Current enclosure designs used to package or house gas turbine engines for use in marine applications provide acoustic transmission loss requirements with heavy metal structures. One form of a wall of such current, prior art enclosures is shown generally at 2 in the diagrammatic, fragmentary sectional view of
Forms of the present invention eliminate heavy metal walls and supports by including wall components that are fabricated utilizing primarily non-metallic composite materials, including fiber reinforced composites, to provide high damping and stiffness characteristics to the wall. As a result, a lighter weight support frame can be used to provide a structurally strong, yet lightweight, enclosure that includes enhanced acoustic characteristics and reduced heat transfer through enclosure walls, along with fire protection and in-plane shear loading capabilities.
The present invention will be more readily understood by reference to the other figures of the drawing.
In operation, air flows into engine inlet 26 through compressor 18 and is compressed. Compressed air is then channeled to combustor 20 where it is mixed with fuel and ignited. Airflow from combustor 20 drives rotating turbines 22 and 24 and exits gas turbine engine 11 through exhaust nozzle 28.
The diagrammatic, perspective, fragmentary, partially sectional view of
Inner panel 60 includes, in sequence outwardly from enclosure hollow interior 10, an inner panel inner sheet 70, typically of a metal such as steel, at hollow interior 10 and including a plurality of perforations 72 therethrough. At sheet 70 is an inner panel sound absorption member 74 substantially made of commercially available non-metallic sound absorption material, for example a polymeric foam or porous material such as is currently made of such materials as polyurethane, rockwool, phenolic, melamine, etc. In
Associated with inner panel 60 is inner panel fastening means shown generally at 84, for example shown as typical bolts, studs, nuts, spacers, and pressure plates. However, fastening means can include interface bonding or adhesive type materials. Fastening means 84 are provided to hold the inner panel inner sheet 70, sound absorption material 74, and inner panel outer sheet 78 in sequence, and to hold stiffening members 82 within inner panel 60.
Outer panel 62 includes, in sequence inwardly from outside 3 of enclosure 36, outer panel sandwich member shown generally at 90 substantially made of a non-metallic composite material, preferably fiber reinforced for enhanced stiffness. Sandwich member 90 includes spaced-apart sandwich member first and second walls 92 and 94, respectively, and a plurality of spaced-apart transverse walls 96 therebetween that define a plurality of hollow chambers 98 therebetween. In the exemplary embodiment, outer panel 62 also includes a plurality of heat, fire resistant, and/or sound absorption cores 100 that are positioned between inner and outer walls 92 and 94 respectively. More specifically, each core 100 is positioned between spaced apart transverse walls 96 within a respective hollow chamber 98. Optionally, outer panel 62 does not include cores 100. In the exemplary embodiment, each core 100 is fabricated using a commercially available non-metallic material, for example a polymeric foam or porous material such as is currently made of such materials as polyurethane, rockwool, phenolic, melamine, etc.
During assembly of wall 40, inner panel 60 is coupled to outer panel 62 using fasteners 84. Specifically, inner panel 60 is coupled to outer panel 62 such that the outer surface of inner panel sound absorption member 74 is flush against the outer surface of second panel second wall 92. That is the exterior surface of inner panel 60 is in contact with, or flush to, the exterior surface of outer panel 62. Optionally, inner panel outer sheet 78 is inserted between panels 60 and 62 to further increase the structural stiffness of the walls and/or to facilitate decreasing noise transmission through the walls.
Described herein is a relatively lightweight enclosure wall that integrates three separate optimized structural elements into one unitized structure. Moreover the enclosure wall has improved acoustic and structural capabilities compared to known enclosure walls. For example, during operation, sound radiating from the gas turbine engine first strikes the surface of the inner panel structure that includes a perforated or solid face sheet backed with a multilayer acoustic absorptive sheet. The multilayer acoustic absorptive sheet may also be subdivided by stiffeners into horizontal or vertical chambers. As such, the inner panel provides acoustic absorptive and transmission loss characteristics.
The enclosure wall also includes an internal skeletal structure that is fabricated utilizing a plurality of beams that acoustically isolate the inner and outer panels, and also provide the primary structural support of the enclosure. The inner and outer panels are fastened to the beams with either mechanical isolation fasteners or bonded with sealants or adhesives. In use, the outer panel provides acoustic transmission loss characteristics, reduced heat flow, fire protection plus in-plane shear loading capabilities. Specifically, the outer panel is fabricated as a sandwich-like structure that includes a pair of composite facesheets that are separated by a medium such as foam or honeycomb, for example. In the exemplary embodiment, the facesheets are connected by both foam and rib stiffeners. The channels between the ribs may be hollow, filled with foam or other sound absorbing media. The high damping and stiffness characteristics of the composite material and sandwich construction facilitate providing an efficient lightweight transmission loss structure. In another embodiment, the wall structure may include a relatively thin metallic plate that is coupled to the outer panel to further increase the transmission loss and also provide fire protection and external damage protection. The low transverse thermal conductivity of composites coupled with the sandwich panel facilitate reducing heat flow and also provides relatively low exterior temperatures.
As a result, the enclosure wall described herein facilitates reducing the overall weight of the engine module structure, provides improved acoustic characteristics, and also reduces outside wall temperatures and fire protection compared to known enclosure walls. As such, the present invention provides an enclosure with a significantly improved combination of reduced weight and structural stability along with sound loss characteristics and heat and fire resistance through the arrangement and use primarily of non-metallic materials. Although the present invention has been described in connection with specific examples, materials and structures, it should be understood that they are intended to be representative of, rather than in any way limiting on, the scope of the present invention. Those skilled in such arts as those relating to sound and heat energy, materials, and enclosure designs will understand that the invention is capable of variations and modifications without departing from the scope of the appended claims.