Computation Of The Added Mass And The Study On Vibration Characteristic Of Submarine In Water

The movement of submarine structures in water will lead fluid around to move following mem. It is equivalent to increasing the inertia of structures, and the effect is equivalent to increasing the mass of the structures, which is called added mass. Added mass can change the vibration characteristics of the overall and local structures of submarines, which means that the vibration frequency and mode of the structures in the water will show different characteristics from that in the air. As a result, responses characteristics of submarines traveling in the water will change accordingly.First of all, based on the potential flow theory, the paper writes the programs of three dimensional Green's function in the frequency domain and in time domain separately using the methods of three dimensional Green's function in the frequency domain and in time domain, and verifies them with the published documentation.Secondly, based on the potential flow theory, the added mass of submarines is calculated in detail according to the features of submarine structures, including the added mass of flow field outside submarines, the added mass of side flow field, the added mass of cabin. At the same time, the added mass of rigid body motion, elastic vibration, and rigid-elastic coupling. The effects of frequency characteristics acting on the added mass are studied, and coupling calculation between different modes are analyzed, by the calculation of the added mass of elastic submarine model.Thirdly, added mass can change vibration characteristics of structures in the water, so in the paper, vibration characteristics of rectangular plates and stiffened plate are analyzed according to all orders elastic vibration added mass as well as coupling added mass, and the accuracy and validity of the calculation method in this article are validated by comparison. On this basis, vibration characteristics of submarines in the water and the rule between wet mode frequency and added mass are mainly studied.Finally, on the basis of added mass of submarines, it is studied that how submarine structures respond to impact load and what effect impact factor exert on the response of submarine structures, in order to provides a new way for studying the response of structures underwater in the future.