Flow-Noise Research Related to the Sonar Self-Noise Problem

Abstract

A sonar dome is excited into bending vibration by random pressure fluctuations of turbulent-boundary-layer flow over the dome. A reverberant acoustic field is set up within the dome. The field appears as an important source of self-noise in the sonar transducer at moderate to high ship speeds. Much of the research on the corresponding aerodynamic-noise problem is directly applicable to the study of this underwater-noise problem; in particular, work characterizing the random pressure field for subsonic boundary-layer flows may be carried over directly. Dome response and the consequent internal acoustic radiation, however, are severely influenced by internal and external water loading. In addition, hydrodynamic coincidence effects play a markedly different rôle in the underwater problem than in the aerodynamic problem. Those aspects of flow-noise research pertinent to the sonar self-noise problem are reviewed in this paper, and directions for further research upon the influence of water loading in the prediction of self-noise levels are pointed out.