Abstract: A method of distributing power within a gas turbine engine is disclosed. In various embodiments, the method includes driving a high pressure turbine having a first stage and a second stage with an exhaust stream from a combustor, the first stage connected to a high pressure turbine first stage spool and the second stage connected to a high pressure turbine second stage spool; driving a high pressure compressor connected to a high pressure compressor spool via a differential system, the differential system having a first stage input gear connected to the high pressure turbine first stage spool, a second stage input gear connected to the high pressure turbine second stage spool and an output gear assembly connected to the high pressure compressor spool; and selectively applying an auxiliary input power into at least one of the high pressure compressor spool and the high pressure turbine.

Abstract: An aircraft turbofan gas turbine engine includes a fan assembly, a compressor module, and a turbine module. An electric machine positioned downstream of the fan assembly is rotationally connected to the turbine module. The fan assembly is in fluid communication with the compressor module by an intermediate duct and includes a highest pressure fan stage having a plurality of fan blades defining a fan diameter. The compressor module includes a lowest pressure compressor stage having a row of rotor blades. An intermediate flow axis is defined joining a radially outer tip of a trailing edge of one of the fan blades of the highest pressure fan stage, and a radially outer tip of a leading edge of one of the rotor blades of a leading edge of a lowest-pressure compressor blade. An intermediate flow axis angle and the intermediate flow axis angle is from ?20 to ?30 degrees.

Abstract: Disclosed herein is a fundamental modeling and control method in dynamic energy conversion and transfers in complex energy systems with multiple energy sources, fuel and electric. The multi-layered modeling enables efficient and stable operation through optimized coordination of engines and electric part of a hybrid turbo-electric distribution system (TeDP). A provable coordination of power and rate of change of power interactions between the components is done at the higher-system level. Advanced nonlinear control of components is disclosed to ensure that components meet power/rate of change of power commands given by the higher level. This method is used to demonstrate, for the first time, how rotor stall and surge instabilities in engines can be eliminated by controlling the electric generators and/or storage.

Abstract: This combustion adjustment method applied to the combustion control of a combustor executes a first step for selecting a combustion parameter for a load of a gas turbine and increasing or decreasing a command value of the combustion parameter from an original location. When the command value reaches a target tolerance upper limit value or a target tolerance lower limit value, the first step is terminated. Furthermore, a second step for decreasing or increasing the command value in a direction opposite to that of the first step is executed. When the command value reaches the target tolerance upper limit value or the target tolerance lower limit value, the present invention includes a combustion tolerance confirmation step for confirming a combustion tolerance range of the combustion parameter at which the second step is terminated.

Abstract: An aircraft propulsion system is disclosed and includes a first gas turbine engine including a first input shaft driving a first gear system, a first fan driven by the first gear system, a first generator supported on the first input shaft and a fan drive electric motor providing a drive input to the first fan, a second gas turbine engine including a second input shaft driving a second gear system, a second fan driven by the second gear system, a second generator supported on the second input shaft and a second fan drive electric motor providing a drive input to the second fan and a controller controlling power output from each of the first and second generators and directing the power output between each of the first and second fan drive electric motors.

Abstract: A first fuel flow rate command value indicating a command value of a fuel input amount is calculated so that an output of a gas turbine matches a target output. An upper limit value of the first fuel flow rate command value is calculated based on a deviation obtained by subtracting, from an estimated value of a turbine inlet temperature of the gas turbine, a second limit value relating to the estimated value set such that the estimated value does not exceed a first limit value of the turbine inlet temperature.

Abstract: The present disclosure is directed to a gas turbine engine including a first frame comprising a first bearing assembly, a second frame comprising a second bearing assembly, and a compressor rotor. A first stage compressor airfoil is defined at an upstream-most stage of the compressor rotor. The compressor rotor is rotatable via the first bearing assembly and the second bearing assembly. The first stage compressor airfoil is disposed between the first bearing assembly and the second bearing assembly.

Abstract: A towershaft support may comprise a mount support, and a mounting ring coupled to an aft portion of the mount support radially inward of the mount support, wherein the mounting ring and the mount support create a perimeter around a central void. The mounting ring may comprise a mounting flange on an outer diameter of the mounting ring and a fluid passageway on an inner diameter of the mounting ring fixedly coupled to the mounting flange, wherein the fluid passageway comprises an outer wall enclosing an internal passage configured to pass fluid therethrough.

Abstract: A gearbox to be attached to a turbine engine to drive at least one apparatus annexed to the turbine engine, the gearbox including a housing; a power take-off member capable of engaging with a radial shaft of the turbine engine; at least one kinematic chain located inside the housing and capable of transmitting the rotational movement of the power take-off member to at least one rotatable shaft of an apparatus. The kinematic chain includes a first end and a second end. The power take-off member is linked to the kinematic chain by a gear having convergent axes and located between the first end and the second end of the kinematic chain.

Abstract: Methods and systems are provided for calibrating a compressor surge line. In one example, a method may include adjusting the compressor surge line based on a vehicle speed in addition to a compressor pressure ratio. For example, at higher vehicle speeds, above a threshold vehicle speed, a less aggressive surge line calibration may be utilized in order to improve drivability while at lower vehicle speeds, below the threshold vehicle speed, a more aggressive surge line calibration may be utilized for NVH mitigation.

Abstract: Hybrid internal detonation-gas turbine engines incorporating detonation or pulse engine technology (such as an internal detonation engine), and methods of manufacturing and using the same are disclosed. The internal detonation engine includes a detonation chamber having a fuel igniter therein, a stator at one end of the detonation chamber having at least a first opening to receive fuel, a rotor adjacent to the stator, and an energy transfer mechanism configured to convert energy from igniting or detonating the fuel to mechanical energy. The detonation chamber and fuel igniter are configured to ignite or detonate a fuel in the detonation chamber. Either the stator or the detonation chamber has a second opening to exhaust detonation gas(es). The rotor has one or more third openings therein configured to overlap with at least the first opening as the rotor rotates.

Abstract: A gas turbine is provided having a secondary combustion chamber and a first guide vane row of a low-pressure turbine, the row being arranged directly downstream of the chamber. The radially outer boundary of the secondary combustion chamber is formed by at least one outer wall segment, which is secured on at least one support element arranged radially outwardly. The flow path of the hot gases is bounded radially outwardly, in the region of the guide vane row, by an outer platform which is secured at least indirectly on at least one guide vane support. A substantially radially extending gap-shaped cavity having a width in the range of 1-25 mm in the axial direction in the inlet region is arranged between the wall segment and the outer platform. At least one step element, which reduces the width by at least 10% in at least one step, extending substantially perpendicularly to the direction of flow of the hot gas in the cavity, is arranged in the inlet region.

Abstract: A system is provided that includes a memory storing a turbomachinery degradation model configured to model degradation of a turbomachinery over time. The system also includes a controller communicatively coupled to the memory and configured to control the turbomachinery based on a feedback signal and the turbomachinery degradation model. Moreover, the turbomachinery degradation model is configured to use a target power to derive a control parameter by estimating a modeled power of the turbomachinery, and the controller is configured to use the control parameter to control the turbomachinery.

Abstract: A method of monitoring a power generation system that includes a steam turbine that is coupled to a gas turbine engine. The method includes calculating, by a control system, a gas turbine engine power output that is based at least in part on a predefined power generation system power output and a predefined steam turbine power output. The power generation system is operated to generate a power output that is approximately equal to the predefined power generation system power output. A signal indicative of a sensed operating power output of the gas turbine engine is transmitted from a sensor to the control system. A condition of the steam turbine is determined based at least in part on the sensed operating gas turbine engine power output and the calculated gas turbine engine power output.

Abstract: A system and way for controlling a gas turbine engine in the event of a partial or full load rejection from a generator is disclosed. Upon detection of a partial or full load rejection, the fuel flow of the combustor is directed to a secondary circuit of a secondary fuel nozzle to maintain a flame in a downstream chamber of the combustor. By maintaining the flame in the downstream chamber while the engine speed is controlled, the recovery process to a load condition avoids use of spark ignition system and flame detectors in the upstream chamber.

Abstract: A control system for controlling a plurality of distinct functions of a turbojet engine, each function being associated with a respective actuation device. The system includes: an electric motor adapted to supply mechanical energy to each of the actuation devices; an electronic control unit for the electric motor; and at least one switching device interposed between the motor and the actuation devices, the switching device(s) serving to distribute the mechanical energy supplied by the electric motor selectively to one of the actuation devices.

Abstract: The present invention discloses a novel apparatus and methods for augmenting the power of a gas turbine engine, improving gas turbine engine operation, and reducing the response time necessary to meet changing demands of a power plant. Improvements in power augmentation and engine operation include additional heated compressed air injection, steam injection, water recovery, exhaust tempering, fuel heating, and stored heated air injection.

Abstract: A combustion system may include a plurality of heated volume portions. At least two of the plurality of heated volume portions may include corresponding respective electrodes. The electrodes may be driven to produce respective electric fields in their respective volumes. The electric fields may be configured to drive desired respective responses.

Abstract: The present invention provides a torque control method for an HEV, the method comprising: detecting an operation failure of an integrated starter-generator (ISG); calculating a driver demand torque based on a current accelerator position sensor (APS); controlling the hydraulic pressure and operation of a clutch so as to increase an engine speed to convert the driving mode of the vehicle from electric vehicle (EV) mode to hybrid electric vehicle (HEV) mode in the event that an operation failure of the ISG is detected and the driver demand torque is out of a predetermined range; and compensating the driver demand torque to a desired level based on a transfer torque from the clutch to a motor. The method can improve driving performance and power performance of HEV, in the event of ISG failure, by performing a hydraulic control for a clutch and calculating a driver request torque and a transfer torque from the clutch to a motor to compensate the drive request torque to a desired level.

Abstract: Heat and power plant with a waste gasification system comprising a gas engine (1) located inside a water tank (2), mounted onto a shaft (3) passing through the walls of the tank (2) to the outside, whereas a generator (4) is installed on an end of the shaft to generate electrical energy. The engine (1) is equipped with at least one supply conduit (5) for feeding fuel to the combustion chamber (14) and at least one outlet conduit (7) for evacuating exhaust gases. The outlet conduit (7) passes through a waste gasification chamber (8) having a gas outlet, connected to the supply conduit of the engine and/or an external tank (16). The water tank (2) has heating water circuit connections (10), (11), as well as a steam outlet through a valve (12). There are blades (15) mounted on the shaft, in the vicinity of the engine, that ensure uniform cooling of the engine (1).

Abstract: A variable nozzle mechanism applied to a turbocharger includes a pair of annular plates located between a scroll passage and a turbine chamber such that the plates are apart from each other in a direction along an axis; a coupling portion which couples the plates; a plurality of variable nozzles which are provided between the plates so as to open and close, and which change a flow speed of exhaust gas blown onto a turbine wheel when an opening degree of the variable nozzles is changed; and an urging portion which urges the plates in the direction along the axis to press one of the plates against a contacted object. The one of the plates includes a contact face which is in contact with the contacted object, and the contact face is located on an action line along which an urging force of the urging portion acts.

Abstract: A dual output accelerometer having first and second output channels, comprises a supporting base, a first transducer comprising a plurality of inter-connected first piezoelectric elements, a second transducer comprising a plurality of inter-connected second piezoelectric elements and a seismic mass. Each of the first piezoelectric elements and the second piezoelectric elements are interleaved with one another, and are co-located with the seismic mass, the co-located first and second piezoelectric elements and the seismic mass being fastened to the supporting base by a rigid mechanical coupling. The interleaved first and second piezoelectric elements provide an improved first output channel to second output channel matching.

Abstract: Methods and apparatus are provided for selectively controlling the rotational speed of a gas turbine engine that drives a load compressor having movable inlet guide vanes and that is coupled to receive fuel at a fuel flow rate up to a maximum fuel flow rate. The rotational speed of the gas turbine engine, and the fuel flow rate to the gas turbine engine, are both sensed. If the sensed rotational speed of the gas turbine engine is less than a predetermined value and the sensed fuel flow rate to the gas turbine engine equals or exceeds the maximum fuel flow rate, the position of the inlet guide vanes is controlled to reduce load compressor mechanical load on the gas turbine engine.

Abstract: A system and method of adaptively synchronizing the performance margin of a multi-engine system includes continuously, and in real-time, determining the performance margin of a first engine and the performance margin of the second engine. A difference between the performance margins of the first and second engines is calculated, and the first and second engines are controlled to attain a predetermined difference between the performance margins of the first and second engines.

Abstract: In some implementations, one or more methods can include producing a hydrogen rich fuel gas for a gas turbine ballasted with nitrogen and steam and superheated to a temperature above its dew point. The fuel gas may have a minimal or reduced content of CO2 or fuel components CO and CH4 which contain carbon so that when combusted in a suitable gas turbine there may be minimal or reduced emissions of CO2 to the atmosphere. These example methods may result in a capture of the bulk of the carbon present in the total natural gas feed as CO2 compressed to pipeline delivery pressure for sequestration.

Abstract: A method of increasing the operational efficiency of an operating gas turbine engine includes supplying mechanical power from a first spool of the operating gas turbine engine to a first electrical machine to thereby generate electrical power using the first electrical machine and supplying mechanical power from a second spool of the operating gas turbine engine to a second electrical machine to thereby generate electrical power using the second electrical machine. The method further includes sensing one or more operational parameters of the operating gas turbine engine and, based on the one or more sensed operational parameters, ceasing to generate electrical power using the second electrical machine, and instead supplying at least a part of the electrical power generated by the first electrical machine to the second electrical machine to operate in motoring mode and to thereby generate and supply mechanical output power to the second spool of the engine.

Abstract: A sensor apparatus and methods for facilitating combustion of a gaseous fuel are provided. The sensor apparatus comprises a combustion apparatus defining a combustion chamber therein. The combustion apparatus is configured to combust a fuel-air mixture within the combustion chamber to produce at least one combustion product. At least one optical diagnostic apparatus is coupled to the combustion apparatus for measuring at least one property of the at least one combustion product within the combustion chamber. A controller is coupled to the at least one optical diagnostic apparatus, and is configured to determine the Wobbe index of the fuel in real-time based on the measured at least one property of the at least one combustion product and pre-determined combustion state data stored within the controller.

Abstract: A control system for operating a device in a turbo machine system. The system includes a first programmable logic control device producing an analog output signal and a relay circuit electrically connected to the first programmable logic control device to receive the analog output signal. A field device is electrically connected to the relay circuit to receive the analog output signal to operate based on the analog output signal to provide a load. In addition, the relay circuit is electrically connected to a second programmable logic control device to communicate the analog output signal to the second programmable logic control device to monitor the analog output signal.

Abstract: An object is to reduce a fluctuation in the gas-turbine output in a nozzle switching period. In the nozzle switching period during which a first nozzle group that has been used is switched to a second nozzle group that is going to be used, the amounts of fuel supplied through the first nozzle group and the second nozzle group are adjusted by using at least one adjustment parameter registered in advance, the adjustment parameter registered in advance is updated according to the operating condition of the gas turbine, and the updated adjustment parameter is registered as an adjustment parameter to be used next.

Abstract: A method and system for measuring a flow profile in a portion of a flow path in a turbine engine is provided. The system includes a mass flow sensor assembly having a plurality of hot wire mass flow sensors, the mass flow sensor assembly disposed in the portion of the flow path at a location where the flow profile is to be measured. The system also includes a controller that converts signals from the temperature sensor, the pressure sensor and the plurality of hot wire mass flow sensors to flow profile measurements.

Abstract: The power generation system includes a fuel cell that generates electric power using a fuel gas, a gas turbine including an air compressor, a combustor, and a turbine, an exhaust fuel line that introduces an exhaust fuel gas discharged from the fuel cell into the combustor, a branch exhaust fuel line branching off midway from the exhaust fuel line, a switching unit that sends the exhaust fuel gas to one of the branch exhaust fuel line and the combustor, and a heating portion that heats the exhaust fuel line at a downstream side of the switching unit.

Abstract: A gas turbine includes a compressor section, a combustion section downstream from the compressor section, a turbine section downstream from the combustion section, and a controller. The controller controls the operation of the gas turbine at a reduced load, and is capable of querying a database including multiple sets of operational parameters for the gas turbine correlated with at least one measured output response at each set of operational parameters. One of the sets of operational parameters provides a desired gas turbine load that meets a target level for the output response. Related methods are also disclosed.

Abstract: Embodiments of the present invention have the technical effect of automatically testing an overspeed protection system of a powerplant machine comprising at least one shaft. An embodiment of the present invention may automatically test the overspeed protection system while the powerplant machine is decelerating from full-speed-no-load (FSNL). Another embodiment of the present invention may automatically test the overspeed protection system of the powerplant machine while the powerplant machine is accelerating to FSNL.

Abstract: Systems and methods for controlling mode transfers of a turbine combustor are provided. According to one embodiment, a system may include a controller to control a combustor, and a processor communicatively coupled to the controller. The processor may be configured to receive current operating conditions, target operating limits, and combustor transfer functions. The combustor transfer functions may be evaluated to estimate operating limits associated with one or more combustion modes under the current operating conditions. The estimated operating limits associated with the one or more combustor modes may be compared to the target operating limits, and, based on the comparison, at least one of the combustion modes may be selected. The combustor may then be selectively transferred to the selected combustion mode.

Abstract: One embodiment according to the present invention is a unique system for gas turbine engine control. Other embodiments include unique apparatuses, systems, devices, and methods relating to gas turbine engines. Further embodiments, forms, objects, features, advantages, aspects, and benefits of the present invention shall become apparent from the following description and drawings.

Abstract: A method for determining the speed of at least one rotating fan, such as a propeller, through sensing pressure waves generated by the blades of the fan. An apparatus operable to execute the method is also disclosed. The apparatus includes a fan having a hub portion and a plurality of blades extending radially outward from the hub portion. The apparatus also includes an engine operable to rotate the fan about an axis of rotation. The apparatus also includes a sensor spaced from the fan along the axis of rotation. The sensor is positioned to sense at least one physical condition that is external of the engine and is changed by rotation of the plurality of blades. The sensor is operable to emit a signal corresponding to at least one physical condition. The apparatus also includes a processor operably engaged with the engine and the sensor. The processor is operable to receive the signal from the sensor and change the operation of the engine in response to the signal to change a speed of the fan.

Abstract: The disclosure relates to a method for determining a temperature in a pressurized flow path of a gas turbine comprising the steps of sending an acoustic signal from an acoustic signal emitting transducer across a section of the pressurized flow path, detecting the acoustic signal with a receiving transducer, measuring the time needed by the acoustic signal to travel from the acoustic signal emitting transducer to the receiving transducer, calculating the speed of sound, and calculating the temperature as a function of the speed of sound, the heat capacity ratio (?) and a specific gas constant (Rspec) of the gas flowing in the pressurized flow path. Besides the method, a gas turbine with a processor and transducers arranged to carry out such a method is disclosed.

Abstract: Systems and methods for distributing torque contribution are provided. According to one embodiment, a system may include a controller and a processor communicatively coupled to the controller. The processor may be configured to receive initial and final transition speeds of the drivetrain, receive a torque reference for accelerating the drivetrain, provide the starting device with primary control of the acceleration of the drivetrain according to the torque reference, and determine that the initial transition speed is reached. Based on the determination, the processor may capture initial transitional conditions of the starting device, define a torque trajectory of the starting device based on the initial and final transition speeds of the drivetrain, and transfer the primary control of the acceleration of the drivetrain from the starting device to the gas turbine.

Abstract: An example method of allocating power within a gas turbine engine includes driving an off-take power delivery assembly using a first amount of power from a spool, the first amount of power corresponding to an off-take power requirement of a gas turbine engine; and driving the spool of the gas turbine engine using a second amount of power, wherein a ratio of the first amount of power to the second amount of power is greater than or equal to 0.009.

Abstract: A bleed valve module for mounting to a support structure within an aircraft includes a pipe, a plurality of bleed valves connected to the pipe, a plurality of pneumatic actuators connected to the plurality of bleed valves, and a vibration isolating element. The pipe contains a flow of bleed air and includes a plurality of inlets and an outlet. The plurality of bleed valves controls the flow of bleed air in the pipe. The plurality of pneumatic actuators actuate the plurality of bleed valves. The vibration isolating element connects the bleed valve module to the support structure within the aircraft and isolates the bleed valve module from vibration.

Abstract: A Controller, a gas turbine, and a method for auto-tuning a combustion system of a gas turbine are provided. The method includes selecting a first tuning curve from a set of tuning curves for the gas turbine; unbalancing a stable operating point of the gas turbine by modifying one or more operational parameters based on a predefined recipe; determining tuning parameters and storing them while a current operating point of the gas turbine is brought back on the first tuning curve; and generating a backup of tuning parameters to recover the stable operating point.

Abstract: A method and apparatus for boosting the performance of gas turbine engines, pipelines, and other applications using gas turbine engine systems. A pressurizing device or other source is preferably used to deliver an intake air stream to the gas turbine engine at at least 2% above atmospheric pressure. The pressurizing device of other source is preferably not mechanically driven by the gas turbine engine itself.

Abstract: A regulator device (10) for regulating a turbine engine (3). The regulator device (10) includes mechanical power take-off means (100) for taking off power mechanically from a gas generator (4), and an engine computer (20) controlling said engine (3) to comply with at least a first limitation (LimTET, LimT45) of a temperature (TET, T45) of the gas within the engine, and with a second limitation (LimNg) of a speed of rotation (Ng) of the gas generator (4). The engine computer (20) determines whether the speed of rotation (Ng) of the gas generator has reached said second limitation (LimNg), and whether said temperature (TET, T45) has reached said first limitation (LimTET, LimT45). An avionics computer (30) causes the mechanical power take-off means (100) to operate if the speed of rotation (Ng) of the gas generator (4) has reached said second limitation (LimNg), and if said temperature (TET, T45) has not reached said first limitation (LimTET, LimT45).

Abstract: The present invention provides a system and method of operating a combined-cycle powerplant at part-load without shutting down an HRSG and steam turbine. The present invention may apply to a powerplant operating in an open-cycle mode. The present invention may also apply to a powerplant operating in a closed-cycle mode.

Abstract: Systems and methods are provided that include a gas turbine, a generator coupled to the gas turbine and configured to generate a first electrical power output, and a variable frequency transformer coupled to the generator and configured to be coupled to an electrical grid such that the variable frequency transformer is configured to transform the first electrical power output into a second electrical power output having one or more power characteristics that correspond to the electrical grid.

Abstract: A method for measuring combustion parameters within a combustion zone of a gas turbine engine, the combustion zone being defined between an inner and outer casing. The method includes transmitting a beam from a transmit optic optically coupled to a bore in the outer casing off a portion of the inner casing and receiving a portion of the beam reflected off the inner casing with a receiving optic optically coupled to a bore in the outer casing. An apparatus for practicing the method includes a laser generating a beam and a transmitting/receiving optics pair, the transmitting/receiving optics pair being configured for operative association with a port in an outer casing of a gas turbine engine, whereby the transmitting/receiving optics are in optical communication by reflecting the beam off a portion of an inner casing.

Abstract: A combined cycle power plant startup system is provided. The system includes a steam turbine, a HRSG, a condenser, and a bypass system. The steam turbine may include a turbine section. The HRSG may be operably connected to the steam turbine for providing steam to the steam turbine. The HRSG may include a reheater. The bypass system may be configured to adjust the steam pressure downstream of the reheater by routing steam downstream of the reheater to the condenser. The bypass system may include at least one bypass line, at least one control valve operably connected to the at least one bypass line, a pressure gauge configured to monitor the steam pressure downstream of the reheater, and a controller configured to communicate with the pressure gauge and operate the at least one control valve.

Abstract: According to one aspect of the invention, a method for conditioning air received by a power generation system includes flowing ventilation air through a turbine system to control a temperature of the turbine system and receiving the ventilation air from the turbine system and mixing the ventilation with an ambient air to form an intake air to be directed to a compressor, wherein a temperature of the ventilation air is greater than the ambient air.

Abstract: Embodiments of the invention can provide systems and methods for modifying the operation and/or performance of a gas turbine. According to one embodiment, a method for modifying the performance of a gas turbine comprising one or more combustors can be provided. The method can include measuring a gas exhaust temperature for the gas turbine and estimating a heat transfer rate for the gas turbine based at least in part on the gas exhaust temperature. After estimating the heat transfer rate, the method can continue by estimating a transiently accurate combustion reference temperature and using this parameter to control the one or more combustors of the gas turbine. In doing so, the performance of the gas turbine can be modified to ensure reliable and consistent operation.

Abstract: Embodiments for controlling a gas turbine engine to minimize combustion dynamics and emissions are disclosed. Methods and an apparatus are provided for controlling the gas turbine engine where a compressor inlet temperature is measured and a turbine reference temperature is calculated in real-time and utilized to determine the most-efficient fuel splits and operating conditions for each of the fuel circuits. The fuel flow for the fuel circuits are then adjusted according to the identified fuel split.