ABSTRACT

Airfoil’s aerodynamic characteristics are vital for the design and performance evaluation of wind turbine rotor blades through blade element momentum theory. Generally, the airfoil’s aerodynamic characteristics are evaluated at an approximated fixed Reynolds number. However, during a typical operation of a wind turbine, the Reynolds number varies along the length of the blade as well as with wind speed. Since airfoil’s aerodynamic characteristics are dependent on Reynolds number, inadequate consideration of Reynolds number in blade element momentum theory may result in discrepancy in an optimum design and performance evaluation. In the present work, the influence of inadequate consideration of Reynolds number on design and performance evaluation of a small horizontal axis wind turbine blade is studied. For the study, a wind turbine blade design with various design considerations, including a range of design tip speed ratio (5, 6, 7, and 8) and a range of inadequately approximated fixed (i.e., 0.5, 0.75, 1.00, and 1.25 million) and operational Reynolds number for aerodynamic characteristics of the airfoil, is considered. The study suggests that inadequate fixed Reynolds number consideration for blade design and performance evaluation can result in blade solidity as high as 17.1% with respect to blade design considering operational Reynolds number consideration and discrepancy in power coefficient prediction as high as 3.6% with fixed Reynolds number consideration for aerodynamic characteristics of the airfoil.

摘要

翼型的空气动力学特性对于通过叶元动量理论进行风力涡轮机转子叶片的设计和性能评估至关重要。通常，翼型的空气动力学特性是在一个近似的固定雷诺数下评估的。然而，在风力涡轮机的典型运行期间，雷诺数沿叶片长度以及风速变化。由于翼型的气动特性取决于雷诺数，因此在叶片元动量理论中对雷诺数的考虑不足可能会导致优化设计和性能评估的差异。在本工作中，研究了雷诺数考虑不足对小型水平轴风力机叶片设计和性能评估的影响。对于研究，具有各种设计考虑的风力涡轮机叶片设计，包括设计叶尖速比范围（5、6、7 和 8）和不充分近似的固定范围（即 0.5、0.75、1.00 和 125 万）和运行考虑了翼型气动特性的雷诺数。研究表明，在叶片设计和性能评估中不充分考虑固定雷诺数可能会导致叶片设计考虑到操作雷诺数的考虑高达 17.1% 的叶片坚固性，并且功率系数预测与固定雷诺数的差异高达 3.6%考虑翼型的空气动力学特性。考虑了翼型气动特性的 0.75、1.00 和 125 万）和运行雷诺数。研究表明，在叶片设计和性能评估中不充分考虑固定雷诺数可能会导致叶片设计考虑到操作雷诺数的考虑高达 17.1% 的叶片坚固性，并且功率系数预测与固定雷诺数的差异高达 3.6%考虑翼型的空气动力学特性。考虑了翼型气动特性的 0.75、1.00 和 125 万）和运行雷诺数。研究表明，在叶片设计和性能评估中不充分考虑固定雷诺数可能会导致叶片设计考虑到操作雷诺数的考虑高达 17.1% 的叶片坚固性，并且功率系数预测与固定雷诺数的差异高达 3.6%考虑翼型的空气动力学特性。