Increased Propulsion and Noise reduction via Molecular-Driven Unsteady Flow

"Torpedoes, mine-countermeasures, and other small underwater vehicles require high thrust levels to achieve speeds in excess of 20 m/s. Concurrent with the performance requirements are the conflicting demands for small size, high efficiency and speed, aswell as stealth. The issue of excessive noise in particular has drawn great attention, because stealth is an integral part of so many modern missions. Noise is transmitted to the water through the hull and structure, as well as through the blade itself,wherein noise scales with the blade tip speed raised to the sixth (or lower) power. For a given vehicle, an increase in blade lift performance thus allows one to consider both reductions in propulsor diameter and rotational speed. In this study wedemonstrate the feasibility of applying unsteady flow to increase thrust, thereby reducing blade speed and noise. Deflecting foils and blades are employed to demonstrate the increased thrust. The forces, displacements, rates and power required to generatesuch flow is also determined. Another key aim is the demonstration of a suitable actuator drive technology. The bandwidth of conducting polymer molecular actuators will be greatly improved, making them capable of deflecting foils and blades with therequired force, displacement, power and bandwidth. Noise reduction and/or increased thrust and/or size reduction in underwater vehicles and pumps. Active Medical Device applications. Improvements in prosthetics, robotics and MEMS actuators."