Extremum seeking control applied to airfoil trailing-edge noise suppression

TL;DR

This paper demonstrates the application of extremum seeking control to reduce airfoil trailing-edge noise in high-fidelity simulations, addressing different noise mechanisms at varying Reynolds numbers.

Contribution

It introduces the use of extremum seeking control for active noise suppression in aerodynamic flows, with detailed implementation in complex simulation environments.

Findings

ESC effectively reduces noise at different Reynolds numbers.

Control strategies include optimizing actuator intensity and position.

Implementation details enhance practical applicability.

Abstract

Extremum seeking control (ESC) and its slope seeking generalization are applied in a high-fidelity flow simulation framework for reduction of acoustic noise generated by a NACA0012 airfoil. Two Reynolds numbers are studied for which different noise generation mechanisms are excited. For a low Reynolds number flow, the scattering of vortex shedding at the airfoil trailing edge produces tonal noise while, for a moderate Reynolds number case, boundary layer instabilities scatter at the trailing edge leading to noise emission at multiple tones superimposed on a broadband hump. Different control setups are investigated and they are configured to either find an optimal steady actuator intensity or an optimal position for a blowing/suction device. Implementation details are discussed regarding the control modules and design of digital filters.