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首页> 外文期刊>Journal of the American Helicopter Society >Modeling Refinements in Simple Tiltrotor Whirl Flutter Analyses
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Modeling Refinements in Simple Tiltrotor Whirl Flutter Analyses

机译：在简单的Tiltrotor Whirl Flutter分析中建模细化

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A new tiltrotor whirl flutter stability analysis has been developed. The analysis retains the simplicity of a rigid blade model, while still providing accurate results. The formulation is physically motivated―blade flap and lag frequencies are evaluated from first principles, rather than provided as tabular inputs (as in existing simple analyses). Several unique features have been incorporated into the present analysis. First, the distribution of blade flexibility inboard and outboard of the pitch bearing allows proper modeling of variations in flap and lag frequency with collective pitch. Second, separate gimbal and blade flapping degrees of freedom are retained. This physically models the low-frequency (gimbal dominated) cyclic modes and the higher frequency collective mode, and does not require the "assignment" of different frequencies to the modes. Third, blade torsion dynamics, which have not been considered by existing simple analyses, are modeled. Accounting for the distribution of blade flexibility when formulating the blade pitch equations allows the derivation of closed-form expressions for pitch-lag and pitch-flap coupling parameters. These expressions can be used in lieu of full torsion dynamics. Results from the present analysis are validated against experimental data for several tiltrotor configurations. The analysis generally shows good agreement, both with experimental data and with results obtained from more complex elastic blade analyses. The influence of the various modeling refinements on whirl flutter stability prediction is evaluated and discussed.
机译：已经开发了一种新的倾斜转子涡动颤振稳定性分析。该分析保留了刚性刀片模型的简单性，同时仍提供了准确的结果。该公式是出于物理动机的-叶片襟翼和滞后频率是根据第一原理评估的，而不是作为表格输入提供的（如现有的简单分析中所述）。几个独特的功能已被纳入当前的分析。首先，变桨轴承内侧和外侧叶片挠性的分布允许对襟翼和滞后频率随整体变桨的变化进行适当的建模。其次，保持了分开的万向节和叶片拍打自由度。这在物理上模拟了低频（万向节主导）循环模式和高频集体模式，并且不需要将不同频率“分配”给这些模式。第三，对现有简单分析未考虑的叶片扭转动力学进行建模。在制定叶片桨距方程时考虑到叶片挠性的分布，可以推导桨距滞后和桨距襟翼耦合参数的闭式表达式。这些表达式可以代替完整的扭转动力学。目前的分析结果已针对几种摆式转子配置的实验数据进行了验证。分析与实验数据以及从更复杂的弹性叶片分析获得的结果总体上显示出良好的一致性。评估和讨论了各种建模改进对旋振稳定性预测的影响。

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