An Efficient POD/ROM-Based Aeroelasticity Model

Abstract

In this paper, an efficient reduced order model (ROM) for aeroelastic and aeroservoelastic modeling has been developed based upon proper orthogonal decomposition (POD). This model is validated by computing the flutter boundary and reduced frequency ratio of aeroelastic AGARD 445.6 wing and successfully applied to flutter/LCO simulation of an advanced fighter plane configuration. The numerical accuracy and efficiency of this POD/ROM is quantified by using the full-order and full-coupled CFD/CSD simulation, experimental measurements and other existing computational results. The initial study has demonstrated that the new approach is highly efficient and accurate, thus can be used to obtain computational solutions which are the most accurate with the current state of the art and to sufficiently and rapidly predict the behavior of aerospace vehicles. I. Introduction Eroelasticitic and aeroservoelastic dynamics of an aircraft involve aerodynamics, structure dynamics and control, therefore is a comprehensive and multidisciplinary research area. The analysis and evaluation of the aeroelastic and aeroservoelastic dynamics is very important for performance, control and stability analysis of aircraft. Many of the methods that have been developed over the years for simpler aeroelastic models that use, for example, doublet lattice aerodynamics can be adopted for this purpose. However, these models are based on potential flow theory and cannot capture the nonlinear system dynamics in transonic flight regime. High-fidelity model do exist, but if high-fidelity computational fluid dynamics (CFD) and computational structure dynamics (CSD) approaches are used, the large degree-of-freedom, nonlinear fluid and structural system may take days to weeks to finish the computation and, thus are cost prohibitive. Fortunately, reduced order model (ROM) that captures the dominant feature of the full system provides an alternative approach and is extremely useful for such purpose. Dowell and Hall 1 presented a comprehensive review of reduced order models, and in recent years Advanced Dynamics Inc. has developed such models and solvers in its commercial software ASTE-P 2,3 . In this paper we present POD based ROM model that is appropriate to high fidelity computational models for aeroelastic and aeroservoelastic modeling of aircraft. A. POD Methods The use of proper orthogonal decomposition (POD) to construct reduced-order models (ROM) for the highest fidelity computational fluid dynamics (CFD) codes, e.g. the Reynolds-Averaged Navier-Stokes(RANS) equations, has been demonstrated by Thomas, Dowell and Hall 1,5-6,13 and more recently by Lucia and Beran 4,7-8 , Slater and