Discontinuous Galerkin Multimodel Methods for Optimal Control of Aeroacoustics

Abstract

DOI: 10.2514/1.23798 A new multimodel computational framework for optimal control of aeroacoustic noise is presented using a nearfield compressible Navier–Stokes solver coupled with a far-field linearized Euler solver, both based on a discontinuous Galerkin formulation. In this approach, the coupling of near- and far-field domains is achieved by weakly enforcing continuity of normal fluxes across a coupling surface that encloses all nonlinearities and noise sources.Foroptimalcontrol,gradientinformationisobtainedbythesolutionofanappropriateadjointproblemthat involves the propagationof adjoint information from the far fieldto the near field. Thiscomputational framework is applied to study optimal boundary control of blade–vortex interaction, which is a significant noise source for helicopters on approach to landing. In the prototype problem presented here, the noise propagated toward the ground is reduced by 12 dB, demonstrating the potential of an optimization-based approach to blade–vortexinteraction noise control.