Efficient unsteady aerodynamic loads prediction based on nonlinear system identification and proper orthogonal decomposition

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• 作者：Maximilian Winter ; ^{maximilian.winter@aer.mw.tum.de" class="auth_mail" title="E-mail the corresponding author} ; Christian Breitsamter ^{christian.breitsamter@aer.mw.tum.de" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Unsteady aerodynamics ; Reduced-order modeling ; Proper orthogonal decomposition ; Nonlinear system identification ; Neuro-fuzzy models ; Transonic flow
• 刊名：Journal of Fluids and Structures
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：67
• 期：Complete
• 页码：1-21
• 全文大小：8934 K

文摘

In the present work, an efficient surrogate-based framework is developed for the prediction of motion-induced surface pressure fluctuations and integral force and moment coefficients. The model construction is realized by performing forced-motion computational fluid dynamics (CFD) simulations, while the result is processed via the proper orthogonal decomposition (POD) to obtain the predominant flow modes. Subsequently, a nonlinear system identification is carried out with respect to the applied excitation and the resulting POD coefficients. For the input/output model identification task, a recurrent local linear neuro-fuzzy approach is employed in order to capture the linear and nonlinear characteristics of the dynamic system. Once the reduced-order model (ROM) is trained, it can substitute the flow solver within unsteady aerodynamic or aeroelastic simulation frameworks for a given configuration at fixed freestream conditions. For demonstration purposes, the ROM approach is applied to the LANN wing in high subsonic and transonic flow. Due to the characteristic lambda-shock system, the unsteady aerodynamic surface pressure distribution is dominated by nonlinear effects. Numerical investigations show a good correlation between the results obtained by the ROM methodology in comparison to the full-order CFD solution. In addition, the surrogate approach yields a significant speed-up regarding unsteady aerodynamic calculations, which is beneficial for multidisciplinary computations.