Novel Methods for Sensor Quieting in Turbulent Flows

Undersea acoustic sensors are a critical need for U.S. Navy surveillance applications. They are used for measuring acoustic energy originating from distance source to help detect and classify quiet threat targets, as in sonar applications. To expand their field of regard, large sensor arrays are placed at multiple locations along the vehicle body where flow turbulence-induced noise plays a major factor in reducing the sensors’ effectiveness. It is desired to quiet this flow turbulence-induced noise floor that severely limits the ability of an acoustic sensor to detect quiet acoustic signals. We propose to design and investigate a novel, localized active flow-control (AFC) approach to quiet an acoustic sensor by significantly attenuating local turbulence and wall pressure fluctuations around the entire boundary layer around the sensor. The Phase I effort will establish feasibility of the hydrodynamic AFC technique using a combination of numerical and experimental studies in addition to filtering and post-processing schemes to correct for fine-scale disturbances that remain in the flow region of interest. The final product is expected to be a quiet acoustic sensor package design with integrated localized, hydrodynamic flow-control system that can be scaled and mass produced to meet the Navy platform requirements.