Numerical Study of Flow and Noise Control Mechanism of Shape-Optimized Series Cylinder

Abstract

The study addresses the critical issue of noise generation attributed to airflow around cylinders and its regulation, a subject of great significance in a range of engineering applications. This paper uses computational fluid dynamics (CFD) in conjunction with acoustic analogy to evaluate the potential of elliptical cylinder configurations to enhance aerodynamic performance and mitigate aerodynamic noise. The analysis focuses on the tandem cylinder, which is a simplified representation of aircraft landing gear, and the mechanism for noise suppression associated with elliptical cylinders. The findings demonstrate the significant influence of elliptical cylinder designs on aerodynamic performance and noise reduction. Specifically, these designs exhibit a capacity to effectively reduce the average drag coefficient and proficiently suppress fluctuations in the lift coefficient, thereby resulting in an overall reduction of noise production by the elliptical cylinder. To investigate the underlying mechanisms of noise suppression, this study assessed the process of vorticity generation around the surface of the elliptical cylinder, and found a profound decrease in the distribution of vorticity on the elliptical cylinder’s surface, accompanied by a remarkable attenuation of the velocity and boundary surface pressure distribution. These changes result in a significant reduction in vorticity generation in the vicinity of the elliptical cylinder wall. These changes directly precipitate a significant contraction of the distribution of vortex structures in the wake of the elliptical cylinder, particularly impacting large-scale vortex structures. Therefore, the noise suppression mechanism proposed for the elliptical cylinder can effectively mitigate aerodynamic noise.