USA As Represented by Secretary of the Navy

David N Beal

Stephen A Huyer

Promode R Bandyopadhyay

Alberico Menozzi

Daniel P Thivierge

Jesse L Belden

Aren M Hellum

David J Daily

Anuradha Annaswamy

Daniel L Macumber

Andrew N Guarendi

Amuradha Annaswamy

A shock mitigator is provided for mitigating physical shock to a joined object. The shock mitigator includes a hollow body capable of being affixed to the object and having two ends defining a volume therein. A cavitating liquid is disposed in the hollow body volume. At least one end cap is slidingly disposed within the hollow body to seal at least one end thereof. When exposed to a physical shock the cavitating liquid changes phase from a liquid to a vapor, absorbing energy from the shock.

Shock mitigation utilizing quiescent cavitation

Systems and methods for maneuvering an underwater vehicle by generating vehicle maneuvering forces from a propulsor of the vehicle are provided. A post-swirl propulsor is configured such that pitch angles of downstream stator blades can be individually varied. The variation in pitch results in the generation of multiple forces and moments for vehicle control.

Systems and methods to generate post-swirl propulsor side forces

Systems and methods for maneuvering an underwater vehicle by generating vehicle maneuvering forces from a propulsor of the vehicle are provided. A ducted, pre-swirl propulsor is configured such that the pitch angles of the stator blades of the upstream stator row can be varied. By varying the pitch angles of the stator blades about the circumference, a mean stator side force is generated. Subsequently, the axial velocity and swirl that is ingested into the inflow is varied. The rotor of the propulsor then generates a side force in response to the inflow.

Systems and methods to generate propulsor side forces

The invention as disclosed is an apparatus that controls the wake of stator blades on an underwater vehicle. The apparatus comprises one or more stator blades each with a movable trailing edge that when actuated in a controlled manner produces a periodic flapping motion upstream of a propulsion rotor. The controlled periodic flapping of the trailing edge the fills the stator blade wake enough to overcome the stator blade's own drag and fill its wake deficit. This has the effect of reducing the blade rate tonal noise of the propulsion rotor.

Apparatus for control of stator wakes

A system is provided to control maneuvering flapping foils of an underwater vehicle. An oscillator generates periodic signals in which effects of external disturbances are minimized or amplified as required; the periodic signal can be either sinusoidal or can depart significantly from a sinusoid; the amplitude and frequency are varied by changing the oscillator parameters and the phase between the signals are varied by changing the parameters. The oscillator restores the parameters after a disturbance. Since the oscillator functions without external sensors, the oscillator serves as an inner-loop controller with a centralized control. An open loop control architecture for the controller, results in a motion where the vehicle maneuvers execute as force and moment commands. The non-linear, auto-catalytic oscillator can be realized using a variety of second-order differential equations. An oscillator model is added to a conventional motor control, where the outputs of the oscillator control the foils in real-time.

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Providence, RI, United States of America

David N Beal