Efficient aeroelastic reduced order model with global structural modifications

Abstract

Time domain aeroelastic analysis has high computing costs when using computational fluid dynamics. These costs become prohibitive when the structural model undergoes large changes from the baseline design, as within an aircraft design process. To overcome this realistic challenge, we have developed, implemented, and demonstrated an efficient method that is robust in the presence of global modifications of the structure. The method consists of: a) a reduced order model of the linearized Navier–Stokes equations generated around an aeroelastic equilibrium that depends, in turn, on the structural model; b) an approximate structural dynamic reanalysis method valid for global modifications of the structure; and c) a mechanism to exchange information between fluid and structural solvers without need for calculating at each iteration of the structural design an eigenvalue problem of the modified structure. The resulting aeroelastic reduced order model is demonstrated for the AGARD 445.6 wing, and material properties are varied up to 100% from their original values. It is found that: a) predictions of the time domain aeroelastic response and of the flutter speed are accurate for all modifications of the structure; and b) the computational efficiency of the proposed aeroelastic reduced order model is linearly proportional to the number of structural configurations considered. The method, therefore, is ideally suited for optimization and uncertainty studies.