Abstract: Disclosed is a dual-mode ramjet engine including: a combustor through which air flowing in from the front passes; a sliding injector configured to perform a sliding operation from an upper surface of the combustor along a height direction perpendicular to an air flow direction; and a cavity-type flame holder formed behind the sliding injector on the upper surface of the combustor and having a cavity that is concavely recessed, wherein the sliding injector includes: a plurality of fuel injection holes formed on both sides and configured to inject fuel; a fuel injection passage passing through the inside along the height direction to be opened downward, and configured to inject fuel; and a first sliding drive unit configured to drive the sliding injector to perform the sliding operation.

Abstract: An infrared suppressor adapted for use with a gas turbine engine includes a first ring arranged circumferentially around a central axis, a second ring arranged circumferentially around the central axis, and a strut that extends radially between and interconnects the first ring and the second ring. A portion of the second ring extends radially toward the first ring such that the portion of the second ring cooperates with the first ring to block line-of-sight into the infrared suppressor.

Abstract: A turbine engine can include a compressor section, a combustion section, and a turbine section in serial flow arrangement. The combustion section can include a combustor liner, a dome assembly coupled to the combustor liner, a fuel nozzle fluidly coupled to the dome assembly, a combustion chamber fluidly coupled to the fuel nozzle, and at least one set of dilution openings located in the dome assembly or combustor liner that fluidly couple to the combustion chamber. A swirler can define at least one passage extending between at least one annular entrance and at least one annular exit, wherein the at least one annular entrance is fluidly coupled to the compressor section. A variable area device is movable relative to the at least one set of dilution openings or at least a portion of the swirler.

Abstract: A turbo type pump configured to pressurize a fluid and supply the fluid to a downstream side of a fluid passage by rotation of an impeller provided in the fluid passage, includes: a reduced-diameter portion having a reduced inner diameter in a state of forming a reverse surface facing a downstream side, the reduced-diameter portion being provided at a portion located on an upstream side of the impeller in the fluid passage; and a reverse partition wall portion provided in the reverse surface and configured to restrict a flow of the fluid in a circumferential direction.

Abstract: A combustor for a gas turbine includes a combustor liner that has an outer liner and an inner liner. At least one of the outer liner and the inner liner includes (a) an upstream liner section fixedly connected in the combustor, (b) a downstream liner section fixedly connected in the combustor, and (c) a dilution liner section including a movable portion including at least a part of the dilution liner section and having at least one dilution opening therethrough. The movable portion is arranged to translate in an upstream direction and in a downstream direction. At least one actuator is connected to the movable portion of the dilution liner section and controls translational movement of the movable portion in the upstream direction and the downstream direction to adjust a volume of a primary combustion zone within the combustor.

Abstract: An engine can utilize a combustor to combust fuel to drive the engine. A fuel nozzle assembly can supply fuel to the combustor for combustion or ignition of the fuel. The fuel nozzle assembly can include a swirler and a fuel nozzle to supply a mixture of fuel and air for combustion, which can supply a primary fuel supply and a secondary fuel supply. Increasing efficiency and reducing emission require the use of alternative fuels, which combust at higher temperatures or burn at faster burn speeds than traditional fuels, requiring improved fuel introduction without the occurrence of flame holding or flashback.

Abstract: A method for detecting flameholding in at least one combustor of a turbine engine includes measuring dynamic pressure data of the at least one combustor of the turbine engine; converting the dynamic pressure data to frequency-domain spectral energy amplitudes for the dynamic pressure data; and comparing the spectral energy amplitudes against a dynamic amplitude threshold value to determine whether the amplitudes exceed the threshold minimum amplitude value, wherein exceeding the dynamic amplitude threshold indicates a flameholding occurrence.

Abstract: An apparatus and method for injectors for use in combustion systems employing multiple non-solid or gas streams such as supercritical CO2 systems. The apparatus and method allow for reactants to be injected into a combustion chamber in such a way that combustion is locally inhibited. Injectors employing an inner and outer tube are designed to minimize mixing between the non-solid gas streams and allow for swirling and stratification of the non-solid or gas streams.

Abstract: A combustor for a gas turbine engine, the gas turbine engine defining a longitudinal centerline extending in a longitudinal direction, a radial direction extending orthogonally outward from the longitudinal centerline, and a circumferential direction extending concentrically around the longitudinal centerline, the combustor including: a forward liner segment; an aft liner segment disposed downstream from the forward liner segment relative to a direction of flow through the combustor, the forward and aft liner segments at least partially defining a combustion chamber; and an intermediate member disposed at least partially between the forward and aft liner segments and extending in the circumferential direction.

Abstract: A gas turbine engine includes a core engine casing and a bypass duct defined between a nacelle and the core engine casing. The gas turbine engine further includes a plurality of diverter fences pivotally coupled to the core engine casing. Each diverter fence is pivotable relative to the core engine casing about a pivot axis, which is circumferentially and obliquely inclined with respect to a principal rotational axis. Each diverter fence is configured to move between a first position in which an outboard edge is disposed adjacent to a casing outer surface, and a second position in which the outboard edge is radially spaced apart from the casing outer surface, such that each diverter fence radially extends outwards from the casing outer surface into the bypass duct.

Abstract: A combustor for a gas turbine engine, the gas turbine engine defining a longitudinal centerline extending in a longitudinal direction, a radial direction extending orthogonally outward from the longitudinal centerline, and a circumferential direction extending concentrically around the longitudinal centerline, the combustor including: a forward liner segment; an aft liner segment disposed downstream from the forward liner segment relative to a direction of flow through the combustor, the forward and aft liner segments at least partially defining a combustion chamber; and an intermediate member disposed at least partially between the forward and aft liner segments and extending in the circumferential direction.

Abstract: A combustor for a gas turbine has a combustor liner including an outer liner and an inner liner, a combustion chamber being defined between the outer liner and the inner liner. The combustion chamber includes a primary combustion zone at an upstream end of the combustion chamber. The combustor also includes an outer liner expanded primary volume portion, and a secondary outer liner portion. One of the outer liner expanded primary volume portion and the secondary outer liner portion is movable to adjust a volume of the primary combustion zone by opening and closing access to the outer liner expanded primary volume portion so as to increase and to decrease the volume of the primary combustion zone.

Abstract: An assembly of a gas turbine engine includes a low pressure compressor, a high pressure compressor, an intermediate case between the low pressure compressor and the high pressure compressor, and a cleaning apparatus having an annular arrangement about the intermediate case. A core flow path is defined through the low pressure compressor, the intermediate case, and the high pressure compressor. The annular arrangement includes a scroll portion configured to extract debris from an airstream at an outer diameter wall of the core flow path and return the airstream to the core flow path.

Abstract: Systems and methods to control gas turbine firing temperatures during air injection. A method of achieving a desired firing temperature of a gas turbine engine during air injection comprises injecting compressed air into the gas turbine engine using an external source. The external source includes a compressor and a recuperator. The method comprises using a controller of the gas turbine engine to: (a) determine an air injection exhaust bias gain using an inlet temperature of the gas turbine engine; (b) calculate, based on the determined air injection exhaust bias gain and a flow rate of the injected compressed air, an air injection exhaust curve bias; and (c) change a fuel flow of the gas turbine engine by adding the air injection exhaust curve bias to an existing exhaust curve of the gas turbine engine to thereby achieve the desired firing temperature during air injection.

Abstract: An injection system for a turbomachine combustion chamber includes a swirler and a mixing bowl. The mixing bowl includes a converging frustoconical portion and a diverging frustoconical portion. The diverging frustoconical portion is connected to the converging frustoconical portion, forming a continuous aerodynamic profile with the converging frustoconical portion. The diverging frustoconical portion is passed through by vortex holes which each includes a circumferential component around a longitudinal axis of the injection system and an axial component along the longitudinal axis of the injection system.

Abstract: An engine can utilize a combustor to combust fuel to drive the engine. A fuel nozzle assembly can supply fuel to the combustor for combustion or ignition of the fuel. The fuel nozzle assembly can include a swirler and a fuel nozzle to supply a mixture of fuel and air for combustion, which can supply a primary fuel supply and a secondary fuel supply. Increasing efficiency and reducing emission require the use of alternative fuels, which combust at higher temperatures or burn at faster burn speeds than traditional fuels, requiring improved fuel introduction without the occurrence of flame holding or flashback.

Abstract: In general, techniques are described by which to provide a turbine engine compressor particulate offtake. A gas turbine engine comprising a compressor may perform the techniques. The compressor may comprise a plurality of compressor stages, where each compressor stage comprises a circumferential row of stator vanes and a rotor. The compressor may also include an outer circumferential casing that defines a fluidic opening within or between adjacent compressor stages. The fluidic opening may be configured to receive particulate flowing and air through the compressor and output the particulate and air outside of the gas turbine engine. The gas turbine engine also includes a combustor in series flow downstream of the compressor, and a turbine in series flow downstream of the combustor.

Abstract: A fuel injector includes a fuel nozzle configured to issue a spray of fuel from a fuel outlet in a downstream direction along an injection axis. The fuel nozzle defines a main flow passage therethrough. An injection fuel line is in fluid communication with the fuel nozzle to supply fuel to the fuel nozzle. A torch ignitor has a flame outlet opening into the main flow passage of the fuel nozzle for issuing flame into the main flow passage.

Abstract: A method of operating a combustor of a gas turbine, the combustor including a combustor liner that defines a total combustion chamber volume, and has a primary combustion zone defining a primary volume. The combustor liner includes a movable portion that is arranged to be actuated to adjust a percentage of the primary volume with respect to the total combustion chamber volume. The method includes, at a first operating state of the gas turbine, adjusting a size of the primary volume to a first percentage of the total combustion chamber volume by actuating the movable portion to adjust the size of the primary volume, and at a second operating state of the gas turbine different from the first operating state, adjusting the size of the primary volume to a second percentage of the total combustion chamber volume by actuating the movable portion to adjust the size of the primary volume.

Abstract: The fuel nozzle for the gas turbine includes a radial swirler and an axial swirler. The radial swirler is arranged to swirl a first flow of a first oxidant-fuel mixture and the axial swirler is arranged to swirl a second flow of a second oxidant-fuel mixture. The first flow may be fed by a central conduit and the second flow may be fed by an annular conduit surrounding the central conduit.

Abstract: Tail cone assemblies for gas turbine engines are described. The tail cone assemblies include a generator housing having an electrical connector, the generator housing defining a longitudinal axis. A first casing is arranged radially outward from the generator housing relative to the longitudinal axis and a second casing arranged radially outward from the first casing relative to the longitudinal axis. A hollow strut extends radially between the first casing and the second casing and defining an interior cavity, the hollow strut located circumferentially relative to the longitudinal axis at a location radially aligned with the electrical connector of the generator housing. An electrical conductor is arranged within the interior cavity of the hollow strut and an adapter is configured to electrically connect the electrical conductor with the electrical conductor.

Abstract: A system has: a combustor; a plenum surrounding the combustor; a transfer tube having an inlet fluidly connected to the plenum and at least two outlets, a first flow passageway defined between the inlet and a first outlet, a second flow passageway defined between the inlet and a second outlet, the second flow passageway connected to a discharge region outside of the plenum; a flow valve disposed within the second flow passageway and operable between an open position and a closed position, in the open position the flow valve fluidly connects the plenum with the discharge region, in the closed position the flow valve blocking fluid communication between the plenum and the discharge region; and a controller communicatively coupled to the flow valve to control operation thereof by: causing the flow valve to open for a time period; and subsequent to the time period, causing the flow valve to close.

Abstract: The electrical power generation system including a micro-turbine including a combustor, a first stage turbine configured to be driven by a combustor exhaust from the combustor, at least one compressor operably connected to the combustor to provide a compressed airflow to the combustor, a catalytic converter configured convert the combustor exhaust to a catalytic exhaust that includes at least exothermic heat, a second stage turbine configured to be driven by the catalytic exhaust from the catalytic converter, and one or more shafts connecting the first stage turbine and the second stage turbine to the at least one compressor such that rotation of the first stage turbine and the second stage turbine drives rotation of the at least one compressor.

Abstract: An engine may include an integrated diffuser-bleed baffle assembly, a diffuser, and a bleed port. The integrated diffuser-bleed baffle assembly fluidly coupled between the diffuser and the bleed port. The integrated diffuser-bleed baffle assembly is configured to flow a boundary layer flow from the diffuser to the bleed port. A baffle hole may be included in the integrated diffuser-bleed baffle assembly such that the assembly may function to dampen acoustic instabilities in the engine.

Abstract: An assembly for a gas turbine having a combustion chamber, a swirler, a combustion zone in the combustion chamber, and an air feed. In a transition region from the air feed to the swirler that is flowed through by the air, a plenum is formed and the assembly adjoining the plenum has the swirler, the combustion chamber, and a cover closing the combustion chamber. The assembly has an air conduction channel designed to conduct part of the air flow flowing into the assembly into the combustion chamber, so that the air flow leading through the air feed is divided into a main flow leading through the swirler into the combustion zone and a bypass flow leading past the combustion zone.

Abstract: A module (4) for an aircraft turbomachine comprises an assembly of constant-volume combustion chambers, and including a first sub-assembly of first chambers succeeding each other along a given sense (76) and forming series of chambers (S1), and within each series (S1), a first ignition chamber (C1.1) located at one of both circumferential ends of the series is defined, the first ignition chamber (C1.1) being connected to the first directly consecutive chamber (C1.2) along the given sense (76) so as to supply the same with exhaust gases, and so forth up to the first chamber (C1.3) located at the other circumferential end of the series. In addition, a control device (46) is configured such that for all the first ignition chambers (C1.1), diametrically opposite two by two, the combustion cycles are simultaneously initiated. Finally, a second sub-assembly comprising second combustion chambers (C2.1-C2.3) is also provided.

Abstract: A self-adapting gas turbine firebox with variable geometry includes at least one system with variable opening for automatically adjusting a combustion configuration inside a combustion chamber according to an air temperature, particularly of air from a compressor. The adjustment is performed by a thermosensitive member that controls at least one cross-sectional area of a passage to the combustion chamber, for air which participates in the combustion of fuel or participates in a dilution of gases effective inside the combustion chamber.

Abstract: The present disclosure relates to systems and methods that are useful for controlling one or more aspects of a power production plant. More particularly, the disclosure relates to power production plants and methods of carrying out a power production method utilizing different fuel chemistries. Combustion of the different fuel mixtures can be controlled so that a defined set of combustion characteristics remains substantially constant across a range of different fuel chemistries.

Abstract: An injection system includes a radial swirler defining an axis and including a plurality of radial swirl vanes configured to direct a radially inward flow of compressor discharge air entering swirler inlets between the radial swirl vanes in a swirling direction around the axis. The radial swirler includes an outlet oriented in an axial direction to direct swirling compressor discharge air in an axial direction. An injector ring is included radially outward from of the swirler inlets. The fuel injector ring is aligned with the axis and includes a plurality of injection orifices directed towards the swirler inlets for injecting fuel into the radial swirler.

Abstract: This disclosure provides an air tube for a combustor of a gas turbine engine. The air tube includes an inner tube and an outer tube to deliver discharged compressor air into a combustion chamber of the combustor. The air tube can include struts and fins that can improve the cooling performance of the air tube during operation of the gas turbine engine.

Abstract: A combustor section of a gas turbine engine includes a combustor having a combustor inlet, and a combustor bypass passage having a passage inlet located upstream of the combustor inlet, the combustor bypass passage configured to divert a selected bypass airflow around the combustor. A combustor bypass valve is located at the combustor bypass passage to control the selected bypass airflow along the combustor bypass passage. The combustor bypass valve including a valve element configured to rotate about an engine central longitudinal axis A to move one or more valve openings relative to one or more bypass passage openings.

Abstract: Embodiments of a combustor for a gas turbine engine are provided herein. In some embodiments, a combustion chamber for a gas turbine engine comprising may include a combustor having an inner volume defined at least partially by a front wall, wherein the wall comprises a plurality of facets each having a through hole fluidly coupled to the inner volume, and wherein the plurality of facets are oriented such that an axis of each of the plurality of facets is offset from a central axis of the combustor by an angle.

Abstract: A fuel injector for a gas turbine engine includes a feed arm defining a conduit extending between an inlet end and an outlet end and a plunger. The plunger is disposed within the conduit and is movable between a plunger first position and a plunger second position. A flow area defined between the plunger and the feed arm is smaller in the plunger first position than in the plunger second position to bias fuel flow through the fuel injector. Fuel systems, gas turbine engines, and methods of controlling fuel flow in gas turbine engine fuel systems are also described.

Abstract: A combustor for a gas turbine, having a pre-combustion chamber having a peripheral wall around a center axis of the pre-combustion chamber, the peripheral wall has an inner panel and an outer panel and a passage provided between the inner and the outer panels, a swirler which is connected to the pre-combustion chamber for providing pre-combustion chamber with a flow of an oxidant gas, at least a pilot fuel injector, wherein the swirler is connected to the peripheral wall in such a way that a portion of the oxidant gas from the swirler is channeled to the passage, and the pilot fuel injector is connected to the passage for injecting a flow of pilot fuel into the passage.

Abstract: A bleed valve system for a gas turbine engine that includes a retaining ring and a metering ring. The retaining ring abuts an end of a bleed air duct and defines a plurality of retaining ring apertures. The metering ring that is at least partially disposed within the bleed air duct and abuts the retaining ring, the metering ring defining a plurality of metering ring apertures, the metering ring being rotatable relative to the retaining ring to selectively facilitate a fluid flow through the bleed air duct.

Abstract: A combustor assembly for a gas turbine engine is provided. The combustor assembly generally includes an annular dome and a liner that at least partially define a combustion chamber. The annular dome defines a plurality of circumferentially spaced fuel injection ports and a plurality of mounting assemblies are configured for receiving and supporting a plurality of fuel injector assemblies within the fuel injection ports. Each mounting assembly includes a ferrule positioned adjacent to and extending around a peripheral edge of the respective fuel injection port. A spring finger is coupled to an interior surface of the ferrule and extends toward a centerline of the fuel injection port to form a seal with the fuel injector assembly.

Abstract: A cylinder for a combustor includes a cylindrical member, a first cooling passage defined in the cylindrical member and a second cooling passage defined in the cylindrical member, and a supply port extender. The first cooling passage includes a supply port that opens to an outer peripheral surface of the cylindrical member. The second cooling passage includes a discharge port that opens to the outer peripheral surface of the cylindrical member downstream of the supply port. The supply port extender includes a first wall that is disposed between the supply port and the discharge port and extends away from the outer peripheral surface of the cylindrical member and a second wall that is disposed upstream of the supply port and extends away from the outer peripheral surface of the cylindrical member.

Abstract: Variable vane devices containing rotationally-driven translating vane structures are provided, as are methods for fabricating variable vane devices. In one embodiment, the variable vane device includes a flow assembly having a centerline, an annular flow passage extending through the flow assembly, cam mechanisms, and rotationally-driven translating vane structures coupled to the flow assembly and rotatable relative thereto. The translating vane structures include vane bodies positioned within the annular flow passage and angularly spaced about the centerline. During operation of the variable vane device, the cam mechanisms adjust translational positions of the vane bodies within the annular flow passage in conjunction with rotation of the translating vane structures relative to the flow assembly.

Abstract: The invention refers to a combustor arrangement of a gas turbine engine or power plant, having at least one combustion chamber, at least one mixer for admixing a dilution medium or air to the hot gas flow leaving the combustion chamber. The mixer is configured to guide combustion gases in a hot gas flow path extending downstream of the combustion chamber, wherein the mixer includes a plurality of injection pipes pointing inwards from the side walls of the mixer for admixing the dilution medium or air to cool the hot gas flow leaving combustion chamber. The mixer includes at least one dilution air plenum having at least one pressure-controlled compartment which is directly or indirectly connected to at least one injection pipe.

Abstract: A combustor is provided in which a fuel and working fluid can be injected in an annulus. In one form the fuel and working fluid is circumferentially flowed within the annulus and traverses the annulus in an axial direction from one side to another side where the flow exits. The working fluid and air can be co-axially admitted to the combustor and in one form the working fluid can be swirled about the fuel dispensed from a fuel injector. The combustor can provide for a rich burning zone. In one embodiment the combustor is configured as an inter-turbine combustor having an outlet at one axial side of the combustor. A lean burn region can be created within a flow path of the turbine.

Abstract: According to one aspect of the present disclosure, a lubrication monitoring system is disclosed that includes a fan, a gear reduction operatively coupled to the fan, and a lubrication pump that is operatively coupled to the fan and is in fluid communication with the gear reduction. A first sensor is configured to detect a windmilling condition of the fan, and a second sensor is configured to detect an operational state of the lubrication pump. A controller in communication with the first and second sensors is configured to monitor the windmilling condition and the operational state of the lubrication pump, and command a status indicator in response thereto.

Abstract: In a featured embodiment, a gas turbine engine has a compressor section having a downstream rotor and a diffuser downstream of the compressor section. A combustor receives air downstream of the diffuser. A turbine section has at least one component to be cooled. A conduit is spaced from the diffuser and defines a cooling airflow path. The cooling airflow path is separate from an airflow downstream the diffuser, and passing to the combustor. The conduit passes cooling air to the component to be cooled.

Abstract: A fuel nozzle configured to channel fluid towards a combustion chamber is provided. The fuel nozzle includes a stem having a central passageway and at least one fuel tube disposed within the passageway. The fuel tube includes an outlet end portion having inner and outer walls separated by a cavity defined by a fixed aft face. The inner wall defines a central bore for delivering fuel to the combustion chamber. Further, the fuel nozzle includes an outer heat shield tube concentrically aligned with the outlet end portion of the fuel tube. The heat shield tube includes a circumferential outer wall having an aft face that stops upstream of the fixed aft face of the fuel tube. Thus, during operation, the heat shield tube is configured to thermally expand by sliding against the outer wall of the fuel tube.

Abstract: This invention provides a gas turbine power generation equipment adapted to prevent step out of an electric power generator due to a system trouble such as a momentary power failure in a local grid including intermittent renewable energy generation equipment and the gas turbine power generation equipment. The gas turbine power generation equipment that supplies electric power in cooperation with the intermittent renewable energy generation equipment in the local grid interconnected to a power grid includes: a fuel flow control valve that controls a flow rate of fuel supplied to a combustor; a bleed valve or inlet air flow control valve that controls a flow rate of air compressed by a compressor and supplied to the combustor; and a control unit configured so that if voltage on the power grid decreases below a threshold V(t), the control unit outputs a control signal to at least one of the fuel flow control valve, the bleed valve, and the inlet air flow control valve.

Abstract: Method and computer-readable model for additively manufacturing a ducting arrangement (20) in a combustion stage are provided. The ducting arrangement may include a combustor wall (40) in a combustion stage fluidly coupled to receive a cross-flow of combustion products (21). An injector assembly (12) may be in fluid communication with cooling fluid conduits (46) in the combustor wall to receive cooling fluid that passes through the cooling fluid conduits. The injector assembly may include means for injecting (24, 25, 26) a flow of the cooling fluid (22) arranged to condition interaction of a flow of reactants (19) injected with the cross-flow of combustion products. Respective duct components or the entire ducting arrangement may be formed as a unitized structure, such as a single piece using a rapid manufacturing technology, such as 3D Printing/Additive Manufacturing (AM) technologies.

Abstract: An adaptation method for a modelling method in which, by means of target geometry, model geometry, which is derived from the target geometry, is created for an object to be produced by a selective laser melting method is provided. In the adaptation method, adapted model geometry is produced from the derived model geometry by dimension adaptation by means of a correction factor and/or by geometry adaptation by means of correction geometry.

Abstract: A system includes a turbine combustor, which includes a first wall disposed about a combustion chamber, a second wall disposed about the first wall, and a third wall disposed about the second wall. The third wall is configured to combine an exhaust gas with an oxidant and the combustion chamber is configured to combust a mixture of a fuel, the oxidant, and the exhaust gas.

Abstract: The present invention discloses a novel and improved apparatus and method for reducing the emissions of a gas turbine combustion system. More specifically, a combustion system is provided having a first combustion chamber and a premixer positioned proximate an outlet end of a combustion liner for mixing a second fuel/air mixture with hot combustion gases and burning the subsequent mixture to achieve reduced emissions levels. The premixer is positioned generally about the combustion liner and includes a plurality of channels and fuel injectors for introducing a fuel/air mixture, induced with a swirl, into a second, axially staged combustor.

Abstract: The present disclosure generally relates to a system with a gas turbine engine including a first combustor and a second combustor. The first combustor includes a first end cover with a first geometry and the second combustor includes a second end cover with a second geometry. The first geometry has one or more geometric differences relative to the second geometry.

Abstract: The invention relates generally to electrical power systems, including generating capacity of a gas turbine, and more specifically to pressurized air injection that is useful for providing additional electrical power during periods of peak electrical power demand from a gas turbine system power plant, as well as to inlet heating to allow increased engine turn down during periods of reduced electrical demand.