US 6,234,751 B1 · Oscillating air jets for reducing HSI noise

Abstract

Porous surfaces on an aerodynamic structure driven with positive and negative pressures are used in an active control system for attenuating shock waves responsible for high-speed impulsive (HSI) noise. The control system includes an array of apertures in the outer skin of the structure providing fluid communication between the exterior flow stream and an interior volume of the structure. A movable diaphragm within the structure pushes air out of and pulls air in through the apertures under the action of a drive mechanism within the structure, thus creating oscillating air jets. The drive mechanism may be actuated by a controller based on information supplied by a sensor in the leading edge of the aerodynamic structure. The array of apertures may be spaced apart along the outer skin of the aerodynamic structure so as to span a distance of about 15% of the chord length. The oscillating airjets may be provided on multiple surfaces of the aerodynamic structure, including the upper and lower surfaces.

Claims19

Dependent claims

An active control system for use on an aerodynamic structure having an outer skin surrounding an interior volume, the active control system comprising:

an array of apertures disposed in the outer skin and providing fluid communication from the exterior of the outer skin to a portion of the interior volume;
a diaphragm positioned in the interior volume and being displaceable between a first position and a second position, an actuating surface of the diaphragm being exposed to the portion of the interior volume such that displacement of the diaphragm between the first and second position moves air through the apertures;
a drive mechanism positioned in the interior volume and connected to displace the diaphragm between the first and second positions and therefore generate an oscillating air jet by virtue of the air movement through the apertures;
at least one sensor mounted on the aerodynamic structure and positioned to sense a parameter on the exterior of the outer skin;
and
a controller connected to receive from the sensor information on the parameter and connected to operate the drive mechanism in response to the parameter information.

3 more elements

Dependencies are inferred from the claim text.

Oscillating air jets for reducing HSI noise

Life of this patent

Oscillating air jets for reducing HSI noise

Life of this patent

Abstract

Claims19