An attempt to reduce airfoil tonal noise using fluid-structure interaction

Airfoil tonal noise at low Reynolds number has received lot of attentions due to the increasing interest in micro air vehicles. However, for decade, researchers have spent plenty of efforts to investigate the fundamental mechanism of tonal noise generation rather than its control. In the present paper an attempt to control airfoil tonal noise leveraging the fluid-structure interaction of a flexible panel installed on a NACA0012 airfoil is carried using direct aeroacoustics simulation approach. The airfoil at angle of attack of 5° is immersed in a free stream of Reynolds and Mach numbers equal 5 × 10⁴ and 0.4, respectively. The selection of flexible panel parameters is based on the numerical results of ordinary airfoil. A modified linear stability analysis is employed to study the interaction between instability and the panel response as well as its effect on eventual tonal noise radiation. Comparison of numerical results with and without flexible panel reveals there is a great possibility of tonal noise reduction around 1.3 dB with carefully selected fluid-structure interaction.