Numerical Modeling of the Low-Medium Frequency Vibration and Acoustic Radiation of Underwater Vehicles

Abstract

Considering the main structures of typical underwater vehicles, three types of numerical model are established, including the beam model, the shell-beam model, and the whole shell model. The results of the three models are compared during the analyses of global vibration, local vibration of cabins, and underwater acoustic radiation. Giving consideration to both the computational cost and accuracy, the proposed shell-beam model is appropriate for the calculation of low-medium frequency acoustic radiation of the main structures of underwater vehicles. The rationality and the frequency range of application of the shell-beam model are verified by calculating the fluid-structure coupling vibration response and the underwater acoustic radiation of the hull subjected to the transverse load excitation, which also demonstrate the significance of this model in engineering practice. The calculation research on the acoustic radiation of typical underwater vehicle structures can be generally divided into three types based on the calculation methods: analytical methods (Caresta & Kessissoglou 2009), numerical methods, and analytical-numerical hybrid methods (Zhu et al. 2014; Meyer et al. 2016; Qu et al. 2017). The analytical methods can be used for the study of basic laws and mechanisms, and can also be treated as benchmarks for numerical algorithms. However, when it comes to real ships with complex structures, it is difficult to accurately predict the forced vibration and underwater acoustic radiation characteristics by analytical methods. Previously, due to the limitation of the computer hardware, a whole ship was usually simplified as a free–free beam of variable cross section (the hull beam) when conducting the analysis of global vibration. In recent years, with the development of computer technology, whole shell models are usually established during analyses of the low-medium frequency vibration and acoustic radiation of underwater vehicles.