Impulse response measurement technique for the analysis of the radiation efficiency of submerged circular plates

The sound radiation of submerged structures is a topic of great interest both in the fields of underwater acoustics and marine engineering. In this context, the radiation efficiency is a very useful parameter to relate the underwater radiated noise and the vibration of a given structure. This paper investigates the average radiation efficiency of submerged circular plates using an impulse response measurement technique. For this purpose, thin plates made from different materials, steel and aluminium, and with either rigid or flexible boundary conditions (i. e. welded or using an O-ring) were manufactured. Each system was excited with an electrodynamic actuator, the vibration level and the underwater sound radiation being measured by using accelerometers and hydrophones, respectively. Experiments were performed in a water tank using a MLS technique along with a robotized positioning system under laboratory-controlled conditions. Additionally, results were compared with preliminary analysis data for air loading conditions, the main differences between both scenarios being discussed.