Unsteady aerodynamic reduced-order modeling method for parameter changeable structure

Computational fluid dynamics (CFD) based unsteady aerodynamic reduced-order model (ROM) can make significant improvement of efficiency of transonic aeroelastic analysis. However, the existing ROM is applicable only to structures with fixed parameters, namely prescribed model shapes (ROM-PMS). When structural parameters should be altered such as structure optimization and uncertainty analysis, ROM-PMS is no longer feasible. To settle the problem, a new unsteady aerodynamic modeling method for arbitrary model shapes is developed based on Ref. [20]. Parametric sampling and modal analysis are conducted on the structure to be designed and analyzed. The basic mode shapes are then obtained through principal component analysis (PCA). Real model shapes of arbitrary structure in the sample space can be synthesized by linearly superimposing basic mode shapes with correct coefficients. The coefficients of superposition change with the alteration of structure parameters. The analysis shows that just small number of basic modes can reach desirable accuracy. Classical modeling method can be used to construct ROM in basic mode shape coordinate. The ROM applicable for various structures can be developed from ROM in basic mode coordinate, which means that structural parameters can be arbitrarily altered in the sample space, while ROM is universal. This method can be widely applied to aeroelastic optimization design and uncertainty analysis, with great improvement in computational efficiency.