适用于曲线叶片运动学的翼型形状优化的低保真方法
A Low-Fidelity Method for Aerofoil Shape Optimisation for Curvilinear Blade Kinematics
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中文总结 AI 辅助
该研究以悬停环翼为案例，开发了曲线叶片运动学下翼型优化的低保真框架，其计算成本远低于高保真优化，可有效提升悬停效率且实用性优于叶片桨距优化。
中文摘要 AI 辅助
本研究以悬停环翼为代表性案例，开发了一种适用于曲线叶片运动学的翼型形状优化的低保真框架。翼型优化可通过抑制动态失速期间的前缘涡分离来提高环翼效率，但传统方法依赖计算成本高昂的基于CFD的优化。所提方法采用单流管模型估算转子通流，并通过独立的前缘和后缘准则优化翼型弯度线。在叶片数量和弦长不同的构型中评估该框架时，其始终能识别出可提高悬停效率（以优值系数量化）的翼型。对于基准四叶片构型，该低保真优化实现了高保真优化所获优值系数提升的77%，而计算成本仅为后者的一小部分。分析还揭示了弦长增加时的另一组扭矩最小化设计，凸显了后缘载荷的影响。此外，将翼型优化与叶片桨距运动学优化进行了比较，后者通过类似的前缘涡控制来提高效率。尽管两种方法均产生相当的效率提升，但优化后的运动学显著降低了推力。因此，翼型优化可能更具实用性，因为采用优化桨距运动学维持目标推力需要更高的转速，可能引发结构和噪声问题。
英文摘要
This study develops a low-fidelity framework for aerofoil shape optimisation under curvilinear blade kinematics, using a hovering cyclorotor as a representative case. Aerofoil optimisation can improve cyclorotor efficiency by suppressing leading-edge vortex separation during dynamic stall, but conventional approaches rely on computationally expensive CFD-based optimisation. The proposed method uses a single-streamtube model to estimate the rotor throughflow and optimises the aerofoil camberline using separate leading- and trailing-edge criteria. Assessed across configurations with varying blade counts and chord lengths, the framework consistently identifies aerofoils that improve hover efficiency, quantified by Figure of Merit. For the baseline four-bladed configuration, the low-fidelity optimum achieves 77% of the Figure of Merit improvement obtained using high-fidelity optimisation at a fraction of the computational cost. The analysis also reveals an additional torque-minimising design family at increased chord lengths, highlighting the influence of trailing-edge loading. Aerofoil optimisation is also compared to blade-pitch kinematics optimisation, which improves the efficiency through similar control of the leading-edge vortex separation. While both approaches produce comparable improvements in efficiency, the optimised kinematics substantially reduces thrust. Aerofoil optimisation may therefore be more practical, as maintaining a target thrust with optimised pitch kinematics would require higher rotational speeds, potentially introducing structural and noise issues.
