Abstract
In order to study turbulence conditions in an underwater square cavity, the large eddy simulation method was adopted to analyze flow field distributions in the cavity as well as its development and pressure pulsation characteristics at some key positions. MATLAB was also adopted to realize Fast Fourier Transform of signals in time domain and obtain pressure pulsation levels in frequency domain. Based on the analyzed results, pressure pulsation characteristics of key points in the cavity were further discussed. The results showed that pressure pulsation frequencies and characteristics were different with different positions in the square cavity and were closely related with relevant vortex motion states. It was found through comparisons with the experimental results, that pressure pulsation simulation had a good consistency with the experiment when the analyzed frequency was more than 31.5 Hz. As a result, feasibility and accuracy of numerical simulation and Fourier analysis methods were verified. Finally, a numerical model of square cavity in near sound field was built, and sound source intensity distributions at two frequency points were extracted. It could be found that the sound source intensity was large at the rear-edge step, which was consistent with the intensity distribution of vortices. Therefore, reliability of the numerical model in this paper was indirectly verified in the results.
Highlights
Noise generated when the fluid flowed through a square cavity was a kind of problems which can often take place in engineering
Flow field and radiation sound field were from vortex under low Mach number conditions, where the source can be eliminated by researching vortex motions in the flow field and sound pressure [5]
1) Vortex situations at different positions in the square cavity were determined through unsteady numerical simulation and analysis of the flow field in the square cavity
Summary
Noise generated when the fluid flowed through a square cavity was a kind of problems which can often take place in engineering. Rowley adopted the direct numerical simulation method to research the flow mechanism and radiation noises of a two-dimensional opened cavity under laminar flow conditions [6]. Gloerfelt adopted LES method to research the aerodynamic noise of a three-dimensional rectangular square cavity caused by laminar flow and turbulent boundary layer [8]. NUMERICAL ANALYSIS OF FLOW NOISES IN THE SQUARE CAVITY VORTEX BASED ON COMPUTATIONAL FLUID DYNAMICS. Flow field characteristics in the square cavity under hydro-dynamic were rarely researched, and it was mainly because that water was an incompressible fluid medium and was generally considered as a low Mach number. This research provided a fast and reliable computation method for analyzing the sound field in the square cavity
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