强台风致风沙耦合运动及其对风力机气动力分布影响研究

WIND-SAND COUPLING MOVEMENT INDUCED BY STRONG TYPHOON AND ITS INFLUENCES ON AERODYNAMIC FORCE DISTRIBUTION OF WIND TURBINE

针对现有土木工程领域台风理论模型过度简化的问题,首先引入基于非静力平衡欧拉方程模型的天气预报模式(WRF)对“鲇鱼”台风进行高时空分辨率模拟,并基于非线性最小二乘法拟合得到边界层风速剖面。同时,为系统对比台风与良态风场的差异性,设置与该台风风速剖面在规范A类地貌梯度高度处风速相同的良态风风速剖面,并分别集成至用户自定义函数(UDF程序)中作为小尺度CFD数值模拟入口条件。在此基础上,以中国东南沿海地区某风电场的5 MW水平轴风力机为研究对象,以风-沙双向耦合算法为核心,采用连续相和离散相模型(DPM)进行风场和沙粒组合的同步迭代模拟,对比研究台风和良态风作用对沙粒运动特征、结构表面等效压力分布模式和升阻力系数特性等的影响规律。结果表明:WRF模式可有效模拟近地面台风风场,拟合的“鲇鱼”台风剖面指数为0.091。与良态风相比,中尺度台风作用显著加剧了风力机结构表面三维气动力分布模式。相较于风荷载,沙荷载主要冲击塔架中下部迎风区域两侧各30°范围,沙荷载与风荷载比值达3.937%,沙压系数最大值为0.09。强台风与大粒径沙粒耦合冲击效应更显著,塔架阻力系数最大增幅可达9.80%,相较于良态风场塔架阻力系数极大值增大13.79%。

To address the excessive simplified theoretical model of typhoon in the civil engineering field,the weather research and forecasting(WRF)mode based on the non-static equilibrium Euler equation model was introduced in for high temporal-spatial resolution simulation of the typhoon“Megi”and the wind speed profile of the boundary layer was gained based on nonlinear least square fitting.For systematic comparison of typhoon field and normal wind field,a normal wind speed profile was set at the same height of standard type-A landform with the typhoon speed profile.Normal wind speed profile and typhoon speed profile were integrated into the user defined function(UDF program)as small-scaled CFD numerical simulation entrance conditions.On this basis,synchronous iteration simulation of wind field and sand particles on a 5 MW horizontal wind turbine in a wind field in the southeastern coastal region in China was carried out centered at the wind-sand two-way coupling algorithm by using the continuous-phase and discrete-phase models.Influencing laws of typhoon and normal wind on sand movement characteristics,equivalent pressure distribution mode on structural surface and lift and drag coefficients characteristics were compared.Results demonstrate that the WRF mode can simulate and analyze near-ground typhoon field effectively and the fitted“Megi”profile index is 0.091.Compared with normal wind,the mesoscale typhoon intensifies the threedimensional aerodynamic distribution mode on the wind turbine structural surface.Sand loads mainly impact on ranges of 30°at two sides of the lower middle windward region of the tower and the sand-wind load ratio reaches 3.937%.The maximum sand pressure coefficient is 0.09.The coupling impact effect of strong typhoon and large sand particles is more significant.The resistance coefficient of the tower can be increased by 9.80%to the maximum extent.The resistance coefficient of tower in the typhoon field is 13.79%higher than that in the normal wind field.