There is described a method of operating a multi-engine system of an helicopter. The multi-engine system has a first turboshaft engine having a first shaft, a second turboshaft engine having a second shaft, a gearbox having a clutch system, and a range of rotation speeds defined as a placarded zone. The method generally has: rotating the first and second shafts at a flight rotation speed above the placarded zone when clutched to a load; decreasing a rotation speed of the first shaft from the flight rotation speed to a first idle rotation speed above the placarded zone; unclutching the first shaft from the load during the decreasing; and subsequently to the decreasing and the unclutching, simultaneously decreasing the rotation speeds of the first shaft and of the second shaft to a second idle rotation speed below the placarded zone, the simultaneously decreasing including clutching the first shaft to the load.

A fan array fan section in an air-handling system includes a plurality of fan units arranged in a fan array and positioned within an air-handling compartment. One preferred embodiment may include an array controller programmed to operate the plurality of fan units at peak efficiency. The plurality of fan units may be arranged in a true array configuration, a spaced pattern array configuration, a checker board array configuration, rows slightly offset array configuration, columns slightly offset array configuration, or a staggered array configuration.

A gas turbine engine comprises a relatively high pressure compressor coupled to a relatively high pressure turbine by a relatively high pressure shaft; a relatively low pressure compressor coupled to a relatively low pressure turbine by a relatively low pressure shaft rotatable independently of the high pressure shaft; a first combustor located downstream of the high pressure compressor and upstream of the high pressure turbine; and a second combustor located downstream of the high pressure turbine, and upstream of the low pressure turbine. The engine further comprises a coupling arrangement configured to selectively transfer torque between the high pressure shaft and the low pressure shaft.

A turbomachine and method for operating a turbomachine comprising a first rotatable component and a second rotatable component each defining a rotatable speed mechanically independent of one another, and an electric machine electrically coupled to the first rotatable component and the second rotatable component such that a load level relative to the first rotatable component and the second rotatable component is adjustable is generally provided. The method includes adjusting a first load at a first rotor assembly of the electric machine electrically 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 rotor assembly of the electric machine electrically 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 electrical energy generated from at least one of the first rotatable component or the second rotatable component.

A method is provided of controlling a gas turbine having a shaft connecting a compressor to a turbine, as well as having a reheat system, and a gas turbine. The method includes the steps of: operating the engine using the reheat system to provide a mass flow rate of reheat fuel into a gas flow of the gas turbine engine downstream of an exit of the turbine; detecting a shaft break event in the shaft; and in response to this detection, maintaining the mass flow rate of the reheat fuel being provided into the gas flow downstream of the turbine exit, whereby the maintained mass flow rate of reheat fuel raises a back pressure downstream of the turbine and thereby reduces a rotational speed of the turbine.

A gas turbine engine includes a compressor. A turbine is mechanically connected to the compressor by a shaft. An air-driven auxiliary turbine is in fluid communication with the compressor and is configured to receive pressurized air from the compressor. An auxiliary generator is operably connected to the auxiliary turbine. The auxiliary generator is configured to generate electrical energy in response to an operation of the auxiliary turbine. An energy storage device is in electrical communication with the auxiliary generator.

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.

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 method for in-flight monitoring of the health of an aero gas turbine engine including in flow series a compressor system, a core gas generator including a combustor, and a turbine, and further including a shaft system connecting the turbine to the compressor system and forming a torque path there between. The method includes: measuring a first rotational speed of a forward portion of the shaft system; measuring a second rotational speed of a rear portion of the shaft system; measuring other operational parameters of the engine; calculating from the measured rotational speeds the power delivered by the torque path from the turbine to the compressor system; calculating from the other measured operational parameters the power delivered to the turbine by the core gas generator; correlating the power delivered by the torque path at a given time with the power delivered to the turbine at that time.

The invention concerns a bypass turbomachine (1) with a primary flow path and a secondary flow path, comprising: —a low-pressure body comprising a low-pressure compressor (120) connected to a low-pressure turbine (122) via a low-pressure shaft (124), —a high-pressure body comprising a high-pressure compressor (130) connected to a high pressure turbine (132), via a high-pressure shaft (134), —a low-pressure power take-off system (220) comprising an electrical generator (226), configured to take power (W12) from the low-pressure body, wherein—the turbomachine comprises a debris removal system (500), located between the two compressors (226, 236), —the low-pressure power take-off system (220) is configured to take power (W12) from the low-pressure shaft (124) using the resistive torque of the electrical generator (226), in order to avoid a risk of surging.