Numerical analysis of flow noise around hydrophone over low-frequency underwater acoustic communications

The low-frequency underwater acoustic communications are one of the significant means to realize the long-distance underwater wireless communications. Extensive applications have reached to oceanographic survey and research, environmental monitoring, military services, et al. However, flow noise has severely restricted the transmission distance of low-frequency underwater acoustic communications. Although the flow noise in towed array has been investigated sufficiently, since the low-frequency underwater acoustic communication system transmits and receives signals with transducer and bare hydrophone respectively, this paper studies the flow noise of the bare hydrophone under different shapes and motion parameters. It uses large eddy simulation to simulate and analyze the hydrophone's flow field and acoustic analogy method to calculate its sound field. The results show that the influence of flow noise over low-frequency underwater acoustic communications cannot be ignored and its sound pressure level increases along with the increasing moving speed . This study lays the theoretic basis in terms of noise for the improvement of low-frequency underwater acoustic communications performance.