复杂三维外形对桨叶动特性影响分析研究

Analysis of Influence Factors on Vibration Characteristics of Blades with the Complex 3D Shape

具有前突后掠、下反的复杂三维外形桨叶先进布局是未来直升机旋翼技术发展的重要方向,准确预测与分析前突后掠带下反桨叶动力学特性是桨叶结构设计和调频优化的基础。基于Hamilton原理建立了一套计及前突后掠、下反的桨叶结构动力学模型,利用UH-60风洞试验数据验证了计算方法的有效性,针对动特性影响因素如后掠角、前突后掠角、下反角和转速等方面进行了剖析,并揭示了桨叶结构耦合效应和影响机理。研究表明,后掠角会引起挥舞扭转负耦合效应,扭转频率随后掠角增加而减小;下反角会引起摆振扭转的正耦合效应,扭转频率随下反角增加而增加;与纯后掠桨叶相比,前突后掠桨叶随着前掠角的增加,扭转频率增加并减缓后掠角导致的负耦合作用,可为后续桨叶结构优化和气动设计奠定技术基础。

The advanced layout of complex 3D shape blades with forward and backward sweep and dihedral is an important direction for the development of helicopter rotor technology in the future, accurately predicting and analyzing the dynamic characteristics of the blade with forward and backward sweep and dihedral is the basis for the blade structure design and frequency modulation optimization. Based on Hamilton principle, the complex structural dynamic model that consists of forward and backward sweep and dihedral is built, the validity of the calculation method is verified by using the UH-60 wind tunnel test data. The influencing factors of dynamic characteristics such as sweep,forward and backward sweep, dihedral and rotational speed are analyzed, and the coupling effect and influencing mechanism of blade structure are revealed. The results suggest that set of backward sweep causes negative coupling effect between flap and torsion. The torsion frequency decreases with the increase of sweep angle, the set of dihedral causes positive coupling effect between lag and torsion, the torsion frequency increases with the increase of dihedral angle. Compared with the pure swept blade, the torsional frequency of the blade with forward and backward sweep increases with the increase of the forward swept angle, and the negative coupling effect caused by the swept angle is slowed down, which can lay a technical foundation for the subsequent blade structure optimization and aerodynamic design.