Patent Application
20170145956
The current disclosure pertains to a control system for a thrust reverse feature of a gas turbine engine.
In some fan engines (also known as “propfan” engines), the axis of the fan propeller is parallel to or coaxial with the axis of the gas engine. Typically, in a turbo-shaft, turbo-propeller engine, the axis of one or more propellers will be perpendicular to the axis of the gas engine. In both configurations, the fan or propeller may have a fixed pitch or a variable pitch. If the pitch is variable, the engine may also have a dedicated pitch change mechanism (PCM). The propeller speed (Nx) is proportional to the gas engine power turbine shaft speed (Np) via a pure mechanical gear-train transformation, that is, Nx=Kgb*Np where Kgb is a constant that represents the gear ratio. Controlling the propeller speed, Nx, is equivalent to controlling the power turbine speed, Np. The primary challenge is to coordinate control of the propeller speed (Nx) or the Power Turbine speed (Np) (denoted generically as Nx due to their relationship with each other), the HP shaft speed (N2), and any PCM pitch angle while maintaining a set of active constraints including but not limited to core pressure (Px), exhaust temperature (T), core speed rate (N2dot), and/or torque (Tq) to stay with defined limits, while rejecting external disturbances including but not limited to load change and/or internal known disturbances including but not limited to variable bleed valves and variable stator vanes.
Further, certain gas turbine engines include a thrust reverse feature for redirecting a flow of air through or around the engine to generate a reverse thrust. Typically, the thrust reverse feature is moved from a stowed position directly to a fully deployed position once a certain condition or conditions are met, such as propeller speed Nx or HP shaft speed N2. However, such control over simplifies the process and can result in a slower activation of the thrust reverser/a longer wait time for the engine to generate a maximum amount of reverse thrust. Accordingly, a control system that can more appropriately activate a thrust reverse feature of a gas turbine engine in coordination with controlling other aspects of the engine would be useful.
Aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention.
In one exemplary aspect of the present disclosure, a method for controlling a gas turbine engine is provided. The method includes receiving, with a controller, a thrust reverse command to activate a thrust reverse feature of the gas turbine engine, and determining the thrust reverse feature is in a starting position. The method also includes confirming a gas turbine engine condition is at a first value, moving the thrust reverse feature to a middle position based on a thrust reverse feature coordination schedule, and confirming the gas turbine engine condition is at a second value in coordination with moving the thrust reverse feature to the middle position. The method also includes moving the thrust reverse feature to a maximum position based on the thrust reverse feature coordination schedule.
In one exemplary embodiment of the present disclosure, a gas turbine engine defining an axial direction is provided. The gas turbine engine includes a core having a compressor and a turbine located downstream of the compressor. The gas turbine engine also includes a thrust reverse feature defining a starting position, a middle position, and a maximum position. The thrust reverse feature is configured for redirecting a flow of air through the core or around the core when in the maximum position. The gas turbine engine also includes a controller operably connected to the core and the thrust reverse feature. The controller is configured to receive a thrust reverse command to activate the thrust reverse feature of the gas turbine engine, determine the thrust reverse feature is in the starting position, and confirm a gas turbine engine condition is at a first value. The controller is also configured to move the thrust reverse feature to the middle position, and confirm the gas turbine engine condition is at a second value in coordination with moving the thrust reverse feature to the middle position. The controller is also configured to move the thrust reverse feature to the maximum position.
These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended Figs.
Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.
Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.
The terms “upstream” and “downstream” refer to the relative direction with respect to fluid flow in a fluid pathway. For example, “upstream” refers to the direction from which the fluid flows, and “downstream” refers to the direction to which the fluid flows.
The current disclosure generally provides for a method of controlling a gas turbine engine to coordinate movement of a thrust reverse feature of the gas turbine engine with various other gas turbine engine conditions. Coordinating the movement of the thrust reverse feature with the various other gas turbine engine conditions may generally have the technical effect of improved control of the gas turbine engine. For example, such coordination may provide for less stress on the thrust reverse feature, as well as for a quicker full utilization of the thrust reverse feature (i.e., an increased amount of reverse thrust more quickly).
In certain exemplary aspects, the thrust reverse feature may generally be movable from a starting position to a maximum position, along with one or more middle positions therebetween. The starting position may be a fully stowed position in which no reverse thrust is generated and the maximum position may be a fully deployed position wherein a maximum amount of reverse thrust may be generated during operation of the gas turbine engine. The thrust reverse feature may be positioned in the starting position when a controller operable with the thrust reverse feature receives a thrust reverser command. In response to receiving the thrust reverser command, the controller may further be configured to move one or more gas turbine engine conditions to a first value corresponding to a desired first value for initiating the thrust reverse feature. The one or more gas turbine engine conditions may include a gas turbine engine speed, a fan speed of a fan of the gas turbine engine, a pitch angle of a plurality of fan blades of the fan of the gas turbine engine, etc. For example, wherein the gas turbine engine condition is a gas turbine engine speed or fan speed, the controller may reduce such engine speed and/or fan speed to a relatively low rotational speed. Additionally, wherein the gas turbine engine condition is a pitch angle, the controller may reduce the pitch angle such that the fan generates a relatively low amount of forward thrust.
Further, after receiving the thrust reverser command and determining the thrust reverse feature is in a starting position and the gas turbine engine condition is at a first value, the controller may coordinate movement of the thrust reverse feature to a middle position along with the gas turbine engine condition to a second value corresponding to a desired value for the thrust reverse feature being at the middle position. For example, wherein the gas turbine engine condition is a gas turbine engine speed or fan speed, the controller may reduce the gas turbine engine speed and/or fan speed to a relatively low rotational speed/a minimum rotational speed. Additionally, wherein the gas turbine engine condition is a pitch angle, the controller may reduce the pitch angle below a fine flight limit for the gas turbine engine.
Moreover, in certain exemplary aspects, after the thrust reverse feature has moved to the middle position and the gas turbine engine condition is at the second value, the controller may further coordinate movement of the thrust reverse feature to the maximum position along with the gas turbine engine condition to a third value corresponding to a desired value for the thrust reverse feature being at the maximum position. For example, wherein the gas turbine engine condition is an engine speed or fan speed, the controller may increase the engine speed and/or fan speed to provide additional airflow through the thrust reverse feature, and thus to generate more reverse thrust. Additionally, wherein the gas turbine engine condition is a pitch angle, the controller may further reduce the pitch angle such that the fan generates reverse thrust as well.
Notably, in certain exemplary aspects, the controller may receive a number of other additional variables to determine the thrust reverse feature position. For example, in certain exemplary aspects, the controller may coordinate movement of the thrust reverse feature with a plurality of the engine conditions noted above, in addition to, or alternatively to, a power lever angle, a Mach number for the gas turbine engine, etc.
Referring now to the drawings, wherein identical numerals indicate the same elements throughout the figures,
The exemplary core turbine engine 16 depicted is generally enclosed within a substantially tubular outer casing 18 that defines an annular inlet 20. The outer casing 18 encases, in serial flow relationship, a compressor section including a booster or low pressure (LP) compressor 22 and a high pressure (HP) compressor 24; a combustion section 26; a turbine section including a high pressure (HP) turbine 28 and a low pressure (LP) turbine 30; and a jet exhaust nozzle section 32. A high pressure (HP) shaft or spool 34 drivingly connects the HP turbine 28 to the HP compressor 24. A low pressure (LP) shaft or spool 36 drivingly connects the LP turbine 30 to the LP compressor 22. The compressor section, combustion section 26, turbine section, and nozzle section 32 together define a core air flowpath 37 therethrough.
For the embodiment depicted, the fan section 14 includes a variable pitch fan 38 having a plurality of fan blades 40. The fan blades 40 are attached at a base to a disk 42, the fan blades 40 and disk 42 together rotatable about the longitudinal axis 12 by the LP shaft 36 across a power gear box 46. The power gear box 46 includes a plurality of gears for stepping down a rotational speed of the LP shaft 36 to a more efficient rotational fan speed. Additionally, the plurality of fan blades 40 are each rotatable about a respective pitch axis P1 by a pitch change mechanism 44. The pitch change mechanism 44 may include one or more rotary or linear actuators for changing a pitch of each of the respective fan blades 40.
Referring still to the exemplary embodiment of
During operation of the turbofan engine 10, a volume of air 58 enters the turbofan 10 through an associated inlet 60 of the nacelle 50 and/or fan section 14. As the volume of air 58 passes across the fan blades 40, a first portion of the air 58 as indicated by arrows 62 is directed or routed into the bypass airflow passage 56 and a second portion of the air 58 as indicated by arrow 64 is directed or routed into the core air flowpath 37. The ratio between the first portion of air 62 and the second portion of air 64 is commonly known as a bypass ratio.
Referring now also to
Referring still to
Each of these sensors is in communication with one or more controllers (not depicted). The one or more controllers may include a computer or other suitable processing unit. The controller may include suitable computer-readable instructions that, when implemented, configure the controller to perform various functions, such as receiving, transmitting and/or executing signals from the sensors. A computer generally includes a processor(s) and a memory. The processor(s) can be any known processing device. Memory can include any suitable computer-readable medium or media, including, but not limited to, RAM, ROM, hard drives, flash drives, or other memory devices. Memory stores information accessible by the processor(s), including instructions that can be executed by the processor(s). The instructions can be any set of instructions that when executed by the processor(s), cause the processor(s) to provide a desired functionality. For instance, the instructions can be software instructions rendered in a computer-readable form. When software is used, any suitable programming, scripting, or other type of language or combinations of languages may be used to implement the teachings contained herein. Alternatively, the instructions can be implemented by hard-wired logic or other circuitry, including, but not limited to application-specific circuits. The computing device can include a network interface for accessing information over a network. The network can include a combination of networks, such as Wi-Fi network, LAN, WAN, the Internet, cellular network, and/or any other suitable network and can include any number of wired or wireless communication links. For instance, computing device could communicate through a wired or wireless network with each sensor and other systems of the engine (e.g., the engine logic control).
It should be appreciated, however, that the exemplary turbofan engine 10 depicted in
Referring now to
The exemplary control system 100 generally includes a parameter interface module 102. The parameter interface module 102 may include one or more separate modules configured to receive or determine various condition/parameter values of the gas turbine engine. For example, the parameter interface module 102 may be operably connected with one or more sensors, such as speed sensors, temperature sensors, pressure sensors, position sensors, etc., to receive engine condition/parameter values and/or to derive a desired engine condition/parameter value. In certain exemplary embodiments, the parameter interface module 102 may be configured to receive and/or determine the following engine conditions: a power lever angle (PLA), a Mach number for an aircraft to which the gas turbine engine is installed, a gas turbine combustor temperature T3, a gas turbine engine turbine temperature T4, a gas turbine engine speed N2, a fan speed N1 of a fan of the gas turbine engine, a pitch angle B1 of a plurality of fan blades of the fan, a pitch angle B2 of one or more outlet guide vanes of the gas turbine engine, etc.
The exemplary control system 100 additionally includes a thrust reverse command module 104. The thrust reverse command module 104 may be configured to receive one or more parameters and, based at least in part on these parameters, confirm a thrust reverse command. For example, a pilot or other operator of an aircraft may initiate a thrust reverse command, such command may be received by the thrust reverse command module 104, and the thrust reverse command module 104 may, based on the one or more parameters received, confirm such thrust reverse command. Alternatively, the thrust reverse command module 104 may automatically initiate and/or confirm a thrust reverse command based on the one or more parameter values received. In certain exemplary embodiments, the thrust reverse command module 104 may receive from the parameter interface module 102 one or more of the PLA, Mach number, turbine temperature T4, and turbine engine speed N2.
The thrust reverse command module 104 may provide the confirmed thrust reverse command TRCMD to a thrust reverse feature position module 106. The thrust reverse feature position module 106 may work in coordination with various other modules, described below, to provide a thrust reverse feature position demand TRFPDMD to a thrust reverse feature. More particularly, the thrust reverse feature position module 106 may actuate the thrust reverse feature between, e.g., a starting position 108, a middle position 110, and a maximum position 112 to implement the thrust reverse command TRCMD received. The thrust reverse feature may include any feature of the gas turbine engine configured to, e.g., redirect a flow of air through or around a core of the gas turbine engine to generate an amount of reverse thrust. For example, the thrust reverse feature may be configured as the exemplary thrust reverse feature 70 described above with reference to
Referring still to
Furthermore, each of the gas turbine engine speed module 114, gas turbine fan speed module 116, gas turbine blade angle module 118, and OGV module 120 may additionally receive the thrust reverse command TRCMD from the thrust reverse command module 104 and/or a thrust reverse feature position from the thrust reverse feature position module 106. As briefly discussed above, the exemplary control system 100 is configured to coordinate movement of the thrust reverse feature with various other gas turbine engine conditions. More specifically, in at least certain exemplary aspects, the exemplary control system 100 may be configured to control the thrust reverse feature position through the thrust reverse feature position module 106 as a function of the thrust reverse command TRCMD and one or more of PLA, Mach number, blade angle B1, gas turbine engine speed N2, fan speed N1 etc. (Thrust reverse feature position=f(TRCMD, PLA, Mach number, blade angle B1, engine speed N2, and/or fan speed N1)).
Referring particularly to the exemplary aspect of the control system 100 depicted, the thrust reverse command module 104 may confirm a thrust reverse command and provide such command TRCMD to the thrust reverse feature position module 106. Such thrust reverse feature position module 106 may determine the thrust reverse feature is in the starting position 108. Simultaneously, or in coordination with such determination, the control system 100 may control one or more of the other control system 100 modules to move various engine conditions to values corresponding to a desired value for initiating the thrust reverse feature. For example, the control system 100 may move the gas turbine engine speed N2 to a first engine speed value 122, move the fan speed N1 to a first fan speed value 124, move the blade angle B1 to a first blade angle value 126, and move the OGV angle B2 to a first OGV angle value 128. More particularly, moving the gas turbine engine speed N2 and fan speed N1 to the first values 122, 124 may include slowing down the gas turbine engine and fan such that less air is flowing through the core of the gas turbine engine or around the core of the gas turbine engine. Similarly, moving the blade angle B1 to the first value 126 may reduce a forward thrust generated by the fan of the gas turbine engine along with an amount of airflow generated by the fan through the core and/or over the core of the gas turbine engine (i.e., through a bypass passage).
Once the control system 100 confirms the various engine conditions are at the first values corresponding with a desired position for such engine conditions when the gas turbine engine initiates the thrust reverse command, the thrust reverse feature position module 106 may move the thrust reverse feature from the starting position 108 to the middle position 110. Again, the control system 100 may simultaneously, or in coordination with such movement, control one or more of the other control system 100 modules such that the respective engine conditions are at a second value—the second value corresponding to a desired value for such conditions when the thrust reverse feature is in/moved to the middle position 110. For example, the gas turbine engine speed module 114 may confirm the gas turbine engine speed N2 is at a second engine speed value 130 and the fan speed module 116 may confirm the fan speed N1 is at a second fan speed value 132. Notably, for the aspect depicted, the second values 130, 132 of the engine speed N2 and fan speed N1 may be less than the first values 122, 124 of the engine speed N2 and fan speed N1 (i.e., the engine speed module 114 and fan speed module 116 may reduce the engine speed N2 and fan speed N1 to a minimum rotational speed). Additionally, the blade angle module 118 may move the pitch angle B1 of the plurality of fan blades from the first blade angle value 126 to a second blade angle value 134 in coordination with movement of the thrust reverse feature position to the middle position 110. Notably, for the aspect depicted, moving the pitch angle B1 of the plurality fan blades from the first value 126 to the second value 134 includes reducing the pitch angle B1 of the plurality fan blades below a fine flight limit for the fan. The fine flight limit of the fan is specified as the minimum positive fan blade pitch angle for forward thrust. Additionally, for the aspect depicted, moving the pitch angle B1 of the plurality of fan blades from the first value 126 to the second value 134 includes reducing the pitch angle B1 of the plurality of fan blades to an angle below zero (which should at least correspond to a minimum reverse thrust of the fan).
Once the control system 100 confirms the various engine conditions are at the second values corresponding with the desired position for such conditions when the thrust reverse feature is in the second position, the thrust reverse feature position module 106 may move the thrust reverse feature from the middle position 110 to the maximum position 112. Again, the control system 100 may simultaneously, or in coordination with such movement, control one or more of the control system 100 modules such that the engine conditions are at a third value—such third value corresponding to a desired value for such engine conditions when the thrust reverse feature is moved to the maximum position 112. For example, the gas turbine engine speed module 114 may move the engine speed N2 to a third engine speed value 136 and the fan speed module 116 may similarly move the fan speed N1 to a third fan speed value 138. For the aspect depicted, the third values 136, 138 of the engine speed N2 and fan speed N1 are greater than the first values 122, 124 and second values 130, 132. Specifically, for the aspect depicted, when the thrust reverse feature is in the maximum position 112, an increased amount of air is desired through the core or over the core to maximize an amount of reverse thrust generated by the engine. Additionally, the blade angle module 118 may move the pitch angle B1 of the plurality fan blades from the second blade angle value 134 to the third blade angle value 140 in coordination with the movement of the thrust reverse feature position to the maximum position 112. The third value 140 of the pitch angle B1 should be less than the second values 126, 134, corresponding to a maximum reverse thrust position for the fan.
In addition to controlling the above modules, the control system 100 may also coordinate movement of the OGV angle B2 between the first OGV angle value 128, a second OGV angle value 142, and a third OGV angle 144 via the OGV module 120 to, e.g., reducing the amount of noise generated by the gas turbine engine.
Referring still to
It should be appreciated, however, that the exemplary control system 100 depicted in
Referring now to
Specifically,
The controlled outputs 210, 212 N2 and Nx form the basis of feedback loops in the control system 200. These feedback signals are combined with shaped (or filtered) references denoted as N2Ref 214 and NxRef 216. The combinations of the feedback signals and the shaped references N2Ref and NxRef form tracking error signals 218, 220. The tracking error signals 218, 220 may go through reference tracking single-input single-output (SISO) controls then be combined with feedforward control actions that result from accounting for the effects of aerodynamic loading changes on the controlled outputs 210, 212 (Nx and N2).
It should be appreciated, however, that in other exemplary embodiments any other suitable control systems may be utilized for controlling, e.g., fan speed N1 and/or engine speed N2.
Referring now to
As depicted, the exemplary method (300) generally includes at (302) receiving, with a controller, a thrust reverse command to activate a thrust reverse feature of the gas turbine engine. In response to receiving the thrust reverse command at (302), the exemplary method (300) includes at (304) determining the thrust reverse feature is in a starting position. Determining the thrust reverse feature is in the starting position at (304) may include sensing a position of the thrust reverse feature with a sensor.
Moreover, the exemplary method (300) additionally includes at (306) confirming a first gas turbine engine condition is at a first value. In certain exemplary embodiments, confirming the first gas turbine engine condition is at the first value at (306) may include moving the first gas turbine engine condition to the first value. Additionally, in certain exemplary aspects, the first gas turbine engine condition may be any gas turbine engine condition desirably moved in coordination with the thrust reverse feature when the thrust reverse feature is activated. For example, in certain exemplary aspects, the first gas turbine engine condition may be an engine speed, a fan speed, a pitch angle of a plurality of fan blades, etc.
Referring still to
Further, the exemplary method (300) includes at (312) moving the thrust reverse feature to a maximum position based on the thrust reverse feature coordination schedule and at (314) confirming the gas turbine engine condition is at a third value in coordination with moving the thrust reverser feature to the maximum position at (312). Notably, moving the thrust reverser feature to the maximum position at (312) may include moving the thrust reverser feature to the maximum position after confirming the gas turbine engine condition is at the second value at (310). Additionally, confirming the gas turbine engine condition is at the third value may include moving the gas turbine engine condition to the third value from the second value.
For example, in exemplary aspects wherein the gas turbine engine condition is a gas turbine engine speed, the first value may be a first gas turbine engine speed, the second value may be a second gas turbine engine speed, and the third value may be a third gas turbine engine speed. The first gas turbine engine speed may be greater than the second gas turbine engine speed, and the third gas turbine engine speed may be greater than the first and second gas turbine engine speeds, such that confirming the gas turbine engine condition at (310) includes decreasing the gas turbine engine speed from the first speed to the second speed and confirming the gas turbine engine condition at (314) includes increasing the gas turbine engine speed from the second speed to the third speed.
Additionally, or alternatively, wherein the gas turbine engine condition is a fan speed, the first value may be a first fan speed, the second value may be a second fan speed, and the third value may be a third fan speed. The first fan speed may be greater than the second fan speed, and the third fan speed may be greater than the first and second fan speeds, such that confirming the gas turbine engine condition at (310) includes decreasing the fan speed from the first speed to the second speed and confirming the gas turbine engine condition at (314) includes increasing the fan speed from the second speed to the third speed.
Additionally, or alternatively, wherein the gas turbine engine condition is a pitch angle of a plurality of fan blades of a fan of the gas turbine engine, the first value may be a first pitch angle, the second value may be a second pitch angle, and the third value may be a third pitch angle. The first pitch angle may be a pitch angle configured to generate forward thrust during operation. The second pitch angle should be less than the first pitch angle. For example, the second pitch angle should be at least less than zero degree. Additionally, the third pitch angle may be less than the second pitch angle, such as a pitch angle configured to generate a maximum amount of reverse thrust during operation. With such an exemplary embodiment, confirming the gas turbine engine condition is at a second value at (310) may include reducing the pitch angle from the first pitch angle to the second pitch angle, and similarly, confirming the gas turbine engine condition is at the third value at (314) may include reducing the pitch angle from the second value to the third value.
Moreover, in certain exemplary aspects, the method (300) may coordinate movement of the thrust reverser feature with a plurality of gas turbine engine conditions. For example, in certain exemplary aspects, the exemplary method (300) may additionally include confirming a second gas turbine engine condition is at a first value in coordination with confirming the first gas turbine engine condition is at the first value at (306). Similarly, in such an exemplary aspect, the exemplary method (300) may additionally include confirming the second gas turbine engine condition is at a second value in coordination with moving the thrust reverser feature to the middle position at (308) and in coordination with confirming the first gas turbine engine condition is at the second value at (310). As with the exemplary embodiment depicted in
Additionally, moving the thrust reverser feature to the maximum position may include moving the thrust reverser feature to the maximum position after confirming the first gas turbine engine condition is at the second value and after confirming the second gas turbine engine condition is a second value.
However, it should be appreciated, that although the exemplary aspect depicted in
This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention 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 include 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.
