Abstract: A piezoelectric actuator assembly allows maximization of the cross-sectional area of a piezoelectric driver assembly such that axial stiffness of the actuator assembly is substantially increased. The actuator assembly is coupled to an application structure and includes the piezoelectric driver assembly having a stack inboard end longitudinally extending in an inboard direction with respect to the application structure. The driver assembly also has a stack outboard end longitudinally extending in an outboard direction with respect to the application structure. The driver assembly further provides a longitudinal displacement in response to an applied voltage. The actuator assembly also includes an amplification arm having an arm outboard end coupled to a load. An outboard hinge mechanism rotatably couples an arm inboard end of the amplification arm to the stack outboard end such that the arm outboard end extends in the outboard direction.

Abstract: A piezoelectric actuator has a substantially increased critical buckling load and resistance to bending moments. The actuator includes a piezoelectric stack having a first column end, a second column end, and a first intermediate section. A rigid support device is axially aligned with the stack. The support device is moveably coupled to the stack at the first and second column ends such that rotational, lateral and vertical displacement of the stack is restrained and axial displacement of the stack is permitted at the column ends. The support device is further moveably coupled to the stack at at least one intermediate section such that rotational, lateral and vertical displacement of the stack is restrained and axial displacement of the stack is permitted at the intermediate section. The support device includes a support structure disposed adjacent to the stack, and an end restraint assembly fixedly coupled to the column ends. The end restraint assembly is also moveably coupled to the support structure.

Abstract: A fan system, such as a turbofan, marine propeller, or a cooling fan, includes a fan noise control system for reducing noise generated by the fan system. The noise control system may be configured to reduce either broadband noise, blade-passage noise, or both. In particular, the fan noise control system suitably includes a pre-swirl generator configured to provide a layer of fluid upstream from the fan blades. The layer swirls in the direction of the fan's rotation, reducing the angular velocity differential between the fan blades and the incident fluid. In addition, the fan noise control system may also include a fluid seal generator configured to create a fluid barrier between the fan blade tips and the interior surface of the fluid flow channel. The fluid seal inhibits leakage flow between the fan blade tips and the interior surface as well as the formation of blade vortices. By minimizing the blade wake and the blade tip vortices without adding solid surfaces, noise tends to diminish.

Abstract: An active control device is disclosed for modifying a tip vortex on a lifting body. The lifting body includes a positive-pressure generating structure and a negative-pressure generating structure, and is adapted for providing lift when a first fluid pressure adjacent to the positive-pressure generating structure is greater than a second fluid pressure adjacent to the negative-pressure generating structure. The active control device includes a fluid source adapted for providing a positive pressure of fluid, such as air, to an interior of the lifting body. The active control device further includes a fluid router, which is disposed on the lifting body and which is adapted for directing a portion of the positive pressure of fluid out of the interior of the lifting body and in a general direction from the fluid router toward the positive-pressure generating structure of the lifting body. The lifting body may be either a rotorcraft blade, an aircraft foil, or a marine foil such as a marine propeller.