大速度条件下的旋翼气弹动载荷特性分析

The analysis on Rotor aeroelastic loads characteristic in high speed condition

  • 摘要: 针对常规直升机大速度状态下的旋翼气弹耦合突出、振动载荷预估难的问题,建立旋翼气弹动载荷分析模型并针对大速度前飞状态下的旋翼载荷特性开展分析。针对桨叶典型的细长柔性梁特征,基于柔性多体动力学框架建立旋翼结构动力学模型,并针对大速度状态下的桨叶负升力和气动干扰特点,采用双峰自由尾迹方法建立旋翼气动模型。在模型验证基础上以B0105旋翼为研究对象,开展大速度状态下旋翼气动、结构载荷计算,结果表明:B0105旋翼在大速度状态下桨尖前行侧出现较大负升力,产生偏置气动力矩效应,气动力矩呈现脉冲式振荡特点;桨根垂向剪力和挥舞弯矩的谐波量呈倍数级地急剧增加,其中桨根挥舞弯矩的四阶谐波幅值增长幅度最大;桨毂垂向力、滚转力矩和俯仰力矩的四阶谐波均大大增加,其中桨毂垂向力增长幅度最大;大速度状态下的桨尖负升力和强力矩造成桨叶高频弹性扭转变形,进一步恶化拉杆载荷。

     

    Abstract: The analysis of Rotor aeroelastic and the prediction of vibration load are still challenges in conventional helicopter design. A rotor aeroelastic loads computing method was adopted and rotor dynamics issue in high speed forward flight was analyzed. With slender and flexible rotor blade, the rotor dynamics model was built with the Hamilton principle and the middle deformation beam theory. The aerodynamic model was built based on dual free wake model to catch the negative lift at blade tip and rotor interaction in high speed flight. Finally the computing method was validated and used in loads characteristic analysis. The result in BO105 rotor analysis indicated that the strong negative lift was rapidly grow at blade tip in advancing side, the lift offset moment was periodically alternate and pulsed. The harmonic loads of blade root vertical shear force and flap bending moment was rapidly grow, the increment of 4/rev blade root flap bending moment was the largest. The 4/rev hub vertical force, roll moment and pitch moment was also rapidly grow, the increment of hub vertical force was the largest. The high frequency elastic torsion deformation appeared due to the strong negative lift and impulse moment, and the pitch link load was deteriorated.

     

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