Flow and Noise Control of a Cylinder with Annular Plates

TL;DR

This study introduces a passive annular plate structure around a cylinder that significantly reduces aerodynamic noise and drag, offering an eco-friendly, cost-effective solution for wind turbine noise mitigation.

Contribution

The paper presents a novel passive control method using annular plates around a cylinder, achieving substantial noise and drag reductions validated through numerical simulations.

Findings

89.46% reduction in mean drag coefficient

86.6% reduction in Strouhal number

Maximum noise reduction of 39 dB

Abstract

With the growing demand for electricity and increasing interest in renewable energy, wind turbine noise pollution has become a more pressing issue. Aerodynamic noise not only impacts human well-being but also affects wildlife. This study investigates the aeroacoustics and aerodynamics of a two-dimensional circular cylinder exposed to turbulent flow at a fixed Reynolds number of 22,000. A key novelty of this research is the introduction of a passive control technique, achieved by designing a structure with two thin annular plates positioned around the cylinder in the circumferential space. The numerical analysis is conducted using unsteady Reynolds-averaged Navier-Stokes (URANS) methods in combination with the Ffowcs Williams and Hawkings (FW-H) acoustic analogy. The control assessments reveal substantial performance improvements, with reductions of 89.46% in the mean drag coefficient and 86.6% in the Strouhal number for the modified cylinder. From an acoustic perspective, the passive control method achieves a maximum noise reduction of 39 dB, with a notable drag reduction of 50.62% in a specific case. This innovative design offers a highly efficient and cost-effective solution for noise reduction and wake control in wind turbine applications. Its eco-friendly nature, ease of implementation, and maintenance-free operation make it a promising approach for enhancing wind turbine performance without additional energy consumption.