Abstract:
One embodiment of the present invention is a unique gas turbine engine. Another embodiment of the present invention is a unique gas turbine engine bearing system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines and gas turbine engine bearing systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     The present application claims benefit of U.S. Provisional Patent Application No. 61/428,737, filed Dec. 30, 2010, entitled GAS TURBINE ENGINE, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to gas turbine engines, and more particularly, to gas turbine engines with bearing systems. 
     BACKGROUND 
     Gas turbine engine bearing systems that effectively remove heat from bearings remain an area of interest. Some existing systems have various shortcomings, drawbacks, and disadvantages relative to certain applications. Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY 
     One embodiment of the present invention is a unique gas turbine engine. Another embodiment of the present invention is a unique gas turbine engine bearing system. Other embodiments include apparatuses, systems, devices, hardware, methods, and combinations for gas turbine engines and gas turbine engine bearing systems. Further embodiments, forms, features, aspects, benefits, and advantages of the present application will become apparent from the description and figures provided herewith. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein: 
         FIG. 1  schematically illustrates some aspects of a non-limiting example of a gas turbine engine in accordance with an embodiment of the present invention. 
         FIG. 2  illustrates some aspects of non-limiting examples of a bearing system and various means for removing heat from a bearing in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     For purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings, and specific language will be used to describe the same. It will nonetheless be understood that no limitation of the scope of the invention is intended by the illustration and description of certain embodiments of the invention. In addition, any alterations and/or modifications of the illustrated and/or described embodiment(s) are contemplated as being within the scope of the present invention. Further, any other applications of the principles of the invention, as illustrated and/or described herein, as would normally occur to one skilled in the art to which the invention pertains, are contemplated as being within the scope of the present invention. 
     Referring to the drawings, and in particular  FIG. 1 , a non-limiting example of some aspects of a gas turbine engine  10  in accordance with an embodiment of the present invention is schematically depicted. In one form, gas turbine engine  10  is an aircraft propulsion power plant. In other embodiments, gas turbine engine  10  may be a land-based or marine engine. In one form, gas turbine engine  10  is a multi-spool turbofan engine. In other embodiments, gas turbine engine  10  may take other forms, and may be, for example, a turboshaft engine, a turbojet engine, a turboprop engine, or a combined cycle engine having a single spool or multiple spools. 
     As a turbofan engine, gas turbine engine  10  includes a fan system  12 , a bypass duct  14 , a compressor  16 , a diffuser  18 , a combustor  20 , a turbine  22 , a discharge duct  26  and a nozzle system  28 . Bypass duct  14  and compressor  16  are in fluid communication with fan system  12 . Diffuser  18  is in fluid communication with compressor  16 . Combustor  20  is fluidly disposed between compressor  16  and turbine  22 . In one form, combustor  20  includes a combustion liner (not shown) that contains a continuous combustion process. In other embodiments, combustor  20  may take other forms, and may be, for example and without limitation, a wave rotor combustion system, a rotary valve combustion system or a slinger combustion system, and may employ deflagration and/or detonation combustion processes. 
     Fan system  12  includes a fan rotor system  30 . In various embodiments, fan rotor system  30  includes one or more rotors (not shown) that are powered by turbine  22 . Bypass duct  14  is operative to transmit a bypass flow generated by fan system  12  to nozzle  28 . Compressor  16  includes a compressor rotor system  32 . In various embodiments, compressor rotor system  32  includes one or more rotors (not shown) that are powered by turbine  22 . Each compressor rotor includes a plurality of rows of compressor blades (not shown) that are alternatingly interspersed with rows of compressor vanes (not shown). Turbine  22  includes a turbine rotor system  34 . In various embodiments, turbine rotor system  34  includes one or more rotors (not shown) operative to drive fan rotor system  30  and compressor rotor system  32 . Each turbine rotor includes a plurality of turbine blades (not shown) that are alternatingly interspersed with rows of turbine vanes (not shown). 
     Turbine rotor system  34  is drivingly coupled to compressor rotor system  32  and fan rotor system  30  via a shafting system  36 . In various embodiments, shafting system  36  includes a plurality of shafts that may rotate at the same or different speeds and directions. In some embodiments, only a single shaft may be employed. Turbine  22  is operative to discharge an engine  10  core flow to nozzle  28 . In one form, fan rotor system  30 , compressor rotor system  32 , turbine rotor system  34  and shafting system  36  rotate about an engine centerline  48 . In other embodiments, all or parts of fan rotor system  30 , compressor rotor system  32 , turbine rotor system  34  and shafting system  36  may rotate about one or more other axes of rotation in addition to or in place of engine centerline  48 . Fan rotor system  30  loads, compressor rotor system  32  loads, turbine rotor system  34  loads and shafting system  36  loads are supported and reacted by a plurality of bearing systems, e.g., including bearing systems  50 ,  52  and  54 . 
     Discharge duct  26  extends between a bypass duct discharge portion  38 , a discharge portion  40  of turbine  22  and engine nozzle  28 . Discharge duct  26  is operative to direct bypass flow and core flow from bypass duct discharge portion  38  and turbine discharge portion  40 , respectively, into nozzle system  28 . In some embodiments, discharge duct  26  may be considered a part of nozzle  28 . Nozzle  28  is in fluid communication with fan system  12  and turbine  22 . Nozzle  28  is operative to receive the bypass flow from fan system  12  via bypass duct  14 , and to receive the core flow from turbine  22 , and to discharge both as an engine exhaust flow, e.g., a thrust-producing flow. In other embodiments, other nozzle arrangements may be employed, including separate nozzles for each of the core flow and the bypass flow. 
     During the operation of gas turbine engine  10 , air is drawn into the inlet of fan  12  and pressurized by fan  12 . Some of the air pressurized by fan  12  is directed into compressor  16  as core flow, and some of the pressurized air is directed into bypass duct  14  as bypass flow, and is discharged into nozzle  28  via discharge duct  26 . Compressor  16  further pressurizes the portion of the air received therein from fan  12 , which is then discharged into diffuser  18 . Diffuser  18  reduces the velocity of the pressurized air, and directs the diffused core airflow into combustor  20 . Fuel is mixed with the pressurized air in combustor  20 , which is then combusted. The hot gases exiting combustor  20  are directed into turbine  22 , which extracts energy in the form of mechanical shaft power sufficient to drive fan system  12  and compressor  16  via shafting system  36 . The core flow exiting turbine  22  is directed along an engine tail cone  42  and into discharge duct  26 , along with the bypass flow from bypass duct  14 . Discharge duct  26  is configured to receive the bypass flow and the core flow, and to discharge both as an engine exhaust flow, e.g., for providing thrust, such as for aircraft propulsion. 
     Referring now to  FIG. 2 , a non-limiting example of some aspects of a bearing system  60  is schematically illustrated. Bearing system  60  may be employed as one or more bearing systems in gas turbine engine  10 , such as one or more of bearing systems  50 ,  52  and  54 . Bearing system  60  includes a rolling element bearing  62 , a shaft  64 , a bearing support structure  66  and a sump housing  68 . Bearing  62  includes a plurality of rolling elements  70 , an inner race  72 , an outer race  74  and a separator  76 . In one form, bearing  62  is a ball bearing. In other embodiments, bearing  62  may take other forms, for example and without limitation, a roller bearing, a tapered roller bearing, a spherical roller bearing, a needle bearing or any other type of bearing. Inner race  72  is mounted on shaft  64 . Shaft  64  may be considered a part of shafting system  36 . Outer race  72  is installed into bearing support structure  66 . Outer race  72  may be anti-rotated by means not shown. In some embodiments, one or more of a squeeze film damper  78  may be disposed between outer race  74  and support structure  66 . In some embodiments, an oil film for squeeze film damping, without additional structure, may be disposed between outer race  74  and support structure  66 . Separator  76  is configured to maintain a spacing relationship between rolling elements  70 . In one form, bearing  62  is configured to react rotor loads. In other embodiments, bearing  62  may not be configured to react rotor loads. Support structure  66  is coupled to sump housing  68 . Support structure  66  and sump housing  68  are configured to transmit rotor loads, e.g., thrust loads and radial loads, from bearing  62  to one or more engine  10  static structures (not shown). 
     It is desirable to remove heat from bearing  62  in order to enhance bearing  62  life and load-bearing capacity and maintain bearing internal clearances. Although oil jets may be employed to impinge one or more jets of liquid oil onto bearing  62  to both lubricate bearing  62  and remove heat from bearing  62 , the inventor has determined that a substantial amount of heat generated by rolling element bearings is the result of viscous heating due to rolling element drag. In an exemplary analysis, it was determined that 76% of rolling element bearing heat generation resulted from viscous heating. Accordingly, other means of removing heat from rolling element bearings are desirable. In various embodiments, bearing system  60  employs one or more of the plurality of means for heat removal set forth herein and/or modifications thereof. In one form, bearing system  60  is configured to remove heat from bearing  62  without using liquid oil, e.g., jets of liquid oil, as a heat transfer medium. Various schemes may be employed to lubricate bearing  62 , for example and without limitation, dry film lubrication and/or oil mist lubrication. 
     In one form, bearing system  60  includes an electro-thermal cooling system  90 . Cooling system  90  is configured to remove heat from bearing  62 , and functions as a heat sink. Cooling system  90  is provided with electrical power by means not shown. In one form, cooling system  90  is a thermoelectric cooler (TEC). TECs are commercially available, for example, from Nextreme Thermal Solutions, Inc., of Durham, N.C., USA. In other embodiments, cooling system  90  may take other forms. For example and without limitation, in some embodiments, cooling system  90  may be in the form of a thermionic cooler. Thermionic coolers, sometimes referred to as thermal chips, are commercially available, for example, from MicroPower Global Corporation of San Marcos, Tex., USA; and from Cool Chips plc of Gibraltar, a British Crown Colony located in Southern Europe. In one form, cooling system  90  is mounted directly on bearing  62 , e.g., on outer race  74 . In other embodiments, cooling system  90  may be positioned elsewhere in, on or about bearing system  60 . In one form, cooling system  90  is thermally bonded to bearing  62 , i.e., using a bonding technique that reduces thermal resistance between mating components. Examples of thermal bonding include the use of thermal bonding compounds, such as a metal-oxide loaded two part epoxy, thermal greases, or direct bonding of the materials, e.g., by brazing. 
     In one form, bearing system  60  includes a high conductivity thermal pathway  92 , which functions as a heat sink. High conductivity thermal pathway  92  is configured to direct heat from bearing  62  to sump housing  68 . High conductivity thermal pathway  92  is coupled to cooling system  90 . In one form, high conductivity thermal pathway  92  is a material system configured to direct heat from cooling system  90 . In other embodiments, high conductivity thermal pathway  92  may be or may include a heat pipe. In one form, high conductivity thermal pathway  92  is thermally bonded to cooling system  90 . In other embodiments, high conductivity thermal pathway  92  may be thermally bonded directly to bearing  62 , e.g., outer race  74 , in addition to or in place of cooling system  90 . This bond could be accomplished, for example and without limitation, by brazing the thermal pathway  92  to bearing  62  or outer race  74 . High conductivity thermal pathway  92  is so named because the high conductivity thermal pathway  92  is constructed of materials having a high thermal conductivity and/or takes the form of a heat pipe. Examples of high thermal conductivity materials include, but are not limited to: copper (˜400 W/m-K); Aluminum (˜200 W/m-K); highly oriented pyrolytic graphite (HOPG) (˜1500+ W/m-K in designated directions); Al-graphite (˜600 W/m-K in designated directions); Al-diamond (˜600 W/m-K); and Cu-diamond (˜600-800 W/m-K). Because these materials are on the order of one order of magnitude greater thermal conductivity than conventional steel, titanium and other materials commonly used to form gas turbine engine bearing system components, they are referred to as high thermal conductivity materials. In one form, sump housing  68  may form a part of high conductivity thermal pathway, e.g., by being formed of a high thermal conductivity material. 
     In one form, sump housing  68  includes a plurality of fins  94 . Disposed between fins  94  and any external heat sources is an aerogel insulation  96 . In other embodiments, other insulation types may be employed in addition to or in place of aerogel. Additional structure may be interposed between fins  94  and aerogel insulation  96 . Aerogel insulation is commercially available from, for example and without limitation, Aspen Aerogels, Inc. of Northborough, Mass., USA. Pressurized cooling air  98 , e.g., from fan  12  is flowed past (e.g., through) fins  94  in order to remove heat from sump housing  68 . Aerogel insulation  96  is disposed around fins  94 , and is configured to shield sump housing  68  from external heat sources, such as turbine  22 . In other embodiments, other insulation types may be employed. 
     In one form, bearing system  60  includes one or more of a cooling air nozzle  100  disposed adjacent to bearing  62 . Cooling air nozzle  100  is configured to direct cooling air to bearing  62  to remove heat from bearing  62 . 
     In one form, bearing system  60  includes one or more of a mist nozzle  102  disposed adjacent to bearing  62 . In one form, mist nozzle  102  is configured to direct a mist of lubricating fluid to bearing  62  to lubricate bearing  62 . In one form, the mist is an oil mist. In other embodiments, other mists may be employed. 
     In one form, a heat pipe  104  is disposed within shaft  64  and rotates with shaft  64 . Heat pipe  104  is hence referred to as a rotating heat pipe  104 . Rotating heat pipe  104  is configured to remove heat from bearing  62 . In one form, a plurality of cooling fins  106  are disposed on shaft  64 . Cooling fins  106  are configured to remove heat from rotating heat pipe  104 . In one form, one or more of a cooling air nozzle  108  is disposed adjacent to cooling fins  106  and configured to discharge cooling air onto fins  106  to remove heat from cooling fins  106 . Heat may thus be removed from bearing  62  via rotating heat pipe  104  and cooling fins  106 . 
     Embodiments of the present invention include a gas turbine engine, comprising: a compressor; a diffuser in fluid communication with the compressor; a combustor in fluid communication with the diffuser; a turbine in fluid communication with the combustor; and a bearing system having a bearing, wherein the bearing is configured to support the compressor and/or the turbine, wherein the bearing system includes an electro-thermal cooling system configured for removing heat from the bearing. 
     In a refinement, the electro-thermal cooling system is a thermoelectric cooler. 
     In another refinement, the electro-thermal cooling system is a thermionic cooler. 
     In yet another refinement, the bearing is a rolling element bearing having a bearing race; and wherein the electro-thermal cooling system is mounted on the bearing race. 
     In still another refinement, the gas turbine engine further comprises a high conductivity thermal pathway coupled to the electro-thermal cooling system and configured to direct heat from the electro-thermal cooling system. 
     In yet still another refinement, the bearing system is configured to remove heat from the bearing without using liquid oil as a heat transfer medium. 
     In a further refinement, the bearing is a rolling element bearing having a bearing race; and wherein the electro-thermal cooling system is mounted on the bearing race, further comprising a high conductivity thermal pathway coupled to the bearing race and configured to direct heat away from the bearing race. 
     In a yet further refinement, the high conductivity thermal pathway is formed at least in part of a high thermal conductivity material. 
     In a still further refinement, the high conductivity thermal pathway is formed at least in part by a heat pipe. 
     In a yet still further refinement, the bearing system includes sump housing; and wherein the high conductivity thermal pathway is configured to direct heat from the bearing to the sump housing. 
     In an additional refinement, the bearing is a rolling element bearing having a bearing race, further comprising a heat sink thermally bonded to the bearing race. 
     In another additional refinement, the bearing system includes sump housing having fins, further comprising means for flowing cooling air past the fins to remove heat from the sump housing. 
     In yet another additional refinement, the gas turbine engine further comprises aerogel insulation disposed around the sump housing and configured to shield the sump housing from an external heat source. 
     In still another additional refinement, the gas turbine engine further comprises a cooling air nozzle configured to direct cooling air to the bearing. 
     In yet still another additional refinement, the gas turbine engine further comprises a mist nozzle configured to direct a mist to the bearing. 
     In an additional further refinement, the mist is an oil mist. 
     In another additional further refinement, gas turbine engine further comprises a shaft, and a heat pipe disposed within the shaft, wherein the bearing is mounted on the shaft; and wherein the heat pipe is configured to remove heat from the bearing. 
     In yet another additional further refinement, the gas turbine engine further comprises a cooling fin mounted on the shaft and configured to remove heat from the heat pipe. 
     In still another additional further refinement, the gas turbine engine further comprises a cooling air nozzle configured to discharge cooling air onto the cooling fin and remove heat from the cooling fin. 
     Embodiments of the present invention include a gas turbine engine, comprising: a fan; a compressor in fluid communication with the fan; a diffuser in fluid communication with the compressor; a combustor in fluid communication with the diffuser; a turbine in fluid communication with the combustor; a bearing configured to support fan loads and/or compressor loads and/or turbine loads; and an electro-thermal cooling system configured to remove heat from the bearing. 
     In a refinement, the electro-thermal cooling system is a thermoelectric cooler thermally coupled to the bearing. 
     In another refinement, the electro-thermal cooling system is a thermionic cooler thermally coupled to the bearing. 
     Embodiments of the present invention include a gas turbine engine, comprising: a rotor; a bearing configured to react loads from the rotor; and means for electro-thermally removing heat from the bearing. 
     In a refinement, the gas turbine engine further comprises a plurality of other means for removing heat from the bearing. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment(s), but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims, which scope is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures as permitted under the law. Furthermore it should be understood that while the use of the word preferable, preferably, or preferred in the description above indicates that feature so described may be more desirable, it nonetheless may not be necessary and any embodiment lacking the same may be contemplated as within the scope of the invention, that scope being defined by the claims that follow. In reading the claims it is intended that when words such as “a,” “an,” “at least one” and “at least a portion” are used, there is no intention to limit the claim to only one item unless specifically stated to the contrary in the claim. Further, when the language “at least a portion” and/or “a portion” is used the item may include a portion and/or the entire item unless specifically stated to the contrary.