Applied Acoustics 18 (1985) 21-33 Flow-Induced Noise of a Sonar Dome Part 1 V. Bhujanga Rao Naval Science and Technological Laboratory, Visakhapatnam 530 006 (India) (Received: 13 July, 1983) SUMMARY A semi-analytical, semi-experimental method oj predicting the flow- induced noise inside a sonar dome is proposed. The validity of the analytical approach and error analysis of the experimental techniques are discussed. INTRODUCTI ON A wide range of ships, such as research vessels, fishing craft, warships, etc., are provided with sonars for different applications. All sonars are mounted inside free flooding domes. The dome is generally viewed as an acoustically transparent streamlined body in order to avoid direct interaction of flow with the sonar array and, at the same time, offer good mechanical strength to overcome the hydrodynamic forces resulting from movement through the water at maximum vessel speed in all weather conditions, and the resultant ship motions. When the fluid flows past the dome wall, a boundary layer, characterised by the turbulent flow involving fluctuating pressures, is formed above a certain speed. Lighthill (see Refs 1 and 2) published a classic paper giving the theory of the sound produced by free turbulence. Curle (see Ref. 1) extended Lighthill's theory to include the effect of a rigid body adjacent to the region of turbulence. Curle and Phillips (see Ref. 1) showed that the intensity of radiation from surface pressure fluctuation on the body is proportional to the sixth power of the mean flow Mach number. This suggests that, for flows over 21 Applied Acoustics 0003-682X/85/$03.30 ~" Elsevier Applied Science Publishers Ltd, England, 1985. Printed in Great Britain