后掠式水平轴潮流能水轮机的载荷与获能特性研究

RESEARCH ON LOAD AND ENERGY CAPTURE CHARACTERISTICS OF SWEPT-BACK HORIZONTAL-AXIS TIDAL STREAM TURBINE

针对双向潮流能有效利用问题,设计一种基于对称翼型的新型后掠式水平轴潮流能水轮机,并研究其水动力性能。根据对称翼型升阻力特性与叶片展向攻角变化,采用变截面设计优化后掠式对称翼型叶片,并基于Buhl修正模型分析不同后掠偏移叶片所受推力与获能特性。通过3D建模与水槽实验,研究不同后掠偏移叶片的载荷与获能情况。模型实验研究表明,同一尖速比下,后掠偏移量为10%和15%的水轮机相对于偏移量为5%的水轮机所受推力最大分别降低4%和13.3%,获能效率最多分别减小3.8%和11.1%,其中推力比获能效率减幅更大。实验结果与理论分析变化趋势吻合,但减幅比理论值偏高。此外,该水轮机3种后掠偏移量下对应获能效率随桨距角的增大分别降低18%、14%和6%,获能效率下降显著,与300 kW样机实海况运行情况变化趋势相同。

To capture the bidirectional tidal current energy effectively,a novel swept-back horizontal-axis tidal stream turbine based on symmetrical airfoils was designed and its hydrodynamic performance was discussed.According to the lift-drag characteristics of the symmetrical airfoils and the different spanwise angle of attack,the backward swept blade was optimized by a variable section design,and the thrust and captured energy of the rotor with different offset blades were analyzed based on the Buhl model.Through 3D modeling and flume experiment,the load and captured energy of the rotor model are presented.The experiment results show that at the same TSR,the thrust of the turbine with backward swept offset of 10%and 15%is reduced by 4%and 13.3%,respectively,compared with the turbine with 5%offset.Meanwhile,the energy harvesting efficiency is reduced by 3.8%and 11.1%,respectively.In contrast,the thrust ratio has a greater reduction than the energy harvesting coefficient.The variation trends of the experimental results are consistent with that of the theoretical analysis,but the reduction range is higher than that of the latter.In addition,the corresponding energy harvesting efficiency of the turbine under the three sweep offsets decreases by 18%,14%,and 6%with the increase of the pitch angle,the trend of which is the same as that of the field test of the 300 k W prototype.