风力机叶片的三维非定常气动特性估算

Prediction of the unsteady aerodynamic characteristics of wind turbine blades with 3-D rotational effects

结合动量-叶素理论、非定常空气动力和动态失速模型来计算风力机叶片的二维非定常气动特性,并在此基础上经过适当修正后考虑三维旋转效应的非定常气动特性。分析比较二维和三维两种计算结果,给出更为合理的计算叶片非定常气动特性的方法。计算结果表明,风力机叶片的三维非定常气动特性计算结果与二维时的计算结果相比有较大改善。

The unsteady aerodynamic characteristics of wind turbines are calculated using the momentumblade theory and the unsteady aerodynamic and dynamic stall model. The calculation method is subsequently modified to include the three-dimensional （3-D） rotational effects. In the 3-D unsteady aerodynamic model, the classical momentum-blade element theory is improved to account for yaw effect in a quasi-steady manner for wind turbines. The unsteady effects during attached flow conditions are simulated by the superposition of indicial aerodynamic responses. Non-linearities in airfoil behaviour are represented using a Kirchhoff flow model, which is here modified to consider the unsteady movement of the separation point. The vortex-induced force and the associated pitching moment are represented empirically in a time-dependent manner during dynamic stall. The basis for 3-D correction is the delay in the forward movement of the separation point due to the centrifugal pumping and Coriolis force. A suggested analystical stall delay model modifies the blade normal force and, together with consideration of the likely chordwise loading distribution, provides the basis for corrections to the blade tangential force and pitching moment. The calculated results with and without 3-D effects are compared with experimental data, showing that the calculation is improved by the inclusion of the 3-D rotational effects.