Investigation On Acoustic Design And Underwater Noise Prediction Of Warship’s Structure

The acoustic design of warship is the premise to realize stealth. It is significant topredict the acoustic performance more accurately at the design stage of the future warship.The structural parameter of the warship is the key effecting the underwater acousticradiation caused by the vibration of warship’s structure. It is very important tostudy the relationship between underwater acoustic radiation and these parameters in orderto match the design during acoustic forecasting. Base structure is the special structure whichis fixed on the hull and bears the weight of the power device. Meanwhile, it is also thevibration transmission path from the power device to the hull. So the investigation on thetransmission characteristics of the base structure are paid universal attention at home andabroad because the transmission characteristics directly affects the overall ship’s underwaternoise.A virtual surface warship was taken as the research object. The vibration transmissioncharacteristic of the base structure was researched. The acoustic design of warshipand the noise prediction technology were researched. A complete model of warship with twodifferent types of bases was established by adopting the finite element method. Thevibration characteristics and the vibration transmission characteristics of the warship wereresearched respectively. Then the vibration transmission characteristic from equipmentbase to the hull structure was obtained. Underwater acoustic forecast in low frequency bandwas carried out combined with acoustic BEM. Meanwhile, the prediction of the underwateracoustic radiation in mid and high frequency band was conducted through SEA. On thisbasis, a related program was developed based on software platform MATLAB according tothe actual requirement of engineering design.Following aspects are included in this paper. Firstly, a three-dimensional FEM modelof warship was established by FEM. The base and hull vibration response were analyzed.Meanwhile, vibration transmission characteristic of the base structure was researched. Theneffects of various parameters of the base structure on sound radiation characteristics ofwarship was studied; Secondly, vibration reduction program of base structure surface pastecomposite damping layer was researched. Meanwhile, effects of various parameters on thesound radiation characteristics were studied by contrast; Thirdly, a underwater hull structureof fluid-solid coupling model was established by FEM and BEM. Vibration and acousticradiation characteristics of underwater shell in low frequency were studied. Meanwhile, a statistical energy model of warship was established with SEA. Prediction of underwateracoustic radiation characteristics in mid and high frequency band were conducted by usingSEA. So a full range of ship noise frequency domain prediction was achieved; Fourthly, aprogram about noise prediction of parametric structure was developed based on MATLABsoftware. Large software of PATRAN, NASTRAN and SYSNOISE were connected witheach other based on MATLAB. Underwater acoustic radiation prediction of warship wasquickly achieved.