Flow noise computation and tail wing optimization of the underwater vehicle based on computational fluid dynamics

In this paper, the underwater vehicle was selected as the research object. Based on Computational Fluid Dynamics (CFD), the unsteady numerical simulation was carried out on the turbulent filed at different stream velocities. Then, the sound source was extracted according to the computational result of the flow field. The flow field and the flow noise of the underwater vehicle were computed by Lighthill acoustic analogy theory and FW-H equation, which were consistent with the experimental results, indicating that the computational method employed was effective. It could be obtained from the computational results that the tail wing had a great influence on the flow noise of the underwater vehicle. Consequently, to reduce resistance and noise, the traditional cross-shaped tail wing was changed into the symmetrically-arranged X-shaped tail wing which was 45° with the transverse and longitudinal sections of the underwater vehicle. Then, the simulation on the resistance and flow noise of the improved X-shaped tail wing was conducted. And the results showed that the blocking effect of the flow field by the improved X-shaped was weaker than that by the traditional cross-shaped. In addition, the flow noise of X-shaped tail wing was improved at a certain extent. However, the improvement was not very obvious. Therefore, this paper attempted to research the position and local shape of X-shaped tail wing in order to further optimize the radiation noise.