Calculation and verification of baffled hydrophone array manifold based on boundary element method

A method for obtaining the hydrophone array manifold with the baffle effect is proposed and verified both by computer simulations and water-tank experiments.In this method,the array baffle is modeled as an acoustical scatterer and the boundary element method is used to calculate the sensor responses which include both the direct sound pressure and the scattered sound pressure at each sensor so as to obtain the array outputs to an incident testing sound wave.Then,the array manifold is obtained by accumulating the array output values at all sensors in all interested directions.By doing so,the effect of the array baffle can be included in the array manifold which will be more approaching the practical situation compared with that based on an ideal assumption without the scattering effect.An arc array with 14 piston transducers mounted on a rigid hemisphere was constructed and its array manifold was calculated using the proposed method.Meanwhile,experiments were conducted in an anechoic water-tank to measure the array manifold.Both the sensor directivities and array manifold were measured and compared with those obtained using the proposed method.The comparison between the sensor directivities shows that the results obtained based on the calculated array manifold have a similar tendency with the measurements.Furthermore,the optimized beam patterns of the constructed array were examined,and it can be seen that the design requirements of beam patterns which use the optimized weighting coefficient obtained from the array manifold calculated by the proposed method are well met in the constructed 14-element array.Using the proposed method,the array manifold can be predicated before the array is physically built and tested under practical conditions and the work in this article is very meaningful in designing practical sonar systems.