Numerical investigation of grooved cylinder-airfoil interaction noise reduction at different Reynolds numbers

Abstract

The grooved model, which is designed for the upstream cylinder, is intended to minimize the interaction noise generated by the cylinder-airfoil model. The impact of the grooved model on noise reduction performance is investigated at Reynolds number (Re) values of 2.6 × 10⁴, 5.3 × 10⁴, and 7.9 × 10⁴ through the application of large eddy simulation (LES). The results demonstrate that the grooved model has a negligible effect on performance at Re = 2.6 × 10⁴. However, as Re increases, the grooved model leads to a reduction in surface pressure pulsation on both the cylinder and airfoil surfaces, resulting in a decrease in peak noise levels of 4.2 dB and 17.7 dB, respectively. The overall sound pressure level (OASPL) is reduced by 3.2 dB and 10.8 dB, respectively. This noise reduction can be attributed to the decrease in shear stress on the cylinder surface with an increasing Re, which inhibits the formation of large-scale spanwise vortex structures in the wake of the cylinder and thus weakens the interaction between the wake and the airfoil. Dynamic mode decomposition (DMD) is used to analyze the modal characteristics of the flow field structure at Re = 7.9 × 10⁴, revealing that the first 7 modes of the smooth model exhibit high-energy, low-frequency characteristics, while the grooved model notably diminishes the intensity and scale of the vortices at the leading edge of the airfoil.