Abstract: The present invention is concerned with the estimation of health parameters p(k) representing symptoms of a slowly degrading system, in particular industrial gas turbines. According to the invention, an estimation of a true health or independent parameter vector at time step k uses the estimation of the true health or parameter vector at a previous time step k?1 as a starting value for the production of a predicted health parameter vector at time step k. Based on the latter and a set of measured values of input variables of an extended model of the system, a prediction of output variables of the model is produced. This predicted model output is compared with measured values of the output variables to yield an error. From this error, a health parameter estimator in turn produces a health parameter estimate as a revision of the predicted health parameters.

Abstract: An estimation unit can estimate, on a real-time basis, a maximum power generation capacity of a single cycle or combined cycle gas turbine power plant. For example, the actual power output and the maximum power generation capacity can be calculated relying on a mathematical process model. Subsequently, the calculated actual power output can be compared with the measured power output yielding a model-estimation error. Based on the model-estimation error, a correction signal can be deduced, to correct the calculated maximum power generation capacity. A controller can maintain a specified power reserve. The controller can use an estimate of the maximum power generation capacity as a reference, subtract a load offset, and apply the resulting signal as upper limit of the load set-point.

Abstract: A method for modeling the performance of a gas turbine engine is provided.

Abstract: Embodiments of the invention can provide systems and methods for using a combustion dynamics tuning algorithm with a multi-can combustor. According to one embodiment of the invention, a method for controlling a gas turbine engine with an engine model can be implemented for an engine comprising multiple cans. The method can include obtaining operating frequency information associated with multiple cans of the engine. In addition, the method can include determining variation between operating frequency information of at least two cans. Furthermore, the method can include determining a median value based at least in part on the variation. Moreover, the method can include determining whether the median value exceeds at least one operating threshold. The method can also include implementing at least one engine control action to modify at least one of the operating frequencies if at least one operating threshold is exceeded.

Abstract: Certain embodiments of the invention may include systems and methods for providing unchoked control of gas turbine fuel control valves. According to an exemplary embodiment of the invention, a method is provided for active control of a gas flow control valve. The method may include receiving a desired fuel command and an inlet pressure parameter, and determining a gas flow gain based at least in part on the inlet pressure parameter. The method may also include determining a valve flow coefficient based at least in part on the desired fuel command and the gas flow gain, and controlling the gas flow control valve based at least in part on the valve flow coefficient.

Abstract: The turbojet comprises a high pressure spool and a low pressure spool driving a fan. In order to produce electricity, it further includes an electricity generator arranged in the fan and taking power therefrom. The generator comprises a rotor incorporated in the fan and a stator incorporated in the fan casing. This disposition for the electricity generator avoids problems of engine operability at low speed and enables mechanical power to be converted into electrical power with high efficiency. In addition, installation and maintenance of the electricity generator are facilitated by the generator being implanted in the fan.

Abstract: A system comprising determination of tuning parameters enabling optimal estimation of unmeasured engine outputs, e.g., thrust. The level of degradation of engine performance is generally described by unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends upon knowledge of these health parameters, but there are usually too few sensors to estimate their values. A set of tuning parameters is determined which accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The method utilizes the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter. Generation of a tuning vector specifically takes into account the variables of interest. The tuning parameters facilitate matching of both measured and unmeasured engine outputs, as well as state variables.

Abstract: An example data assessment method for a diagnostic system includes receiving a set of initialization data, analyzing the set of initialization data to identify a data outlier in the set of initialization data, and determining whether the set of initialization data is bimodal. The method further includes establishing a set of cleaned data based on the analysis and establishing a baseline operating condition for the device using the set of cleaned data.

Abstract: A system to detect a plurality of elements is proposed. The system includes one or more X-ray sources for transmitting X-rays towards a sample and also includes plurality of photon detectors. An array of crystals are arranged in a curvature with appropriate geometry for receiving a plurality of photon energies emitted from the sample and focusing the photon energy on the plurality of detectors. The plurality of photon detectors are spatially arranged at Bragg angles corresponding to signature photon energies to detect the plurality of elements simultaneously.

Abstract: A gas turbine engine and an apparatus for operating the gas turbine engine includes at least one microphone to detect the sound of impacts of particles, recorder to record the sound of the impacts, an analyser to analyse the sound of the impacts of the particles, and a store of sounds of impacts, the stored sounds of impacts correspond to unfavourable weather conditions. A comparator compares the sound of the impacts of particles with one or more sounds of impacts stored in the store 68 sounds of impacts and if the comparator determines that the sound of the impacts of particles matches one or more stored sounds of impacts, a signal is sent to a control system for the gas turbine engine to adjust the operation of the gas turbine engine such that it operates in a safe mode of operation.

Abstract: A lean blowout protection system and method is provided that facilitates improved lean blowout protection while providing effective control of turbine engine speed. The lean blowout protection system and method selectively and gradually biases the lean blowout (LBO) schedule based on current engine data. This facilitates improved lean blowout protection while providing effective control of turbine engine speed and temperature.

Abstract: Embodiments of the invention can provide systems and methods for using a combustion dynamics tuning algorithm with a multi-can combustor. According to one embodiment of the invention, a method for controlling a gas turbine engine with an engine model can be implemented for an engine comprising multiple cans. The method can include obtaining operating frequency information associated with multiple cans of the engine. In addition, the method can include determining variation between operating frequency information of at least two cans. Furthermore, the method can include determining a median value based at least in part on the variation. Moreover, the method can include determining whether the median value exceeds at least one operating threshold. The method can also include implementing at least one engine control action to modify at least one of the operating frequencies if at least one operating threshold is exceeded.

Abstract: The present invention relates to control of engine variable of a gas turbine engine to regulate the surge margins of at least two compressors. A controller (20) receives data measured from engine sensors (22, 23) and uses said data to determine an indication of surge margin for each of at least two compressors (6, 7) of the gas turbine engine. The controller (20) uses the indications of surge margin for each of the compressors to determine a control strategy that balances the requirements of each compressor. In one embodiment a surge margin operating map divided into different control domains (40, 43, 43) is used. The indication of surge margin determined for each compressor is plotted to determine which control domains the current operating point on the surge margin operating map falls within.

Abstract: A method of determining lubrication oil consumption in a gas turbine engine that has an engine operating cycle interval comprising a starting phase, a running phase and a shutdown phase, comprises the steps of: measuring lubrication oil level upon initialization of the starting phase of each engine operating cycle interval; comparing the starting phase measured lubrication oil level during the starting phase with a starting phase baseline lubrication measurement; recording the starting phase lubrication oil level measurement; determining average engine lubrication oil consumption rate during the complete engine operating cycle interval by dividing the difference between the starting phase lubrication oil measurement and the baseline lubrication oil measurement; and repeating these steps for each subsequent engine operating cycle interval; wherein the starting phase baseline lubrication oil level measurement is initially a predetermined lubrication oil level and then the previous starting phase lubrication oil

Abstract: An apparatus for controlling an aeroplane gas turbine engine has various sensors and devices for operating the engine, and two control channels each calculating a command value for controlling operation of the engine based on signals outputted from the sensors. In each of the control channels, it is determined whether any of the sensors and devices is abnormal based on the signals to determine a failure level of the control channel concerned with a numerical value. The failure level is compared with that of the other control channel and based thereon, the command value calculated by the control channel of smaller failure level is sent to the devices. With this, even when both control channels are failed, the engine control can be continued with taking the failure level into account.

Abstract: Starter control valve failure prediction machines, systems, program products, and computer implemented methods to predict and trend starter control valve failures in gas turbine engines using a starter control valve health prognostic and to make predictions of starter control valve failures, are provided. A computer implemented method according to an embodiment of the present invention can include the steps of generating a continuous starter control valve deterioration trend function responsive to a plurality of health indices derived from gas turbine engine startup data downloaded from gas turbine engine sensors for a plurality of startups and analyzing the continuous starter control valve deterioration trend function to identify potential starter control valve failure points where the points on the starter control valve deterioration trend function correlate to a starter control valve health prognostic responsive to historic gas turbine engine startup data downloaded from gas turbine engine sensors.

Abstract: A gas turbine engine control system comprises a data acquisition and analysis system for receiving a signal from a combustion dynamics sensor and providing an output signal and a combustion dynamics control system for controlling combustion dynamics based on the output signal. The control system is associated with a purge-air flow and comprises an acoustic driver, or a flow-manipulating device, or both to perturb the purge-air flow entering the combustor can for controlling combustion dynamics.

Abstract: A method of analysing measured data from a system having multiple associated system variables, the method including the steps of: a) optimizing an error function relating the measured data to a predetermined number of the system variables to adjust the system variables; b) selecting a subset of the adjusted variables; and c) re-optimizing the error function by adjusting only the variables in the subset. A method of identifying likely contributors to an error caused in measured data from a system which has multiple associated system variables. A method of analysing measured engine service or test data form an engine having a plurality of associated system variables, includes the step of optimizing an error function which relates the measured data to a predetermined number of the system variables, by least-absolutes optimization wherein the error function is a sum of absolute variations.

Abstract: A system and method of monitoring oil consumption in a gas turbine engine system are provided. When the gas turbine engine is not running the reservoir oil level, reservoir oil temperature, and reservoir attitude are sensed. The current gas turbine engine system oil quantity is determined based on at least the sensed reservoir oil level, the sensed reservoir oil temperature, and the sensed reservoir attitude. When a predetermined event has occurred, an average gas turbine engine system oil quantity is automatically calculated. The gas turbine engine system oil consumption rate is determined from a plurality of the average oil quantities.

Abstract: The present invention is concerned with the estimation of health parameters p(k) representing symptoms of a slowly degrading system, in particular industrial gas turbines. According to the invention, an estimation of a true health or independent parameter vector at time step k uses the estimation of the true health or parameter vector at a previous time step k?1 as a starting value for the production of a predicted health parameter vector at time step k. Based on the latter and a set of measured values of input variables of an extended model of the system, a prediction of output variables of the model is produced. This predicted model output is compared with measured values of the output variables to yield an error. From this error, a health parameter estimator in turn produces a health parameter estimate as a revision of the predicted health parameters.

Abstract: In a heating apparatus for heating the air sucked into a gas turbine by a heat exchanger, the temperature fluctuation of the heated air is suppressed even in the period, for which a steam source to be fed to the heat exchanger is changed. For that suppression, a heat exchanger (30) is fed with both a self-can steam (S1), the feed rate of which is controlled by a self-can steam control valve (41), and the auxiliary-steam (S2), the feed rate of which is controlled by an auxiliary-steam control valve (51). At the starting time, the quantity of the auxiliary-steam (S2) is reduced at a constant rate, and the quantity of the self-can steam (S1) is increased while a feedback control and a feedforward control are being made. At the stopping time, the quantity of the self-can steam (S1) is reduced at a constant rate, and the quantity of the auxiliary-steam (S2) is increased while the feedback control and the feedforward control are being made.

Abstract: A control system for a turbofan comprises a variable area nozzle for regulating core flow through the turbofan, an actuator, a temperature sensor, a flight controller and a nozzle control. The actuator is coupled to the variable area nozzle to regulate the core flow by positioning the variable area nozzle. The temperature sensor is positioned in the turbofan to sense a gas path temperature of the core flow. The flight controller is connected to the turbofan to make a thrust demand based on a flight condition of the turbofan. The nozzle control is connected to the flight controller and the actuator for directing the actuator based on the gas path temperature and the flight condition, such that the gas path temperature is controlled by adjusting the variable area nozzle to regulate the core flow while the turbofan meets the thrust demand.

Abstract: Provided is a gas turbine control method and control device whereby a design performance and an operating state based on ideal fuel flow rate and air flow rate simulated at the time of designing can be maintained by preventing an operation deviated from an operating condition that is based on ideal fuel flow rate and air flow rate simulated by initial design values, in a gas turbine control method designed to search optimal operating conditions automatically using control inputs such as a pilot ratio. The gas turbine controller comprises a second database that stores load sensitivity, i.e.

Abstract: A gas turbine comprises a plurality of target exhaust temperature determination modules, the plurality of target exhaust temperature modules comprising a nitrogen oxide (NOx) compliance module configured to determine an exhaust temperature at which an exhaust of the gas turbine complies with a maximum permitted level of NOx; at least one bias module, the at least one bias module configured to apply a bias to an output of at least one of the plurality of target exhaust temperature determination modules; and a controller configured to operate the gas turbine to produce the exhaust temperature determined by the NOx compliance module.

Abstract: A new linear point design technique is presented for the determination of tuning parameters that enable the optimal estimation of unmeasured engine outputs such as thrust. The engine's performance is affected by its level of degradation, generally described in terms of unmeasurable health parameters related to each major engine component. Accurate thrust reconstruction depends upon knowledge of these health parameters, but there are usually too few sensors to be able to estimate their values. In this new technique, a set of tuning parameters is determined which accounts for degradation by representing the overall effect of the larger set of health parameters as closely as possible in a least squares sense. The technique takes advantage of the properties of the singular value decomposition of a matrix to generate a tuning parameter vector of low enough dimension that it can be estimated by a Kalman filter.

Abstract: A turbo machine includes a speed probe that is configured to detect a speed of a rotating feature. Engine controls are used by a processor to control operation of the turbo machine. The processor communicates with the speed sensor and receives the speed signal to produce a command signal. A detection module is arranged in parallel with the processor and communicates with the speed probe to receive the speed signal. The detection module compares the speed signal with data to determine whether the speed signal is reliable. In one example, the detection module bypassed the processor and sends a corrective command directly to an engine control device in response to an unreliable speed signal.

Abstract: A combustor includes a combustor housing defining a combustion chamber having a plurality of combustion zones. A plurality of temperature detectors are disposed in communication with the combustion chamber. The plurality of temperature detectors detect a temperature in the plurality of combustion zones. A controller communicating with the plurality of temperature detectors is programmed to determine an occurrence of a flame holding condition or a flashback condition in the plurality of combustion zones based on signals from the plurality of temperature detectors.

Abstract: Embodiments of the invention can provide systems and methods for initializing dynamic model states using a Kalman or similar type filter. In one embodiment, a system for controlling a gas turbine engine is provided. The system can include at least one sensor adapted to obtain dynamic-type information about a current state of the engine. The system can also include an engine model adapted to receive information from the sensor, and further adapted to reflect the current state of the engine. Furthermore, the system can include a model filter adapted to initialize the engine model with at least a portion of the dynamic-type information, wherein at least one value based at least in part on the filtered dynamic-type information is input to the engine model to determine an engine control action.

Abstract: A combustion turbine engine that includes: a compressor; a combustor that receives fuel from a fuel line; a turbine; a heat exchange portion comprising a portion of the fuel line in heat transfer relationship with a heat source for heating the fuel; a rapid heating value meter disposed to test the heating value of the fuel that is configured to provide heating value test results within approximately 1 minute; a cold leg bypass comprising a fuel line that bypasses the heat exchange portion, the cold leg bypass being connected to the fuel line at an upstream fork and at a fuel mixing junction; and valves for controlling the fuel being directed through the heat exchange portion and the fuel being direct through the cold leg bypass; wherein the length of fuel line between the fuel mixing junction and the combustor is less than 20 meters.

Abstract: A method for detecting the opening of a thrust reverser for a jet engine of an aircraft is disclosed. According to the method, an operating parameter of the turbojet (1) is determined being responsive to the opening of a mobile element (2a, 2b) of the thrust reverser and reacting to such an opening by a sudden variation of the value thereof, the parameter is measured continuously and the mobile element (2a, 2b) is considered as being opened when the sudden variation is detected.

Abstract: An integrated system for monitoring a deployed product on a movable platform, gathering data about the deployed product, and disseminating the, data about the deployed product is disclosed. The system includes a server located on the movable platform capable of communication with the server from a remote location. The server communicates with a source of data about the deployed communicates with a source of data about the deployed product. The system further includes a portal onto which data gathered by the server may be downloaded and with which one can upload information to the server. The server may be provided in the form of a card adapted to be mounted into a pre-existing electronic controller of the deployed product.

Abstract: A method and apparatus for measuring a start fuel flow to a pilot nozzle of a fuel system of a gas turbine engine using pressure differential between fuel passages leading to fuel nozzles.

Abstract: An event-driven starter controller regulates the speed of a gas turbine engine based on detected events. The event-driven starter controller is used to supply motive force to the gas turbine engine prior such that the gas turbine engine is able to ignite (i.e., achieve light-off). In particular, in response to engine speed reaching a defined threshold, the event-driven starter controller causes the speed of the starter motor to ramp or increase through a defined range of speeds suitable for engine light-off (i.e, light-off window). Upon reaching an upper threshold of the light-off window, the event-driven starter controller causes the speed of the starter motor to decrease through the range of speeds suitable for engine light-off. If at any time during the light-off window the event-driven starter controller detects a successful light-off condition, the event-driven starter controller causes the speed of the gas turbine engine to increase toward a second threshold.

Abstract: Systems and methods for steam turbine remote monitoring, calculating corrected efficiency, monitoring performance degradation, diagnosing and benchmarking are disclosed with an example turbine system including a turbine, a data acquisition device coupled to the turbine, the data acquisition device for collecting turbine data that includes performance parameters of the turbine and a central monitoring system coupled to the data acquisition device, the central monitoring system for receiving the collected turbine data and processing the turbine data to determine turbine performance.

Abstract: In a gas turbine aeroengine control system, in Ch-A (first control channel), a first CPU monitors the operation of a second CPU and the second CPU monitors the operation of the first CPU; in Ch-B (second control channel), third and fourth CPUs similarly monitor each other, and when the operation of at least one of the first and second CPUs in Ch-A is found not to be normal, the output sent to an FCU (fuel control unit) is switched from the output of one or the other of the first and second CPUs of Ch-A to the output of one or the other of the third and fourth CPUs of Ch-B, thereby achieving improved CPU failure detection and realizing high redundancy and high reliability.

Abstract: An example method of estimating gas turbine engine performance deterioration includes monitoring debris in at least a portion of an engine and estimating performance deterioration of at least one component of the engine using information from the monitoring. The method may use gas path parameters, such as pressures, temperatures, and speeds to establish the estimated performance deterioration. An example gas turbine engine performance assessment system includes a debris monitoring system configured to monitor debris moving through a portion of an engine and a controller programmed to estimate performance deterioration of at least one component of the engine based on information from the debris monitoring system.

Abstract: The present invention provides a method of controlling engine performance that includes obtaining at least one optical wavelength-dependent measurement from at least one combustion event in at least one combustion chamber. The method further includes analyzing the optical wavelength-dependent measurement for determining adjustments to the at least one combustion event. Additionally, the method includes adjusting the at least one combustion event or at least a next combustion event by changing at least one physical parameter, at least one constituent parameter, or at least one physical parameter and at least one constituent parameter to control the engine performance. The engine can include steady-flow engines or periodic flow engines, and the engine performance can be selected by an engine user.

Abstract: A method of controlling variable extraction flow in a combustion turbine engine, wherein extraction flow comprises a supply of compressed air extracted from the compressor and supplied to the turbine through extraction conduits, and wherein the extraction conduits includes a variable extraction orifice, the method comprising the steps of: measuring a plurality of turbine engine operating parameters; monitoring, by a control unit, the measured operating parameters of the combustion turbine engine; setting the variable extraction orifices to a setting that allows an approximate maximum level of extraction flow; calculating, by the control unit, at least one calculated operating parameter based upon model-based control and the measured operating parameters, including at least a current turbine inlet temperature and a maximum turbine inlet temperature; and manipulating the setting for the supply of fuel to the combustor such that an increased and/or maximum level of engine output is determined by comparing the va

Abstract: A system for tuning the operation of a gas turbine is provided based on measuring operational parameters of the turbine and directing adjustment of operational controls for various operational elements of the turbine. A controller is provided for communicating with sensors and controls within the system. The controller receiving operational data from the sensors and comparing the data to stored operational standards to determining if turbine operation conforms to the standards. The controller then communicates selected adjustment in an operational parameter of the turbine. The controller then receives additional operational data from the sensors to determine if an additional adjustment is desired or is adjustment is desired of a further selected operational parameter.

Abstract: A gas turbine includes a rotor, and a controller for controlling a shutdown of the gas turbine based on a target fuel-to-air ratio profile and/or controlling a rotor speed according to a target speed schedule to attain a specified duration for the shutdown. The controller controls the rotor speed by engaging the starting system to turn the rotor.

Abstract: Systems and methods for controlling fuel flow to a turbine component are provided. One or more parameters associated with a fuel flow to a turbine component may be monitored. The fuel flow may be modeled based at least in part on the one or more monitored parameters. The fuel flow may be adjusted to a target flow based at least in part on the modeling of the fuel flow.

Abstract: A method for monitoring and controlling a gas turbine, comprises predicting frequencies of combustion dynamics in a combustor using operating conditions of a gas turbine, receiving a signal from a sensor that is indicative of combustion dynamics in the combustor, and detecting a flashback if a frequency of the received signal does not correspond to the predicted frequencies.

Abstract: According to one aspect, the subject application involves a method of controlling a transition of a gas turbine. The method includes receiving a request of the gas turbine to drive an increased load. The increased load is greater than a load being driven by the gas turbine when the request is received. The method further includes determining that a temperature of a fuel to be ignited within a combustor of the gas turbine is less than a target temperature of the fuel to be introduced into the combustor for driving the increased load. Responsive to this determination, the method also includes controlling introduction of an additive into the combustor of the gas turbine when the temperature of the fuel is less than the target temperature to establish a suitable Wobbe Index of a fuel combination to promote a substantially continuous transition of the gas turbine to drive the increased load, wherein the fuel combination includes the fuel and the additive.

Abstract: Operation of gas turbine engines and in particular gas turbine engines utilised for aircraft, in an efficient manner is a desired objective. Thus engine efficiency is typically determined through use of an engine performance parameter. One such engine performance parameter is with regard to specific fuel consumption. However, such parameters may vary as a result of inherent deterioration with regard to the engine. By utilising a computational model to determine variations in the performance parameter such as the specific fuel consumption changes as a result of such inherent engine degradation can be accommodate. Thus, such degradation may not swamp actual changes in fuel consumption or the engine performance parameter which are indicative of changes of engine efficiency.

Abstract: In a system for monitoring an output of a sensor for detecting an operating state of a gas turbine engine by comparing a value of an output of the sensor with a prescribed reference value, a calibration map for converting the output of the sensor into a variable that is normally used for controlling the engine is used for defining the reference value for determining the state of the sensor. Thereby, a fault of a sensor can be detected both accurately and promptly by using the existing resource without unduly complicating the control program. It is particularly desirable to monitor the output of the sensor by taking into account the current operating condition of the engine to improve the reliability in detecting a fault in the sensor.

Abstract: A distributed electronic engine control system includes an airframe module, an electronic engine control module, and an engine I/O module. The modules are arranged in locations remote from one another. A serial communications bus interconnects the modules with one another. A first engine controls device is connected to the engine I/O module and is configured to interact with an engine component and provide a first data. The engine I/O module includes inner loop control logic that uses the first data and produces a second data in response thereto. The electronic engine control module includes an outer loop control logic using the second data and produces a third data in response thereto. The airframe module receives power and distributes the power to the electronic engine control and engine I/O modules. The first, second and third data are provided on the serial communications bus.

Abstract: Systems and methods for providing surge protection to turbine components are provided. A surge protection limit may be determined for the turbine component. One or more measurements associated with operation of the turbine component may be received and provided to a cycle model executed to predict an operating condition of the turbine component. The predicted operating condition of the turbine component may be adjusted based at least in part on the received one or more measurements. The surge protection limit may be adjusted based on the adjusted predicted operating condition of the turbine component.

Abstract: A method includes controlling an aircraft during descent, and controlling the engine pressure ratio of a jet engine so that the engine has a substantially equal pressure at the exhaust, and at the front of the engine during the descent.

Abstract: The subject application involves a method of controlling operation of a gas turbine. The method includes determining a first temperature associated with a portion of the gas turbine during operation of said gas turbine, and sensing an operational parameter of the gas turbine during operation of the gas turbine. An ambient pressure in an ambient environment of the gas turbine is also sensed, and the operational parameter corrected using the ambient pressure sensed in the ambient environment of the gas turbine to establish a corrected operational parameter. A threshold temperature is determined based at least in part on the corrected operational parameter, and a backup routine is initiated to limit operation of the gas turbine when the temperature associated with the gas turbine is greater than or equal to the threshold temperature.

Abstract: An embodiment of the present invention has the technical effect of utilizing a model-based system and real time data to adjust a parameter of at least one valve. An embodiment of the present invention may reduce the need of multiple sensors within a fuel system by integrating a model-based controller with real-time or approximately real-time data to adjust a parameter of at least one valve. An embodiment of the present invention may utilize a model-based controller to calculate the fuel flow through the at least one valve, in or near real-time.