Wind turbine blades are inevitable to be eroded in wind-sand environment,so it is crucial to identify the flow conditions under which the erosion happens.Here,the effect of the sand diameter on wind turbine airfoil is...Wind turbine blades are inevitable to be eroded in wind-sand environment,so it is crucial to identify the flow conditions under which the erosion happens.Here,the effect of the sand diameter on wind turbine airfoil is first investigated.When the sand diameter is less than 3μm,the sands will bypass the airfoil and no erosion occurs.When the sand diameter is larger than 4μm,the sand grains collide with the airfoil and the erosion happens.Thus,there must be a critical sand diameter between 3μm and 4μm,at which the erosion is initiated on the airfoil surface.To find out this critical value,aparticle Stokes number is introduced here.According to the range of the critical sand diameter mentioned above,the critical value of particle Stokes number is reasonably assumed to be between 0.007 8and 0.014.The assumption is subsequently validated by other four factors influecing the erosion,i.e.,the angle of attack,relative thickness of the airfoil,different series airfoil,and inflow velocity.Therefore,the critical range of Stokes number has been confirmed.展开更多
强湍流风对偏航状态风力机叶片的动态载荷会产生显著影响,叶片根部载荷的动态特性是影响风力机使用寿命和安全运行的关键因素。该研究采用NWTCUP(The NREL National Wind Technology Center Model)风谱模型耦合KHB(Kelvin-Helmholtz Bil...强湍流风对偏航状态风力机叶片的动态载荷会产生显著影响,叶片根部载荷的动态特性是影响风力机使用寿命和安全运行的关键因素。该研究采用NWTCUP(The NREL National Wind Technology Center Model)风谱模型耦合KHB(Kelvin-Helmholtz Billow)流动,构建了一种强湍流相干结构风况,利用FAST(Fatigue,Aerodynamics,Structures and Turbulence)程序计算了该风况下NREL 1.5 MW风力机在不同偏航角下的气动载荷,研究了KHB湍流相干结构对偏航状态下风力机叶根动态载荷的影响。研究表明,湍流相干结构会使风力机载荷的波动幅值和能量增加。偏航角的增大对叶根摆振力矩影响较小,但对叶根挥舞力矩影响较大,并使二者波动程度增强。湍流相干结构使叶根摆振力矩的最大值、标准差平均升高28.30%和0.64%,最小值和平均值平均降低27.28%和1.903%,叶根挥舞力矩的最大值、标准差和平均值平均升高36.27%、59.57%和2.906%,最小值平均降低114.83%。叶根载荷的小波分析表明,湍流相干结构对摆振力矩频域能量影响较小,且能量主要集中在低频段并与雷诺应力的剪应力分量(u′w′、v′w′)对应较好;对叶根挥舞力矩频域能量影响显著,且能量变化与雷诺应力的剪应力分量(u′w′)对应较好,随着偏航角的增大,叶根挥舞力矩频域能量整体升高。对叶片根部进行加固则可以有效提升叶片的使用可靠性。展开更多
基金supported partly by the National Basic Research Program of China(″973″Program)(No.2014CB046201)the National Natural Science Foundation of China(No.51166009)+4 种基金the National High Technology Research and Development Program of China(No.2012AA052900)the Natural Science Foundation of Gansu ProvinceChina(No.1308RJZA283145RJZA059)the Gansu Province University Scientific Research ProjectChina(No.2013A-026)
文摘Wind turbine blades are inevitable to be eroded in wind-sand environment,so it is crucial to identify the flow conditions under which the erosion happens.Here,the effect of the sand diameter on wind turbine airfoil is first investigated.When the sand diameter is less than 3μm,the sands will bypass the airfoil and no erosion occurs.When the sand diameter is larger than 4μm,the sand grains collide with the airfoil and the erosion happens.Thus,there must be a critical sand diameter between 3μm and 4μm,at which the erosion is initiated on the airfoil surface.To find out this critical value,aparticle Stokes number is introduced here.According to the range of the critical sand diameter mentioned above,the critical value of particle Stokes number is reasonably assumed to be between 0.007 8and 0.014.The assumption is subsequently validated by other four factors influecing the erosion,i.e.,the angle of attack,relative thickness of the airfoil,different series airfoil,and inflow velocity.Therefore,the critical range of Stokes number has been confirmed.
文摘强湍流风对偏航状态风力机叶片的动态载荷会产生显著影响,叶片根部载荷的动态特性是影响风力机使用寿命和安全运行的关键因素。该研究采用NWTCUP(The NREL National Wind Technology Center Model)风谱模型耦合KHB(Kelvin-Helmholtz Billow)流动,构建了一种强湍流相干结构风况,利用FAST(Fatigue,Aerodynamics,Structures and Turbulence)程序计算了该风况下NREL 1.5 MW风力机在不同偏航角下的气动载荷,研究了KHB湍流相干结构对偏航状态下风力机叶根动态载荷的影响。研究表明,湍流相干结构会使风力机载荷的波动幅值和能量增加。偏航角的增大对叶根摆振力矩影响较小,但对叶根挥舞力矩影响较大,并使二者波动程度增强。湍流相干结构使叶根摆振力矩的最大值、标准差平均升高28.30%和0.64%,最小值和平均值平均降低27.28%和1.903%,叶根挥舞力矩的最大值、标准差和平均值平均升高36.27%、59.57%和2.906%,最小值平均降低114.83%。叶根载荷的小波分析表明,湍流相干结构对摆振力矩频域能量影响较小,且能量主要集中在低频段并与雷诺应力的剪应力分量(u′w′、v′w′)对应较好;对叶根挥舞力矩频域能量影响显著,且能量变化与雷诺应力的剪应力分量(u′w′)对应较好,随着偏航角的增大,叶根挥舞力矩频域能量整体升高。对叶片根部进行加固则可以有效提升叶片的使用可靠性。
