Focusing Energy Underwater Through Optimization of a Spherical Source Array.

The concept of focusing energy from multiple underwater sources is of interest as a potential new approach for defeating underwater threats. An array of spherical shock sources arranged in a two-dimensional pattern has been suggested to achieve this aim. The goal of the present research effort is to identify optimal arrangement and detonation timing schemes for the creation of desired shock waveform characteristics at the target. First, a physics-based reduced order model has been developed for the multiple-source array. The reduced order model captures important shock phenomena including propagation speed, pressure-time histories throughout the fluid domain, and shock wave interaction phenomena. Rarefaction waves appearing in the array flow field have also been incorporated. The development of a reduced order model was prompted by the constraints of mathematical optimization. Optimization using evolutionary algorithms, which have been chosen for the present effort, requires the evaluation of an equation, function, or model hundreds or thousands of times before converging on an optimal solution. Existing models for underwater shock phenomena are either too crude to capture complex shock interactions or too computationally expensive for optimization analysis. The reduced order model developed herein is capable of modeling complex shock physics while maintaining a relatively inexpensive execution time that enables optimization analysis. An optimization framework has been constructed and is applied to the design of a rectangular grid array using the reduced order model.PhDNaval Architecture & Marine EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/99904/1/nastowe_1.pd