Shallow and deep water propagation experiments in tanks
Résumé
The aim of this work was to show that tank experiments can provide the underwater community with data obtained in well controlled conditions. The use of a scaling parameter allows simulating in water tanks, different conditions of sound propagation at sea. Low cost and repeatability are two other advantages of using scaled models. Experiments described in this paper have been carried out in a waveguide consisting of a water column lying over a flat sand bottom in which physical and acoustical properties are well known and controlled. We performed the experiments with different water depths (3cm to 70cm), and with wide band signals covering a very large range of frequencies (from 140 kHz to 800 kHz). The objective was to simulate sound propagation in very different condition (from very low frequency and shallow water conditions to high frequency and deep water conditions). Another series of experiments was carried out to study the coupling between propagation and scattering when a target is introduced in the waveguide. The target we used in this experiment was an elastic hollow sphere (b/a=0.96) placed at different positions (surface, mid depth and bottom). The acoustical field was measured both around the object and in the far field. First results of measurements are discussed.