| With the increasing of fossil energy crisis in the world,wind energy,as one of the mature technologies in many green renewable energy sources,has developed rapidly,and its proportion in energy is increasing.The wind turbine rotor is the key part of the wind turbine to capture energy.However,when the wind turbine blade appears erosion due to external factors such as sand particles and raindrops,its aerodynamic performance will be greatly affected.Therefore,the numerical simulation of the six section airfoils and the rotor of the external wind turbine blade is carried out to study the erosion process of the wind turbine airfoil surface and the influence of different erosion conditions on the aerodynamic performance of the airfoil and rotor in the wind-blown environment.In this paper,the six section airfoils of the field experimental wind turbine blade of Lanzhou University of Technology are taken as the research object.The SST k-ω turbulence model and DPM model are used to solve the gas-solid two-phase flow,and the erosion model is used to simulate the flow.The influence of wind turbine airfoil surface erosion on its flow field,aerodynamic performance,and the evolution process and erosion mechanism of the airfoil surface are studied.Then based on the OpenFOAM platform,taking the wind turbine rotor as the research object,the method of actuation line model coupling large eddy simulation and the aerodynamic data of the eroded airfoil obtained by numerical simulation are used to simulate the influence of blade erosion on rotor power,velocity field and load in wind-blown environment.The main conclusions are as follows:(1)Two years later,when the airfoil occurs erosion,pits,gouges and delamination with different degrees appear in each section airfoil.As the erosion time increases,new pits and gouges appear on the airfoil surface,the inside of the leading edge delamination gradually appears pits,gouges and local delamination,which causes the depth of the leading edge delamin ation to increase locally,some adjacent pits and gouges on the suction face of 4# and 5# sections connect to form larger gouges and local delamination,and the horizontal size of them continues to expand as time progresses.The erosion area of the suction surface remains substantially unchanged.Compared with the suction surface of the airfoil,the pressure surface has a greater delamination depth,more pits,and larger erosion area.At the same time,the erosion degree of blade gradually increases from th e root to the tip.Observing the erosion process of each section airfoil to obtain three stages of erosion:1)the airfoil surface is constantly impacted by the particles,resultin g in pits with different sizes;2)due to the impact of the particles on the inner wall of the pits,the size of the pits gradually increases,becoming a larger gouges;3)due to the concentrated collision of particles on the right inner wall,gouges continuously expand to the right along the airfoil surface,and develop into the dela mination of small area.(2)The erosion of the airfoil surface has certain influence on the flow field of the airfoil leading edge and trailing edge.The airfoil surface of the 1# and 2# section basically doesn’t occur erosion,compared with the smooth airfoil,and the flow fields of the leading edge and trailing edge of the airfoil are basically unchanged,the front edge of airfoil doesn’t occur flow separation.The airfoil surfaces of the 3#-6# section occur severe erosion,as the time increases,the erosion of airfoil surface becomes more severe.The separation position of the airfoil suction surface moves forward along the airfoil surface,and the trailing edge separation area expands constantly.Because the front edge has pits,gouges and delamination with large depth,the airflow generates a leading edge separation bubble behind the suction surface step,it reattaches to the airfoil and continues to flow after the airflow flows through the recirculation zone,and the area of the leading edge separation b ubble expands constantly as erosion becomes more and more serious.(3)The erosion of the blade surface makes its aerodynamic performance drop significantly,when the erosion reaches a certain level,the aerodynamic performance of the airfoil doesn’t change significantly.With the increase of time,the pressure coefficient of each section decreases,and the more severe the airfoil surface erosion,the greater the pressure coefficient reduction;the pressure coefficient of the position of the pits,gouges and the delamination will be abrupt,and the leading edge delamination has the largest mutation.(4)Wind turbine blade surface erosion causes the rotor torque and power to drop drastically.When the wind turbine is running for five years,the wind turbine torque and power drop 34% at most.As the running time increases,the ability of the rotor to capture wind energy continuously reduces,the speed loss of the rotor also gradually reduces,and t he sp eed o f t he radial plane of the rotor and the speed behind the rotor gradually increase.As the degree of erosion increases,the amplitudes of the power spectrum of the flapwise and lagwise moment gradually decrease,and the flapwise and lagwise load decrease. |
