Acoustic-vibration Prediction And Characteristics Analysis Of A Underwater Vehicle

Vibration and noise are generated when the submarine vehicle is sailing. It has been the focus of the study. It is important to carry out prediction evaluations of structure's submarine noise characteristics in the stages of designing and constructing to discover problems in the acoustic design of the underwater vehicle. For vibro-acoustic prediction,there mainly exist analytical method, engineering estimation method, numerical calculation method, and so on. Analytical method is suitable for the underwater noise prediction of simple structure. Engineering estimation method can be used for the underwater noise prediction of structure with similar forms. Numerical methods, especially the presence of Finite Element Method , Boundary Element Method, FEM/BEM, have provided abundant approaches for underwater noise prediction of vehicle. Hydrodynamic noise is an important noise source of underwater vehicles with high speed. In this paper,the actual vehicle structure is researched. Equipment exciting loads identification method, vibro-acoustic prediction method and hydrodynamic noise prediction method are investigated.In this paper, the analysis model of the actual vehicle structure is created firstly. In order to fix this modal and ensure the accuracy , modal test result is used in the modeling process.This paper carries out research on the input of vehicle structural borne prediction-exciting loads from equipment to vehicle. Base on frequency-domain load identification theory and the FE model of cabin, a simulation test is created. The precision influence factor of identification is discussed. The regularization method is employed to deal with ill - posed problem. The condition number is recommended as a criterion for regularization solution. Regularization results are calculated with different condition number. The method that different condition numbers are used for different ill-degree in frequency domain when the regularization results are calculated is presented. According to cabin test response, base on the load identification and regularization method form the simulation test, the cabin equivalent excitation force is got. Base on the equipment endogenous characteristics,the equivalent excitation force is applied to the vehicle model.The responses of vibration are calculated and contrasted with the experimental data. The error shows the feasibility of the prediction method.Hydrodynamic noise is an important noise source of underwater vehicles with high speed. By using LES, the flow field is calculated. Then by using BEM, the flow noise is calculated and flow noise characteristic under different flow velocity is discussed. This paper studies the flow-excited noise of the model under flow structure interaction. Lastly,This paper compare the relationship between mechanical noise, flow noise and flow-excited noise.