On Investigation Of Vector Identity Of The Flow-induced Noise In The Application Of Towed Linear Array

The towed linear array sonar is one of the most important equipments which used todetect submarine. The researches show that when the flow speed is fast, the flow-inducenoise is the main factor that limits the performance of the towed linear array sonar. Recentyears, as the vector hydrophone technology improved, the vector hydrophone towed lineararray is becoming one of the most important investigation aspects. Do the research related tothe flow noise of vector hydrophone towed linear array, and do the in-depth theory analyzeand accurate acoustic theorize, from the production mechanism, coupling mode and thedistribution of sound field, to find the method which to decrease the flow noise of vectorhydrophone towed linear array, which is very important in application.First，explain the production mechanism of flow noise, Flow noise is excited mostly byTBL(Turbulent Boundary Layer) pressure fluctuation, the differences between Corcospressure fluctuation model which based on plane and Carpenter model which based on longcylindrical have been discussed on the wave-number spectrum and wave-frequencyspectrum, The cable jacket can transfer the flow noise, through the cable jacket, derive thewave-frequency spectrum of the flow noise in the inner wall of the cable jacket,whichexcited by the two TBL models.Second, following Carpenter model, derive the general mathematic forms of theacoustic pressure and particle velocity and calculate the power spectrum of flow noise forpoint hydrophone and finite hydrophone by numerical integration, then analyze the methodto decrease the flow noise from the flow speed,the hydrophone shape, dimensions and theparameters of the cable jacket. Also discuss the influence of flow noise when the vectorhydrophone has a few distances between the axes of the cable jacket.At last, the axial and the radial spatial correlations of the flow noise incepted by pointhydrophone and finite hydrophone in narrowband and wideband have been calculated, thencalculate the power spectrum of flow noise in the interior hose of various vector hydrophonetowed linear arrays, after that analyze the method to decrease the flow noise from thehydrophone numbers and the distance of hydrophones.