Adjoint-based Trailing-Edge Noise Minimization using Porous Material

Abstract

In this paper, we present a discrete adjoint-based optimization framework to obtain the optimal distribution of the porous material over the trailing edge of a 3-D flat plate. The near-body strength of the noise source generated by the unsteady turbulent flow field is computed using a high-fidelity large-eddy simulation (LES). The acoustic signal thus generated is then propagated to the far-field using the acoustic perturbation equations (APE). The design gradients are computed using the forward and reverse modes of automatic differentiation (AD). The increase of memory requirement in the reverse mode AD is alleviated by checkpointing. By optimally controlling the material porosity and permeability, it is possible to minimize the turbulence intensity responsible for noise generation at the trailing edge and thus significantly reduce the radiated noise. We demonstrate, using a simple geometry as a first step, the efficacy of the discrete adjoint method in achieving minimum-noise design via optimal distribution of porous media, with future applications to aircraft high-lift devices.

Numerical simulation of a turbulent channel flow with an acoustic liner

“…Apart from sound damping in ducts, there is a growing interest in passive methods for aeroacoustics and flow control [26], and a better knowledge of the behavior of the flow in the vicinity of non-rigid wall is useful in general. This paper makes a new contribution to the investigation of turbulent channel flows with acoustic liners (limited to locally reacting, perforate-like liners).…”