Heat Extraction from Underwater Acoustic Projectors

The present proposal is focused on developing novel methods to counteract excessive heat build-up in underwater sonar projectors. Building on over 25 years of experience in the design of Navy sonar devices and thermal management applied to high power density transducers and smart material actuators, Active Signal Technologies and Alfred University will model several readily implemented passive and active techniques for enhanced heat transfer to the surrounding water. A Terfenol driven transducer was selected because of its very high intrinsic power density at low frequency and its broad operating temperature range. In addition to model-based optimization of various combinations of convective, conductive and evaporative cooling, driver designs will also be developed that minimize the source-heat through efficiency improvements in the Terfenol rod and its associated drive elements (magnetic circuit design including laminations, permanent bias magnets, coil configuration, etc). Using an integrated systems approach the team will also examine and attempt to mitigate any adverse impacts of the cooling mechanism on acoustic performance, reliability and methods/materials of construction. Similarly, while distortion is not the central theme of the present effort, the baseline transducer design will incorporate a novel depth compensation mechanism that is effective in minimizing it.