基于NURBS和遗传算法的潮流能水轮机翼型优化

Tidal turbine hydrofoil optimization design based on NURBS and genetic algorithm

潮流能发电水轮机翼型性能参数优劣是决定水轮机效率高低的重要因素之一,如何构造叶片翼型线是水轮机叶片设计过程中的关键问题。基于NURBS曲线构造水轮机叶片翼型参数化表征方法所构造的叶片翼型与原始翼型相比吻合度好,拟合精度较高。利用流体计算方法与XFOIL软件计算获得翼型性能参数样本,通过多目标遗传算法对NACA4415翼型升阻比展开多工况优化设计。结果表明,经过优化后的翼型升阻比性能与原始翼型相比较在所设计攻角工况下均得到提升,升阻比提升幅度随着攻角增大而增大。根据优化翼型建立的叶片功率系数相比原始叶片也得到提高,在桨距角为6°时功率系数最高提高了约7%,验证了该优化方法的正确性与合理性。

The performance parameter of marine current blade is one of the important factors that determine the efficiency of turbine,so how to construct the blade profile is a key problem in the design process.In this study,the NURBS curve was used to parameterize the turbine blade profile,and the constructed blade profile agrees well with the original one,meanwhile the fitting accuracy is very high.The blade profile performance parameter samples are obtained by using the fluid calculation method and XFOIL software.Then multi-conditions optimal design was performed for the lift-drag ratio of the NACA4415 airfoil profile.Optimization results show that the performance of the lift-drag ratio is improved in the condition of attack angle design,and the increasing amplitude increases with the increase of the attack angle.The power coefficient based on the optimal airfoil profile also increases compared with the original one,and it is increased by 7%around when the propeller pitch angle is 6°.The results validate the rationality and validity of the proposed optimal problem.