Apparatus for a gas turbine engine, the apparatus comprising: a low pressure compressor; a high pressure compressor; a first electrical machine configured to provide torque to the low pressure compressor; a second electrical machine configured to receive torque from the high pressure compressor; and wherein the high pressure compressor does not comprise a sub-idle bleed valve.

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.

A turbomachine includes a single ducted fan including a first shaft rotated by a second shaft via a speed reduction gearset, the second shaft being rotated by a third shaft of a turbine, the first shaft being guided in rotation with respect to a fixed structure via a first bearing and a second bearing placed upstream of the speed reduction gearset. The second shaft is guided in rotation with respect to the first shaft via a rolling bearing placed upstream of the speed reduction gearset, the rolling bearing comprising an outer ring housed in the first shaft, an inner ring connected to the second shaft and rolling elements arranged between the inner and outer rings.

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.

A two-shaft gas turbine control system and method are provided that can enhance the efficiency and reliability thereof by controlling the amount of intake air spray and the rotational speed of a high-pressure turbine in accordance with the aperture of an inlet guide vane in a state where a two-shaft gas turbine is being operated with the efficiency of its compressor reduced. The control system includes a droplet spray device for spraying droplets to intake air for the compressor and a controller. The controller includes a fuel control section for adjusting a flow rate of the fuel to be supplied to the combustor, a spray flow rate control section for adjusting a flow rate of spray water to be supplied to the droplet spray device, an inlet guide vane aperture control section for adjusting the aperture of the inlet guide vane, and an efficiency improvement control section for outputting a command signal for bringing a balance between driving force for the compressor and power output of the high-pressure turbine to the fuel control section, the spray flow rate control section and the inlet guide aperture control section. In response to the commands from the improvement control section, the controller reduces the rotational speed of the high-pressure turbine and controls the inlet guide vane so as to be more open, thereby appropriately controlling the flow rate of the spray water.

A method for coupling a first sub-shaft, which has a first turbomachine and a generator connected to a mains supply, to a second sub-shaft, which has a second turbomachine, by means of an overrunning clutch, has the following steps: a) rotating the second sub-shaft with a starting rotational speed which is lower than the rotational speed of the first sub-shaft; b) measuring the mains frequency of the mains supply; c) measuring a differential angle between the first sub-shaft and the second sub-shaft; d) accelerating the second sub-shaft with an acceleration value which is produced using the mains frequency measured in step b), the differential angle and the starting rotational speed, and therefore the overrunning clutch couples the two sub-shafts to each other with a previously determined target coupling angle.

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.

A gas turbine engine comprises a low speed spool and a high speed spool, with each of the spools including a turbine to drive a respective one of the spools. The high speed spool rotates at a higher speed than the low speed spool. A high speed power takeoff is driven to rotate by the high speed spool, and a low speed power takeoff is driven to rotate by the low speed spool. The high speed power takeoff drives a starter generator and a permanent magnet alternator. The low speed power takeoff drives a variable frequency generator.

A method manages a gas turbine assembly during start up or shut down, the gas turbine assembly including a twin shaft gas turbine having an input shaft and an output shaft and a speed sensor for measuring a speed of the output shaft, the gas turbine assembly further having a rotor mounted on said output shaft and provided with at least a dry gas seal for preventing leakage of a process gas. The method includes monitoring the speed of the output shaft, and in parallel, reducing or increasing the speed of the input shaft after the monitored speed of the output shaft has remained above zero and below a predefined slow roll speed limit for a predefined acceptable time.

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.