Meccanica ( IF 2.7 ) Pub Date : 2021-07-05 , DOI: 10.1007/s11012-021-01390-8 Amit Kumar Onkar 1
In this work, a successive robust flutter prediction technique is developed by coupling nominal analysis, ground vibration test, wind tunnel test, uncertainty model updation and robust analysis based on the structured singular value method to predict the worst flutter boundary of a swept back wing in transonic flow regime. Here, uncertainties in both structural and unsteady aerodynamics parameters are considered in the generalized coordinates. These uncertainties are introduced in the nominal aeroelastic system in a linear fractional transformation framework. The magnitudes of structural uncertainties are estimated based on the difference in natural frequencies between ground vibration test and nominal analysis. The magnitudes of aerodynamic uncertainties are estimated using a model updation technique based on the structured singular value method considering the difference in damping values between wind tunnel test and nominal analysis. The capability of the present successive robust flutter prediction technique is investigated by estimating the robust flutter boundary of a swept back wing in transonic flow regime. From the results, it is observed that the uncertainty model updation provides a reasonable estimate of aerodynamic uncertainty magnitude. Further, the present flutter prediction approach gives a good estimate of transonic flutter boundary (transonic dip) by successively updating the aerodynamic uncertainty bounds using wind tunnel data for various set of test Mach numbers.
中文翻译:
一种基于μ方法的气动弹性系统连续鲁棒颤振预测技术
在这项工作中,通过耦合标称分析、地面振动试验、风洞试验、不确定性模型更新和基于结构奇异值方法的鲁棒分析,开发了一种连续鲁棒颤振预测技术,以预测后掠翼最坏颤振边界。跨音速流动状态。在这里,在广义坐标中考虑了结构和非定常空气动力学参数的不确定性。这些不确定性是在线性分数变换框架中的名义气动弹性系统中引入的。结构不确定性的大小是根据地面振动试验和标称分析之间的固有频率差异来估计的。考虑到风洞试验和标称分析之间阻尼值的差异,使用基于结构奇异值方法的模型更新技术来估计空气动力学不确定性的大小。通过估计跨音速流态中后掠翼的鲁棒颤振边界来研究当前连续鲁棒颤振预测技术的能力。从结果可以看出,不确定性模型更新提供了对气动不确定性大小的合理估计。此外,本颤振预测方法通过使用各种测试马赫数集的风洞数据连续更新空气动力学不确定性边界,给出了跨音速颤振边界(跨音速倾角)的良好估计。