风力机叶片三维速度场PIV测量及数值模拟研究

PIV Measurement and Numerical Investigation of Three-dimensional Velocity Field sround Wind Turbine Blades

采用PIV测速技术,对水平轴风力机在尖速比为7.0的轴流工况进行风洞测量,获得不同叶高处翼型截面的高保真三维速度场;同时,采用OpenFOAM对风力机该工况进行数值模拟,实验结果验证数值模拟的准确性。结果表明对于轴向、切向和径向速度,CFD与实验测量有较好的一致性;对比了叶素动量理论、无黏面元法和CFD等气动模型对叶片载荷的预测结果,并与从PIV速度场推导出的气动力进行比较。结果显示CFD比BEM和面元法更准确地预测叶片载荷,BEM和面元法因为叶尖损失模型和无黏假设等原因对叶尖处载荷预测失效。

A horizontal axis wind turbine under axial flow condition, with a tip speed ratio of 7.0, is measured in the wind tunnel by using PIV technology. Three-dimensional velocity field at different blade sections is obtained. Meanwhile, the same condition is simultaneously simulated with OpenFOAM in order to evaluate the accuracy of the prediction by comparison with experimental measurement. The results show that in terms of axial, tangential and radial velocity, the CFD prediction has a good agreement with measured data. Different aerodynamic models, including the blade element momentum theory, unsteady panel method and CFD simulation are compared to predict the aerodynamic loads on blades. The numerical results from aerodynamic models are compared with the forces derived from PIV measured velocity field. Results show that CFD has a better prediction than BEM and panel methods, while BEM and panel methods fail to predict the blade tip loads accurately due to tip loss correction and inviscous assumption, respectively.