A Study on the Hydrodynamic Noise of Open Cavity by Using Computational Fluid Dynamics

Abstract

Stealthiness is very important for submarines Hydrodynamic noise is one of the three main sources of noise in submarines The open cavity on the surface of submarines is the most likely source of low frequency radiated noise Thus it is necessary to examine this structure in understanding the characteristic of its noise and fluid flow This research begins with the cavity experiment data which is similar to Reynolds number as the test subject Initially the computer design software SolidWords is utilized for modeling followed by the computational fluid dynamics software FLUENT Numeric simulation for verifying the cavity is made based on both the theory of large eddy simulation and the Lighthill theory The results are then compared with the published experimental data confirming that the numerical simulation has a degree of feasibility and accuracy The underwater cavity structure designed by this research institution then undergoes simulation The noise and flow field difference of each configuration were analyzed by changing the input velocity opening angle opening aspect ratio and double hole spacing Finally through the study it is discovered that the underwater cavity flow field in the body is relatively stable the main flow divergence occurs at the opening The inflow rate noise value and is proportional to the oscillation frequency; the opening length is inversely proportional to the oscillation frequency It is also discovered that changing the opening angle can effectively alter the radiation noise under the premise of the design configuration in our study a 60-degree opening angle generates the least amount of radiation noise Additionally under the condition that the opening area is the same the stand-up radiation noise is significantly greater than that of the double cavity design Thus the double cavity columns should be adopted to replace a single opening

Date of Award	2020
Original language	English
Supervisor	Jeng-Horng Chen (Supervisor)