Numerical Simulation Of Flow-induced Noise With Underwater Vehicle

The hydrodynamic noise of a submarine sailing underwater is caused byvelocity fluctuation in turbulence boundary layer, fluctuating pressure on solidboundaries and structural vibration due to fluid structure interaction. The velocityfluctuation in turbulence and fluctuating pressure on solid boundaries are acousticquadruples and dipoles respectively, which comprise of flow noise. The structuralvibration due to fluid structure interaction results in flow-excited noise, whichincreases the value of noise.Hydrodynamic noise severely damages the sound-stealthcapability of a submarine.Therefore, it is of primary importance to study thegeneration and characteristics of hydrodynamic noise.Lighthill’s acoustic analogy marks the beginning of research on flownoise.Traditional acoustic analogy is based on the assumption of compact acousticsource,under which it can get an accurate result for acoustic information in thefar-field, but it could lead into mistakes when dealing with the near-field acoustics.As an alternative method in solving acoustic problems.This paper takes the SUBOFFsubmarine as research model. Firstly, by SIMPLE algorithm combined withRNG k turbulence model, the flow field around submarine is calculated. Thenumerical solution is compared with experimental data, which validates thenumerical simulation. Then by using traditional acoustic analogy FW-H equation andBEM, the flow noise at certain feature points along X, Y direction is calculated.Comparison between the results acquired by these two methods show that in far-fieldthe results are quite similar.Secondly, we study the impact of free liquid face submarine radiated noise, useof Fluent and LMS virtual.lab co-simulation using Fluent provide accurate pulsatingpressure, which is the source of information, and then import the information intolms virtual.lab students in various acoustic set of boundary conditions, and finallycalculate the sound field radiated noise work. The results show that free surfaceradiated noise impact on the cross-section is relatively large, relatively small impacton the longitudinal section.