Robert Eugene Kraft

Actively controlled acoustic treatment panel

An actively controlled acoustic treatment panel for suppressing noise in a gas turbine engine nacelle including a backsheet formed by a planar matrix of adjacent individually controllable elements, where each of the controllable elements has a transducer and a honeycomb cell enclosing the transducer. A facesheet is also bonded to the controllable elements. A plurality of sensors are positioned within the acoustic treatment panel for sensing acoustic pressure of the noise propagated against the facesheet. A driver is provided for electrically driving each of the transducers to effect displacement thereof in a direction substantially perpendicular to the facesheet. Circuitry is also operatively connected to the pressure sensors and the driver for controlling velocity magnitude and phase of the transducers during displacement, wherein a resulting acoustic impedance at the facesheet achieves a desired acoustic impedance boundary condition at the nacelle. The transducer is further made up of an inner lamination layer, an outer lamination layer, and a piezoelectric membrane positioned between the inner and outer lamination layers, wherein a plurality of aligned openings are provided in the inner and outer lamination layers so that the piezoelectric membrane can be displaced either toward or away from the facesheet.