考虑气动不确定性的气动弹性系统模型确认

Model Validation of Aeroelastic Systems with Aerodynamic Uncertainties

研究了机翼气动弹性系统的不确定性建模及其模型确认问题。结构的不确定性考虑为参数形式,气动力的不确定性分为未建模动力学和参数不确定性两种形式进行讨论。建立不确定气动弹性系统的线性分式变换(LFT)模型,给出了频域的模型有效性检验方法,对有效模型集进行参数化并将不确定性幅值最小的模型集求解归结为优化问题。在建模中计入了实际存在的、未知但能量有界的外扰和噪声的影响,降低了结果的保守性。最后,根据模型确认的结果,使用结构奇异值μ-分析方法进行不确定系统的鲁棒颤振分析。仿真计算结果表明了模型确认方法的有效性。

The problems of uncertainty modeling and model validation of a wing aeroelastic system are investigated. The parametric uncertainties in structure are considered and both the parametric form and the unmodeled dynamic form which are used to represent the uncertainty in unsteady aerodynamic forces are discussed. The linear fractional transformation （LFT） representation of an uncertain aeroelastic system is formulated to perform model validation and robust flutter analysis. Easily computable tests in the frequency-domain for the existence of a model validating set are given, and then a parameterization of the model validating sets is implemented and the smallest uncertainty set is determined based on optimization algorithms. The influence is considered of exogenous disturbances and noise of unknown but energy bounded sources that actually exist in practice, and this could reduce the conservatism of the results. Finally, for an uncertain aeroelastic system with the obtained uncertainty magnitudes, a robust flutter analysis based on the structured singular value theory is performed to predict the robust stability boundary. Numerical results of the simulation demonstrate the validity of the developed method.