Patent Application
20240094067
This disclosure relates generally to gas turbine engine operating limits and, more particularly, to systems and methods for determining an indicated turbine temperature (ITT) for a gas turbine engine.
A gas turbine engine for an aircraft may be subject to various operational power checks to verify that the aircraft can satisfy minimum power requirements for a flight or operation. In some cases, an indicated turbine temperature (ITT) for the gas turbine engine is used for determining operational power limits and maintenance requirements. Various systems and methods are known in the art for determining an ITT for a gas turbine engine. While these known systems and methods have various advantages, there is still room in the art for improvement.
It should be understood that any or all of the features or embodiments described herein can be used or combined in any combination with each and every other feature or embodiment described herein unless expressly noted otherwise.
According to an aspect of the present disclosure, a system for determining an indicated turbine temperature (ITT) for a gas turbine engine includes an engine control system. The engine control system includes a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to: determine a first estimated outlet temperature value for a high-pressure turbine of the gas turbine engine, determine an estimated work ({dot over (W)}HPT) of the high-pressure turbine, determine an estimated inlet temperature value for the high-pressure turbine using the estimated work ({dot over (W)}HPT), and determine the ITT by calculating a second estimated outlet temperature value using the estimated inlet temperature value, the second estimated outlet temperature value different than the first estimated outlet temperature value.
In any of the aspects or embodiments described above and herein, the instructions, when executed by the processor, may further cause the processor to determine an ITT operating margin for the gas turbine engine.
In any of the aspects or embodiments described above and herein, the instructions, when executed by the processor, may further cause the processor to compare the ITT operating margin to a predetermined threshold operating margin value to identify that a maintenance requirement of the gas turbine engine is present or absent.
In any of the aspects or embodiments described above and herein, the instructions, when executed by the processor, may further cause the processor to compare the ITT to a predetermined ITT threshold value to identify that a high-temperature condition of the gas turbine engine is present or absent.
In any of the aspects or embodiments described above and herein, the instructions, when executed by the processor, may further cause the processor to measure an exhaust gas temperature for the gas turbine engine. The step of determining the first estimated outlet temperature value may include determining the first estimated outlet temperature value using the exhaust gas temperature.
In any of the aspects or embodiments described above and herein, the first estimated outlet temperature value may be different than the second estimated outlet temperature value.
In any of the aspects or embodiments described above and herein, the step of determining the estimated inlet temperature value may include determining the estimated inlet temperature value using a state variable model executed by the engine control system.
According to another aspect of the present disclosure, a method for determining an indicated turbine temperature (ITT) for a gas turbine engine includes: determining a first estimated turbine outlet temperature value, determining an estimated compressor temperature increase value, determining an estimated turbine inlet temperature value using the first estimated outlet temperature value and the estimated compressor temperature increase value, applying a relationship constant for the turbine inlet and the turbine outlet to the estimated turbine inlet temperature value to determine the ITT for the gas turbine engine, and comparing the ITT to a predetermined ITT threshold value to identify that a high-temperature condition of the gas turbine engine is present or absent.
In any of the aspects or embodiments described above and herein, the method may further include determining an ITT operating margin for the gas turbine engine.
In any of the aspects or embodiments described above and herein, the first estimated turbine outlet temperature value may represent a temperature value at an outlet of a high-pressure turbine of the gas turbine engine, the high-pressure turbine upstream of a low-pressure turbine of the gas turbine engine.
In any of the aspects or embodiments described above and herein, the method may further include measuring an exhaust gas temperature for the gas turbine engine. The step of determining the first estimated turbine outlet temperature value may include determining the first estimated turbine outlet temperature value using the exhaust gas temperature.
In any of the aspects or embodiments described above and herein, the first estimated outlet temperature value may be different than the ITT.
In any of the aspects or embodiments described above and herein, the step of determining the estimated turbine inlet temperature value may include determining the estimated inlet temperature value using a state variable model.
In any of the aspects or embodiments described above and herein, the method may further include measuring a compressor inlet temperature and a compressor outlet temperature. The step of determining the estimated compressor temperature increase value may include determining the estimated compressor temperature increase value using the compressor inlet temperature and the compressor outlet temperature.
According to another aspect of the present disclosure, a gas turbine engine includes a high-pressure spool, a low-pressure spool, and an engine control system. The high-pressure spool includes a high-pressure compressor, a high-pressure turbine, and a high-pressure shaft.
The high-pressure shaft interconnects the high-pressure turbine and the high-pressure compressor. The high-pressure turbine includes a turbine inlet and a turbine outlet. The high-pressure compressor includes a compressor inlet and a compressor outlet. The low-pressure spool including a low-pressure compressor, a low-pressure turbine, and a low-pressure shaft. The low-pressure shaft interconnects the low-pressure turbine and the low-pressure compressor. The engine control system including a processor in communication with a non-transitory memory storing instructions, which instructions when executed by the processor, cause the processor to: determine a first estimated outlet temperature value for the high-pressure turbine, determine an inlet temperature value for the high-pressure turbine using the first estimated outlet temperature value, and determine the indicated turbine temperature (ITT) by calculating a second estimated outlet temperature value using the inlet temperature value and a relationship constant for the turbine inlet and the turbine outlet.
In any of the aspects or embodiments described above and herein, the instructions, when executed by the processor, may further cause the processor to determine a temperature increase value for the high-pressure compressor. The step of determining the inlet temperature value may include determining the inlet temperature value using the first estimated outlet temperature value and the temperature increase value.
In any of the aspects or embodiments described above and herein, the step of determining the temperature increase value for the high-pressure compressor may include determining the temperature increase value using an inlet temperature for the high-pressure compressor and an outlet temperature for the high-pressure compressor.
In any of the aspects or embodiments described above and herein, the step of determining the temperature increase value for the high-pressure compressor may include estimating the inlet temperature and the outlet temperature using a state variable model executed by the engine control system.
In any of the aspects or embodiments described above and herein, the gas turbine engine may further include a first sensor and a second sensor. The first sensor may be disposed at the compressor inlet. The second sensor may be disposed at the compressor outlet. The step of determining the temperature increase value for the high-pressure compressor may include measuring the inlet temperature with the first sensor and measuring the outlet temperature with the second sensor.
In any of the aspects or embodiments described above and herein, the gas turbine engine may further include a first sensor and a second sensor. The first sensor and the second sensor may be disposed at the high-pressure shaft. The step of determine the inlet temperature value for the high-pressure turbine includes: measuring a shaft rotation speed of the high-pressure shaft with the first sensor and measuring a shaft torque of the high-pressure shaft with the second sensor and determining work ({dot over (W)}HPT) of the high-pressure turbine using the shaft rotation speed and the shaft torque.
The present disclosure, and all its aspects, embodiments and advantages associated therewith will become more readily apparent in view of the detailed description provided below, including the accompanying drawings.
The gas turbine engine 20 of
The gas turbine engine 20 of
The first rotational assembly 36 includes a first shaft 40, a bladed first compressor rotor 42, and a bladed first turbine rotor 44. The first shaft 40 interconnects the bladed first compressor rotor 42 and the bladed first turbine rotor 44. The second rotational assembly 38 includes a second shaft 46, a bladed second compressor rotor 48, a bladed second turbine rotor 50, and a bladed fan 52. The second shaft 46 of
During operation of the gas turbine engine 20 of
The engine control system 22 of
The engine control system 22 may form or otherwise be part of an electronic engine controller (EEC) for the gas turbine engine 20. The EEC may control operating parameters of the gas turbine engine 20 including, but not limited to, fuel flow, stator vane position, compressor air bleed valve position, etc. so as to control an engine power and/or thrust of the gas turbine engine 20. In some embodiments, the EEC may be part of a full authority digital engine control (FADEC) system for the gas turbine engine 20.
The engine control system 22 receives data associated with operation of the gas turbine engine 20 and/or an associated aircraft. The data may include operational parameters (e.g., pressure, temperature, rotation speed, torque, etc.) for the gas turbine engine 20. The engine control system 22 may include and be in communication (e.g., signal communication) with one or more sensors 62 distributed throughout the gas turbine engine 20 and/or an associated aircraft. The sensors 62 may include, but are not limited to, one or more of the following: an exhaust gas temperature (EGT) sensor 62A, a LPC bleed flow sensor 62B, a HPC bleed flow sensor 62C, a HPC inlet temperature (T2.5) sensor 62D, a HPC outlet temperature (T3.0) sensor 62E, a first shaft rotation speed (RHP) sensor 62F, or a first shaft torque (THP) sensor 62G.
The engine control system 22 may additionally include one or more data tables (e.g., data tables stored in the memory 60), which data tables may include expected operational parameters associated with various operational conditions for the gas turbine engine 20 and/or an associated aircraft. Additionally or alternatively, data associated with operation of the gas turbine engine 20 and/or an associated aircraft may be derived or modeled by the engine control system 22. For example, the engine control system 22 may include instructions which, when executed, allow the engine control system 22 to execute a model (e.g., a computer-implemented model) of one or more operational parameters of the gas turbine engine 20 and/or an associated aircraft in a virtual (e.g., digital) environment which closely represents the physical system (e.g., a component, assembly, system, etc. of a gas turbine engine) by accounting for factors such as, but not limited to, kinematics, static and dynamic behaviors, component surface characteristics, component geometry, shaft torque, engine power, pressure, temperature, altitude, vibration, and the like. For example, the memory 60 may include instructions which, when executed by the processor 58, cause the processor to execute a state variable model, which state variable model may be a simplified linear representation of the gas turbine engine 20 thermodynamics. For example, the state variable model may include or otherwise use first-order differential equations which describe a dynamic set of state variables (e.g., variables used to describe the mathematical state of a dynamic system). The engine control system 22 may evaluate and/or estimate various operational parameters of the gas turbine engine 20 using, for example, using the state variable model. The engine control system 22 may use equations derived, for example, using the first law of thermodynamics [1], which equations may be further calibrated using gas turbine engine test data (e.g., test data for instances of the gas turbine engine 20):
{dot over (Q)}−{dot over (W)}={dot over (m)}C
p(Tout−Tin) [1]
Gas turbine engines, such as the gas turbine engine 20, may undergo periodical engine power assurance checks (EPAC) to verify that the gas turbine engine and/or an associated aircraft can satisfy the minimum power requirements for a planned flight or operation. The EPAC may be used to estimate one or more engine operating margins for one or more engine parameters the gas turbine engine. The available engine operating margins may provide an indication of the engine operational time and/or capability which is available before the gas turbine engine should undergo maintenance (e.g., a periodic overhaul). An indicated turbine temperature (ITT) of a gas turbine engine may be used to monitor the engine health of the gas turbine engine, for example, by determining engine operating margins, verifying minimum power requirements, as well as monitoring degradation of the gas turbine engine over time. As an example, the ITT may refer to or be derived from an estimated value of a core gas temperature (e.g., T4.5) at (e.g., on, adjacent, or proximate) an outlet of a high-pressure turbine, such as the HPT 30B of
A maximum temperature of the core gas in the thermodynamic cycle of the gas turbine engine 20 may be quantified and monitored during operation of the gas turbine engine 20. The limiting operational temperature may occur, for example, at (e.g., on, adjacent, or proximate) an inlet of a high-pressure turbine, such as the HPT 30B of
The temperature T4.1 66 and the temperature T4.5 64 may generally be understood to have a relationship such that a value of the temperature T4.1 66 may be estimated using a value of the temperature T4.5 64. The relationship between the temperature T4.1 66 and the T4.5 64 may be determined, for example, during a development phase and/or testing of a gas turbine engine, such as the gas turbine engine 20. For example, the temperature T4.1 66 and the temperature T4.5 64 may be assumed to have a fixed relationship such that temperature T4.5 64 may be multiplied by a relationship constant (k4.5-4.1) to arrive at an estimated value of the temperature T4.1 66. For example, the temperature T4.5 64 may be approximately equal to k4.5-4.1T4.1, where 0<k4.5-4.1<1. Alternatively, the relationship between the temperature T4.1 66 and the T4.5 64 may be determined using one or more computer-implemented models.
The ITT for the gas turbine engine 20 may be estimated by the engine control system 22 based, at least in part, on a directly measured or estimated value of the temperature T4.5 64. The value of the ITT may be trimmed (e.g., modified) by the engine control system 22 to ensure that the related temperature T4.1 66 does not exceed an operational limit. For example, the ITT may be trimmed using the relationship constant (k4.5-4.1) so that the ITT is representative of an estimated value of the temperature T4.1 66. By using the relationship between the temperature T4.1 66 and the temperature T4.5 64, the ITT may be used to account for temperature T4.1 66 operational limitations during operation of the gas turbine engine 20. In other words, the ITT may be trimmed such that maintaining the ITT within acceptable operational limits may also maintain the temperature T4.1 66 within acceptable operational limits (e.g., below maximum operating temperature value for the temperature T4.1 66).
We have observed that the temperature T4.1 66 and the temperature T4.5 64 relationship changes as a gas turbine engine, such as the gas turbine engine 20, is deteriorated through operational use. In some cases, most or a substantial amount of the deterioration experienced by a gas turbine engine may be contributed by the high-pressure turbine. As a result, the trimmed ITT value may become increasingly over-estimated (e.g., over-conservative) as the gas turbine engine experiences increasing levels of deterioration. This is because the fixed relationship constant (k4.5-4.1), assumed for trimming the ITT, may no longer be accurate. While the over-estimated ITT value may facilitate additional safety margin for operation of the gas turbine engine, the over-estimated ITT value may also present an unnecessary limitation on the field life of the gas turbine engine, thereby potentially presenting increased maintenance requirements (e.g., engine overhaul) which can be costly and burdensome.
Referring to
Step 202 may include determining an exhaust gas temperature (EGT) of the exhaust gas in the exhaust section 32. The EGT may be determined, for example, by directly measuring the EGT temperature using the EGT sensor 62A.
Step 204 includes determining a first estimated HPT outlet temperature T4.5 value for the HPT 30B. As used herein, the term “estimated” refers to a value of a parameter (e.g., a temperature) which is not directly measured, for example, by a sensor, a probe, or the like. An estimated value may be calculated or otherwise determined using, for example, assumed values, modeled values, theoretical values, etc. An estimated value may, of course, also be determined using one or more values of directly measured parameters in combination with other non-measured values (e.g., assumed values, modeled values, theoretical values, etc.). The first estimated HPT outlet temperature T4.5 value for the HPT 30B may be determined, for example, using a computer-implemented model, such as a model of the gas turbine engine 20 executed by the engine control system 22.
Referring now to
Step 206 may include determining an estimated work ({dot over (W)}HPT) for the HPT 30B. The estimated value of the work ({dot over (W)}HPT) may be determined, for example, using the state variable model 302. Work ({dot over (W)}HPT) for the HPT 30B may be estimated, for example, by applying an energy and flow continuity balance relationship for the first rotational assembly 36 (e.g., a high-pressure spool). Equation [2] indicates an exemplary derivation of the work ({dot over (W)}HPT) for the HPT 30B using the first law of thermodynamics, including work ({dot over (W)}HPC) for the HPC 26B, work ({dot over (W)}HYD) for one or more hydraulic pumps for hydraulic systems of the gas turbine engine 20, work ({dot over (W)}IDG) for an integrated drive generator (IDG) of the gas turbine engine 20, and work ({dot over (W)}PARR) for parasitic losses associated with the first-rotational assembly 36.
{dot over (W)}
HPT
={dot over (W)}
HPC+({dot over (W)}HYD+{dot over (W)}IDG)+{dot over (W)}PARR [2]
The present disclosure, of course, is not limited to the aforementioned Equation [2] for determining the estimated work ({dot over (W)}HPT) for the HPT 30B and additional or alternative work values or other gas turbine engine 20 parameters may be used. Values of the work ({dot over (W)}HYD), work ({dot over (W)}IDG), and work ({dot over (W)}PARR) may be estimated (e.g., modeled), directly measured from the gas turbine engine 20, and/or experimentally or theoretically determined. As an alternative, for example, the work ({dot over (W)}HPT) for the HPT 30B may be estimated or otherwise determined by directly measuring one or both of the first shaft 40 rotation speed (RHP) or the first shaft 40 torque (THP) with the sensors 62F, 62G.
Step 206 may include determining an estimated value of the work ({dot over (W)}HPC) for the HPC 26B. The estimated value of the work ({dot over (W)}HPC) may be determined, for example, by the state variable model 302 using additional operational parameters of the gas turbine engine 20 such as, but not limited to, HPC inlet temperature (T2.5), HPC outlet temperature (T3.0), inlet core gas flow rate (W2.5) for the HPC 26B, pressurized air extraction flow rates for the LPC 26A and/or the HPC 26B (collectively referred to as “BLEEDS” in
{dot over (W)}
HPC
=f(W2.5,BLEEDS)CP3.0(T3.0−T2.5) [3]
Step 208 includes determining an estimated inlet temperature T4.1 value 310 for the HPT 30B. The estimated inlet temperature T4.1 value 310 may be determined using the first estimated HPT outlet temperature T4.5 value 304 and an estimated temperature decrease value 312 for the HPT 30B (e.g., a temperature decrease of the core gas from the HPT 30B inlet to the HPT 30B outlet). The estimated temperature decrease value 312 is represented in
In Step 210, the ITT for the gas turbine engine 20 is determined. Determining the ITT may include calculating a second estimated HPT outlet temperature T4.5 value 312 using the estimated inlet temperature T4.1 value 310. The second estimated HPT outlet temperature T4.5 value 312 may be different than (e.g., lower than) the first estimated HPT outlet temperature T4.5 value 304. As previously discussed, the temperature T4.1 66 and the temperature T4.5 64 may generally be understood to have a relationship such that a value of the temperature T4.1 66 may be estimated using a value of the temperature T4.5 64, for example, by applying the relationship constant (k4.5-4.1) to the temperature T4.5 64. Step 210 may include, therefore, applying the known relationship constant (k4.5-4.1) for the gas turbine engine 20 to the estimated inlet temperature T4.1 value 310 to calculate an estimated value of the second estimated HPT outlet temperature T4.5 value 312, which second estimated HPT outlet temperature T4.5 value 312 may be understood as the ITT for the gas turbine engine 20.
The Method 200 of the present disclosure uses an energy balance relationship of the first rotational assembly 36 (e.g., a high-pressure spool) to estimate the temperature T4.1 66 from the temperature T4.5 64, thereby facilitating estimation of the temperature T4.1 66 without regard to component efficiencies of the first rotational assembly 36. The determination of the ITT in the Method 200 may prevent overestimation of ITT values as a result of HPT 30B deterioration which, in turn, may facilitate longer times between gas turbine engine maintenance (e.g., engine overhauls) as well as cost saving for the particular gas turbine engine program.
Referring to
In Step 402, the engine control system 22 may obtain or otherwise determine an ITT value for the gas turbine engine, for example, using the Method 200. The ITT value may be compared to a predetermined ITT threshold value. For example, the engine control system 22 may determine if the ITT value has or has not increased above the predetermined ITT threshold value. The engine control system 22 may compare the ITT value to the predetermined ITT threshold value to identify that a high-temperature condition of the gas turbine engine 20 is present or absent. In the event that a high-temperature condition of the gas turbine engine 20 is identified to be present, the engine control system 22 may provide a warning notification (e.g., a warning light, an audible alarm, etc.) to a pilot and/or crew for an associated aircraft for the gas turbine engine 20. A determination that the ITT value has increased above the predetermined ITT threshold value may also indicate that the gas turbine engine 20 may require an engine overhaul.
In Step 404, the engine control system 22 may determine an ITT operating margin for the gas turbine engine 20, which ITT operating margin may represent an allowable operational range between the determined ITT value and a maximum ITT value for the gas turbine engine 20. The engine control system 22 may cause the ITT operating margin to be displayed. For example, the ITT operating margin may be displayed (e.g., on a computer screen, digital display, etc.) for a pilot and/or crew of an aircraft (e.g., the aircraft 1000, see
In Step 406, the ITT operating margin may be compared to a predetermined threshold operating margin value. For example, the engine control system 22 may determine if the ITT operating margin has or has not decreased below a predetermined threshold operating margin value. The engine control system 22 may compare the ITT operating margin to the predetermined operating margin value to identify that a maintenance requirement of the gas turbine engine is present or absent. If the ITT operating margin decreases below the predetermined threshold operating margin value, the engine control system 22 may flag (e.g., identify) the gas turbine engine 20 for scheduling and/or performance of maintenance. The engine control system 22 may provide a maintenance notification to a pilot, crew, and/or maintenance personnel for an associated aircraft for the gas turbine engine 20.
It is noted that various connections are set forth between elements in the preceding description and in the drawings. It is noted that these connections are general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. A coupling between two or more entities may refer to a direct connection or an indirect connection. An indirect connection may incorporate one or more intervening entities. It is further noted that various method or process steps for embodiments of the present disclosure are described in the following description and drawings. The description may present the method and/or process steps as a particular sequence. However, to the extent that the method or process does not rely on the particular order of steps set forth herein, the method or process should not be limited to the particular sequence of steps described. As one of ordinary skill in the art would appreciate, other sequences of steps may be possible. Therefore, the particular order of the steps set forth in the description should not be construed as a limitation.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element herein is to be construed under the provisions of 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises”, “comprising”, or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
While various aspects of the present disclosure have been disclosed, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the present disclosure. For example, the present disclosure as described herein includes several aspects and embodiments that include particular features. Although these particular features may be described individually, it is within the scope of the present disclosure that some or all of these features may be combined with any one of the aspects and remain within the scope of the present disclosure. References to “various embodiments,” “one embodiment,” “an embodiment,” “an example embodiment,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. Accordingly, the present disclosure is not to be restricted except in light of the attached claims and their equivalents.
