A coupled LES-APE approach for jet noise prediction

Despite the continuing advances of computing power, the state-of-the-art direct numerical simulations of jet noise are still restricted to simple problems. Additionally, many established CFD codes are potentially too dissipative for propagating acoustic waves. Hence, alternative methods are needed for complex realistic configurations. Traditionally, the combination of Large-Eddy Simulations (LES) with surface integral methods has been widely used by the research community to predict jet noise in the far-field. However, its application in complex installed configurations poses quite a challenging task in defining a suitable surrounding integral surface. Furthermore, these methods only provide information of single observer locations. In the present work, a coupled LES-APE (Acoustic Perturbation Equations) strategy is presented as an alternative to traditional methods. Two different solvers are used. The LES is performed with a density based, second order finite volume solver with the σ-subgrid-scale model. The APE code is a high-order Discontinuous Galerkin spectral/hp finite element solver. It solves the APE which does not suffer from instability issues related to the more common Linearised Euler Equations (LEE). Moreover, the APE is advantageous by means of a filtered source, propagating only true sound. It is also planned to apply this methodology to more realistic configurations such as coaxial nozzles and jet-wing-flap interaction cases.