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.

An enhanced engine starter system controls an air turbine starter at the startup of operation of a turbine engine. The engine starter system includes an air turbine starter (ATS) that operates in accordance with more than one speed/torque curve during the startup procedure. A controller commands the starter control valve to provide a regulated pressure to the ATS in accordance with a first speed/torque curve to initiate the gas turbine engine startup without exceeding a maximum or design limiting torque. Overall duration of the startup procedure is reduced by the controller subsequently operating the ATS in accordance with a second speed/torque curve having a higher operational pressure once the ATS reaches a predetermined transition speed. The torque at the predetermined transition speed on the higher pressure second curve remains less than the design limiting torque, but provides a higher torque as compared to the first speed/torque curve to reduce the duration of the startup procedure.

An aircraft propulsion system includes a gas turbine engine; a generator; a storage battery; a motor which drives a rotor, using at least one of the electric power which is output from the generator and the electric power which is output from the storage battery; a detection unit which detects the number of revolutions of the engine shaft; an engine control unit which controls at least a fuel flow rate of the gas turbine engine; and a generator control unit which controls the operation of the generator. When the number of revolutions satisfies a predetermined condition, at least the generator control unit executes a control for reducing a sudden change in the number of revolutions.

Cooling a torque probe involves an elongated sleeve extending along a sleeve axis between a first sleeve end and a second sleeve end. The sleeve is mountable about the torque probe to define a flow passage between an inner surface of the sleeve and an outer surface of the torque probe. The flow passage is in fluid communication with a flow passage inlet of the sleeve and with a flow passage outlet of the sleeve spaced apart along the sleeve axis from the flow passage inlet. A cooling airflow is configured to flow into the flow passage via the flow passage inlet, through the flow passage along the outer surface of the torque probe to cool the torque probe, and out of the flow passage via the flow passage outlet.

A rotor dynamics adjustment system includes a rotor system with at least one compressor section and at least one turbine section operably coupled to a shaft. The rotor dynamics adjustment system also includes one or more rotor system sensors configured to collect a plurality of sensor data from the rotor system, an electric motor operably coupled to the rotor system, and a controller. The controller is operable to monitor the one or more rotor system sensors while the rotor system is rotating. A dynamic motion of the rotor system is characterized based on the sensor data from the one or more rotor system sensors. A damping correction torque is determined to diminish the dynamic motion of the rotor system. The electric motor is commanded to apply the damping correction torque to the rotor system.

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.

Cooling a torque probe involves an elongated sleeve extending along a sleeve axis between a first sleeve end and a second sleeve end. The sleeve is mountable about the torque probe to define a flow passage between an inner surface of the sleeve and an outer surface of the torque probe. The flow passage is in fluid communication with a flow passage inlet of the sleeve and with a flow passage outlet of the sleeve spaced apart along the sleeve axis from the flow passage inlet. A cooling airflow is configured to flow into the flow passage via the flow passage inlet, through the flow passage along the outer surface of the torque probe to cool the torque probe, and out of the flow passage via the flow passage outlet.

An aircraft propulsion system includes a gas turbine engine; a generator; a storage battery; a motor which drives a rotor, using at least one of the electric power which is output from the generator and the electric power which is output from the storage battery; a detection unit which detects the number of revolutions of the engine shaft; an engine control unit which controls at least a fuel flow rate of the gas turbine engine; and a generator control unit which controls the operation of the generator. When the number of revolutions satisfies a predetermined condition, at least the generator control unit executes a control for reducing a sudden change in the number of revolutions.

Methods and systems for operating a gas turbine engine are described. The method comprises obtaining, at a control system associated with the gas turbine engine, a measured engine core speed and an actual power demand for the gas turbine engine during operation thereof, determining an expected engine core speed based on the actual power demand from a predicted relationship between engine core speed and engine output power, comparing the measured engine core speed to the expected engine core speed, detecting a torque-related fault when the measured engine core speed differs from the expected engine core speed by more than a threshold; and accommodating the torque-related fault when detected.