Northrop Grumman Systems Corporation

Grumman Aerospace Corporation

Vought Aircraft Industries, Inc.

Charles A Parente

Noe Arcas

Robert E Anderson

James A Clarke

Shepard G Kay

Frederick M Hutto

Belur N Shivashankara

Ronald F Olsen

Runyon H Tindell

Charles J Weizenecker

William C Van Nostrand

Fredrick M Hutto

Sonya J Westerback

Joseph P Gow

A microporous sheet having both acoustical and structural functionality and a process for producing the sheet. Construction of the sheet requires, first of all, providing a sheet capable of functioning as a structural element of a component. A laser device capable of producing a free electron laser beam is provided, and the free electron laser beam is directed to a surface of the sheet to penetrate the sheet at a plurality of sites and thereby form a plurality of apertures. These apertures are generally uniformly dispersed and of a size and number sufficient to enable the sheet to function as an acoustical noise suppressor while retaining capability of functioning as a structural element. Use of free electron laser technology permits formation of smooth-walled, circular or non-circular apertures tailored to exact geometry specifications controlled to a nanometer in size, and produces a microporous sheet having structural functionality while meeting acoustic requirements with clean, unclogged apertures and with low friction-to-surface and/or boundary-layer control airflow.

Acoustical and structural microporous sheet

An acoustic liner employable in jet engine housing construction for sound absorption such as for inclusion in nacelle components. The liner has a solid backface sheet having a surface to which is attached a first side of a honeycomb core structure. Attached to the opposing second side of the honeycomb core structure is a mesh structure to which is attached a perforated face sheet to be exposed to the exterior. As is thus apparent, the liner of the present invention provides a mesh situated below a protective perforate sheet. This construction produces an acoustic liner having substantially the efficiency of a linear liner system and the durability of a perforate face sheet system.

Method of fabricating an acoustic liner

An extended reaction acoustic liner for use in jet engine noise mitigation has a substantially non-porous outer layer, a honeycomb core disposed in laminar juxtaposition to the outer layer, and a porous inner layer in laminar juxtaposition to the honeycomb core such that the honeycomb core is sandwiched between the outer layer and the inner layer. The honeycomb core comprises a plurality of cell walls defining a plurality of cells. Some of the cells are in fluid communication with one another via the openings formed in the cell walls. The openings in the cell walls cause viscous acoustic losses, resulting in acoustic energy dissipation and enhanced noise attenuation.

Extended reaction acoustic liner for jet engines and the like

A device for measuring the acoustic absorption properties of materials such as liners for jet engines has a first housing, an acoustic driver configured to provide acoustic energy to the first housing, a second housing attached to the first housing, and an acoustic driver configured to provide acoustic energy to the second housing. Acoustic sensors are used to measure the acoustic energy emitted from the two housings and to measure the absorption of each of the housings.

Apparatus and method for measuring the acoustic properties of acoustic

Laser perforating process for producing an acoustical and structural

An air intake system disposable in an air vehicle turbo engine housing disposed in an exterior airflow for selectively reducing external engine boundary layer separation drag and external engine friction drag on the engine housing comprising an air inlet member for receiving engine intake air disposable within the engine housing. The air intake system further comprising a first air exit port disposed in fluid communication with the air inlet member, adapted to direct intake air from the air inlet member and to direct intake air substantially in the direction of exterior airflow, to reduce external engine boundary layer separation drag. The air intake system further comprising a second air exit port disposed in fluid communication with the air inlet member, adapted to direct intake air from the air inlet member and to direct intake air substantially in a direction perpendicular to the exterior airflow, to reduce external engine friction drag. The air intake system further comprising a control device for regulating intake airflow through the first and second air exit ports in response to sensed external engine conditions to mitigate at least one of external engine boundary layer separation drag and external engine friction drag.

Low drag inlet design using injected duct flow

The present invention is embodied in an aircraft engine noise absorption system having a resonator cavity for absorbing incident noise except for a residue noise signal having a predominant frequency, the system comprising an actuator providing an actuator acoustic signal, a noise sensor for sensing the predominant frequency, and a controller for setting the actuator acoustic signal to the predominant frequency and varying one of a phase and an amplitude of the actuator acoustic signal to decrease the residue noise signal.

Noise absorption system having active acoustic liner

058410796 In accordance with the present invention, in an air vehicle having a turbo engine including an inlet which receives intake airflow and is defined by an inner surface and a D-nose of the turbo engine, there is provided an inlet liner for improved acoustic, anti-ice and drag performance. The inlet liner is provided with a permeable acoustic layer formed to attenuate sound and defines the D-nose. The inlet liner is further provided with a pressurized fluid injecting device. The pressurized fluid injecting device is in fluid communication with the permeable acoustic layer and formed to inject fluid through the permeable acoustic layer at the D-nose to reduce drag of the intake airflow. The pressurized fluid injecting device is further formed to inject fluid through the permeable acoustic layer at a temperature sufficient to perform an anti-ice function at the D-nose.

Combined acoustic and anti-ice engine inlet liner

An acoustic liner jet engine inlet barrel is formed from a perforated permeable skin, a honeycomb core, and a solid facesheet, each of which is formed in a one-piece configuration such that at most only a narrow single fore-to-aft splice, or no spice at all, is present in the finished product. The acoustic modal content remains unaffected, thus preserving a high degree of liner effectiveness, increasing the total active acoustic area of the barrel while decreasing its weight, and increasing its durability.

One-piece engine inlet acoustic barrel

A noise suppression system for a jet engine, the system having a substrate formed of open cell material, a layer of microporous material covering at least a portion of one surface of the substrate, a layer of substantially non-porous material covering at least one portion of an opposite surface of the substrate, and a pressurized air source for providing pressurized air to the substrate. The substrate, the microporous material, and the non-porous material are configured to define an inner surface of an inlet for the jet engine. The pressurized air is communicated from the substrate, through the microporous material, and into the inlet so as to provide a layer of less turbulent airflow along the inner surface of the inlet, thus mitigating noise generation.

Noise suppression system for a jet engine

A portable two microphone acoustic impedance data acquisition and analysis system provided in a lightweight, fully portable, battery powered instrument with a dual capability of either on-site or remote-site analysis of measured data on the acoustic impedance of acoustically absorbing duct liners of aircraft jet engines. The fully portable instrument is capable of being operated by relatively unskilled personnel to provide acoustic impedance and non-linearity measurements on acoustic liners at airports and aircraft maintenance facilities. The measured data on the engine duct acoustic liner can be an input directly to the data analysis system at the data acquisition site for on-site analysis, or can be recorded for input to a data analysis system at a later time, or can be recorded and transmitted, such as by a telephone modem, to a data analysis system at a remote-site. The remote-site analysis of data eliminates the requirement for skilled personnel at the aircraft to perform the relatively complex data analysis procedures.

Portable acoustic impedance data acquisition and analysis system

An acoustic liner jet engine inlet barrel is formed from a perforated permeable skin, a honeycomb core, and a solid facesheet, each of which is formed in a one-piece configuration such that at most only a narrow single fore-to-aft splice, or no splice at all, is present in the finished product. The acoustic modal content remains unaffected, thus preserving a high degree of liner effectiveness, increasing the total active acoustic area of the barrel while decreasing its weight, and increasing its durability.

A device for permitting evaluation of the acoustic impedance of liner designs used to attenuate noise in engine aircraft inlet and exhaust ducts, and in particular multiple degree of freedom designs of the type which include a porous facesheet followed by a backing depth followed by successive facesheet/backing depth combinations, includes a plurality of spacers of different thicknesses for varying the backing depths, and a movable plunger with a threaded adjustment mechanism for establishing the final backing depth. Gaskets and seals are installed at various interfaces to eliminate noise leakage paths. Two attachment bolts are used to hold the plunger assembly, face sheets, and spacers together, and an alignment disc positioned on the first facesheet is used to properly align an impedance tube waveguide on facesheet.

Multi-degree linear liner impedance testing device

An acoustic attenuating liner has a non-metallic honeycomb core bonded on a backsheet. A corrosion-insulated perforated sheet is bonded to the honeycomb core by adhesive between the perforated sheet and the core. The mesh is woven to a plurality of different determined weave patterns from material on and affixed to the perforated sheet, whereby the mesh has a plurality of different resistances. The mesh is aligned with the perforated sheet and is bonded to the perforated sheet by additional adhesive between the mesh and the perforated sheet, thereby providing a segmented liner with a plurality of facesheet resistances.

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Oyster Bay, NY, United States of America

Charles A Parente