A method and control system for controlling compressor output for a gas turbine engine is disclosed. The power output of a gas turbine engine can vary and be below desired output levels due to operating conditions such as ambient temperature and elevation. These operating conditions can lead to lower output of the gas compressor of the turbine engine and lower operating temperatures within or proximate to a turbine of the gas turbine engine and lead to less power output. Additional fuel can be added to increase power to the gas producer shaft and increase turbine temperature of the gas turbine engine. A power transfer device can be used to remove or add power to the gas producer shaft to balance the gas producer mechanical limits and turbine thermal limits at maximum levels and lead to higher power output.

Systems and methods to pump fracturing fluid into a wellhead may include a gas turbine engine including a compressor turbine shaft connected to a compressor, and a power turbine output shaft connected to a power turbine. The compressor turbine shaft and the power turbine output shaft may be rotatable at different rotational speeds. The systems may also include a transmission including a transmission input shaft connected to the power turbine output shaft and a transmission output shaft connected to a hydraulic fracturing pump. The systems may also include a fracturing unit controller configured to control one or more of the rotational speeds of the compressor turbine shaft, the power turbine output shaft, or the transmission output shaft based at least in part on target signals and fluid flow signals indicative of one or more of pressure or flow rate associated with fracturing fluid pumped into the wellhead.

Methods and related apparatus for improving synchronization of two or more engines on an aircraft are disclosed. Such method may be used where each engine comprises a first spool and a second spool, and, where a rotational speed of a first spool of a first engine has been substantially synchronized with a rotational speed of a first spool of a second engine. An exemplary method comprises receiving a value of a sensed parameter useful in controlling the first engine; adding a bias to the value; and using the biased value for controlling the first engine to cause a change in rotational speed of the second spool of the first engine in relation to the rotational speed of the first spool of the first engine.

There is provided a gas turbine engine comprising a low pressure shaft and a high pressure shaft; wherein the low pressure shaft connects a fan to a fan drive turbine, and the high pressure shaft connects a high pressure turbine to a compressor section. The low pressure shaft and the high pressure shaft are arranged such that when operating at idle the idle shaft speed ratio is greater than 6.05. The idle shaft speed ratio is the ratio of the speed of the high pressure shaft to the speed of the low pressure shaft at idle conditions.

A turbomachine and method for operation turbomachine are provided, the method including adjusting a first load at a first electric machine operably coupled to a first rotatable component, in which the first electric machine is operably coupled to the first rotatable component such that a first speed of the first rotatable component is increased or decreased based on an engine condition and the first load; adjusting a second load at a second electric machine operably coupled to a second rotatable component, in which the second electric machine is operably coupled to the second rotatable component such that a second speed of the second rotatable component is decreased or increased based on the engine condition and the second load; and transferring energy generated from at least one of the first electric machine or the second electric machine.

A retaining collar is disclosed for a bayonet mount comprising a rotor disc having a male mounting member defining a pair of apertures and an auxiliary annular wheel defining a plurality of mounting slots. The retaining collar comprises a ring-shaped body and a pair of retention pins. The ring-shaped body has a pair of circumferential end portions separated by a circumferential gap, and an arcuate radial outer surface extending circumferentially between the end portions. The body is dimensioned so that the radial outer surface frictionally engages a radial inner surface of a cylindrical male mounting member in the bayonet mount. The pair of retention pins each extend radially outward from one of the circumferential end portions. Each of the retention pins are dimensioned to extend radially outward from the body through one of said apertures and one of said mounting slots.

An embodiment of an engine assembly includes a plurality of offtakes powered by a combustion turbine engine having a high spool and at least one lower spool, and a controller configured to operate the combustion turbine engine through a range between a first low-idle mode, a second high idle mode, and a maximum takeoff power rating mode. The controller operates the engine in the low-idle mode by directing at least a first portion of power from the at least one lower spool to the plurality of offtakes, and wherein the controller operates the engine in the high idle mode by increasing a speed of the high spool relative to a speed of the high spool in the low-idle mode, thereby increasing a compressor outlet (T.sub.3) temperature in the high idle mode relative to a T.sub.3 temperature in the low-idle mode.

In one embodiment, a plant control apparatus includes a first stop controller configured to, when stopping a plant, stop a steam turbine to start to drop rotating speed of a second shaft of the steam turbine from rated speed, and start to drop rotating speed of a first shaft of a gas turbine from the rated speed while continuing combustion of a combustor after the stop of the steam turbine. The apparatus further includes a second stop controller configured to shut off fuel of the combustor to stop the gas turbine when the rotating speed of the first shaft drops to first speed. The second stop controller stops the gas turbine such that the rotating speed of the first shaft catches up with the rotating speed of the second shaft at second speed that is equal to or lower than the first speed and a clutch is engaged.

A method and control system for controlling compressor output for a gas turbine engine is disclosed. The power output of a gas turbine engine can vary and be below desired output levels due to operating conditions such as ambient temperature and elevation. These operating conditions can lead to lower output of the gas compressor of the turbine engine and lower operating temperatures within or proximate to a turbine of the gas turbine engine and lead to less power output. Additional fuel can be added to increase power to the gas producer shaft and increase turbine temperature of the gas turbine engine. A power transfer device can be used to remove or add power to the gas producer shaft to balance the gas producer mechanical limits and turbine thermal limits at maximum levels and lead to higher power output.

A regulator device for automatically regulating a power plant of a rotary wing aircraft having a turbine engine includes a computer system. The computer system, while implementation of an idling mode of operation of the turbine engine is requested and the aircraft is standing on ground, implements the idling mode of operation and operates the turbine engine in compliance with idling mode of operation as a function of operational and hierarchically ordered conditions either through a first mode of regulation by regulating a speed of rotation (Ng) of a gas generator of the turbine engine or through a second mode of regulation by regulating a speed of rotation (NTL) of a free turbine of the turbine engine.