A power turbine control system for a gas turbine engine may comprise a controller comprising one or more processors in communication with the gas turbine engine. The processors may comprise an engine control module configured to receive a torque request signal and generate a torque achieved signal. A rate of change of power turbine speed estimation module may generate an estimated rate of change of power turbine speed signal. A dynamic inversion power turbine governor module may generate the torque request signal based on the torque achieved signal and estimated rate of change of power turbine speed signal.

Processes for controlling at least one process condition of a chemical processing unit with a turbine. In the processes, a flow of a fluid is adjusted with a turbine in order to provide the fluid with a flow associated with at least one process condition of a chemical processing unit. The turbine wheel is rotated within the turbine, and the turbine wheel is configured to transmit rotational movement to an electrical generator. The resistance of the turbine is modulated and adjusts the flow of the fluid through the turbine. A response time of at least one steady state process condition to a new steady state process condition of at least 10% difference is at least one second to reach 50% of the difference between the at least one steady state process condition and the new steady state process condition after modulating the resistance of the turbine.

A torque converter is provided. The torque converter includes a turbine including a turbine shell and a plurality of turbine blades fixed to the turbine shell by tabs of the turbine blades. The turbine shell includes a rounded blade supporting portion supporting the turbine blades. The torque converter also includes an inertia ring and a connector fixing the inertia ring to the turbine shell. Some of the turbine blade tabs fix the connector to the turbine shell. A method of constructing a torque converter is also provided.

A propulsion assembly includes a first torque source coupled with a first shaft and a second torque source coupled with a second shaft. A coupler selectively couples the first and second torque sources. When the first and second torque sources are coupled via the coupler, in response to a command to decouple the first torque source, an unloading operation is performed to decrease the torque output provided by the first torque source to a threshold, and when reached, the first shaft is decoupled from the coupler. When the first torque source is coupled with the coupler but the second torque source is not, in response to a command to couple the second torque source, a speed matching operation is performed to increase the speed of the second shaft to match a speed of the first shaft, and when the speeds are matched, the second shaft is coupled to the coupler.

Herein provided are methods and systems for operating a gas-turbine engine comprising a gearbox and a power turbine coupled to the gearbox. A first torque at the gearbox is obtained via a sensor. A second torque at the power turbine is determined based on the first torque. A power at the power turbine is determined based on the second torque. Operation of the engine is controlled based on the power.

A multi-shaft gas turbine engine has plural engine spools. A first spool of the engine and a second spool of the engine are operatively connected by an electrical machine that transfers power from one of the spools to the other.

A propulsion assembly includes a first torque source coupled with a first shaft and a second torque source coupled with a second shaft. A coupler selectively couples the first and second torque sources. When the first and second torque sources are coupled via the coupler, in response to a command to decouple the first torque source, an unloading operation is performed to decrease the torque output provided by the first torque source to a threshold, and when reached, the first shaft is decoupled from the coupler. When the first torque source is coupled with the coupler but the second torque source is not, in response to a command to couple the second torque source, a speed matching operation is performed to increase the speed of the second shaft to match a speed of the first shaft, and when the speeds are matched, the second shaft is coupled to the coupler.

Herein provided are methods and systems for controlling an engine having a variable geometry mechanism. A pressure ratio between a first pressure at an inlet of the engine and a predetermined reference pressure is determined. An output power for the engine is determined. The output power is adjusted based at least in part on the pressure ratio to obtain a corrected output power. A position control signal for a variable geometry mechanism of the engine is generated based on the corrected output power and the pressure ratio. The position control signal is output to a controller of the engine to control the variable geometry mechanism.

The present disclosure is directed to a system for controlling an output of a gas generator via an operator manipulated input device. The system includes one or more sensors measuring one or more environmental conditions, a gas generator shaft speed, and a power turbine torque. The system further includes an operator manipulated input device and one or more controllers including one or more processors and one or more memory devices. The one or more memory devices stores instructions that when executed by the one or more processors cause the one or more processors to perform operations. The operations include receiving, via an operator manipulated input device, a throttle lever position defining at least an idle position, a takeoff position, and one or more intermediate positions therebetween; receiving, via one or more sensors, one or more environmental conditions, wherein the environmental condition includes one or more of an ambient air temperature, an ambient air pressure, and an ambient airflow rate; determining, via the controller, a first commanded fuel flow of the gas generator based on a gas generator speed output curve based at least on the throttle lever position, the one or more environmental conditions, and a coefficient reference table; determining, via the controller, a second commanded fuel flow of the gas generator based on a power turbine torque output curve based at least on the one or more environmental conditions; and generating, via the gas generator, a gas generator output based on the first commanded fuel flow or the second commanded fuel flow.

Techniques are described for using an electrical motor to slow down or stop a propulsor during an operation mode where the engine is to be otherwise running but the speed of the propulsor should be low or the propulsor should be stopped.