classes of surface ships. All of these advances are supported or enabled by a sustained capability in hydromechanics research and design.
In the late 1970s, the Navy needed to improve the target acquisition range of the Mk 48 torpedo. A limiting factor in the performance of the acoustic array was a basic hydrodynamic phenomenon, the noise caused by the transition from laminar to turbulent flow. The Naval Undersea Warfare Center (NUWC) developed the methodology to optimize array diameter, acoustic window thickness, transition location, and cavitation index and to resolve the key issue of window deformation under hydrodynamic loading. Experiments determined the location and intensity of the transition region, so that techniques to predict transition location could be validated. These advances in technology capabilities led to a substantial reduction in self-noise and a major improvement in torpedo performance.
Hydrodynamic modeling based on theoretical and experimental research has played a critical role in the development and improvement of fleet weapons by providing estimates of forces and moments experienced by these vehicles during launch and maneuvers. Hydrodynamic force and moment predictions generated through this research were used as inputs to vehicle launch and trajectory simulations and throughout the development and design process. This process was instrumental in the development of Mk 46 and Mk 48 torpedo hardware and software and to a succession of advanced weapons such as the advanced capability and Mk 50 torpedoes.
Basic research in hydromechanics and naval technical expertise have enabled advances in propulsor design through enhanced simulation and experimental methods that directly and indirectly reduced the noise signatures of Navy submarines, weapons, and tactical-scale vehicles. Substituting a single rotation propulsor for the traditional counterrotating propellers has meant indirect noise reduction due to machinery simplification while maintaining high efficiency and off-design performance. Using alternatives to traditional propulsor design reduces propulsor-radiated noise.