner thickness,smoother camber line distribution and smaller leading-edge curvature,so that the airflow can be better attached to the airfoil suction surface,thereby reducing the flow separation in the low-speed area of the trailing-edge of the suction surface,making the flow separation point closer to the trailing,the separation vortex area smaller,and the turbulence produced less.And as the angle of attack increases,this phenomenon becomes more pronounced.(2)The seagull airfoil and owl trailing-edge serrated structures are further coupled,and the serrations structure is installed on the trailing-edge of the seagull blade at an angle of attack of 5。to establish a coupling serrations blade with excellent aerodynamic performance and certain excellent noise characteristics.The aerodynamic and noise characteristics of the three blades were numerically calculated by using the large eddy simulation coupled Ffowcs Williams and Hawkings(FW-H)equations The aerodynamic performance of the coupled serrated blades is better among the three types of blades,and the aerodynamic performance of the S1223 blades is poor.And coupled serrated blades have better audible acoustic characteristics for the human ear.In the analysis of the serrations structure,since the serrations structure naturally extends backward and downward from the blade trailing-edge,the distribution of flow velocity will be reduced,and the shedding vortex of the blade trailing-edge will be broken into small vortices at the serrations gap,so that the energy can be better dissipated.This is the main reason why coupling serrated blades have better aerodynamic performance and noise characteristics than seagull blades.(3)Finally,the sawtooth characteristics of coupled sawtooth airfoil blades are combined with real wind turbine blades,two bionic blades are designed,and the SST k-ω turbulence model is used to numerically calculate the three blades.The results show that only when the incoming wind speed is 10m/s,the serrations will reduce the aerodynamic performance of the wind turbine blades,and this phenomenon is more obvious with the increase of the serrations wavelength.At this incoming wind speed,the lift-to-drag ratio of bionic blade A is relatively high from the tip to the middle of the blade compared with the prototype blade,and the lift-to-drag ratio from the middle to the tip is relatively low.The lift-to-drag ratio of bionic blade B in the direction of blade expansion is lower than that of the prototype blade.When the incoming wind speed is 10m/s,the velocity distribution of the serrations gaps at the trailing-edges of the three blades was analyzed.The prototype blade suction surface has better aerodynamic performance due to the presence of a more stable separation vortex.For bionic blades,the flow velocity is higher in the serrated gap,resulting in a smaller flow velocity the surface of the bionic blade,which may be a potential mechanism for the serrations to affect the aerodynamic noise of wind turbine blades.