考虑附加质量力的小型风力机风轮数值模型研究

Numerical Model of Aerodynamic Performance of Rotor With Added Mass Force for Small Wind Turbine

针对风力机动态环境变化时诱导速度滞后的特征,本文基于叶素动量理论、加速势流理论进一步修正平衡尾流模型,提取出一种新型的附加质量力表达式m_(A)=128/75ρR^(3),并建立考虑附加质量力的小型风力机风轮气动载荷数值模型。利用该模型计算拥有自主知识产权300 W S型风力机在三种定常风、湍流风作用下的风轮非定常动态气动载荷。经风洞实验及GH bladed验证,考虑附加质量力的数值模型能够更真实准确地反映风轮气动性能,风轮功率波动幅度小于不考虑附加质量力的平衡尾流模型计算值,计算结果更加准确。风轮轴向载荷、叶根挥舞弯矩与风轮轴功率,均表现出与湍流风速变化一致的随机特性;叶根摆振由于受到叶片自身重力交变载荷作用呈现出周期性脉动;风轮轴向推力系数、风轮轴功率系数表现与湍流风相反的变化趋势。本课题研发的动态气动数值模型具有较高的准确度,为快速获取小型水平轴风力机风轮气动载荷提供一种新思路。

Face to the lag characteristics of induced speed due to wind turbine dynamic environment changing, a new expression of added mass force m_(A)= 128/75ρR^(3)was extracted, and a numerical model of aerodynamic load of small wind turbine considering the added mass force was established using modified the balance wake model using the theory of blade element momentum(BEM) and acceleration potential flow in this paper. The model was used to calculate the unsteady dynamic aerodynamic loads of 300 W S-type wind turbine at three steady wind speeds and turbulence condition. The results of wind tunnel experiment and soft GH bladed both showed that the numerical model considering the added mass force can reflect the aerodynamic performance of the rotor more truly and accurately, and the fluctuation amplitude of the rotor power was smaller than the calculated value of the balance wake model without considering the added mass force. The blade root flapwise bending moment, axial loadand power of the rotor all showed the same random characteristics with the change of turbulence, while the axial thrust coefficient and power coefficient of the rotor showed the opposite trend. The blade root edgewise bending moment presented periodic pulsation due to the action of alternating blade gravity. The dynamic aerodynamic numerical model developed in this paper has high accuracy, which provides a new idea for quickly obtaining the aerodynamic load of small horizontal wind turbine.