Statistical Sensitivity Study of Frequency Mistuning on the Prediction of the Flutter Boundary in a Transonic Fan
Statistical Sensitivity Study of Frequency Mistuning on the Prediction of the Flutter Boundary in a Transonic Fan
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DOI：
10.1115/gt2016-57295
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发表时间：
2016-06
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影响因子：
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通讯作者：
A. Tateishi;Toshinori Watanabe;T. Himeno;M. Aotsuka;T. Murooka
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文献类型：
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作者：
A. Tateishi;Toshinori Watanabe;T. Himeno;M. Aotsuka;T. Murooka
本文旨在量化失谐对跨音速风扇颤振的稳定作用。这些结果用于支持颤振边界的评估，并澄清在我们先前研究中报告的数值预测中观察到的不匹配的原因。以叶片振型频率偏差为模型，将叶片振动的稳定性分析描述为流固耦合运动方程的特征问题，包括流固耦合作用下的自激气动力。通过蒙特卡罗模拟获得了有关模式特性的统计数据。平均阻尼率和颤振边界的变化是在广泛的失谐水平和运行条件下进行评估的。由于制造公差引起的名义失谐水平对颤振边界的影响很小，因为气动阻尼的下降非常陡峭。因此，与计算流体力学相关的精度很可能导致颤振边界的不匹配。模态特性的直方图表明，即使失谐程度是正常的，颤振模式下的叶片间相位角和叶片幅度也可能是高度分散的。对于严重失谐的情况，在特征值直方图中出现了标称情况下不存在的新的波峰。它们被发现是高度本地化的单刀片主导模式。版权所有©2016由ASME
This paper aims at quantifying the stabilization effect of mistuning in transonic fan flutter. The results are used to support the evaluation of flutter boundary and to clarify the reason for the mismatch observed in the numerical predictions reported in our previous study. Mistuning is modeled by the deviation of blade-mode frequency, and the stability analysis of vibrating blades is formulated as an eigenproblem of the equation of motion including self-excited aerodynamic force obtained by fluid-structure interaction simulations. Statistics about the modal properties are obtained by Monte Carlo simulation. The change in the averaged damping rate and flutter boundary is evaluated in a wide range of mistuning levels and operating conditions. Nominal levels of mistuning due to manufacturing tolerance have little effect to the flutter boundary because the decline in aerodynamic damping is very steep. Therefore, the accuracy associated with the computational fluid dynamics is likely to have caused the mismatch in the flutter boundary. Histograms of modal properties show that the inter-blade phase angle and blade amplitudes in flutter mode can be highly scattered, even if the level of mistuning is nominal. For largely mistuned cases, new crests which do not exist in nominal cases appear in the eigenvalue histogram. They were found to be highly-localized, single-blade dominant mode.Copyright © 2016 by ASME