GAS FUEL FLOW MEASUREMENT COMPENSATION AND IMPROVED TURBOMACHINE REGULATION

Abstract

A compensation method for drag error in a flow meter measurement (QFlow Meter) of a gaseous fuel in a turbomachine line is proposed. The flow meter has a transfer function (H(p)). A flow measurement (Qm) derived from a pressure ratio across the metering device is obtained by measuring the pressures upstream and downstream of the metering device and then applying the Saint-Venant law to these pressures. A dynamic error (ΔQm) in the flow meter measurement is calculated using the transfer function and this flow measurement (Qm) derived from the pressure ratio. The dynamic error is then added to the flow meter measurement to obtain a corrected measurement (QCorrectedFlow Meter). Figure for the abstract: [Fig 3]

Description

Title of the invention: COMPENSATION FOR MEASURING GASY FUEL FLOW AND IMPROVED TURBOMACHINE REGULATION technical field

[0001] The present invention relates to the field of aircraft turbomachinery, and more particularly to the regulation of the gas supply to the combustion chamber of an aircraft turbomachine, as well as to an aircraft turbomachine operating with gaseous fuel and equipped with a fuel system offering such supply regulation. Previous techniques

[0002] Climate change is a major concern for many legislative and regulatory bodies worldwide. Indeed, various restrictions on carbon emissions have been, are being, or will be adopted by various states. In particular, an ambitious standard applies to both new types of aircraft and those currently in operation, requiring the implementation of technological solutions to bring them into compliance with current regulations. Civil aviation has been actively contributing to the fight against climate change for several years now.

[0003] Technological research efforts have already led to very significant improvements in the environmental performance of aircraft. The Applicant takes into account the factors impacting all phases of design and development in order to obtain aeronautical components and products that are less energy-intensive, more environmentally friendly, and whose integration and use in civil aviation have moderate environmental impacts, with the aim of improving the energy efficiency of aircraft. Consequently, the Applicant is constantly working to reduce its climate impact by employing methods and operating virtuous development and manufacturing processes that minimize greenhouse gas emissions to the minimum possible in order to reduce the environmental footprint of its activity.

[0004] This sustained research and development work focuses on new generations of aircraft engines, the weight reduction of aircraft, particularly through the materials used and lighter on-board equipment, the development of the use of electrical technologies to provide propulsion, and finally aviation fuels.

[0005] In this context, the use of a cryogenic fuel to power the combustion chamber of an aircraft turbomachine is known. Such a cryogenic fuel is, for example, liquid natural gas (known by the acronym "LNG") or liquid hydrogen (known by the designation "LH2").

[0006] While cryogenic fuels are less expensive than conventional kerosene, their main advantage is that they significantly reduce CO2 emissions. On the one hand, LNG emits 25% less CO2 per unit of energy. On the other hand, LH2 emits no CO2.

[0007] Aeronautical propulsion by hydrogen combustion is therefore a major challenge in the decarbonisation of the aviation sector.

[0008] Cryogenic fuel is stored in liquid form, generally at low pressure (2-3 bars) and low temperature (113K or -160°C for LNG, 20K or -253°C for LH2), to limit its volume to be transported.

[0009] However, it is injected into the combustion chamber in a gaseous state.

[0010] The so-called "fuel" system is the set of components from the tank to storage which allows the distribution and metering of fuel in the combustion chamber, in order to meet a given engine performance requirement.

[0011] Figure 1 schematically illustrates such a fuel system 100. This includes a tank 110 for storing cryogenic fuel in liquid form, connected to injectors 117 placed in the combustion chamber, by a supply line or conduit 120. Mounted on the conduit 120 from the tank 110 are a pressurization device 111 maintaining an injection pressure, a heating device 112 raising the cryogenic fuel to temperature to allow its evaporation into gaseous fuel, a gaseous fuel accumulator 113 acting as a buffer and an injection system 114 controlling the injection of the gaseous fuel from the accumulator 113 into the combustion chamber.

[0012] The injection system 114 includes a metering device 115 metering the mass flow of gaseous fuel at the inlet of the combustion chamber, an optional shut-off valve 116 and the injector(s) 117.

[0013] These different organs are controlled according to measurements taken through sensors, such as a temperature sensor 130 upstream of the dosing organ 115, a pressure sensor 131 also upstream of the dosing organ 115 and a flow sensor 132 as close as possible to the injectors 117.

[0014] The thrust control of a turbojet engine is carried out through the metering unit 115, coupled to the flow sensor 132 - typically a Coriolis flow meter - to allow the metering unit 115 to supply the desired quantity of gaseous fuel to the injectors 117 corresponding to a thrust command.

[0015] More generally, the regulation of a turbomachine requires measuring the fuel flow accurately and quickly in order to comply with various engine constraints, including the pumping protection constraints of the high-pressure compressor.

[0016] However, flow measurement sensors or probes, such as the Coriolis flow meter, exhibit inertia and latency in the delivery of measurements, particularly during flow transients. These induce a measurement lag effect, which is detrimental to the proper control of the turbomachine, and even to its integrity, by disrupting the fuel metering regulation.

[0017] There is therefore a need to improve the regulation of gaseous fuel flow in fuel systems, and in particular to improve the accuracy of the measurement of the flow rate (mass or volume) of a gaseous fuel in a turbomachine pipeline. Description of the invention

[0018] The invention aims to overcome at least some of the aforementioned drawbacks and to offer an improved fuel system, and in particular a more responsive fuel system capable of more precisely regulating the amount of gaseous fuel injected into the combustion chamber.

[0019] Such a fuel system would be more durable over time. It would therefore promote the development of environmentally friendly turbomachinery powered by cryogenic fuel.

[0020] To this end, the invention relates firstly to a method for measuring the flow rate of a regulated gaseous fuel in a turbomachine pipeline by a metering device, the method comprising the following steps: obtaining, from a flow meter, a flow rate measurement in the pipeline, the flow meter having a transfer function, determining a dynamic measurement error of the flow meter using the transfer function and a flow rate measurement derived from a ratio of pressures across the terminals of the metering device, and Add the determined dynamic error to the flow meter measurement to obtain a corrected measurement of gaseous fuel flow in the turbomachine line.

[0021] Indeed, the flow measurement derived from the pressure ratio provides good representation of the relative differences (i.e., variations) in flow rates during flow transients, that is, in dynamic regimes, because the pressures are easily recovered instantaneously. The dynamic error, representative of the drag of the measurements by the flowmeter, can thus be calculated in real time based on the modeling of this drag, through the flowmeter's transfer function.

[0022] This error is then added to the value of the flowmeter measurement, allowing the flowmeter drag to be compensated for.

[0023] The method thus proposes a hybridization of a reliable measurement in static (or stationary) regime, namely the measurement of the flowmeter, with a reliable measurement in dynamic (or transient) regime, namely the measurement from the pressure ratio, in order to correct in real time the dynamic error of the reliable measurement in static regime.

[0024] This method is particularly suited to an aeronautical environment insofar as Coriolis effect type flow meters are already qualified for such an environment, as are easily integrable pressure sensors.

[0025] The invention also relates to a method of regulating the flow of a gaseous fuel in a turbomachine, comprising the following steps: defining a flow control setpoint at the inlet of a gaseous fuel metering device, measuring in real time a gaseous fuel flow in a turbomachine pipe, in order to control the metering device, a method in which the measurement of the gaseous fuel flow conforms to the aforementioned measurement method.

[0026] The invention also relates to a system for measuring the flow rate of a regulated gaseous fuel in a turbomachine pipeline by a metering device, comprising: a flow meter configured to obtain a flow measurement in the pipeline, the flow meter having a transfer function, and a controller configured for: - determine a dynamic measurement error of the flow meter using the transfer function and a flow measurement derived from a ratio of pressures across the metering device, and - add the determined dynamic error to the flow measurement from the flow meter in order to obtain a corrected measurement of gaseous fuel flow in the turbomachine line.

[0027] A system for regulating the flow of a gaseous fuel in a turbomachine can, therefore, use such a measurement system to facilitate the control of the metering device.

[0028] Optional features of embodiments are defined in the appended claims. Some of these features are explained below with reference to a method, while they can be transposed into system features.

[0029] In one embodiment, determining the dynamic error includes: obtaining the flow measurement from the ratio of pressures across the metering device, applying the transfer function of the flowmeter to the measurement obtained to obtain a filtered measurement, and calculating the difference between the flow measurement obtained and the filtered measurement, said difference corresponding to the dynamic error.

[0030] The drag compensation principle proposed here is based on estimating the drag by filtering the flow measurement obtained from the pressure ratio with the flow meter's transfer function. By calculating the difference between this measurement and its equivalent filtered by the transfer function, the drag of the flow measurement by the flow meter is deduced in real time.

[0031] In one embodiment, obtaining the flow measurement from the ratio of pressures across the metering device includes: obtaining a pressure upstream of the metering device and a pressure downstream of the metering device, and applying the Saint Venant Barré relation to the upstream and downstream pressures to obtain a flow rate.

[0032] In one embodiment, the transfer function is of the form low-pass filter with pure delay.

[0033] In one embodiment, the transfer function is of the form p ) - eTrP~[^ ■> with Tr a pure delay, and r a time constant. Brief description of the drawings

[0034] The invention will be better understood upon a detailed study of two embodiments taken by way of non-limiting examples and illustrated by the accompanying drawings, in which:

[0035] [Fig.1] represents a known fuel system;

[0036] [Fig.2] represents an example of the realization of a structure of a turbomachine, here a double-flow, double-body turbomachine;

[0037] [Fig.3] schematically illustrates a method for measuring the flow rate of a regulated gaseous fuel in a turbomachine pipeline according to embodiments;

[0038] [Fig.4] represents a detailed realization of an injection system for implementing the process, according to embodiments;

[0039] [Fig.5] illustrates a numerical realization of the transfer function H{p) = ; and

[0040] [Fig.6] illustrates, through flow curves, the benefits of the proposed measurement method.

[0041] For the sake of clarity, the same elements are designated by the same reference numerals in the different figures. Furthermore, the various figures are not drawn to scale, as is customary in schematic representations. Detailed description

[0042] With reference to [Fig. 1], the tank 110 can be any type of tank for cryogenic fuel in liquid form, such as liquid natural gas (known by the acronym "LNG") or liquid hydrogen (known by the acronym "LH2"). Cryogenic fuel is typically stored at low pressure (2-3 bar) and low temperature (113K or -160°C for LNG, 20K or -253°C for LH2).

[0043] The pressurization device 111 allows the cryogenic fuel in liquid form to be pressurized in the supply line 120 so as to maintain an injection pressure higher than that of the turbomachine's combustion chamber. In particular, at a given injection flow rate, the difference between the pressure at the outlet of the pressurization device 111 and the pressure in the combustion chamber is maintained greater than the sum of the pressure losses of the various equipment or components along the supply line 120 of the fuel system 100 up to the injectors 117.

[0044] By way of illustration only, the pressurization unit 111 can be one or more high-pressure pumps, for example centrifugal pumps in series, controlled by a controller (not shown in the figure, 'CTRL' in [Fig.4]), such as the electronic control unit or ECU (for "Engine Control Unit").

[0045] The pressure in the injection chamber for aeronautical applications can be several tens of bars for a maximum takeoff regime, typically between 30 and 50 bars for dihydrogen and a few bars for LPG.

[0046] The heating element 112 raises the cryogenic fuel to a temperature that allows its evaporation into gaseous fuel, in particular within a range of temperatures permissible for its injection into the combustion chamber and therefore for its combustion.

[0047] By way of example, the range of permissible temperatures, and therefore targeted at the outlet of the heating element 112, can be set at 300K + / - 15K (27°C + / - 15°C) for dihydrogen and at 323K + / - 15K (50°C + / - 10°C) for LPG.

[0048] The heating element 112 can be of any type, and in particular those described in publication FR3110938A1. By way of illustration only, it is a closed-circuit heat exchanger with heat transfer fluid which recovers heat from the exhaust gases at the outlet of the nozzle 220 ([Fig.2]), to return it to the cryogenic fuel at the exchanger.

[0049] The heating element 112 is controlled by the controller, for example on the central value of the range in stabilized regime.

[0050] The accumulator 113 is any container suitable for storing a gas such as LPG or H2 in a gaseous state. The accumulator 113 operates as a buffer zone for gaseous fuel, i.e., an intermediate reserve ensuring the fuel supply to the injectors 117 under all circumstances – particularly during sudden fuel demands – without the pressure in the supply line 120 dropping under the injection pressure.

[0051] The accumulated gas is stored in particular at the pressure fixed by the pressurization device 111, taking into account any pressure losses (from the heating device 112 and in the accumulator 113).

[0052] The injection system 114 controls the injection of gaseous fuel from the accumulator 113 into the combustion chamber. It includes a metering device 115, an optional shut-off valve 116 and the injector(s) 117 opening into the combustion chamber.

[0053] The metering device 115 is, for example, a pressure regulator coupled to an adjustable neck or a metering valve, configured to meter the mass flow rate of the gaseous fuel at the inlet of the combustion chamber. It is notably controlled by the controller according to pilot commands.

[0054] These different organs, typically the pressurization organ 111, the heating organ 112, the internal heating organ 113 and the injection system 114 (therefore its internal organs) are controlled by one or more controllers (hereinafter "the controller") which receive measurements taken on the supply line 120.

[0055] In particular, a temperature sensor 130 provides temperature measurements of the fuel in the pipeline 120 to the controller.

[0056] In one embodiment, the temperature sensor 130, for example a temperature probe or thermocouple sensor, is positioned upstream of the dosing unit 115, after the accumulator 113. Alternatively, the temperature sensor 130 is an internal temperature sensor of the accumulator.

[0057] A pressure sensor 131 provides fuel pressure measurements in the line 120 to the controller. The pressure sensor 131 can also be positioned upstream of the metering unit 115, after the accumulator 113.

[0058] Thus, the state (temperature and pressure) of the gaseous fuel at the level of the inlet pipe of the injection system 114 was reported to the controller.

[0059] Finally, a flow sensor or flow meter 132 provides fuel flow measurements in the line 120 to the controller. For example, a mass flow meter can be placed as close as possible to the injectors 117 opening into the combustion chamber.

[0060] The controller can also receive external pilot commands, typically a command to vary the fuel flow to meet a need to modify the turbomachine thrust (engine acceleration or deceleration).

[0061] A sensor acquisition frequency on the order of one hundredth to one tenth of a second allows dynamic control of all the organs.

[0062] For example, the pump or pressurization unit 111 is activated by the controller when the pressure measured by the sensor of 131 falls below a low trigger threshold, higher than the pressure in the combustion chamber, and is deactivated by the controller when the measured pressure reaches a high stop threshold.

[0063] Figure 2 schematically illustrates the structure of a double-flow turbomachine and dual-body.

[0064] The double-flow turbomachine 2 comprises successively, in the direction of air circulation, i.e. from upstream (left in the figure) to downstream (right in the figure), an air inlet 20 and a blower 21, which delivers air on the one hand into a primary channel 22 and on the other hand into a secondary channel 23. By "channel", we mean the volume through which an airflow circulates.

[0065] The airflow circulating in the primary channel 22 passes successively through a low pressure compressor 24a, a high pressure compressor 24b, a combustion chamber 25, a high pressure turbine 26a and a low pressure turbine 26b, before being ejected through a primary flow nozzle 220.

[0066] Furthermore, the secondary airflow which flows in the secondary vein 23 is ejected separately through a secondary flow nozzle 230, after passing through a series of guide vanes 231.

[0067] Figure 3 schematically illustrates a method for measuring the flow rate of a regulated gaseous fuel in the pipeline 120, according to various embodiments. Figure 4 illustrates a detailed embodiment of the injection system 114 for implementing the method.

[0068] The process is implemented by a computing entity, typically the CTRL controller ([Fig.4]).

[0069] The method includes obtaining a flow measurement in the pipe 120. This measurement, denoted QFlowmeter, is carried out by the flowmeter 132. The QFlowmeter flow can be a mass or volumetric flow rate, depending typically on the flowmeter used.

[0070] In one embodiment, a Coriolis mass flow meter is used. In particular, H2 mass flow meters are commercially available for hydrogen and LNG meters for LNG-type fuel. Coriolis mass flow meters typically provide flow rate measurements at a frequency of 10 to 100 Hz.

[0071] Of course, other flow sensors, for example vortex, ultrasonic or electromagnetic, can be used.

[0072] The flowmeter 132 has a real transfer function, that is to say a mathematical model of the relationship between the input (the real flow QReel in the pipe 120) and the output (measured flow QFlowmeter), a model most often considered to be invariant: QFlowmeter=QReal*H(p).

[0073] We subsequently call 'transfer function H(p)' such a transfer function representative of the flowmeter 132 providing the measurement QFlowmeter, regardless of the model used, 'p' is the Laplace variable.

[0074] It is therefore possible to have a mathematical model of the flow meter. The transfer function H(p) can be provided by the manufacturer of the flow meter 132 or determined on a test bench.

[0075] In one embodiment, a configurable reference transfer function is used on the test bench, with only its parameters being determined by the tests. For example, the transfer function is of the form of a low-pass filter of any order, in particular first or second order. It may also include a pure delay characterizing the inertia and latency of the flow meter.

[0076] In a particular embodiment, a first-order low-pass filter type transfer function is used, i.e., having the form / / (p) - e-Tr.p—l-, with Tr a pure delay, and r a time constant.

[0077] The tests allow Tr and r to be determined. These two time parameters take values ​​between a few tens of milliseconds (e.g., 20 or 30 ms) and a few seconds (e.g., 3 to 5 s).

[0078] Of course, transfer functions other than the low-pass filter can be used. Similarly, instead of using a parameterized transfer function, it is possible to obtain a set of trial data (inputs, outputs) and use this set to select a transfer function (from a library) that is most suitable, or even to use this set in a generative artificial intelligence tool to generate a mathematical model H(p).

[0079] This transfer function H(p) characterizes the entire flowmeter 132; it therefore models both the static and dynamic components of the measurement. For a flowmeter with good static accuracy but insufficient dynamic performance, as is the case with flowmeters generally used in aeronautics, the transfer function H(p) presents The advantage, after subtracting its static part, is to model the dynamic or transient error of the flow meter.

[0080] It is this feature which is used, as described below, to correct the measurement QFlowmeter.

[0081] Following the acquisition of the flowmeter measurement Q, the process continues with the determination 310 of this dynamic measurement error of the flowmeter. The determination 310 is carried out using the transfer function H(p) and a flow measurement, denoted Qm, derived from a ratio of pressures across the metering element 115.

[0082] For this purpose, a pressure sensor is provided upstream of the dosing unit 115, noted Pam, for example sensor 131, and a pressure sensor 133 is provided downstream of the dosing unit 115, noted Pav.

[0083] In the case, for example, of a pressure-reducing type dosing device coupled to a neck, the pressure sensors can be arranged on either side of the neck, preferably as close as possible to the neck. Similarly, the flow meter 132 is placed on the pipe 120 as close as possible to the point where the pressure ratio is measured (i.e., to the pressure sensors and the dosing device 115) so that both devices see the flow rate at the same time.

[0084] Conventional pressure sensors are used, capable of providing pressure measurements at a frequency of 50 to 1000 Hz.

[0085] The upstream pressure is noted Pam while the downstream pressure is noted Pav.

[0086] The Barré Saint Venant relation known to those skilled in the art allows the flow rate through an orifice to be calculated, here the neck of the dosing device 115. This relation provides a flow rate measurement as a function of the ratio of the pressures Pav / Pam at the terminals of the dosing device, the calculation formula being different depending on whether the flow rate is sonic (Pav / Pam > a threshold) or not (Pav / Pam < the threshold).

[0087] Obtaining a flow measurement by this relationship has the advantage of obtaining fast measurements (therefore reliable on the dynamic part of flow variation) due to a very low time constant (at the level of the pressure sensors), regardless of the quality of the measurement in static regime.

[0088] The Barré-Saint-Venant relation for calculating mass flow rate is as follows:

[0089] for p^ / 2 \ h (sonic regime) Pam “ \ y+1 /

[0090] Qm = CdA

[0091] and for p^ , ? x (subsonic regime) Pam < \ y+1 / PanFamV{ y+1 )

[0092] Qm = CdA

[0093] where Cd is the discharge coefficient, for example of the neck, A is the passage area (in m2) in the neck, pam is the density of the upstream gas (in kg.m3) and y is a constant of the gas considered, equal to Cp / Cv (Cp and Cv being the specific heat capacities of the gas).

[0094] The parameters Cd and A are correlated to the pilot control (thrust) of the metering unit 115. Indeed, the flow rate is regulated by the variation of the opening of the passage section A. The relationship between the pilot control and the product Cd.A can be determined on a test bench, using in particular the flow meter 132 in static / stabilized regime, or be provided by the manufacturer of the metering unit.

[0095] A sensor of the RVDT (Rotary Variable Differential Transformer) or LVDT (Linear Variable Differential Transformer) type, known to those skilled in the art, can be used to determine the exact positioning 'DosingPosition' of the dosing unit 115 at various test points under steady-state conditions. The LVDT type sensor is used when the control element of the dosing unit 115 has a linear displacement, typically a cylinder. The RVDT type sensor is used when the control element of the dosing unit 115 has an angular displacement.

[0096] At the various test points in steady state, the flowmeter 132 is used to determine the actual flow QFlowmeter=QActual in the pipe 120 (to within the static accuracy of the flowmeter), while the pressures Pam and Pav are also obtained.

[0097] By reversing the formulas of the Barré Saint Venant relation (the other parameters being known) knowing that QFlowmeter=Qm thanks to the stabilized regime, it is possible to obtain the values ​​of the product A.Cd as a function of each position of the dosing element 115 at the test points, and thus establish the relation A.Cd= f(DosingPosition).

[0098] This relationship can be modeled, and the resulting mathematical model (for example, a function) can be used subsequently. Alternatively, a lookup table can be used that links several DoserPosition positions to the corresponding values ​​of the product A.Cd.

[0099] Step 310 then consists of determining the dynamic error of the flowmeter 132 using the Barré Saint Venant relation, given the relation A.Cd= f(PositionDoseur).

[0100] In operation, a flow measurement derived from the pressure ratio Pav / Pam across the metering unit 115 is first determined. This involves obtaining the pressure Pam upstream of the metering unit 115 and the pressure Pav downstream of the dosing device, then the application of the Barré de Saint Venant relation to the upstream and downstream pressures to obtain the flow rate Qm.

[0101] The application of the Saint Venant Barré relation also takes into account the 'PositionDoseur' position of the dosing element 115 to know A.Cd. The 'PositionDoseur' position is given by the RVDT or LVDT type sensor.

[0102] Once the flow rate measurement Qm is obtained, the transfer function of the flow meter is applied to it. This is substep 312 which allows obtaining a filtered Qm measurement.

[0103] Figure 5 illustrates a numerical realization of the transfer function H(P)

[0104] The person skilled in the art is able to develop digital implementations for any other type of transfer function.

[0105] The numerical implementation of the figure first comprises a sub-block 3120 for calculating the pure delay component, having as inputs the pure delay parameter Tr and the flow rate measurement Qm. It then comprises a sub-block 3122 for a first-order low-pass filter, having as inputs the time constant r, the flow rate measurement Qm and the output of sub-block 3120.

[0106] The SampleTime parameter ST represents the calculation period of the algorithm. The time parameters (Tr and r) are therefore converted into algorithm units using the SampleTime parameter.

[0107] Returning to [Fig. 3], once the filtered flow measurement Qm has been obtained, the difference between the flow measurement Qm and this filtered measurement QmFiltered is calculated. Substep 314 provides an estimate of the dynamic error AQm, that is, an estimate of the measurement drag error by the flowmeter 132.

[0108] This dynamic error AQm is added to the flow measurement QFlowmeter of the flowmeter. It is step 320 which makes it possible to obtain a corrected measurement QFFCorriged of the gaseous fuel flow rate in the turbomachine line 120.

[0109] The idea described above aims to compensate for the drag of a gas flow measurement probe. The compensation is based on estimating the probe's drag by filtering a reliable dynamic measurement Qm with the probe's transfer function H(p). By calculating the difference between the measurement Qm and its equivalent filtered by H(p), the probe's measurement drag is deduced in real time. This estimate of the dynamic error thus calculated is then added to the probe's flow measurement QFMeasurement, thereby compensating for the drag induced by H(p). This results in a more accurate gas flow measurement QCorrected, both statically and dynamically.

[0110] Figure 6 illustrates the more precise measurement of the gas flow rate thanks to the proposed hybridization. The figure represents the flow rates QFlowmeter, Qm, and QCorrected as a function of time.

[0111] The figure shows the slow dynamics of the flowmeter's QFlowmeter measurement, and conversely, the rapid evolution of the Qm measurement derived from the pressure ratio Pav / Pam. However, this Qm measurement is unreliable in static conditions (hence the ordinate shift between the two curves). The QCorrected result of hybridizing the two measurements using the measurement method described above allows us to recover the dynamics of the Qm measurement with the absolute accuracy of the QFlowmeter measurement.

[0112] This drag compensation is advantageously used in regulating the gaseous fuel flow rate in the turbomachine 2. The CTRL controller can define a flow control setpoint at the inlet of the metering unit 115, for example, as a function of a desired thrust. To control the metering unit, it is useful to measure the gaseous fuel flow rate in the pipe 120 in real time, typically as close as possible to the metering unit 115. This real-time measurement is carried out according to the measurement method described above, incorporating measurement drag compensation by adding the dynamic measurement error obtained using H(p) and the flow rate measurement Qm derived from the pressure ratios across the metering unit 115.

[0113] Of course, the present invention is not limited to the embodiments described above by way of example; it extends to other variants.

Claims

Demands

1. Method for measuring the flow rate of a regulated gaseous fuel in a turbomachine (2) pipeline (120) by a metering device (115), the method comprising the following steps: obtaining (300), from a flowmeter (132), a flow rate measurement (QFlowmeter) in the pipeline, the flowmeter having a transfer function (H(p)), determining (310) a dynamic error (AQm) of measurement of the flowmeter (132) using the transfer function and a flow rate measurement (Qm) from a ratio of pressures across the metering device (115), and adding (320) the determined dynamic error to the flow rate measurement (QFlowmeter) of the flowmeter to obtain a corrected measurement (QCorrectedFlow) of the gaseous fuel flow rate in the turbomachine pipeline (120).

2. Method according to claim 1, wherein determining (310) the dynamic error comprises: obtaining the flow measurement (Qm) from the ratio of pressures across the metering device (115), applying (312) the transfer function (H(p)) of the flowmeter (132) to the measurement obtained to obtain a filtered measurement (QmFiltered), and calculating (314) the difference (AQm) between the flow measurement obtained and the filtered measurement, said difference corresponding to the dynamic error.

3. Method according to claim 2, wherein obtaining the flow measurement (Qm) from the ratio of pressures across the metering member (115) comprises: obtaining a pressure (Pam) upstream of the metering member and a pressure (Pav) downstream of the metering member, and applying the Saint Venant Barré relation to the upstream and downstream pressures to obtain a flow.

4. A method according to any one of claims 1 to 3, wherein the transfer function is of the form of a low-pass filter with pure delay.

5. A method according to any one of claims 1 to 4, wherein the transfer function is of the form H(p) - eT'py~ ■> with Tr a pure delay, and r a time constant.

6. A method for regulating the flow rate of a gaseous fuel in a turbomachine (2), comprising the following steps: defining a flow control setpoint at the inlet of a metering device (115) of the gaseous fuel, measuring in real time a flow rate (QDébCorrigé) of gaseous fuel in a turbomachine pipe (120), in order to control the metering device, a method in which the measurement of the gaseous fuel flow rate conforms to the measurement method according to any one of claims 1 to 5.

7. A system for measuring the flow rate of a regulated gaseous fuel in a turbomachine (2) pipeline (120) by a metering device (115), comprising: a flowmeter (132) configured to obtain a flow rate measurement (QFlowmeter) in the pipeline, the flowmeter having a transfer function (H(p)), and a controller (CTRL) configured to: - determine a dynamic error (AQm) of the flowmeter (132) measurement using the transfer function and a flow rate measurement (Qm) from a ratio of pressures across the metering device (115), and - add the determined dynamic error to the flow rate measurement of the flowmeter in order to obtain a corrected measurement (QCorrectedFlow) of the gaseous fuel flow rate in the turbomachine pipeline (120).

8. System according to claim 7, wherein the controller (CTRL) is configured to: obtain the flow measurement (Qm) from the ratio of pressures across the metering device (115), apply (312) the transfer function (H(p)) of the flowmeter (132) to the measurement obtained to obtain a filtered measurement (QmFiltered), and calculate (314) the difference (AQm) between the flow measurement obtained and the filtered measurement, said difference corresponding to the dynamic error.

9. A system according to claim 8, wherein the controller (CTRL) is configured to: obtain a pressure (Pam) upstream of the metering device and a pressure (Pav) downstream of the metering device, and 16. Apply the Saint Venant Barré relation to the upstream and downstream pressures to obtain the flow measurement (Qm) from the pressure ratio.

10. System according to any one of claims 7 to 9, wherein the transfer function is of the form p) = , with Tr a pure delay, and r a time constant.

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