Abstract: A twin-spool gas turbine engine including a high-pressure rotor and a low-pressure rotor, which rotors are mounted in bearings supported by an intermediate casing, at least one accessory gear box, and a drive device which drives radial and coaxial shafts for transmitting movement to the accessory gear box is disclosed. The drive device includes a high-pressure drive gear driving one of the radial shafts and connected to the high-pressure rotor and a low-pressure drive gear connected to the low-pressure rotor upstream of the high-pressure drive gear and driving the other of the radial shafts. The low-pressure drive gear is supported in the intermediate casing by an axial-positioning bearing.

Abstract: A gas turbine engine having an adaptive core capable of maintaining a substantially constant core pressure ratio while having a variable flow rate is disclosed. In one aspect, the adaptive core comprises a front block compressor and a rear block compressor.

Abstract: A gas turbine engine comprises a fan drive gear system, a low spool connected to the fan drive gear system, and a high spool disposed aft of the low spool. The low spool comprises a rearward-flow low pressure compressor disposed aft of the fan drive gear system, and a forward-flow low pressure turbine disposed aft of the low pressure compressor. The high spool comprises a forward-flow high pressure turbine disposed aft of the low pressure turbine, a combustor disposed aft of the high pressure turbine, and a forward-flow high pressure compressor disposed aft of the combustor.

Abstract: A gas turbine engine is provided that includes a low pressure spool, a high pressure spool, a stationary support frame, and at least one support arch. The low pressure spool extends between a low pressure compressor and a low pressure turbine. The high pressure spool extends between a high pressure compressor and a high pressure turbine. The spools are rotatable about a center axis of the engine. The support arch has a stationary support mount disposed between a low spool mount and a high spool mount. The support arch is disposed relative to the spools and the stationary support frame so that a load from each spool caused by the rotation of that spool can be transferred to the stationary support frame through the support arch. The support arch can freely rotate about the center axis of the engine relative to the spools and the stationary structural frame.

Abstract: A system for attaching the end of a shaft of a gas turbine engine engaged inside a coupling supported by a bearing is disclosed. The system includes a nut with a first thread which is screwed into the shaft and a second thread which is screwed to the coupling. Advantageously, the screw pitches of the two threads of the nut are reversed relative to one another so as to form an adjusting nut.

Abstract: A method of emergency operation of an aircraft turbofan engine during an aircraft flight is provided. The engine includes a fan shaft with a fan, and an electric motor/generator mounted for rotation therewith. The method includes shutting down the engine while allowing the engine to windmill, operating the electric motor/generator to rotate the shaft at a determined windmilling speed which is desired for the fan shaft, and operating the engine at the desired windmilling speed for substantially a remainder of the aircraft flight.

Abstract: A gas turbine engine includes in serial flow relationship: a first compressor provided with at least one row of compressor blades distributed circumferentially around the first compressor; a combustion chamber; and a first turbine provided with at least one row of turbine blades distributed circumferentially around the first turbine, wherein the first compressor and the first turbine are rotationally rigidly connected by a first shaft. The first turbine is adapted to influence a gas flow rate through the gas turbine engine depending on a rotational speed of the first turbine, wherein the gas turbine engine further includes an arrangement for controlling the rotational speed of the first turbine. A method for controlling a gas flow rate in an axial flow gas turbine engine is also provided.

Abstract: A turbine engine emergency power system includes low and high pressure spools, the lower pressure spool including a low pressure compressor. A turbofan is coupled to the low pressure spool. The turbofan drives the low pressure spool in a windmill condition in which the low pressure turbine fails to provide rotational drive to the turbofan. A generator is rotationally driven by the low pressure spool in the windmill condition. A gear train is used to increase the speed of the generator in one example. In one example embodiment, a centrifugal clutch is used to selectively decouple the generator from the low pressure spool at a predetermined engine speed, which corresponds to normal operating speeds when the turbine engine is under power.

Abstract: A gas turbine engine is disclosed having a compressor, a combustion chamber downstream of the compressor, and a turbine downstream of the combustion chamber. The compressor includes a first group of compressor blade wheels and a second group of compressor blade wheels downstream of the first group of compressor blade wheels and rotating in an opposite direction such that a deviation of a performance, defined as air mass flow per second between the first group of compressor blade wheels and the second group of compressor blade wheels, is minimized, and a detachment of the air mass flow from blades of a first blade wheel of the second group of compressor blade wheels is substantially eliminated. A bypass enables the air mass flow flowing from the first group of the compressor blade wheels to substantially serve all of the second group of compressor blade wheels substantially simultaneously.

Abstract: A turbine engine assembly includes, a core gas turbine engine, a first low-pressure turbine section in serial flow communication with the core gas turbine engine, the first low-pressure turbine section configured to rotate in a first rotational direction, a first gear assembly coupled to the first low-pressure turbine section, a second low-pressure turbine section coupled to the gear assembly, the second low-pressure turbine section configured to rotate in a second rotational direction, and a fan assembly coupled to the second low-pressure turbine section.

Abstract: A turbine engine particularly suited for VTOL aircraft is disclosed. According to various embodiments, the core of the turbine engine includes two spools—a low pressure (LP) spool and a high pressure (HP) spool—where the LP spool is independently mounted remote to the HP spool. The engine may be modulated for operation by a modulation diverter valve assembly and through the fuel flow to the engine. The power output from the engine can be modulated from high levels to low levels and vice versa through control of the air flow through the engine using the modulation diverter valve assembly. In lift mode operation both the LP and HP spools may be operational, while during the forward flight cruise mode of operation the HP spool is operational and the LP spool may or may not be operational depending upon the power required for the flight condition. For HP spool only operation, the LP spool may be shut down using the modulation diverter valve assembly and an inlet flow diverter valve assembly.

Abstract: A system for actively controlling the working line location within a low pressure compressor. The system includes a plurality of variable inlet guide vanes that are adjusted to maintain the working line at a constant level as the low pressure compressor rotates at a constant speed.

Abstract: A turbine engine particularly suited for VTOL aircraft is disclosed. According to various embodiments, the core of the turbine engine includes two spools—a low pressure (LP) spool and a high pressure (HP) spool—where the LP spool is independently mounted remote to the HP spool. The engine may be modulated for operation by a modulation diverter valve assembly and through the fuel flow to the engine. The power output from the engine can be modulated from high levels to low levels and vice versa through control of the air flow through the engine using the modulation diverter valve assembly. In lift mode operation both the LP and HP spools may be operational, while during the forward flight cruise mode of operation the HP spool is operational and the LP spool may or may not be operational depending upon the power required for the flight condition. For HP spool only operation, the LP spool may be shut down using the modulation diverter valve assembly and an inlet flow diverter valve assembly.

Abstract: A method of assembling a gas turbine assembly includes providing a core gas turbine engine including a high-pressure compressor, a combustor, and a turbine, coupling a low-pressure turbine axially aft from the core gas turbine engine, coupling a fan assembly axially forward from the core gas turbine engine, and coupling a booster compressor to the low-pressure turbine such that the booster compressor and the low-pressure turbine rotate at a first rotational speed.

Abstract: A system for fastening the end of a gas turbine engine shaft engaged inside a sleeve supported by a bearing is disclosed. The system includes a nut that is screwed at one end inside the sleeve, and is connected by a split annular ring with the shaft at the other end.

Abstract: An inner rotor shaft for use in a small twin spool gas turbine engine, the inner rotor shaft having a hollow middle section formed of a smaller diameter hollow section on a compressor end and a larger diameter hollow section on the turbine end of the shaft. Solid shaft end extend from the hollow section to form a forward solid shaft end to secure the fan rotor disk and an aft solid shaft end to secure the turbine rotor disk. A parabolic shaped transition section joins the forward shaft end to the smaller diameter hollow section, and a conical shaped transition section joins the aft shaft end to the larger diameter hollow section. A conical shaped transition piece joins the two hollow sections together to form an inner rotor shaft that can fit within a minimal space between the compressor rotor disk and the annular combustor assembly of the engine.

Abstract: A method of transmitting power among a plurality of shafts in a turbine engine is disclosed herein as well as a turbine engine for practicing the method. The turbine engine includes a compressor section having a low pressure portion and a high pressure portion. The turbine engine also includes a turbine section spaced from the compressor section along a centerline axis. The turbine section includes a low pressure portion and a high pressure portion. The turbine engine also includes a low pressure shaft extending between the low pressure portion of the compressor section and the low pressure portion of the turbine section. The turbine engine also includes a high pressure shaft extending between the high pressure portion of the compressor section and the high pressure portion of the turbine section. The turbine engine also includes a tower shaft operably engaged with both of the low pressure shaft and the high pressure shaft.

Abstract: The method for operating a piston engine system that includes modifying valve timing such that the gas displaced from the piston chamber is at a pressure and temperature nearly equivalent to the temperature and pressure at the end of the combustion stroke rather than being throttled as is the case for traditionally valve timings. When the high temperature and pressure gas enters an exhaust channel, thermally isolating means may line the exhaust channel such that the high temperature of the exhaust gas is maintained. A heat exchanger and an expander may be placed along the exhaust channel such that the high temperature and pressure of the exhaust gas are captured for useful work.

Abstract: A pneumatically driven turbine drive system is coupled to a gas turbine engine that includes low and high pressure compressors, low and high pressure turbines, a lock-up clutch, and at least one engine accessory driven by the high pressure compressor. The pneumatically driven turbine drive system selectively bleeds air discharged from the high pressure compressor and supplies it to an air turbine that is coupled to the at least one engine accessory. Thus, the system selectively reduces the power extracted from the high pressure compressor and is capable of supplying power back to the engine core. This, coupled with the bleed air that is diverted from the high pressure turbine and the low pressure turbine, allows the high pressure spool and the low pressure spool to run at lower speeds when high engine thrust is not needed or desired, but when the at least one engine accessory is still needed.

Abstract: The engine comprises a low pressure stage (1) and a high pressure stage (2) with two independent rotors (3,4) and associated fixed fluid preparation members (9,10,13,14), combining “compressor” means (15,16) and “expander” means (17,18) and at least one combustion chamber (19,20) in a central volume defined axially by the rotors (3,4) and laterally by three substantially cylindrical, coaxial walls (22,23,24), defining in pairs an outer duct (25) connecting the outlet of the LP compressor (15) to the inlet of the HP compressor (16) and an inner duct (26) connecting the outlet of the HP compressor (16) to the inlet of a first combustion chamber (19), whose outlet supplies the HP expander (18) with gases produced by combustion guided to the inlet of the LP expander (17), whose outlet is in communication with the outside via at least one exhaust opening (41) for the combustion gases.

Abstract: A gas turbine propulsion system comprises a turbofan engine, a peripheral duct, an annular frame, an auxiliary turbine and an auxiliary fan. The turbofan engine is configured to produce bypass air and combustion air. The bypass air flows through a bypass duct and the combustion air flows through a core engine. The peripheral duct surrounds the turbofan engine and is configured to selectively receive peripheral inlet air. The annular frame is disposed aft of the bypass duct and the peripheral duct, and is rotatable to alternately guide the bypass air out the bypass duct or the peripheral duct. The auxiliary turbine is connected to an aft end of the core engine and is configured to receive the combustion air. The auxiliary fan is connected to the auxiliary turbine and is configured to receive airflow from the peripheral duct.

Abstract: A method and apparatus are disclosed for a gas turbine power plant with a variable area turbine nozzle and an integrated motor/alternator device for starting the gas turbine and power extraction after starting.

Abstract: A core engine of a variable cycle gas turbine engine includes a low pressure spool for generating streams of bypass air and pressurized air, and a high pressure spool for further pressurizing the stream of pressurized air to generate streams of combustion air and supercharged auxiliary air. A peripheral case surrounds the engine case to form a peripheral duct. An auxiliary combustor and propulsor are positioned within the peripheral duct. A bleed duct extends from the high pressure spool to the auxiliary combustor. Variable ductwork directs airflow through the bleed duct and peripheral duct in two modes. A first mode comprises directing the stream of auxiliary air to the auxiliary combustor, and directing stream of inlet air through the peripheral duct. A second mode comprises directing the stream of auxiliary air into the stream of bypass air, and preventing inlet air from entering the peripheral duct.

Abstract: A gas turbine engine includes a high towershaft driven by a high pressure spool and a low towershaft driven by a low pressure spool.

Abstract: A hybrid microturbine to produce electrical output power within a engine housing, having a combustor, and a two spool multi stage compressor wherein the 1st spool has a compressor rotor and a turbine rotor as a turbocharger and the 2nd rotor spool has an alternator rotor integrated with a compressor rotor and turbine rotor. The two individual compressor rotors have rotating blades attached and located in compressor housings with fluid communication. The alternator rotor as part of the 2nd spool has permanent magnets integrated and positioned in close proximity and co-axial to the electrical stator module having an iron laminated structure with electrical wires. Relative rotational motion between the stator and alternator rotor cause electricity to be generated.

Abstract: The invention relates to a twin spool turbine engine comprising a high-pressure rotor and a low-pressure rotor, at least one accessory gearbox, a drive means, driving coaxial transmission shafts that transmit movement to the accessory gearbox, characterized in that the drive means comprises a high-pressure drive pinion secured to the high-pressure rotor near its upstream end, a low-pressure drive pinion secured to the low-pressure rotor upstream of the high-pressure rotor, and a power take-off module in direct mesh with the drive pinions, driving the transmission shafts. By virtue of the invention, the transmission shafts run coaxial with one another and therefore pass through a single arm. The use of a power take-off module simplifies the mechanism. The turbine engine is simpler to assemble.

Abstract: A turbofan gas turbine propulsion engine includes a system to transfer power from the low pressure turbine to the high pressure turbine and/or extract additional load from the low pressure turbine during certain turbofan engine operational conditions. The systems include a hydrostatic power transfer system that includes a hydraulic pump and a hydraulic motor coupled to the low pressure and high pressure turbine, respectively. The systems additionally include a mechanical and electrical load shifting/loading sharing systems that use clutches and gear assemblies to share and/or shift load between the turbines.

Abstract: A tip turbine engine (10) provides first and second turbines (32) rotatably driven by a combustor (30) generating a high-energy gas stream. The first turbine (32) is mounted at an outer periphery of a first fan (24a), such that the first fan is rotatably driven by the first turbine (32a). The second turbine (32b) is mounted at an outer periphery of a second fan (24b), and is rotatably driven by the high-energy gas stream. In one embodiment, the first turbine (32a) rotatably drives a plurality of stages of first compressor blades (54) in an axial compressor (22) in a first rotational direction, while the second turbine (32b) rotatably drives a plurality of stages of second compressor blades (52) in the axial compressor (22) in a second rotational direction opposite the first. By rotatably driving alternating stages of compressor blades in opposite directions, the efficiency of the axial compressor (22) is increased and/or the number of stages of compressor blades can be reduced.

Abstract: A power take-off system for a gas turbine engine includes a starter coupled to a second spool, and a clutch assembly coupled between the starter and a first spool, the clutch assembly configured to couple the first spool to the starter when starting the gas turbine engine assembly. A method of assembling a gas turbine engine assembly that includes the power take-off system, and a gas turbine engine assembly including the power take-off system are also described.

Abstract: An inner rotor shaft for use in a small twin spool gas turbine engine, the inner rotor shaft having a hollow middle section formed of a smaller diameter hollow section on a compressor end and a larger diameter hollow section on the turbine end of the shaft. Solid shaft end extend from the hollow section to form a forward solid shaft end to secure the fan rotor disk and an aft solid shaft end to secure the turbine rotor disk. A parabolic shaped transition section joins the forward shaft end to the smaller diameter hollow section, and a conical shaped transition section joins the aft shaft end to the larger diameter hollow section. A conical shaped transition piece joins the two hollow sections together to form an inner rotor shaft that can fit within a minimal space between the compressor rotor disk and the annular combustor assembly of the engine.

Abstract: A turbofan gas turbine propulsion engine includes a multi-speed transmission between the high pressure and low pressure turbines and associated high pressure and low pressure starter-generators. The multi-speed transmission reduces the operating speed range from the low pressure turbine to its associated starter-generator, and is configurable to allow the starter-generator associated with the low pressure turbine to supply starting torque to the engine.

Abstract: The invention relates to a device for producing electrical power in a multi-spool gas turbine engine comprising at least one first rotary spool (69), for example a low-pressure spool, and a second rotary spool (24), for example a high-pressure spool, and driving an electrical machine (10). The device is one wherein, with the electrical machine (10) being of the twin-rotor type with a first rotor (13) and a second rotor (14), the first rotor (13) is mechanically connected to the first rotary spool (69) and the second rotor is mechanically connected to the second rotary spool (24).

Abstract: A turbine engine includes low and high pressure spools. A high power take-off shaft is coupled to the high spool. An auxiliary component, such as a generator, is configured to be driven by the high power take-off shaft at a first speed. The low spool, in part, drives the auxiliary component, for example, by interconnecting the high power take-off shaft to a lower power take-off shaft through a speed summing gearbox. The gearbox drives the auxiliary component and increases the rotational speed of the auxiliary component from the first speed to the second speed. The low power take-off shaft also drives another generator, in one example. The turbine engine can be started by the low pressure generator, for example, in response to a command from a controller, which transforms the generator into a starter motor.

Abstract: A high-pressure system and method utilizing an input fluid. The system includes a reactor treating a material to produce an effluent having an energy content, a plurality of stages compressing the input fluid in a stepwise manner providing a high-pressure reactor input stream to the reactor, and a cascading effluent energy recovery system mechanically communicating with the plurality of stages. The cascading effluent energy recovery system imparts a portion of the energy content of the effluent into each of the plurality of stages powering that stage. The method includes receiving an input fluid, compressing the input fluid over a plurality of stages producing the high-pressure stream, providing the high-pressure stream to the reactor, recovering a portion of the energy content of the effluent at each of the plurality of stages, and using each the portion of the energy in compressing the input fluid at a corresponding respective stage.

Abstract: A gas turbine engine assembly is provided. The gas turbine engine assembly includes a core engine. The gas turbine engine assembly further includes a first rotor spool including a first fan assembly, an intermediate-pressure turbine, and a first shaft. The first fan assembly includes a single stage fan assembly coupled upstream from the core engine. The intermediate-pressure turbine includes a single stage turbine coupled downstream from the core engine. The first shaft extends between the first fan assembly and the intermediate-pressure turbine. The gas turbine engine assembly further includes a second rotor spool including a second fan assembly, a low-pressure turbine, and a second shaft. The second fan assembly includes a single stage fan assembly coupled upstream from the first fan assembly. The low-pressure turbine includes a single stage turbine coupled downstream from the intermediate-pressure turbine. The second shaft extends between the second fan assembly and the low-pressure turbine.

Abstract: The invention relates to a turbine engine (1) with a semi-fixed turbine, particularly for aircraft driving a receiver (2) controlled so as to preserve a roughly constant rotation speed. The turbine engine, in particular via a gear system (20), drives the receiver and an LP compressor (6) with an LP turbine (14). According to the invention, the gear system has a torque control system (26) maintaining a constant ratio between the drive torque of the receiver transmitted by the gear system and the drive torque of the LP compressor transmitted by this same gear system.

Abstract: A low-pressure turbine of a gas turbine is disclosed. The turbine comprises a number of stages arranged one behind the other in an axial manner in the flow-through direction of the turbine. Each stage is formed from a fixed vane ring having a number of vanes and from a rotating blade ring having a number of blades. Each stage is characterized by a characteristic value vane-to-blade ratio that indicates the ratio of the number of vanes to the number of blades within a stage. One of the stages of the turbine is designed in such a manner that, in the event of noise-critical conditions of the turbine, the characteristic value vane-to-blade ratio of this stage is between a lower cut-off limit for mode k=?1 of the blade-passing frequency (BPF) of said stage and an upper cut-off limit for the mode k=?2 of the blade-passing frequency (BPF) of this stage.

Abstract: With an engine for aircraft with high electric power demand, the power of the low-pressure shaft (7) operating in a lower speed range is transmitted to the high-pressure shaft (6) by an electromagnetic clutch (10). In the clutch element (14) on the side of the low-pressure shaft a frequency-controllable rotary field is generated, which drives a magnet (13) connected to the high-pressure shaft.

Abstract: Systems and methods for supplementing a power system to achieve consistent operation at varying altitudes are disclosed herein. A hybrid power system comprising a single power source driving multiple generators may implement a power recovery turbine to drive a supercharger compressor, which may provide compressed air at increased altitudes. The supplemental power system disclosed herein provides necessary shaft horsepower at high altitudes to drive a generator and produce cooling air.

Abstract: Systems and methods for supplementing a power system to achieve consistent operation at varying altitudes are disclosed herein. A hybrid power system comprising a single power source driving multiple generators may implement a power recovery turbine to drive a supercharger compressor, which may provide compressed air at increased altitudes. The supplemental power system disclosed herein provides necessary shaft horsepower at high altitudes to drive a generator and produce cooling air.

Abstract: A gas turbine engine having a longitudinal centerline axis therethrough, including: a fan section at a forward end of the gas turbine engine including at least a first fan blade row connected to a drive shaft; a booster compressor positioned downstream of the fan section including a plurality of stages, where each stage includes a stationary compressor blade row and a rotating compressor blade row connected to the drive shaft and interdigitated with the stationary compressor blade row; and, a combustion system for producing pulses of gas having increased pressure and temperature of a fluid flow provided to an inlet thereof so as to produce a working fluid at an outlet.

Abstract: The present invention relates to a gas storage power station (1) having a turbine group (3) and a compressor group (4). The turbine group (3) has at least one turbine (5, 6) and a generator (10). During normal operation of the turbine group (3), the generator (10) emits power directly to a main load (11). The compressor group (4) has at least one compressor (12) and one electric motor (15). The gas storage power station (1) furthermore has a power consumption device (20), which can be activated in order to consume turbine and/or generator power.

Abstract: A mechanical drive system for an accessory gearbox of a gas turbine engine is provided. The gas turbine engine includes a high-pressure drive shaft and a low-pressure drive shaft. The mechanical drive system includes a tower shaft and a lay shaft. The tower shaft is connected by a first gear arrangement to the low-pressure drive shaft of the gas turbine engine. The lay shaft is connected by a second gear arrangement to the first tower shaft, and connected to the accessory gearbox.

Abstract: The present invention relates to an engine integrated auxiliary power unit. The engine comprises a high pressure spool which includes a high pressure compressor connected to a high pressure turbine and a low pressure spool which includes a low pressure compressor connected to a low pressure turbine. The engine further has a system for independently operating the high pressure spool and thus allowing the high pressure spool to function as an auxiliary power unit.

Abstract: A gas turbine system includes a gas turbine (1, 2, 3) having a compressor (1) and a turbine (2), which via a common shaft (3) drive a generator (4), and a combustion chamber (6), the exit of which is connected to the entry to the turbine (2) of the gas turbine (1, 2, 3), has a fuel feed (8) and receives combustion air from the exit of the compressor (1) of the gas turbine (1, 2, 3) via the high-pressure side of a recuperator (5), the exit of the turbine (2) and the entry to the compressor (1) of the gas turbine (1, 2, 3) being connected via the low-pressure side of the recuperator (5), and a first exhaust-gas turbocharger (ATL2) which sucks in air being connected to different locations (9, 10) of the low-pressure side of the recuperator (4) via the exit of its compressor (13) and the entry to its turbine (14).

Abstract: A method and apparatus for controllable distribution of power from a turbine of a gas turbine engine between two rotatable loads of the gas turbine engine, comprises transferring a shaft power of the turbine to the respective rotatable loads using differential gearing operatively coupled with the turbine and the rotatable loads, respectively; and controlling the power transfer using machines operatively coupled with the respective rotatable loads, operable as a generator or a motor for selectively taking power from one of the rotatable loads to drive the other of the rotatable loads, or the reverse.

Abstract: A gas turbine engine (10) comprises a first compressor (16), a combustor (22) and a first turbine (24) arranged in flow series. The first turbine (24) is arranged to drive the first compressor (16). The first compressor (16) has variable inlet guide vanes (38) and the first turbine (24) has variable inlet guide vanes (42). A second compressor (48) is arranged upstream of the first compressor (16). An auxiliary intake (12) is arranged upstream of the first compressor (16) and downstream of the second compressor (48). A valve (54) is arranged upstream of the first compressor (16) and downstream of the second compressor (48). The valve (54) is movable between a first position in which the second compressor (48) supplies air to the first compressor (16) and a second position in which the second compressor (48) does not supply fluid to the second compressor (16) and the auxiliary intake (12) supplies fluid to the first compressor (16).

Abstract: An APU system includes a gas turbine engine having a low pressure spool, a high pressure spool and an electrical generator. The electrical generator is driven by the high pressure spool which is governed to a constant speed. Conversely, the low pressure spool is not governed at all, but is allowed to seek a speed that balances the power developed by the low pressure turbine (LPT) and power absorbed by the low pressure compressor (LPC). A step increase/decrease in electrical power demand is met with a step increase/decrease in fuel flow, which results in an overshoot/undershoot of the new equilibrium turbine inlet temperature TIT. The TIT returns to the new equilibrium when the LP spool has achieved it's new shaft speed and new equilibrium power balance. The HP Spool and generator maintain essentially constant speed and frequency, while the LP Spool responds to restore equilibrium.

Abstract: A gas turbine engine turbine assembly includes a high pressure spool having a high pressure turbine drivingly connected to a high pressure compressor by a high pressure shaft which is rotatable about an engine centerline. A low pressure turbine has counter rotatable low pressure inner and outer shaft turbines with a row of low pressure variable vanes disposed therebetween and drivingly connected to coaxial low pressure inner and outer shafts respectively which are located radially inwardly of the high pressure spool. The low pressure inner and outer shaft turbines are drivingly connected to a forward and aft fan blade rows by the low pressure inner and outer shafts. A single direction of rotation booster is drivenly connected to the low pressure outer shaft and axially located aft and downstream of the aft fan blade row.

Abstract: A variable cycle gas turbine engine (10) includes first and second compressors (18,16), combustion apparatus (20) and first and second turbines (22,24) operable to drive the first and second compressors (18,16) respectively via interconnecting shafts. The capacity of one of the turbines (24) may be varied, for example by means of guide vanes (32) which can be adjusted to reduce or increase a throat area (40) through which air leaves the guide vanes to impact the turbine. The capacity of the turbine may be increased at low engine speeds, to reduce the pressure ratio across the turbine and across the compressor (16) which it drives, thereby improving the surge margin of the compressor.