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王人凤, 尤云祥, 陈科, 段金龙. 两自由度舵-轴系统振动三维效应修正模型[J]. 力学学报, 2017, 49(4): 920-928. DOI: 10.6052/0459-1879-17-042
引用本文: 王人凤, 尤云祥, 陈科, 段金龙. 两自由度舵-轴系统振动三维效应修正模型[J]. 力学学报, 2017, 49(4): 920-928. DOI: 10.6052/0459-1879-17-042
Wang Renfeng, You Yunxiang, Chen Ke, Duan Jinlong. A MODIFIED MODEL FOR THE VIBRATIONS OF A TWO-DEGREE-OF-FREEDOM HYDROFOIL-ROD SYSTEM CONSIDERING 3D EFFECT[J]. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(4): 920-928. DOI: 10.6052/0459-1879-17-042
Citation: Wang Renfeng, You Yunxiang, Chen Ke, Duan Jinlong. A MODIFIED MODEL FOR THE VIBRATIONS OF A TWO-DEGREE-OF-FREEDOM HYDROFOIL-ROD SYSTEM CONSIDERING 3D EFFECT[J]. Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(4): 920-928. DOI: 10.6052/0459-1879-17-042

两自由度舵-轴系统振动三维效应修正模型

A MODIFIED MODEL FOR THE VIBRATIONS OF A TWO-DEGREE-OF-FREEDOM HYDROFOIL-ROD SYSTEM CONSIDERING 3D EFFECT

  • 摘要: 考虑到小展弦比舵所存在的三维效应,利用附加质量系数ε和环量系数δ对经典Theodorsen两自由度运动方程进行修正,并与经典颤振实验结果进行比较,验证了修正后两自由度运动方程的适用性.质量比μ的不同会引起两自由度舵-轴系统振动V-g曲线形态的差异,故根据V-g曲线形状的不同将系统的振动分为第一类振动和第二类振动,其对应情况下可能发生的颤振为第一类颤振和第二类颤振.利用修正后的两自由度颤振理论模型分析了支撑刚度kh、扭转刚度kα、舵弦向重心位置xα和初始攻角AOA对舵-轴系统颤振特性的影响规律,并通过开展相关实验对理论计算值进行验证,实验结果与计算值吻合良好.计算结果表明,khkαxαAOA对颤振速度VF存在显著影响,它们可以分别在一定的取值范围内导致系统发生第二类颤振.并且,VFkh的增大单调增大,随kαxα的增大先增大再减小,随AOA的增大则逐渐减小.其中,令VF存在非零值的xα取值范围狭小,反映了系统振动形态对xα的敏感性.因此,在设计阶段避免将xα设置在这个狭小的范围内可以降低颤振的发生几率.另一方面,由于VFkhkα的反应缓慢,一旦颤振发生就可以通过将刚性轴锁紧来消除颤振效应.

     

    Abstract: The classical Theodorsen equation for the motions of two-degree-of-freedom foils is modified with associated mass parameter ε and circulation parameter δ by considering the 3D effect of low aspect ratios, and the comparison between the calculation and classical experimental values demonstrates the modified equation is effective. According to the shape of V-g curve which varies with the mass ratio μ, two types (Type Ⅰ and Type Ⅱ) of flutter are defined. The influences of the bracing stiffness kh, the torsional stiffness kα, the locations of the center of gravity xα and the angle of attack AOA on the characteristics of the flutter of a hydrofoil-rod system have been analyzed, and the comparison with experimental values shows that the numerical results are reasonable. The calculation shows the significant impacts of kh, kα, xα and AOA on the flutter speed VF. When the values of the parameters are in certain ranges respectively, flutter Type Ⅱ may occur. Specifically, a larger kh or a smaller AOA leads into a larger VF. While, VF first increases and then decreases with the increase of k α or xα. Moreover, VF only exists in a relatively narrow range of xα, which reflects that the vibration pattern of the hydrofoil-rod system is high sensitive to xα. Therefore, the probability of the occurrence of flutter can be reduced by avoiding the narrow range of xα during design phase. On the other hand, according to the slow reaction of VF to kh and kα, once flutter occurs, flutter can be eliminated by locking the rigid shaft with hydraulic devices.

     

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