A ventilation system includes a cavity, a fluid motive force device, and a motive fluid supply system. The cavity includes different ventilation level requirements for a plurality of modes of operation. The fluid motive force device includes a suction port, an outlet port, and a motive fluid inlet port. The suction port is coupled in flow communication with the cavity to be vented. A flow supply to the motive fluid inlet port determines a ventilation flow through the suction port. The motive fluid supply system is coupled in flow communication with the motive fluid inlet port. An operation of the motive fluid supply system determines a flow of motive fluid from the motive fluid supply system to the motive fluid inlet port. The flow of motive fluid to the motive fluid inlet port generates a ventilation flow through the suction port approximately matching a current ventilation demand of said cavity.

A ventilation system includes a cavity, a fluid motive force device, and a motive fluid supply system. The cavity includes different ventilation level requirements for a plurality of modes of operation. The fluid motive force device includes a suction port, an outlet port, and a motive fluid inlet port. The suction port is coupled in flow communication with the cavity to be vented. A flow supply to the motive fluid inlet port determines a ventilation flow through the suction port. The motive fluid supply system is coupled in flow communication with the motive fluid inlet port. An operation of the motive fluid supply system determines a flow of motive fluid from the motive fluid supply system to the motive fluid inlet port. The flow of motive fluid to the motive fluid inlet port generates a ventilation flow through the suction port approximately matching a current ventilation demand of said cavity.

A gas turbine engine for an aircraft and a method of operating a gas turbine engine on an aircraft. Embodiments disclosed include a gas turbine engine for an aircraft including: an engine core has a turbine, a compressor, and a core shaft; a fan located upstream of the engine core, the fan has a plurality of fan blades; a nacelle surrounding the engine core and defining a bypass duct and bypass exhaust nozzle; and a gearbox that receives an input from the core shaft and outputs drive to the fan wherein the gas turbine engine is configured such that a jet velocity ratio of a first jet velocity exiting from the bypass exhaust nozzle to a second jet velocity exiting from an exhaust nozzle of the engine core at idle conditions is greater by a factor of 2 or more than the jet velocity ratio at maximum take-off conditions.

A gas turbine engine for an aircraft and a method of operating a gas turbine engine on an aircraft. Embodiments disclosed include a gas turbine engine for an aircraft including: an engine core has a turbine, a compressor, and a core shaft; a fan located upstream of the engine core, the fan has a plurality of fan blades; a nacelle surrounding the engine core and defining a bypass duct and bypass exhaust nozzle; and a gearbox that receives an input from the core shaft and outputs drive to the fan wherein the gas turbine engine is configured such that a jet velocity ratio of a first jet velocity exiting from the bypass exhaust nozzle to a second jet velocity exiting from an exhaust nozzle of the engine core at idle conditions is greater by a factor of 2 or more than the jet velocity ratio at maximum take-off conditions.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

Systems and methods for variable pressure inventory control of a closed thermodynamic cycle power generation system or energy storage system, such as a reversible Brayton cycle system, with at least a high pressure tank and an intermediate pressure tank are disclosed. Operational parameters of the system such as working fluid pressure, turbine torque, turbine RPM, generator torque, generator RPM, and current, voltage, phase, frequency, and/or quantity of electrical power generated and/or distributed by the generator may be the basis for controlling a quantity of working fluid that circulates through a closed cycle fluid path of the system.

Systems and methods for regulating oil flow to an engine are described herein. An oil pressure target for the engine is determined based on one or more engine operating parameters. Oil flow to the engine is controlled based on the oil pressure target. Closed-loop feedback of oil pressure of the engine is obtained from at least one sensor during the controlling of the oil flow to the engine. A pressure difference between the oil pressure target and the closed-loop feedback of the oil pressure of the engine is determined. The oil flow to the engine is adjusted based on the pressure difference.

Systems and methods for regulating oil flow to an engine are described herein. An oil pressure target for the engine is determined based on one or more engine operating parameters. Oil flow to the engine is controlled based on the oil pressure target. Closed-loop feedback of oil pressure of the engine is obtained from at least one sensor during the controlling of the oil flow to the engine. A pressure difference between the oil pressure target and the closed-loop feedback of the oil pressure of the engine is determined. The oil flow to the engine is adjusted based on the pressure difference.

Systems and methods relating to variable pressure turbines are disclosed. A power generation system may include a closed cycle system configured to generate power, a combustor, and a control system. The closed cycle system may include a working fluid circulating in a closed cycle path. The combustor may provide thermal energy to the working fluid. Further, the control system may be configured to determine to increase an amount of power generated by the closed cycle system, and in response to the determination to increase the amount of power generated by the closed cycle system, cause an increase in pressure of the working fluid in the closed cycle path.

Systems and methods relating to variable pressure turbines are disclosed. A power generation system may include a closed cycle system configured to generate power, a combustor, and a control system. The closed cycle system may include a working fluid circulating in a closed cycle path. The combustor may provide thermal energy to the working fluid. Further, the control system may be configured to determine to increase an amount of power generated by the closed cycle system, and in response to the determination to increase the amount of power generated by the closed cycle system, cause an increase in pressure of the working fluid in the closed cycle path.