Patent Application
20170314471
The field of the disclosure relates generally to turbine engines and, more particularly, to a system and method for air-oil heat exchange within a gas turbine engine.
Gas turbine engines typically include components requiring lubrication by engine oil. Two such components that represent primary sources of heat in gas turbine engines are engine bearings, engine gearbox, and engine electrical generators such as integrated drive generator (IDG) or variable frequency generator (VFG) systems. Gas turbine engines require fuel-oil coolers and air-oil coolers to keep oil within specific temperature limits. Known air-oil coolers include compact heat exchangers, surface coolers, and compact bar and plate coolers. Such known air-oil coolers form a part of a fan case-mounted oil thermal management architecture in gas turbine engines including oil reservoir and air-oil cooler, along with associated ducting and mounting components.
Known fan case-mounted oil thermal management architectures may represent significant size, weight, fan drag (i.e., dP/P), and complexity costs impacting specific fuel consumption, performance, and maintenance efficiency. Further, use of thermal management architectures including outlet guide vanes (OGVs) as condensers through which oil flows in internal ducts to be cooled therein requires maintenance of a of an oil pressure budget. Furthermore, known air-oil coolers require increasing oil pressure drop budgets to effectively cool lubricating oil in higher performance gas turbine engines.
In one aspect, a fluid cooling system for a gas turbine engine is provided. The gas turbine engine includes a core engine and an annular fan casing. The fluid cooling system includes a fluid reservoir positioned within the gas turbine engine and configured to contain a fluid. The system also includes a cold sink positioned within the gas turbine engine and having a lower temperature than the fluid. The system further includes a heat pipe including a first end, a second end, and a conduit extending therebetween, the second end thermally coupled to the cold sink, and the first end thermally coupled to the fluid, where the heat pipe facilitates a transfer of a quantity of heat from the fluid to the cold sink.
In another aspect, a gas turbine engine is provided. The gas turbine engine includes a core engine, an annular fan casing, and a fluid cooling system. The fluid cooling system includes a fluid reservoir positioned within the gas turbine engine and configured to contain a fluid. The system also includes a cold sink positioned with the gas turbine engine and having a lower temperature than the fluid. The system further includes a heat pipe including a first end, a second end, and a conduit extending therebetween, the second end thermally coupled to the cold sink, and the first end thermally coupled to the fluid, where the heat pipe facilitates a transfer of a quantity of heat from the fluid to the cold sink.
In yet another aspect, a method of cooling a fluid in a gas turbine engine is provided. The gas turbine engine includes a core engine, a fluid reservoir configured to contain a fluid, and a cold sink having a lower temperature than the fluid. The method includes selecting a heat pipe having performance parameters to facilitate following a predetermined heat transfer characteristic including a thermal resistance between the fluid and the cold sink. The method also includes thermally coupling a first end of the heat pipe to the fluid. The method further includes thermally coupling a second end of the heat pipe to the cold sink. The method also includes receiving heat into the first end from the fluid. The method further includes transferring heat through the heat pipe to the cold sink.
These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Although specific features of various embodiments may be shown in some drawings and not in others, this is for convenience only. Any feature of any drawing may be referenced and/or claimed in combination with any feature of any other drawing.
Unless otherwise indicated, the drawings provided herein are meant to illustrate features of embodiments of the disclosure. These features are believed to be applicable in a wide variety of systems comprising one or more embodiments of the disclosure. As such, the drawings are not meant to include all conventional features known by those of ordinary skill in the art to be required for the practice of the embodiments disclosed herein.
In the following specification and the claims, reference will be made to a number of terms, which shall be defined to have the following meanings.
The singular forms “a”, “an”, and “the” include plural references unless the context clearly dictates otherwise.
“Optional” or “optionally” means that the subsequently described event or circumstance may or may not occur, and that the description includes instances where the event occurs and instances where it does not.
Approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about”, “approximately”, and “substantially”, are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. Here and throughout the specification and claims, range limitations may be combined and/or interchanged, and such ranges are identified and include all the sub-ranges contained therein unless context or language indicates otherwise.
The following detailed description illustrates embodiments of the disclosure by way of example and not by way of limitation. It is contemplated that the disclosure has general application to a method and system for using heat pipes for transferring heat from fluids within a gas turbine engine to cooler portions thereof.
Embodiments of the systems and methods for thermally integrating an oil reservoir and a plurality of outlet guide vanes (OGVs) using heat pipes described herein facilitate maintaining engine oil within predetermined temperature limits during operation of gas turbine engines. Also, the systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes described herein simplify engine oil thermal management architectures by reducing the number, size, and weight of components. Further, the systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes described herein enable decreased specific fuel consumption (SFC), reduced fan drag, increased performance, and simplified maintenance of gas turbine engines. Furthermore, the systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes described herein facilitate effective heat exchange of lubricating oil in gas turbine engines without requiring increased engine oil pressures.
During operation of exemplary gas turbine engine 100, air flows from a forward 121 end of gas turbine engine 100 along a central axis 122 to an aft 123 end, and compressed air is supplied to HPC 104. The highly compressed air is delivered to combustor assembly 106. Exhaust gas flows (not shown in
In operation, in the exemplary fan module 300, OGVs 302 serve as structural members (sometimes referred to as “fan struts”) which connect core cowl 113 and nacelle 128. In alternative embodiments, not shown, these support functions may be served by other or additional components. OGVs 302 are constructed from any material which has adequate strength to withstand the expected operating loads and which can be formed in the desired shape. Use of thermally conductive material for OGVs 302 enhances heat transfer in gas turbine engine 100, not shown.
Also, in the exemplary embodiment, passive thermal management system 400 includes at least one heat pipe 416. Heat pipe 416 is thermally coupled to and between evaporator 412 and condenser 414. Further, in the exemplary embodiment, heat pipe 416 includes a first end 418, a second end 420, and a conduit 422 extending therebetween. Heat pipe 416 extends into interior of fluid reservoir 402 through a sealed aperture 423, which is configured to prevent leakage of at least one of fluid 408 and pressure from an interior of fluid reservoir 402. At least a first portion of each heat pipe 416 is wrapped with suitable thermal insulation, not shown. At least a second portion of each second end 420 is uninsulated. First end 418 is disposed upon or within evaporator 412 and thermally coupled thereto. Second end 420 is disposed upon or within condenser 414, and thermally coupled thereto. In other alternative embodiments, not shown, evaporator 412 and condenser 414 are not separate components, but rather are integrally formed as parts of first end 418 and second end 420, respectively. In still other embodiments, not shown, at least one of evaporator 412 and condenser 414 are not present, and heat pipe 416 is thermally coupled to and between heat source 410 and cold sink 415 (located on at least one portion of gas turbine engine 100, including, without limitation, locations outside of gas turbine engine 100, which are of a lower temperature than heat source 410 as further shown and described below with reference to
In operation, in the exemplary embodiment, first end 418 and second end 420 are mounted within or upon evaporator 412 and condenser 414, respectively, to facilitate thermal heat exchange therebetween. Also, in operation of the exemplary embodiment, at least one of heat source 410 and fluid 408 are at higher temperatures than condenser 414, including, without limitation, on account of condenser being located further away from gas turbine engine 100 or in a region thereof having a lower temperature than at least one of heat source 410 and fluid 408. Under those conditions, heat from heat source 410 is transmitted through heat pipe 416 from first end 418 to second end 420.
Also, during operation of the exemplary embodiment, each heat pipe 416 has an elongated outer wall with closed ends which together define a cavity (not shown in
Further, in operation of the exemplary embodiment, heat from heat source 410 circulates into evaporator 412 where it heats first end 418 of heat pipe 416. Working fluid within heat pipe 416 absorbs that heat and evaporates. The vapor thus generated then travels through the cavities inside heat pipe 416, and condenses at second end 420, thereby transferring heat from heat source 410 to colder areas of gas turbine engine 100 proximate condenser 414. Condensed working fluid then transports, including, without limitation, by capillary action, from second end 420 back to first end 418 at hotter areas of gas turbine engine 100, including, without limitation, at least one of heat source 410 and fluid 408 contained within fluid reservoir 402, thereby completing the circuit. Furthermore, in operation of the exemplary embodiment, the resultant heat transfer from heat source 410 to condenser 414 facilitates passive thermal management system 400 providing effective prevention of at least one of ice formation (i.e. anti-icing) and ice removal in areas of gas turbine engine 100 proximate condenser 414, depending on the heating rate. Moreover, in operation of the exemplary embodiment, passive thermal management system 400 is passive and, therefore, is sealed and requires no valves. Design parameters including, without limitation, number, size, and location of heat pipes 416 can be selected to provide heat removal and heat transfer as needed, and such design parameters may be varied to facilitate following a predetermined heat transfer characteristic including a thermal resistance between heat source 410 and cold sink 415.
Furthermore, in operation of the exemplary embodiment, depending upon the exact configuration chosen, the system performance may be used only for anti-icing or for de-icing. The gas turbine engine cooling system makes use of heat which is undesired in one portion of an engine and uses that heat where it is needed in another portion of the engine, avoiding both the losses associated with known cooling systems and the need for a separate anti-icing heat source.
Also, in the exemplary embodiment, heat pipes 416 are positioned inside a material of construction of OGV 302 including, without limitation, within tubular cavities (not shown in
In operation, in the exemplary embodiment, at least one of heat source 410, fluid 408, and fluid reservoir 402 are at higher temperatures than OGV 302 during operation of gas turbine engine 100, including during soakback. As such, OGV 302 is the cold sink 415 to which at least one of second end 420 and condenser 414 (not shown in
Also, in the alternative embodiment, passive thermal management system 600 includes at least one heat pipe 416. Heat pipe 416 is thermally coupled to and between evaporator 412 and condenser 414, as shown and described above with reference to
Further, in the alternative embodiment, passive thermal management system 600 includes at least one condenser 414 thermally coupled to at least one of opposed sides 312 and 314 of at least one OGV 302 disposed between annular fan casing 202 and annular inner housing 316. Furthermore, in the alternative embodiment, heat pipe 416 is thermally coupled to and between evaporator 412 and condenser 414, as shown and described above with reference to
Furthermore, in the alternative embodiment, passive thermal management system 600 includes at least one condenser 414 coupled to at least one portion of annular inner housing 316 including, without limitation, on a radially outward surface thereof. In other alternative embodiments, not shown, at least one condenser 414 is thermally coupled to at least one portion of radially inward surfaces of annular inner housing 316, not shown, either alone, or in combination with at least one radially outward surface thereof. Heat pipe 416 is thermally coupled to and between evaporator 412 and condenser 414, as shown and described above with reference to
Moreover, in the alternative embodiment, passive thermal management system 600 includes at least one condenser 414 coupled to at least one portion of annular fan casing 202 including, without limitation, on a radially inward surface thereof. Heat pipe 416 is thermally coupled to and between evaporator 412 and condenser 414, as shown and described above with reference to
In operation, in the alternative embodiment, heat source 410 (i.e., hot fluid 408 contained within fluid reservoir 402) is typically at a higher temperature than thrust link support 602, OGV 302, annular fan casing 202, and annular inner housing 316 during typical operating conditions of gas turbine engine 100, including during soakback. As such, thrust link support 602, OGV 302, annular inner housing 316, and annular inner housing 316 are cold sinks 415 to which condensers 414 are thermally coupled. As described above with reference to
The above-described embodiments of systems and methods for thermally integrating an oil reservoir and a plurality of OGVs using heat pipes effectively facilitate maintaining engine oil within predetermined temperature limits during operation of gas turbine engines. Also, the above-described systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes simplify engine oil thermal management architectures by reducing the number, size, and weight of components. Further, the above-described systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes enable decreased SFC, reduced fan drag, increased performance, and simplified maintenance of gas turbine engines. Furthermore, the above-described systems and methods for thermally integrating the oil reservoir and the OGVs using heat pipes facilitate effective heat exchange of lubricating oil in gas turbine engines without requiring increased engine oil pressures.
Example systems, apparatus, and methods for thermally integrating oil tank and OGVs using heat pipes are described above in detail. The apparatus illustrated is not limited to the specific embodiments described herein, but rather, components of each may be utilized independently and separately from other components described herein. Each system component can also be used in combination with other system components.
This written description uses examples to describe the disclosure, including the best mode, and also to enable any person skilled in the art to practice the disclosure, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
