Patent Application
20170226886
The subject matter disclosed herein generally relates to clearance control between rotating and static components of a gas turbine engine and, more particularly, to thrust balance manipulation for clearance control.
Gas turbine engines, such as those used to power modern commercial and military aircrafts, generally include a compressor section to pressurize an airflow, a combustor section for burning hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. The airflow flows along a gas path between components through the gas turbine engine.
Accordingly, a gas turbine engine includes a plurality of rotating components arranged along an axis of rotation of the gas turbine engine, in both the compressor section and the turbine section. The gas turbine engine also includes a number of static components. The rotating and static components of the gas turbine engine are made from many different materials and vary in size, thickness, and dimensions. Therefore, each component has a growth pattern that includes thermally and mechanically expanding and contracting at different rates. Such component growth during operation, if left unaccounted for, could cause rotating components of the gas turbine engine to undesirably come into contact with static components causing damage to the gas turbine engine.
Accordingly there is a desire to find a way to control the clearance distances between the rotating components and the static components of gas turbine engines.
According to one embodiment a gas turbine engine with clearance control is provided. The gas turbine engine includes a static component, and a rotating component that shifts axially in one of an aft direction and a forward direction in relation to the static component during a first operating condition of the gas turbine engine, and shifts axially in the other of the aft direction and the forward direction in relation to the static component during a second operating condition of the gas turbine engine. The first operating condition is when a rotating component growth and a static component growth change at different rates. The second operating condition is when the rotating component growth and static component growth normalize.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include wherein the rotating component increases a clearance distance between the rotating component and the static component by shifting axially in the first operating condition, and wherein the rotating component decreases the clearance distance between the rotating component and the static component by shifting axially in the second operating condition.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include wherein a backward most position in the aft direction and a forward most position in the forward direction have a maximum separation distance defined by a thrust bearing freeplay distance.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include wherein the static component growth and the rotating component growth each include a mechanical expansion value and a thermal expansion value.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include a compressor that manipulates thrust balance within the compressor that shifts the rotating component axially.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include thrust balance vents that vent certain parts of the compressor, wherein venting generates axial force within the compressor that shifts the rotating component axially.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include wherein the compressor includes a plurality of rotating disks with a chamber between each of the plurality of rotating disks, and wherein the chamber on a forward side of each rotating disk has a lower pressure than the chamber on an aft side of each rotating disk that has a higher pressure.
In addition to one or more of the features described above, or as an alternative, further embodiments of the gas turbine engine may include a higher pressure chamber that axially shifts the rotating component in the aft direction when the higher pressure chamber is vented, and a lower pressure chamber that axially shifts the rotating component in the forward direction when the lower pressure chamber is vented.
According to one embodiment a system in a gas turbine engine for clearance control is provided. The system includes a gas turbine engine controller that generates a clearance control signal based on operating conditions of the gas turbine engine, wherein the control signal controls axial shifts within the system, a static component, and a rotating component that shifts axially in one of an aft direction and a forward direction in relation to the static component during a first operating condition of the gas turbine engine in response to receiving the clearance control signal, and shifts axially in the other of the aft direction and the forward direction in relation to the static component during a second operating condition of the gas turbine engine in response to receiving the clearance control signal. The first operating condition is when a rotating component growth and a static component growth change at different rates. The second operating condition is when the rotating component growth and static component growth normalize.
According to one embodiment a method for clearance control between a rotating component and a static component of a gas turbine engine is provided. The method includes shifting the rotating component axially in one of an aft direction and a forward direction in relation to the static component during a first operating condition of the gas turbine engine, wherein the first operating condition is when a rotating component growth and a static component growth change at different rates, determining that the first operating condition has ended and that the gas turbine engine is operating in a second operating condition during which the rotating component growth and static component growth normalize, and shifting the rotating component axially in the other of the aft direction and the forward direction in relation to the static component during the second operating condition.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein shifting the rotating component axially in the aft direction includes increasing a clearance distance between the rotating component and the static component, and wherein shifting the rotating component axially in the forward direction includes decreasing the clearance distance between the rotating component and the static component.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include maintaining the clearance distance within a max threshold value and a minimum threshold value.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein a backward most position in the aft direction and a forward most position in the forward direction have a maximum separation distance defined by a thrust bearing freeplay distance.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein the rotating component includes a high spool that includes a compressor and a turbine.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein the static component growth and the rotating component growth each include a mechanical expansion value and a thermal expansion value.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein shifting the rotating component axially includes manipulating thrust balance in a compressor of the gas turbine engine.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein manipulating the thrust balance includes venting certain parts of the compressor using thrust balance vents, wherein venting generates axial force within the compressor that shifts the rotating component axially.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include wherein the compressor includes a plurality of rotating disks with a chamber between each of the plurality of rotating disks, wherein a lower pressure is provided in the chamber on a forward side of each rotating disk and a higher pressure is provided in the chamber on an aft side of each rotating disk.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include venting a higher pressure chamber by axially shifting the rotating component in the aft direction.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include venting a lower pressure chamber by axially shifting the rotating component in the forward direction.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting.
The foregoing and other features, and advantages of the present disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:
As shown and described herein, various features of the disclosure will be presented. Various embodiments may have the same or similar features and thus the same or similar features may be labeled with the same reference numeral, but preceded by a different first number indicating the figure to which the feature is shown. Thus, for example, element “a” that is shown in FIG. X may be labeled “Xa” and a similar feature in FIG. Z may be labeled “Za.” Although similar reference numbers may be used in a generic sense, various embodiments will be described and various features may include changes, alterations, modifications, etc. as will be appreciated by those of skill in the art, whether explicitly described or otherwise would be appreciated by those of skill in the art.
Embodiments described herein are directed to a method and system for clearance control between a rotating component and a static component of a gas turbine engine. Specifically, according to an embodiment, mechanical growth of components can occur in orders of magnitude faster than thermal growth. Thus, a system as disclosed herein utilizes a sloped flow path and a thrust balance valve that allows additional clearance during initial transient periods and clearance adjustments once thermals and mechanical growth values normalize.
For example, turning now to
Specifically,
The gas turbine engine 10 further includes a turbine section 20 for extracting energy from the combustion gases. Fuel is injected into the combustor 18 of the gas turbine engine 10 for mixing with the compressed air from the compressor 16 and ignition of the resultant mixture. The fan 12, compressor 16, combustor 18, and turbine 20 are typically all concentric about a common central longitudinal axis of the gas turbine engine 10. In some embodiments, the turbine 20 includes one or more turbine stators 22 and one or more turbine rotors 24. Likewise, the compressor 16 includes one or more compressor rotors 26 and one or more compressor stators 28. It is to be appreciated that while the description below relates to compressors 16 and compressor rotors 26, one skilled in the art will readily appreciate that the present disclosure may be utilized with respect to turbine rotors 24.
Further, according to one or more embodiments, during a transient period of operation different elements of the gas turbine engine can expand and contract due to, for example, rotational mechanical forces and thermal expansion. Further, the elements of the gas turbine engine will expand and contract at different rates and can also expand toward each other. To prevent the different components from coming into contact with each other the clearance distance between the rotating and static components is adjusted by moving the rotating component axially in either the forward or aft direction.
For example,
For example,
For example,
According to another embodiment, shifting the rotating component axially in the aft direction includes increasing a clearance distance between the rotating component and the static component. Further, shifting the rotating component axially in the forward direction includes decreasing the clearance distance between the rotating component and the static component. Further, the method includes maintaining the clearance distance within a max threshold value and a minimum threshold value.
According to another embodiment, a backward most position in the aft direction and a forward most position in the forward direction have a maximum separation distance defined by a thrust bearing freeplay distance. According to another embodiment, the rotating component includes a high spool that includes a compressor and a turbine. According to another embodiment, the static component growth and the rotating component growth each include a mechanical expansion value and a thermal expansion value.
According to another embodiment, shifting the rotating component axially includes manipulating thrust balance in a compressor of the gas turbine engine. Manipulating the thrust balance further includes venting certain parts of the compressor using thrust balance vents. Further, venting generates axial force within the compressor that shifts the rotating component axially. According to another embodiment, the compressor includes a plurality of rotating disks with a chamber between each of the plurality of rotating disks. Additionally, a lower pressure is provided in the chamber on a forward side of each rotating disk and a higher pressure is provided in the chamber on an aft side of each rotating disk. According to another embodiment, the method can further include venting a higher pressure chamber axially shifting the rotating component in the aft direction. Alternatively, the method includes venting a lower pressure chamber axially shifting the rotating component in the forward direction.
According to one or more embodiments, clearances between rotating airfoils and static walls are critical for efficient engine operation. They are driven by both thermal and mechanical deflections. Mechanical deflections happen essentially instantly with throttle movement, well before thermal deflections. This means mechanically driven pinches in clearance values set minimum running clearances, meaning that steady state running positions are open by some amount. This sacrifices steady state performance in order to protect against mechanically driven transient pinches.
One or more embodiments use thrust balance modulation, in conjunction with an axially sloped flow path, to manipulate axial rotor position in response to transient throttle excursions. By doing this, clearances can be manipulated on the same order of time magnitude as the mechanical deflections. Allowing the rotor to move backwards (increasing clearance) as the transient occurs, providing additional room to allow the mechanical growths to pass, before readjusting thrust balance to move the rotor back to the tighter steady state position as thermals stabilize.
One or more embodiments include a system in a gas turbine engine for clearance control. The system includes a gas turbine engine controller that generates a clearance control signal based on an operating period of the system, wherein the control signal controls axial shifts within the system. The system also includes a static component, and a rotating component that shifts axially in an aft direction in relation to the static component during a transient period of operation of the gas turbine engine in response to receiving the clearance control signal, and shifts axially in a forward direction in relation to the static component during a normal period in response to receiving the clearance control signal. The transient period is when a rotating component growth and a static component growth change at different rates, and the normal period is when the rotating component growth and static component growth normalize.
One or more embodiments, allow steady state operation to achieve tighter running clearances but still maintain similar levels of transient protection. Overall this would help achieve a more efficient cruise segment and limit climb/throttle transient induced deterioration.
While the present disclosure has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to such disclosed embodiments. Rather, the present disclosure can be modified to incorporate any number of variations, alterations, substitutions, combinations, sub-combinations, or equivalent arrangements not heretofore described, but which are commensurate with the scope of the present disclosure. Additionally, while various embodiments of the present disclosure have been described, it is to be understood that aspects of the present disclosure may include only some of the described embodiments.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.
The corresponding structures, materials, acts, and equivalents of all means or step plus function elements in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description has been presented for purposes of illustration and description, but is not intended to be exhaustive or limited to the embodiments in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the disclosure. The embodiments were chosen and described in order to best explain the principles of the disclosure and the practical application, and to enable others of ordinary skill in the art to understand various embodiments with various modifications as are suited to the particular use contemplated.
The present embodiments may be a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of the present disclosure.
The computer readable storage medium can be a tangible device that can retain and store instructions for use by an instruction execution device. The computer readable storage medium may be, for example, but is not limited to, an electronic storage device, a magnetic storage device, an optical storage device, an electromagnetic storage device, a semiconductor storage device, or any suitable combination of the foregoing. A non-exhaustive list of more specific examples of the computer readable storage medium includes the following: a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), a static random access memory (SRAM), a portable compact disc read-only memory (CD-ROM), a digital versatile disk (DVD), a memory stick, a floppy disk, a mechanically encoded device such as punch-cards or raised structures in a groove having instructions recorded thereon, and any suitable combination of the foregoing. A computer readable storage medium, as used herein, is not to be construed as being transitory signals per se, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through a waveguide or other transmission media (e.g., light pulses passing through a fiber-optic cable), or electrical signals transmitted through a wire.
Computer readable program instructions described herein can be downloaded to respective computing/processing devices from a computer readable storage medium or to an external computer or external storage device via a network, for example, the Internet, a local area network, a wide area network and/or a wireless network. The network may include copper transmission cables, optical transmission fibers, wireless transmission, routers, firewalls, switches, gateway computers and/or edge servers. A network adapter card or network interface in each computing/processing device receives computer readable program instructions from the network and forwards the computer readable program instructions for storage in a computer readable storage medium within the respective computing/processing device.
Computer readable program instructions for carrying out operations of the present disclosure may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Java, Smalltalk, C++, or the like, and conventional procedural programming languages, such as the “C” programming language or similar programming languages. The computer readable program instructions may execute entirely on the user's computer, partly on the user's computer, as a stand-alone software package, partly on the user's computer and partly on a remote computer or entirely on the remote computer or server. In the latter scenario, the remote computer may be connected to the user's computer through any type of network, including a local area network (LAN) or a wide area network (WAN), or the connection may be made to an external computer (for example, through the Internet using an Internet Service Provider). In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects of the present disclosure.
Aspects of the present disclosure are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments. It will be understood that each block of the flowchart illustrations and/or block diagrams, and combinations of blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer readable program instructions.
These computer readable program instructions may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions/acts specified in the flowchart and/or block diagram block or blocks. These computer readable program instructions may also be stored in a computer readable storage medium that can direct a computer, a programmable data processing apparatus, and/or other devices to function in a particular manner, such that the computer readable storage medium having instructions stored therein comprises an article of manufacture including instructions which implement aspects of the function/act specified in the flowchart and/or block diagram block or blocks.
The computer readable program instructions may also be loaded onto a computer, other programmable data processing apparatus, or other device to cause a series of operational steps to be performed on the computer, other programmable apparatus or other device to produce a computer implemented process, such that the instructions which execute on the computer, other programmable apparatus, or other device implement the functions/acts specified in the flowchart and/or block diagram block or blocks.
The flowchart and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of instructions, which comprises one or more executable instructions for implementing the specified logical function(s). In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the Figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems that perform the specified functions or acts or carry out combinations of special purpose hardware and computer instructions.
The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope of the described embodiments. The terminology used herein was chosen to best explain the principles of the embodiments, the practical application or technical improvement over technologies found in the marketplace, or to enable others of ordinary skill in the art to understand the embodiments disclosed herein.
Accordingly, the present disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.
