Patent Application
20190219021
The embodiments herein generally relate to gas turbine engines and more specifically, systems and method for cooling gas turbine engines.
Aircraft gas turbine engines are being designed with tighter internal clearances between engine cases and blades of the compressor and turbine to increase efficiency and reduce fuel burn. These tighter clearances can result in compressor blade tips and turbine blade tips rubbing on the engine cases if the engine core bows as it cools down between flights and an engine start is attempted.
After engine shutdown, the main shafts, compressor disks, turbine disks and other parts with large thermal mass cool at different rates. The heat rises to the top of the engine allowing the lower portions of these parts to become cooler than the upper portions. This causes blade tip clearance between the engine case and blades of the compressor and turbine to decrease as the engine shafts and cases bow temporarily due to uneven thermal conditions. This does not present a problem for the engine unless an engine start is attempted while the bowed condition exists. To address this engine manufacturers have found that motoring the engine at relatively low speed for a period of time prior to engine start allow the parts to achieve uniform thermal conditions and eliminate the bowed condition restoring blade tip to engine case clearances.
The problem is how to motor the engine at very specific speeds for up to four minutes prior to engine start? Pneumatic or Air Turbine Starters are typically duty cycle limited due to lubrication issues and heat dissipation. Butterfly type start valves are typically solenoid actuated and have diaphragms and linkage in the actuator piston assembly that are prone to wear if they are being used to modulate and control starter speed. This type of operation decreases the valve and start life significantly. A more efficient method of motoring the gas turbine engine that does not cause excessive wear and tear is desired.
According to one embodiment, a system for cooling a gas turbine engine is provided. The system comprising: a gas turbine engine including rotational components comprising an engine compressor, an engine turbine, and a rotor shaft operably connecting the engine turbine to the engine compressor, wherein each rotational component is configured to rotate when any one of the rotational components is rotated; a permanent magnet alternator operably connected to at least one of the rotational components, the permanent magnet alternator being configured to rotate the rotational components; and a motor controller in electronic communication with the permanent magnet alternator, the motor controller being configured to command the permanent magnet alternator to rotate the rotational components at a selected angular velocity for a selected period of time.
In addition to one or more of the features described above, or as an alternative, further embodiments of the system may include an accessory gearbox operably connecting the permanent magnet alternator to at least one of the rotational components.
In addition to one or more of the features described above, or as an alternative, further embodiments of the system may include where the permanent magnet alternator is configured to generate electricity when the rotational components are rotating under power of the gas turbine engine.
In addition to one or more of the features described above, or as an alternative, further embodiments of the system may include: an air turbine starter comprising a turbine wheel including a hub integrally attached to a turbine rotor shaft and a plurality of turbine blades extending radially from the hub, the turbine rotor shaft being operably connected to at least one of the rotational components and configured to rotate the rotational components when air flows through the turbine blades and rotates the turbine wheel.
In addition to one or more of the features described above, or as an alternative, further embodiments of the system may include: an auxiliary power unit fluidly connected to the air turbine starter and electrically connected to the permanent magnet alternator, the auxiliary power unit being configured to generate electricity to power the permanent magnet alternator and provide air to the air turbine starter to rotate the turbine blades.
In addition to one or more of the features described above, or as an alternative, further embodiments of the system may include: a starter air valve fluidly connecting the auxiliary power unit to the air turbine starter, the starter air valve being configured to adjust airflow from the auxiliary power unit to the air turbine starter.
According to another embodiment, a method of assembling a system for cooling a gas turbine engine is provided. The method of assembling comprising: obtaining a gas turbine engine including rotational components comprising an engine compressor, an engine turbine, and a rotor shaft operably connecting the engine turbine to the engine compressor, wherein each rotational component is configured to rotate when any one of the rotational components is rotated; operably connecting a permanent magnet alternator to at least one of the rotational components, the permanent magnet alternator being configured to rotate the rotational components; and electrically connecting a motor controller to permanent magnet alternator, the motor controller being configured to command the permanent magnet alternator to rotate the rotational components at a selected angular velocity for a selected period of time.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of assembling the system may include where the permanent magnet alternator is operably connected to at least one of the rotational components through an accessory gearbox.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of assembling the system may include where the permanent magnet alternator generates electricity when the rotational components are rotating under power 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 of assembling the system may include: operably connecting an air turbine starter to at least one of the rotational components, the air turbine starter comprising a turbine wheel including a hub integrally attached to a turbine rotor shaft and a plurality of turbine blades extending radially from the hub, wherein the turbine rotor shaft is configured to rotate the rotational components when air flows through the turbine blades and rotates the turbine wheel.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of assembling the system may include: fluidly connecting an auxiliary power unit to the air turbine starter, the auxiliary power unit being configured to provide air to the air turbine starter to rotate the turbine blades; and electrically connecting the permanent magnet alternator to the auxiliary power unit, the auxiliary power unit being configured to generate electricity to power the permanent magnet alternator.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of assembling the system may include where a starter air valve fluidly connects the auxiliary power unit to the air turbine starter, the starter air valve being configured to adjust airflow from the auxiliary power unit to the air turbine starter.
According to another embodiment, a method of cooling a gas turbine engine is provided. The method of cooling a gas turbine engine comprising: rotating, using a permanent magnet alternator, rotational components of a gas turbine engine, the rotational components comprising an engine compressor, an engine turbine, and a rotor shaft operably connecting the engine turbine to the engine compressor, wherein each rotational component is configured to rotate when any one of the rotational components is rotated.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include controlling, using a motor controller, operation of the permanent magnet alternator, the motor controller being configured to command the permanent magnet alternator to rotate the rotational components at a selected angular velocity for a selected period of time.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include: detecting a failure in a starter air valve prior to rotating the gas turbine engine with the permanent magnet alternator, the starter air valve being fluidly connected to an air turbine starter and configured to provide air to the air turbine starter, wherein the air turbine starter is operably connected to at least one of the rotational components and configured to rotate the rotational components.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include: detecting when a temperature of the gas turbine engine is less than a selected temperature; and displaying a message on a cockpit display when the temperature of the gas turbine engine is less than a selected temperature.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include stopping the utilization of the permanent magnet alternator to rotate the gas turbine engine when a temperature of the gas turbine engine is less than a selected temperature.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include opening a starter air valve after the message has been displayed on the cockpit display, the starter air valve being fluidly connected to an air turbine starter and configured to provide air to the air turbine starter, wherein the air turbine starter is operably connected to at least one of the rotational components and configured to rotate the rotational components.
In addition to one or more of the features described above, or as an alternative, further embodiments of the method of cooling a gas turbine engine may include rotating, using the air turbine starter, rotational components of the gas turbine engine when the starter air valve is opened, the air turbine starter comprising a turbine wheel including a hub integrally attached to a turbine rotor shaft and a plurality of turbine blades extending radially from the hub, the turbine rotor shaft being operably connected to at least one of the rotational components and configured to rotate the rotational components when air flows through the turbine blades and rotates the turbine wheel.
Technical effects of embodiments of the present disclosure include utilizing a permanent magnet alternator operably connected to an aircraft main engine for cool-down motoring to prevent bowed rotor.
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 following descriptions should not be considered limiting in any way. With reference to the accompanying drawings, like elements are numbered alike:
A detailed description of one or more embodiments of the disclosed apparatus and method are presented herein by way of exemplification and not limitation with reference to the Figures.
Various embodiments of the present disclosure are related to a bowed rotor start mitigation system in a gas turbine engine. Embodiments can include using a permanent magnet alternator to control a rotor speed of a gas turbine engine to mitigate a bowed rotor condition using a cool-down motoring process. Cool-down motoring may be performed by running an engine starting system at a lower speed with a longer duration than typically used for engine starting using a permanent magnet alternator to maintain a rotor speed and/or profile. Cool-down motoring (engine bowed rotor motoring) may be performed by the permanent magnet alternator, which may rotate the gas turbine engine continuously between about 0-3000 RPM (engine core speed).
Referring now to the figures,
An air turbine starter 120 of the engine starting system 100 is operably connected to the gas turbine engine 250 through an accessory gearbox 70 and drive shaft 60 (e.g., a tower shaft), as shown in
The air turbine starter 120 is further operable to drive rotation of the rotor shaft 259 at a lower speed for a longer duration than typically used for engine starting in a motoring mode of operation (also referred to as cool-down motoring) to prevent/reduce a bowed rotor condition. If a bowed rotor condition has developed, for instance, due to a hot engine shutdown and without taking further immediate action, cool-down motoring may be performed by the air turbine starter 120 to reduce a bowed rotor condition by driving rotation of the rotor shaft 259.
A electronic engine controller 320, such as full authority digital engine control (FADEC), typically controls engine starting system 100, the gas turbine engine 250, and controls performance parameters of the gas turbine engine 250 such as for example engine temperature, engine, speed, and fuel flow. The electronic engine controller 320 may include at least one processor and at least one associated memory comprising computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including FPGA, central processing unit (CPU), ASIC, digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.
The electric engine controller 320 controls valve operation, for instance, modulation of the starter air valve 116 to control a motoring speed of the gas turbine engine 250 during cool-down motoring. The starter air valve 116 delivers air through a duct 140 to the air turbine starter 120. If the starter air valve 116 fails shut, a corresponding manual override 150 can be used to manually open the starter air valve 116. The manual override 150 can include a tool interface 152 to enable a ground crew to open the starter air valve 116. During regular operation, the starter air valve 116 may be opened and closed using a solenoid 154. The solenoid 154 may be modulated to control a motoring speed of the gas turbine engine 250 during cool-down motoring. The solenoid 154 may be in electrical communication with the electronic engine controller 320.
Alternatively, the motoring speed of the gas turbine engine 250 may also be controlled by a permanent magnet alternator (PMA) 500. Advantageously, the a permanent magnet alternator 500 may be utilized for cool-down motoring in many scenarios including but not limited to when the solenoid 154 fails and can no longer modulate the starter air valve 116 for cool-down motoring. In the event the starter air valve 116 is failed and a manual start is required, the electronic engine controller 320 may transmit a message to be displayed on a cockpit display 320 indicating that a manual start is required. In this case, the permanent magnet alternator 500 could motor the gas turbine engine 250 until it is cooled and then the electronic engine controller 320 could provide a cockpit message to the cockpit display 430 indicating when the engine is cooled sufficiently to allow a crew member to manually open the starter air valve 116 using the manual override 150 and start the gas turbine engine 250. Also advantageously, the permanent magnet alternator 500 may be used regularly for cool-down motoring in order to reduce wear-tear on the starter air valve 116 and associated solenoid 154 that may be caused by the modulation of the starter air valve 116 when the starter air valve 116 performs cool down motoring.
The permanent magnet alternator 500 may be used as the primary means for motoring the gas turbine engine 250 and the starter air valve 116 may be used as secondary means for motoring the gas turbine engine 350 or vice versa. The permanent magnet alternator 500 and the starter air valve 116 may also be used in combination with each other to motor the gas turbine engine 350. As seen in
The permanent magnet alternator 500 may be controlled by the electronic engine controller 320 and/or a motor controller 420 electrically connected to the permanent magnet alternator 500. The motor controller 420 is in electronic communication with the permanent magnet alternator 500. The motor controller 420 is configured to command the permanent magnet alternator 500 to rotate the rotational components 260 at a selected angular velocity for a selected period of time to perform cool-down motoring. The motor controller 420 may include at least one processor and at least one associated memory comprising computer-executable instructions that, when executed by the processor, cause the processor to perform various operations. The processor may be but is not limited to a single-processor or multi-processor system of any of a wide array of possible architectures, including FPGA, central processing unit (CPU), ASIC, digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be a storage device such as, for example, a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium.
Referring now to
Referring now to
The turbine wheel 36 is driven by the compressed airflow such that the turbine rotor shaft 42 may mechanically drive a starter output shaft 58 though a gear system 60, such as a planetary gear system. The air turbine starter 120 thereby transmits relatively high loads through the gear system 60 to convert the pneumatic energy from the compressed air into mechanical energy to, for example, rotate the gas turbine engine 250 for start. The turbine blades 38 of the turbine wheel 36 and the vanes 50 of the nozzle 48—both of which are defined herein as airfoils—may be defined with computational fluid dynamics (CFD) analytical software and are optimized to meet the specific performance requirements of a specific air turbine starter.
Turning now to
The method 600 may also include: operably connecting an air turbine starter 120 to at least one of the rotational components 260. The air turbine starter 120 comprising a turbine wheel 36 including a hub 40 integrally attached to a turbine rotor shaft 42 and a plurality of turbine blades 38 extending radially outward from the hub 40. As mentioned above, the turbine rotor shaft 42 is configured to rotate the rotational components 260 when air flows through the turbine blades 38 and rotates the turbine wheel 36. The method 600 may further include: fluidly connecting an auxiliary power unit 310 to the air turbine starter 120. The auxiliary power unit 114 is configured to provide air to the air turbine starter 120 to rotate the turbine blades 38. The method 600 may also further include: electrically connecting the permanent magnet alternator 500 to the auxiliary power unit 114. The auxiliary power unit 114 is configured to generate electricity to power the permanent magnet alternator 500.
While the above description has described the flow process of
Turning now to
In the event that the engine starter system 100 also includes a starter air valve 116 and an air turbine starter 120, the method 700 may also include detecting a failure in a starter air valve 116 prior to rotating the gas turbine engine 250 with the permanent magnet alternator 500. As mentioned above, the permanent magnet alternator 500 may be used as a secondary means of cool-down motoring when the start air valve 116 fails. As also mentioned above, the starter air valve 116 is fluidly connected to an air turbine starter 120 and configured to provide air to an air turbine starter 120. The air turbine starter 120 is operably connected to at least one of the rotational components 260 and configured to rotate the rotational components 260. The method 700 may also include: detecting when a temperature of the gas turbine engine 250 is less than a selected temperature; and displaying a message on a cockpit display when the temperature of the gas turbine engine 250 is less than a selected temperature. The message may indicate that the gas turbine engine 250 has sufficiently cooled.
The method 700 may further include stopping the utilization of the permanent magnet alternator 500 to rotate the gas turbine engine 250 when a temperature of the gas turbine engine 250 is less than a selected temperature. When the gas turbine engine 250 is less than the selected temperature the cool-down motoring may be complete and the permanent magnet alternator 500 may no longer be needed to rotate the rotation components 260 of the gas turbine engine 250. Following the completion of the cool-down motoring, the pilot may desire to start the gas turbine engine 250, and thus the method 700 may also include: opening the starter air valve 116 after the message has been displayed on the cockpit display 430 indicating that a temperature of the gas turbine engine 250 is less than a selected temperature. Once the air valve 116 is opened, the method 700 may further include: rotating, using the air turbine starter 120, rotational components 260 of the gas turbine engine 250 when the starter air valve 116 is opened.
While the above description has described the flow process of
As described above, embodiments can be in the form of processor -implemented processes and devices for practicing those processes, such as a processor. Embodiments can also be in the form of computer program code containing instructions embodied in tangible media, such as floppy diskettes, CD ROMs, hard drives, or any other computer-readable storage medium, wherein, when the computer program code is loaded into and executed by a computer, the computer becomes a device for practicing the embodiments. Embodiments can also be in the form of computer program code, for example, whether stored in a storage medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, loaded into and/or executed by a computer, or transmitted over some transmission medium, such as over electrical wiring or cabling, through fiber optics, or via electromagnetic radiation, wherein, when the computer program code is loaded into an executed by a computer, the computer becomes an device for practicing the exemplary embodiments. When implemented on a general -purpose microprocessor, the computer program code segments configure the microprocessor to create specific logic circuits.
The term “about” is intended to include the degree of error associated with measurement of the particular quantity based upon the equipment available at the time of filing the application. For example, “about” can include a range of ±8% or 5%, or 2% of a given value.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. 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, element components, and/or groups thereof.
While the present disclosure has been described with reference to an exemplary embodiment or embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the present disclosure. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the essential scope thereof. Therefore, it is intended that the present disclosure not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this present disclosure, but that the present disclosure will include all embodiments falling within the scope of the claims.
The present application is a divisional of U.S. patent application Ser. No. 15/429,742, filed on Feb. 10, 2017. This application claims priority to and the benefit of U.S. provisional patent application Ser. No. 62/294,548, filed on Feb. 12, 2016, and all the benefits accruing therefrom under 35 U.S.C. § 119, the content of which is incorporated herein in its entirety by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62294548 | Feb 2016 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 15429742 | Feb 2017 | US |
| Child | 16365963 | US |
