Patent Description:
In a gas turbine engine, continuous inlet air is compressed, mixed with fuel in an inflammable proportion, and exposed to an ignition source to ignite the mixture which then continues to burn to produce combustion products. The combustion of the air-fuel mixture can be used to power various mechanical components, which in turn can be used to produce thrust.

Monitoring of various temperatures within the engine during operation thereof can be of interest in assisting a control system or an operator responsible for the engine. Although existing approaches for measuring engine temperature are suitable for their purposes, improvements remain desirable.

<CIT> discloses means for calculating the turbine inlet temperature of a gas turbine engine.

According to an aspect of the present invention, there is provided a method for controlling operation of a gas turbine engine in accordance with claim <NUM>.

Optionally, and according to the above, the at least one operating condition of the gas turbine engine comprises at least one of a flight mission stage and an engine power level.

Optionally, and according to either or both of the above, the estimated vane mass flow is based on an estimated inlet mass flow for an inlet of the gas turbine engine.

Optionally, and according to any or all of the above, the method further comprises determining the combustor pressure based on a compressor pressure for a compressor of the gas turbine engine.

Optionally, and according to any or all of the above, the method further comprises adjusting the corrected vane mass flow based on an altitude of operation of the gas turbine engine.

Optionally, and according to any or all of the above, the method further comprises adjusting the corrected vane mass flow based on a compressor bleed associated with a compressor of the gas turbine engine.

Optionally, and according to any or all of the above, the estimated combustor temperature is a temperature at an inlet 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.

Optionally, and according to any or all of the above, the estimated combustor temperature is a temperature at a vane throat for the high-pressure turbine of the gas turbine engine.

Optionally, and according to any or all of the above, the engine temperature is an inter-turbine temperature, and wherein issuing the signal comprises generating the inter-turbine temperature by applying a scaling factor to the estimated combustor temperature and issuing the signal to cause the inter-turbine temperature to be displayed to an operator of the gas turbine engine.

Optionally, and according to any or all of the above, the condition associated with the mass flow correction factor comprises an evaluation of whether the mass flow correction factor is less than a threshold.

According to another aspect of the present invention, there is provided a system for determining an engine temperature for a gas turbine engine in accordance with claim <NUM>. The system comprises a processing unit, and a non-transitory computer-readable medium. The computer-readable medium has stored thereon instructions which are executable by the processing unit for: determining an estimated combustor temperature based on at least one operating condition of the gas turbine engine and an estimated vane mass flow; by determining a corrected vane mass flow based on the estimated combustor temperature, the estimated vane mass flow, and a combustor pressure; and by comparing the corrected vane mass flow to a reference vane mass flow to obtain the mass flow correction factor; when a condition associated with the mass flow correction factor is not satisfied, the estimated combustor temperature is adjusted based on the mass flow correction factor to produce an adjusted combustor temperature; and the mass flow correction factor is updated based on the adjusted combustor temperature; when the condition associated with the mass flow correction factor is satisfied, issuing a signal to assign the estimated combustor temperature as the engine temperature.

Optionally, the at least one operating condition of the gas turbine engine comprises at least one of a flight mission stage and an engine power level.

Optionally, the estimated vane mass flow is based on an estimated inlet mass flow for an inlet of the gas turbine engine.

Optionally, the instructions are further executable for determining the combustor pressure based on a compressor pressure for a compressor of the gas turbine engine.

Optionally, the instructions are further executable for adjusting the corrected vane mass flow based on an altitude of operation of the gas turbine engine.

Optionally, the instructions are further executable for adjusting the corrected vane mass flow based on a compressor bleed associated with a compressor of the gas turbine engine.

Optionally, the estimated combustor temperature is a temperature at an inlet 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.

Optionally, the estimated combustor temperature is a temperature at a vane throat for the high-pressure turbine of the gas turbine engine.

Optionally, the engine temperature is an inter-turbine temperature, and wherein issuing the signal comprises generating the inter-turbine temperature by applying a scaling factor to the estimated combustor temperature and issuing the signal to cause the inter-turbine temperature to be displayed to an operator of the gas turbine engine.

Optionally, the condition associated with the mass flow correction factor comprises an evaluation of whether the mass flow correction factor is less than a threshold.

Features of the systems, devices, and methods described herein may be used in various combinations, in accordance with the embodiments described herein.

<FIG> illustrates a gas turbine engine <NUM> of a type provided for use in subsonic flight, generally comprising in serial flow communication, a fan <NUM> through which ambient air is propelled toward an inlet <NUM>, a compressor section <NUM> for pressurizing the air, a combustor <NUM> in which the compressed air is mixed with fuel and ignited for generating an annular stream of hot combustion gases, and a turbine section <NUM> for extracting energy from the combustion gases, which exit via an exhaust <NUM>. High-pressure rotor(s) of the turbine section <NUM> (referred to as "HP turbine rotor(s) <NUM>") are drivingly engaged to high-pressure rotor(s) of the compressor section <NUM> (referred to as "HP compressor rotor(s) <NUM>") through a high-pressure shaft <NUM>. The turbine section <NUM> includes a vane <NUM> between the combustor <NUM> and the HP turbine rotor(s) <NUM>. Low-pressure rotor(s) of the turbine section <NUM> (referred to as "LP turbine rotor(s) <NUM>") are drivingly engaged to the fan rotor <NUM> and to low-pressure rotor(s) of the compressor section <NUM> (referred to as "LP compressor rotor(s) <NUM>") through a low-pressure shaft <NUM> extending within the high-pressure shaft <NUM> and rotating independently therefrom.

Although illustrated as a turbofan engine, the gas turbine engine <NUM> may alternatively be another type of engine, for example a turboshaft engine, also generally comprising in serial flow communication a compressor section, a combustor, and a turbine section, and an output shaft through which power is transferred. A turboprop engine may also apply. In addition, although the engine <NUM> is described herein for flight applications, it should be understood that other uses, such as industrial or the like, may apply.

Control of the operation of the engine <NUM> can be effected by one or more control systems, for example an engine controller <NUM>, which is communicatively coupled to the engine <NUM>. The engine controller <NUM> can modulate a fuel flow provided to the engine <NUM>, the position and orientation of variable geometry mechanisms within the engine <NUM>, a bleed level of the engine <NUM>, and the like, based on predetermined schedules or algorithms. In some embodiments, the engine controller <NUM> includes one or more FADEC(s), electronic engine controller(s) (EEC(s)), or the like, that are programmed to control the operation of the engine <NUM>. The operation of the engine <NUM> can be controlled by way of one or more actuators, mechanical linkages, hydraulic systems, and the like. The engine controller <NUM> can be coupled to the actuators, mechanical linkages, hydraulic systems, and the like, in any suitable fashion for effecting control of the engine <NUM>.

With additional reference to <FIG>, the engine <NUM> is illustrated schematically as having multiple elements forming a gas path along which gas flows from the inlet <NUM> to the exhaust <NUM> of the engine <NUM>. The engine <NUM> illustrated in <FIG> includes two spools, namely a low-pressure spool <NUM>, and a high-pressure spool <NUM>. The low-pressure spool <NUM> includes a low-pressure compressor stage <NUM><NUM>, which includes the LP compressor rotor(s) <NUM>, and a low-pressure turbine <NUM><NUM>, which includes the LP turbine rotors(s) <NUM>. In other embodiments of the engine <NUM>, the low-pressure spool <NUM> can include more than one compressor stage. The high-pressure spool <NUM> includes two high-pressure compressor stages <NUM><NUM> and <NUM><NUM> which include the HP compressor rotor(s) <NUM>, and a high-pressure turbine <NUM><NUM>, which includes the HP turbine rotor(s) <NUM>. In other embodiments of the engine <NUM>, the high-pressure spool <NUM> can include only one compressor stage, or more than two compressor stages. In the illustrated embodiment, an inter-compressor case (ICC) <NUM> is disposed between the low-pressure compressor stage <NUM>, and the high-pressure compressor stage <NUM><NUM>.

As fluids, for instance a gas mixture, pass through the engine <NUM>, they undergo numerous pressure and temperature changes. Example temperature measurement locations, T0 to T8, for the flow of the gas mixture along the gas path <NUM> are illustrated in <FIG>. T0, taken upstream of the inlet <NUM>, refers to an ambient temperature of the environment surrounding the engine <NUM>. Although illustrated here as being captured upstream of the inlet <NUM>, it should be understood that the ambient temperature T0 can be captured at any suitable location in the environment in which the engine <NUM> is operating. T1 refers to an inlet temperature, taken at the inlet <NUM> of the engine <NUM>, just as the air from the environment enters through the fan rotor <NUM>.

T2 refers to a low-pressure compressor inlet temperature, taken before the LP turbine rotor(s) <NUM> of the low-pressure compressor stage 14i. <NUM> refers to a high-pressure compressor temperature, taken between the ICC <NUM> and the high-pressure compressor stage <NUM><NUM>.

T3 refers to a high-pressure compressor delivery temperature, taken after the high-pressure compressor stages <NUM><NUM> and <NUM><NUM>, for instance after the HP compressor rotor(s) <NUM>. T4 refers to a combustor outlet temperature, taken before the HP turbine rotor(s) <NUM>, and after the combustor <NUM>. <NUM> refers to a temperature taken at or near an entry to the high-pressure turbine <NUM><NUM>. Measurements for T4. <NUM> can serve as a proxy for T4 because the exit of the combustor (where T4 is taken) and the entry to the high-pressure turbine <NUM><NUM> (where T4. <NUM> is taken) are connected to one another. <NUM> refers to a temperature taken between the high-pressure turbine <NUM><NUM> and the low-pressure turbine <NUM><NUM>.

Located at an intermediate point between the combustor <NUM> and the high-pressure turbine <NUM><NUM> is the vane <NUM>. The vane <NUM> directs the gas mixture passing through the engine <NUM> toward the high-pressure turbine <NUM><NUM>. The geometry of the vane <NUM> defines a vane throat, which is referred to hereinafter as a high-pressure turbine (HPT) vane throat <NUM>. The HPT vane throat <NUM> is a narrowing at the exit of the combustor <NUM> formed by the vane <NUM>. For the purposes of the present disclosure, temperature values, pressure values, or other values which are said to be evaluated at the combustor <NUM> may be evaluated at an outlet of the combustor <NUM>, at the HPT vane throat <NUM>, or at any other suitable location at or proximate to the combustor <NUM>.

T5 refers to the turbine outlet temperature, taken after the LP turbine rotor(s) <NUM> of the low-pressure turbine <NUM><NUM>. T6 refers to an exhaust gas temperature, taken between the low-pressure turbine <NUM><NUM> and the exhaust <NUM>. T8 refers to an exhaust gas temperature, taken at the outlet of the exhaust <NUM>.

It should be noted that the above description of <FIG> pertains to an embodiment of the engine <NUM> which includes multiple spools, namely the low- and high-pressure spools <NUM>, <NUM>. The present disclosure may be applied to other types of engines, including engines with only one spool, or with more than two spools, as appropriate. Additionally, it should be understood that the foregoing disclosure relating to temperatures measurable within the engine <NUM> is not exhaustive, and various physical and/or virtual sensors may be deployed within the engine <NUM> to assess other temperature values for other locations within the engine <NUM>.

A maximum temperature in the thermodynamic cycle of the engine is quantified and monitored during operation. The maximum temperature usually occurs at location T4 or at location T4. <NUM>, which may be difficult to measure in at least some engines due to possible instrumentation and material temperature limitations. One approach to overcoming such difficulties is deriving the temperature at location T4 based on a temperature measured downstream from location T4, where the temperature is cooler, and where instrumentation and material temperature limitations are lowered. One example includes measuring the temperature at location T4. <NUM> is sometimes referred to as an inter-turbine or indicated turbine temperature (ITT) and in this embodiment is taken between the HP turbine rotor(s) <NUM> and LP turbine rotor(s) <NUM>. A relationship between the temperatures at locations T4 to T4. <NUM>, used for deriving the temperature at location T4, can be determined during the development phase of the engine <NUM>. The relationship can be provided to the engine controller <NUM> to derive the T4 temperature as may be required for operation of the engine <NUM>. The present disclosure provides additional approaches for obtaining the ITT (the temperature at location T4. <NUM>), and other relevant temperatures within the engine <NUM>, including T4 and/or T4.

With reference to <FIG>, there is illustrated a flowchart for a method <NUM> for determining an engine temperature of a gas turbine engine, for instance of the engine <NUM>. The engine temperature determined via the method <NUM> can be the temperature at location T4, at location T4. <NUM>, or at any other location near or within the combustor <NUM>. For simplicity, the description of the embodiment illustrated in <FIG> will refer to the temperature at location T4. The engine temperature at location T4 obtained via the method <NUM> can be used to produce the aforementioned ITT. For example, a scaling factor can be applied to the engine temperature at location T4 to obtain the ITT. Other modifications of the engine temperature at location T4 are also considered.

In the illustrated embodiment, the method <NUM> uses the equation <MAT> where P<NUM> is a combustor pressure of the combustor <NUM> (absolute pressure at the HPT vane throat <NUM>); T<NUM> is a combustor temperature of the combustor <NUM> (absolute temperature at the HPT vane throat <NUM>, at location T4. <NUM>, or at any other suitable location); W<NUM> is a vane mass flow (a measure of mass flow of gases at the HPT vane throat <NUM>); and Q<NUM> is a corrected vane mass flow (a corrected measure of the mass of gases at the HPT vane throat <NUM>, sometimes referred to as a turbine flow capacity). Equation <NUM> is associated with a particular state of operation of the engine <NUM>, referred to as a choked state. The engine <NUM>, as illustrated in <FIG>, is said to be operated in a choked state when the corrected vane mass flow Q<NUM> reaches a maximum value, which is dependent on the geometry of the vane <NUM>.

In the illustrated embodiment, Equation <NUM> is evaluated until a particular condition is met, for example at one or more time intervals, or until a number of evaluations are performed. Once the condition is met, the value of T<NUM> may be assigned as the engine temperature at location T4, may be used to produce the ITT (temperature at location T4. <NUM>), and may be used to derive other engine temperatures, as appropriate. In some cases, the method <NUM> is repeated at particular intervals, selected to suit each particular application of the method <NUM>.

At step <NUM>, the method <NUM> includes determining a mass flow correction factor, CorrQ4. The mass flow correction factor CorrQ4 is the difference between two values of the corrected vane mass flow Q<NUM>, obtained via two separate approaches. A first one of the values of the corrected vane mass flow Q<NUM>, called Q4est, is obtained using Equation <NUM> with estimated values for W<NUM>, T<NUM>, and P<NUM>. The second value of the corrected vane mass flow Q<NUM>, called Q4target, is based on the physical characteristics of the engine <NUM> when operated in a choked state: Q4target is the maximum corrected mass flow which can pass through the HPT vane throat <NUM>.

At decision step <NUM>, the method <NUM> includes determining whether the mass flow correction factor CorrQ4 satisfies a mass flow correction condition. In some embodiments, the mass flow correction condition is satisfied when the corrected vane mass flow Q4est and the reference vane mass flow Q4target sufficiently match, for instance such that the mass flow correction factor CorrQ4 is below a particular threshold, or that the mass flow correction factor CorrQ4 is within a particular range. In one example, the mass flow correction condition is satisfied when the corrected vane mass flow Q4est and the reference vane mass flow Q4target are within <NUM>% of one another. In some other embodiments, the mass flow correction condition is satisfied when the mass flow correction factor CorrQ4 has been determined a particular number of times. When the mass flow correction factor CorrQ4 does not satisfy the mass flow correction condition, the method <NUM> moves to step <NUM>. When the mass flow correction factor CorrQ4 satisfies the mass flow correction condition, the method <NUM> moves to step <NUM>.

At step <NUM>, when the mass flow correction factor CorrQ4 does not satisfy the mass flow correction condition, the method <NUM> includes adjusting the estimated combustor temperature T4est based on the mass flow correction factor CorrQ4 to produce an adjusted combustor temperature T4adj. Since the mass flow correction factor CorrQ4 is an indicator of the mismatch between the corrected vane mass flow Q4est and the reference vane mass flowQ4target, it is also indicative of whether or not the estimated combustor temperature T4est is a suitable estimate of the engine temperature at location T4. As a result, the estimated combustor temperature T4est can be adjusted-or, put differently, re-estimated-based on the mass flow correction factor CorrQ4 to generate the adjusted combustor temperature T4adj.

In some embodiments, adjusting the estimated combustor temperature T4est includes adjusting the estimated vane mass flow W4est and re-estimating the estimated combustor temperature T4est. In some embodiments, adjusting the estimated vane mass flow W4est includes adjusting an estimate of the inlet mass flow W<NUM>, which can be referred to as an estimated inlet mass flow W1est. In some further embodiments, the estimated combustor temperature T4est is additionally adjusted in other fashions, for instance by re-evaluating the operating conditions of the engine <NUM>, or the like.

At step <NUM>, the method <NUM> includes updating the mass flow correction factor CorrQ4 based on the adjusted combustor temperature T4adj. The mass flow correction factor CorrQ4 can be updated by re-determining the first corrected vane mass flow Q4est using one or more adjusted values for W<NUM>, T<NUM>, and P<NUM> and re-computing Equation <NUM>. Step <NUM> can then be performed anew using the new mass flow correction factor CorrQ4, as illustrated in <FIG>.

As described hereinabove, until the mass flow correction factor CorrQ4 satisfies the mass flow correction condition, the method <NUM> will continue looping through steps <NUM>, <NUM>, and <NUM>. Once the mass flow correction factor CorrQ4 satisfies the mass flow correction condition, the method <NUM> moves from decision step <NUM> to step <NUM>.

At step <NUM>, the method <NUM> includes issuing a signal to assign the estimated combustor temperature T4est as the engine temperature at location T4. The signal can be issued, for instance, via a controller associated with the engine <NUM>. In some embodiments, the most recent estimated combustor temperature T4est is assigned as the engine temperature at location T4. In some other embodiments, the temperature assigned as the engine temperature at location T4 is a combination of one or more estimated combustor temperatures T4est, for instance an average of the most recent estimated combustor temperature T4est and one or more preceding estimated combustor temperature T4est. Other statistical approaches can also be applied as part of assigning the engine temperature at location T4, including rolling averages.

In some embodiments, assigning the estimated combustor temperature T4est as the engine temperature at location T4 includes assigning the estimated combustor temperature T4est as the ITT. The ITT can be provided to an operator of the engine <NUM>, or of a larger system of which the engine <NUM> is a component. In some embodiments, the ITT is a modified version of the estimated combustor temperature T4est. For instance, the estimated combustor temperature T4est is scaled by a particular factor, or has a particular constant added thereto or subtracted therefrom, in order to produce the ITT. Other approaches are also considered. The ITT can be displayed to the operator via a gauge, a screen or other display, or via any other suitable type of instrument.

With additional reference to <FIG>, the mass flow correction factor CorrQ4 determined at step <NUM> is based on comparing the two values of the corrected vane mass flow Q<NUM>. In the embodiment illustrated in <FIG>, step <NUM> includes steps <NUM>, <NUM>, and <NUM>.

Step <NUM> includes step <NUM> of determining an estimated combustor temperature T4est, based on at least one operating condition of the engine <NUM>, and based on an estimated vane mass flow W4est. The operating condition of the engine <NUM> can include one or more of a power level of the engine <NUM>, a mode of operation of the engine <NUM>, for instance a flight stage of an aircraft of which the engine <NUM> is a component, a temperature measured elsewhere within the engine <NUM>, or the like. Other operating conditions can also be used to determine the estimated combustor temperature T4est. For example, the estimated combustor temperature T4est is based on one or more of an engine inlet temperature T1, an exhaust gas temperature T6, an output torque, a power turbine speed, an ambient pressure (taken at location T1 in <FIG>), and one or more of intermediate or exit compressor temperatures or pressures. Intermediate compressor temperatures and pressures can be taken at location T2. <NUM> in <FIG> (or at any other location between locations T2 and T3). Exit compressor temperatures and pressures can be taken at location T3 in <FIG>.

The estimated vane mass flow W4est can be obtained based on the mass flow of another portion of the engine, for instance an inlet mass flow W<NUM>. The inlet mass flow W<NUM> can be measured, estimated, or otherwise derived in any suitable fashion. For instance, a relationship between W<NUM> and W4est is known, and W<NUM> is derived, estimated, or instantiated (i.e. whereby an instance for W<NUM> is created) as a particular value, which is based on other operating conditions within the engine <NUM>.

Step <NUM> includes step <NUM> of determining a corrected vane mass flow Q4est based on the estimated combustor temperature T4est, the estimated vane mass flow W4est, and the combustor pressure P<NUM>. The corrected vane mass flow Q4est can be determined using Equation <NUM> described hereinabove, which becomes <MAT> using the parameters obtained during previous steps.

Step <NUM> includes step <NUM> of comparing the corrected vane mass flow Q4est to a reference vane mass flow, referred to as Q4target, to obtain a mass flow correction factor CorrQ4, as per step <NUM>. In the illustrated embodiment, the reference vane mass flow Q4target is established based on the physical characteristics of the vanes <NUM> of the engine <NUM>. Because the engine <NUM> is operated in a choked state, the corrected mass flow at the HPT vane throat <NUM> is expected to be equivalent to the maximum corrected mass flow which can pass through the HPT vane throat <NUM>. Thus, the reference vane mass flow Q4target is set to the maximum corrected mass flow, which can be established during the manufacturing process of the engine <NUM>, as part of a testing or calibration procedure, or the like.

In one example, the mass flow correction factor CorrQ4 is obtained by taking the difference between the corrected vane mass flow Q4est and the reference vane mass flow Q4target, such that CorrQ4 = Q4est - Q4target. In another example, the mass flow correction factor CorrQ4 is obtained based on a ratio of the corrected vane mass flow Q4est and the reference vane mass flow Q4target, such that CorrQ4 = Q4est/Q4target. Other approaches for determining the mass flow correction factor CorrQ4 are also considered.

With reference to <FIG>, an alternative step <NUM> for determining the mass flow correction factor CorrQ4 is illustrated as step <NUM>'. The step <NUM>' includes step <NUM> of determining an estimated combustor temperature T4est, based on at least one operating condition of the engine <NUM>, and based on an estimated vane mass flow W4est. Step <NUM> illustrated in <FIG> is substantively similar to step <NUM> of <FIG>.

The step <NUM>' includes step <NUM> of determining a combustor pressure P<NUM> based on a compressor pressure P<NUM>. In the illustrated embodiment, the compressor pressure P<NUM> is the pressure at the outlet to the high-pressure compressor stages <NUM>. It should be noted, however, that the compressor pressure P<NUM> can be based on another pressure value elsewhere within the engine <NUM>, depending on the structure of the engine <NUM>. The relationship between the combustor pressure P<NUM> and the compressor pressure P<NUM> can be established based on one or more thermodynamic principles, or from schedules or other established relationships.

The step <NUM>' includes step <NUM> of determining a corrected vane mass flow Q4est based on the estimated combustor temperature T4est, the estimated vane mass flow W4est, and the combustor pressure P<NUM>. Step <NUM> illustrated in <FIG> is substantively similar to step <NUM> of <FIG>.

The step <NUM>' includes step <NUM> of adjusting the corrected vane mass flow Q4est based on one or more factors. For example, the corrected vane mass flow Q4est is adjusted based on an altitude of operation of the engine <NUM>, for instance in cases in which the engine <NUM> is operated as part of an aircraft. In another example, the corrected vane mass flow Q4est is adjusted based on a compressor bleed associated with one or more of the compressors of the engine <NUM>, including the two high-pressure compressor stages <NUM><NUM> and <NUM><NUM> and/or the low-pressure compressor stage 14i. Other approaches for adjusting the corrected vane mass flow Q4est are also considered.

The step <NUM>' includes step <NUM> of comparing the corrected vane mass flow Q4est to a reference vane mass flow, referred to as Q4target, to obtain a mass flow correction factor CorrQ4, as per step <NUM>. Step <NUM> illustrated in <FIG> is substantively similar to step <NUM> of <FIG>.

With reference to <FIG>, there is illustrated an embodiment of a computing device <NUM> for implementing part or all of the method <NUM> described above. The computing device <NUM> can be used to perform part or all of the functions of the engine controller <NUM> of the engine <NUM>. In some embodiments, the engine controller <NUM> is composed only of the computing device <NUM>. In some embodiments, the computing device <NUM> is within the engine controller <NUM> and cooperates with other hardware and/or software components within the engine controller <NUM>. In both cases, the engine controller <NUM> performs the method <NUM>. In some embodiments, the computing device <NUM> is external to the engine controller <NUM> and interacts with the engine controller <NUM>. In some embodiments, some hardware and/or software components are shared between the engine controller <NUM> and the computing device <NUM>, without the computing device <NUM> being integral to the engine controller <NUM>. In this case, the engine controller <NUM> can perform part of the method <NUM>.

The processing unit <NUM> may comprise any suitable devices configured to cause a series of steps to be performed such that instructions <NUM>, when executed by the computing device <NUM> or other programmable apparatus, may cause the functions/acts/steps specified in the method <NUM> described herein to be executed. The processing unit <NUM> may comprise, for example, any type of general-purpose microprocessor or microcontroller, a digital signal processing (DSP) processor, a CPU, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, other suitably programmed or programmable logic circuits, or any combination thereof.

The memory <NUM> may include a suitable combination of any type of computer memory that is located either internally or externally to device, for example random-access memory (RAM), read-only memory (ROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM) or the like.

It should be noted that the computing device <NUM> may be implemented as part of a FADEC or other similar device, including an electronic engine control (EEC), engine control unit (EUC), engine electronic control system (EECS), an Aircraft Avionics System, and the like. In addition, it should be noted that the techniques described herein can be performed by a computing device <NUM> substantially in real-time.

With reference to <FIG>, there is illustrated an example system <NUM> for determining an engine temperature of a gas turbine engine, for instance the engine temperature at location T4 of the engine <NUM>. The system <NUM> is, for example, an example implementation of part or all of the computing device <NUM>. The system <NUM> includes a combustor temperature estimator <NUM>, a vane mass flow estimator <NUM>, a combustor pressure determiner <NUM>, a vane mass flow corrector <NUM>, a vane mass flow comparator <NUM>, as well as an input providing operating conditions <NUM>, an input providing a compressor pressure <NUM>, and an input providing a reference vane mass flow <NUM>.

The combustor temperature estimator <NUM> receives one or more operating conditions <NUM> of the engine <NUM> as an input. The combustor temperature estimator <NUM> also receives a vane mass flow W<NUM> from the vane mass flow estimator <NUM>, and a mass flow correction factor CorrQ4 from the vane mass flow comparator <NUM>. When no mass flow correction factor CorrQ4 is available, the combustor temperature estimator <NUM> can receive an initial value for the mass flow correction factor CorrQ4, which can be any suitable value, or obtains no input from the vane mass flow comparator <NUM>. The combustor temperature estimator <NUM> produces an estimated combustor temperature T4est. The combustor temperature estimator <NUM> also adjusts the estimated combustor temperature T4est.

The vane mass flow estimator <NUM> produces an estimated vane mass flow W4est, which is provided to the combustor temperature estimator <NUM> and to the vane mass flow corrector <NUM>. The estimated vane mass flow W4est produced by the vane mass flow estimator <NUM> can be determined based on a variety of inputs, or using one or more starting values of the estimated vane mass flow W4est. The vane mass flow estimator <NUM> can also receive the mass flow correction factor CorrQ4 from the vane mass flow comparator <NUM>, when available. The vane mass flow estimator <NUM> additionally adjusts the estimated vane mass flow W4est based on the mass flow correction factor CorrQ4.

The combustor pressure determiner <NUM> receives a measure of the compressor pressure <NUM>, denoted as P<NUM>, via an input. The combustor pressure determiner <NUM> determines the combustor pressure P<NUM> using the compressor pressure <NUM> (P<NUM>).

The vane mass flow corrector <NUM> receives the estimated combustor temperature T4est from the combustor temperature estimator <NUM>, the estimated vane mass flow W4est from the vane mass flow estimator <NUM>, and the combustor pressure P<NUM> from the combustor pressure determiner <NUM>. The vane mass flow corrector <NUM> uses the estimated combustor temperature T4est, the estimated vane mass flow W4est, and the combustor pressure P<NUM> to determine a corrected vane mass flow Q4est. For example, the vane mass flow corrector <NUM> can apply Equation <NUM> discussed hereinabove. In some embodiments, the vane mass flow corrector <NUM> can also adjust the corrected vane mass flow Q4est based on one or more factors, including an altitude of operation of the engine <NUM>, a compressor bleed of the engine <NUM>, and the like.

The vane mass flow corrector <NUM> provides the corrected vane mass flow Q4est to the vane mass flow comparator <NUM>, which also receives the reference vane mass flow <NUM>, denoted as Q4target, via an input <NUM>. The vane mass flow comparator <NUM> compares the corrected vane mass flow Q4est to the reference vane mass flow <NUM> (Q4target) to obtain a mass flow correction factor CorrQ4.

When the mass flow correction factor CorrQ4 satisfies the associated mass flow correction condition, the vane mass flow comparator <NUM> outputs the mass flow correction factor <NUM>, denoted as CorrQ4, for instance by issuing a signal. When the mass flow correction factor <NUM> (CorrQ4) does not satisfy the associated condition, the vane mass flow comparator <NUM> can provide the mass flow correction factor <NUM> (CorrQ4) to the combustor temperature estimator <NUM>, so that the combustor temperature estimator <NUM> can adjust the estimated combustor temperature T4est. The system <NUM> can then update the mass flow correction factor <NUM> (CorrQ4) based on the adjusted combustor temperature.

With reference to <FIG>, there is illustrated an alternative system <NUM> for determining an engine temperature of a gas turbine engine, for instance the engine temperature at location T4 of the engine <NUM>. The system <NUM> includes a plurality of interconnected blocks, which each perform a function. The particular implementation of each of the blocks in the system <NUM> can employ one or more thermodynamic relationships which can be known, derivable via experiments, or the like.

Block <NUM> receives an inlet mass flow W<NUM> and produces an exhaust mass flow W<NUM>, which is provided to block <NUM>. Block <NUM> receives a power turbine speed NP and an engine output torque TQ of the engine from inputs, and produces an engine output power SHP. Block <NUM> receives the inlet mass flow W<NUM>, as well as an inlet temperature T<NUM>, and a high-pressure compressor temperature T<NUM> from inputs, and produces a low-pressure spool output power LPCSHP. The engine output power SHP and the low-pressure spool output power LPCSHP are added via adder <NUM> and provided to block <NUM>. Block <NUM> receives the output of adder <NUM>, the exhaust mass flow W<NUM> from block <NUM>, and an exhaust temperature T<NUM> from an input, and produces an inner-turbine temperature T<NUM>, which is provided to block <NUM>.

Block <NUM> receives the inlet mass flow W<NUM> and produces a vane mass flow W<NUM>, which is provided to blocks <NUM> and <NUM>. Block <NUM> receives the inlet mass flow W<NUM> and produces a compressor mass flow W<NUM>, which is provided to block <NUM>. Block <NUM> receives the high-pressure compressor temperature T<NUM> from block <NUM>, the compressor mass flow W<NUM> from block <NUM>, and a compressor temperature T<NUM> from an input, and produces a high-pressure compressor load HPCLOAD, which is provided to block <NUM>. It should be noted that the compressor temperature T<NUM> provided to block <NUM> can be a measured value or a synthesized value, depending on the implementation of the system <NUM> and of the engine <NUM>. Block <NUM> receives the inner-turbine temperature T<NUM> from block <NUM>, the high-pressure compressor load HPCLOAD from block <NUM>, and the vane mass flow W<NUM> from block <NUM>, and produces a combustor temperature T<NUM> (for instance, T4est).

The combustor temperature T<NUM> is provided to block <NUM>, to block <NUM>, or to an output <NUM>. For example, if the combustor temperature T<NUM> as produced by block <NUM> is found to produce a value of the corrected vane mass flow which sufficiently matches the reference vane mass flow (i.e., the mass flow correction factor CorrQ4 satisfies the mass flow correction condition), then the combustor temperature T<NUM> as produced by block <NUM> can be output at <NUM>.

Block <NUM> includes sub-blocks <NUM>, <NUM>, <NUM>, and <NUM>, and serves to implement Equation <NUM>. Sub-block <NUM> produces a square-root of the combustor temperature T<NUM>. Sub-block <NUM> multiplies the square root of the combustor temperature T<NUM> by the vane mass flow W<NUM>. Sub-block <NUM> receives the compressor pressure P<NUM> and produces the combustor pressure P<NUM>. Sub-block <NUM> receives the product of sub-block <NUM> and the combustor pressure P<NUM> from sub-block <NUM> and performs a division operation, which produces the corrected vane mass flow Q<NUM>.

Block <NUM> produces the reference vane mass flow Q4target, which is provided to block <NUM>. Block <NUM> compares the reference vane mass flow Q4target from block <NUM> to the corrected vane mass flow Q<NUM> from block <NUM>, and produces a mass flow correction factor CorrQ4. The mass flow correction factor CorrQ4 can then be used to adjust the inlet mass flow W<NUM>, which is provided from block <NUM> to blocks <NUM>, <NUM>, <NUM>, and <NUM> after being fed through a delay block <NUM>.

When the mass flow correction factor CorrQ4 is found to satisfy the associated condition, the combustor temperature T<NUM> produced by block <NUM> can be output at <NUM>. Additional operations can be performed to the output <NUM>, including scaling or other modifications, for instance to produce the aforementioned ITT.

The methods and systems described herein may be implemented in a high level procedural or object oriented programming or scripting language, or a combination thereof, to communicate with or assist in the operation of a computer system, for example the computing device <NUM>. Alternatively, the methods and systems described herein may be implemented in assembly or machine language. The language may be a compiled or interpreted language. Program code for implementing the methods and systems for monitoring a temperature of a gas turbine engine may be stored on a storage media or a device, for example a ROM, a magnetic disk, an optical disc, a flash drive, or any other suitable storage media or device. The program code may be readable by a general or special-purpose programmable computer for configuring and operating the computer when the storage media or device is read by the computer to perform the procedures described herein. Embodiments of the methods and systems described herein may also be considered to be implemented by way of a non-transitory computer-readable storage medium having a computer program stored thereon. The computer program may comprise computer-readable instructions which cause a computer, or more specifically the processing unit <NUM> of the computing device <NUM>, to operate in a specific and predefined manner to perform the functions described herein.

Claim 1:
A method for controlling operation of a gas turbine engine (<NUM>), comprising:
determining an engine temperature comprising:
determining an estimated combustor temperature (T4est) for a combustor (<NUM>) of the gas turbine engine (<NUM>) based on at least one operating condition of the gas turbine engine (<NUM>) and an estimated vane mass flow (W4est) for the gas turbine engine (<NUM>);
determining a corrected vane mass flow (Q4est) for the gas turbine engine (<NUM>) based on the estimated combustor temperature (T4est), the estimated vane mass flow (W4est), and a combustor pressure (P<NUM>) for the combustor (<NUM>) of the gas turbine engine (<NUM>);
comparing the corrected vane mass flow (Q4est) to a reference vane mass flow (Q4target) to obtain a mass flow correction factor (CorrQ4);
when a condition associated with the mass flow correction factor (CorrQ4) is not satisfied:
adjusting the estimated combustor temperature (T4est) based on the mass flow correction factor (CorrQ4) to produce an adjusted combustor temperature (T4adj); and
updating the mass flow correction factor (CorrQ4) based on the adjusted combustor temperature (T4adj); and
when the condition associated with the mass flow correction factor (CorrQ4) is satisfied, issuing, via a controller (<NUM>) associated with the gas turbine engine (<NUM>), a signal to assign the estimated combustor temperature (T4est) as the engine temperature; and
using the controller (<NUM>) to control operation of the engine (<NUM>) based on the determined engine temperature.