Research Of The Effect Of The Rigid Motion In Cabin Model Test On Underwater Radiation Noise

With the development of modern military technology,underwater acoustic detection technology constantly improve,low noise performance of military vessels directly affects its operations and survival ability,ship's underwater radiation noise prediction and control is of great importance in the field of national defense.The mechanical noise of ship is the main part of the underwater radiation noise frequency(tens Hz)mainly affects ships radiated noise,and imitate the low-frequency with appear.Experts and scholars at home and abroad have long-term commitment to the research of the mechanical noise prediction and control technology,high accuracy and to carry out a large number of model experiment verification,including shrinkage than compartment model test is considered to be one of the most efficient and economical test method.Although compartment model validation method is widely used now,but due to the tank model on shrinkage ratio,and the testing result that the quality of the original structure,rigidity,size,etc.There is a big difference,especially the dynamic characteristics of structure change,natural frequency of the compartment will be greatly increased,causing compartment model is more widely distributed on the rigid body motion in the frequency domain.The current studies on testing result of the underwater radiation noise due to the rigid motion of the structure of components is very small,when the frequency is very low,so often ignore the effects of rigid motion on the testing result of the underwater radiation noise,but for the compartment model,its light quality,high natural frequency,in the same way under the action of load,the rigid motion is obvious,so we must consider the rigid motion segment model of compartment model,the effects of underwater radiation noise at present very few people have done the work analysis.In this paper,the main work is aimed at a segment mechanical noise test of the model test,the research on the effects of rigid motion of underwater radiation noise.First lewis section of compartment model,using the theory of vertical and horizontal slice to solve the coefficient of fluid dynamics,and common software the calculation program of the structural response,theoretically analyze the rigid motion segment model;And then adopt the method of numerical analysis of the compartment model of rigid motion and elastic body movement compares the effects of underwater radiation noise of analysis;Finally by tank with the theory,the numerical method of shrinkage ratio model test results,verify the correctness of the theory and numerical method,and further the effects of rigid motion on radiated noise was discussed.By comparing the theoretical calculation results of compartment model,numerical analysis and experiment results show that before the first order natural frequency main compartment model of rigid motion,and after the first order natural frequency segment model mainly for elastic vibration;Before the first order natural frequency of the underwater radiation noise is mainly generated by the rigid motion of the structure,but after the first order natural frequency of the structure of the underwater radiation noise is mainly caused by the elastomer movement of the structure.And caused by tank section of the rigid motion of underwater radiation noise contribution to the total sound level in the whole frequency domain cannot be ignored.In order to further improve the shrinkage than tank section of the applicability of the model to simulate mechanical noise method.finally,suggested further shrinkage than compartment model frequency equivalent or dynamic equivalence and related research.