Acoustics flow analysis in circular duct using sound intensity and dynamic mode decomposition

21st Fluid Mechanics Conference

物理学;力学

Weyna, S.^1

West Pomeranian University of Technology, Faculty of Marine Technology and Transport, Szczecin, Poland^1

关键词: Cylindrical ducts;    Diffraction and scattering;    Dynamic mode decompositions;    Frequency regions;    Low-Mach-number flow;    Orthogonal decomposition;    Particle velocities;    Physical pictures;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/530/1/012046/pdf
DOI  :  10.1088/1742-6596/530/1/012046

学科分类：力学，机械学

来源: IOP

【 摘 要 】

Sound intensity generation in hard-walled duct with acoustic flow (no mean-flow) is treated experimentally and shown graphically. In paper, numerous methods of visualization illustrating the vortex flow (2D, 3D) can graphically explain diffraction and scattering phenomena occurring inside the duct and around open end area. Sound intensity investigation in annular duct gives a physical picture of sound waves in any duct mode. In the paper, modal energy analysis are discussed with particular reference to acoustics acoustic orthogonal decomposition (AOD). The image of sound intensity fields before and above "cut-off" frequency region are found to compare acoustic modes which might resonate in duct. The experimental results show also the effects of axial and swirling flow. However acoustic field is extremely complicated, because pressures in non-propagating (cut-off) modes cooperate with the particle velocities in propagating modes, and vice versa. Measurement in cylindrical duct demonstrates also the cut-off phenomenon and the effect of reflection from open end. The aim of experimental study was to obtain information on low Mach number flows in ducts in order to improve physical understanding and validate theoretical CFD and CAA models that still may be improved.