Aircraft hydrogen fuel systems and methods and systems of starting such systems are described. The aircraft hydrogen fuel systems include a hydrogen burning main engine, a main tank configured to contain liquid hydrogen to be supplied to the main engine during a normal operation, and a starter tank configured to contain gaseous hydrogen to be used during a startup operation of the main engine. Methods and processes for starting and/or restarting such systems are described.

A bleed valve assembly includes a flow duct with an inlet and an outlet disposed downstream from the inlet. The outlet is smaller in cross-sectional area than a region of the flow duct disposed between the inlet and the outlet. A piston housing is disposed inside the flow duct between the inlet and the outlet so as to form an annular flow passage between the flow duct and the piston housing. The piston housing is axially aligned with a center axis of the flow duct. At least one rib extends between the flow duct and the piston housing. A sleeve piston is disposed inside the piston housing and is configured to extend downstream of the piston housing in a closed position. The sleeve piston comprises an outer wall that is at least the same in cross-sectional area as the outlet of the flow duct.

A gas turbine engine including a compressor has a first compressor section and a second compressor section, a combustor fluidly connected to the compressor, and a turbine fluidly connected to the combustor. The turbine includes a first turbine section and a second turbine section. A first shaft connects the first compressor section and the first turbine section. A second shaft connects the second compressor section and the second turbine section. A fan is connected to the first shaft via a geared architecture. The first shaft includes at least one magnetic section. An electromagnet is disposed radially outward of the first shaft at an axial location of the at least one magnetic section, relative to an axis defined by the gas turbine engine.

A gas turbine engine including a compressor has a first compressor section and a second compressor section, a combustor fluidly connected to the compressor, and a turbine fluidly connected to the combustor. The turbine includes a first turbine section and a second turbine section. A first shaft connects the first compressor section and the first turbine section. A second shaft connects the second compressor section and the second turbine section. A fan is connected to the first shaft via a geared architecture. The first shaft includes at least one magnetic section. An electromagnet is disposed radially outward of the first shaft at an axial location of the at least one magnetic section, relative to an axis defined by the gas turbine engine.

The invention relates to a device for starting a gas turbine, comprising an initiation system able, on command, to rotate said gas turbine.

The starting device comprises means for receiving information representing the rotation speed of the gas turbine, means for calculating a set torque value according to said information representing the rotation speed of the gas turbine, and means for transmitting said set torque value to the initiation system, and the means for calculating the set torque value are suitable for making a comparison of the information representing the rotation speed of the gas turbine with a predetermined speed profile and calculating the set torque value from said comparison.

The invention relates generally to gas turbine engines used for electrical power generation. More specifically, embodiments of the present invention provide systems and ways for improving the life and reducing start-up time necessary for bringing gas turbine engines online and up to full power.

The invention relates generally to gas turbine engines used for electrical power generation. More specifically, embodiments of the present invention provide systems and ways for improving the life and reducing start-up time necessary for bringing gas turbine engines online and up to full power.

An aircraft cabin blower system is described having a hydraulic circuit comprising a first hydraulic device and a second hydraulic device. The first hydraulic device is mechanically coupled to a cabin blower compressor and the second hydraulic device is arranged in use to be mechanically coupled to a spool of a gas turbine engine. The first hydraulic device is capable of performing as a hydraulic motor and the second hydraulic device is capable of performing as a hydraulic pump. When, in use, the system is operating in a cabin blower configuration, a driving force supplied by the spool of the gas turbine causes the second hydraulic device to pump liquid provided in the hydraulic circuit and thereby to drive the first hydraulic device, which in turn rotates the cabin blower compressor.

A bowed rotor start mitigation system for a gas turbine engine is provided. The bow rotor start mitigation system includes a controller operable to receive a speed input indicative of a rotor speed of the gas turbine engine and a measured temperature of the gas turbine engine. The controller is further operable to drive motoring of the gas turbine engine by oscillating the rotor speed within a motoring band for a motoring time based on the measured temperature when a start sequence of the gas turbine engine is initiated.

A bowed rotor start mitigation system for a gas turbine engine is provided. The bow rotor start mitigation system includes a controller operable to receive a speed input indicative of a rotor speed of the gas turbine engine and a measured temperature of the gas turbine engine. The controller is further operable to drive motoring of the gas turbine engine by oscillating the rotor speed within a motoring band for a motoring time based on the measured temperature when a start sequence of the gas turbine engine is initiated.