Hybrid Discontinuous Galerkin and Finite Volume Method for Launch Environment Acoustics Prediction

Launch vehicles experience extreme acoustic loads during liftoff driven by the interaction of rocket plumes and plume-generated acoustic waves with ground structures. Currently employed predictive capabilities to model the complex turbulent plume physics are too dissipative to accurately resolve the propagation of acoustic waves throughout the launch environment. Higher fidelity liftoff acoustic analysis tools to design mitigation measures are critically needed to optimize launch pads for the Space Launch System and commercial launch vehicles. To this end, a new coupled two-field simulation capability has been developed to enable accurate prediction of liftoff acoustic physics. Established unstructured computational fluid dynamics algorithms are used for simulation of acoustic generation physics and a high-order-accurate discontinuous Galerkin nonlinear Euler solver is employed to accurately propagate acoustic waves across large distances. An innovative hybrid computational fluid dynamics/computational aeroacoustics coupling method is used to transmit the computational fluid dynamics-predicted acoustic field to the computational aeroacoustics domain for accurate propagation throughout the launch environment. Implementation of the coupling procedure is described in detail, and results are presented that demonstrate the accuracy of the capability for aeroacoustics predictions. Additionally, the merits of the approach are evaluated for acoustic propagation using a notional Space Launch System environment in which rocket plumes are represented by transient acoustic sources.