The suppression of hydrodynamic noise from underwater sonar domes by flow control

Abstract

Hydrodynamic noise is one of the three major noise sources of underwater vehicles. The sonar dome is a device placed in front of the ship and the submarine to absorb the flow fluctuation and to reduce the hydrodynamic noise, so that the sonar inside the dome is not affected by the external fluid. However, with the increase of the velocity of ships and submarines, cavitation can usually form in the bulge of the sonar domes, which will bring high level of noise to the sonar. The internal self-noise of the sonar dome mainly comes from two areas: the leading-edge stagnation point and the transition zone of boundary layer. In the paper, we designed the leading-edge serrations and dimples in the leading-edge and transition areas of the sonar dome respectively to reduce the movement resistance and prevent the separation of the boundary layer. The research on leading-edge serrations and dimple technology is carried out by using theoretical analysis, numerical calculations. The results show that the leading-edge serrations and dimples can add energy from the outer flow into the boundary layer; the cavitation phenomenon can be delayed. The hydrodynamic noise has been suppressed by about 20dB.

Similarity analysis of the flow-induced noise of a benchmark submarine

“…In the anechoic chamber wind tunnel, Li et al [16] verified that the frequencies of the different scale cylinders satisfy the similarity of the Strouhal number, and they studied the similarity in different media based on the FW-H numerical method. There were abundant numerical calculations to discuss the submarine performance under small-scale models, including resistance characterization [17], flow characterization [18], radiated noise [19], and self-noise [20]. As for the full-scale model, Sezen et al [21] analyzed the scale effect of the submarine's hydrodynamic performance based on the Reynolds-averaged Navier-Stokes (RANS) method.…”