A gas turbine engine for an aircraft, including: staged combustion system having pilot fuel injectors and main fuel injectors, staged combustion system being operable in pilot-only range of operation and pilot-and-main range of operation; and fuel delivery regulator arranged to control delivery of fuel to pilot and main fuel injectors. Fuel delivery regulator arranged to receive fuel from a first fuel source containing a first fuel having a first fuel characteristic and a second fuel source containing a second fuel having a different second fuel characteristic. The fuel delivery regulator is arranged to deliver fuel to the pilot fuel injectors during at least part of the pilot-only range of operation having a different fuel characteristic from fuel delivered to one or both of the pilot and main fuel injectors during at least part of the pilot-and-main range of operation. A method of operating a gas turbine engine is also disclosed.

An aircraft has first and second fuel sources containing fuels with different characteristics, and one or more gas turbine engines powered by the fuels and each having a staged combustion system having pilot and main fuel injectors and being operable in pilot-only and pilot-and-main ranges of operation. The gas turbine engines each have a fuel delivery regulator arranged to control fuel delivery to the pilot and main fuel injectors. The method includes: obtaining a proposed mission description; obtaining nvPM impact parameters for the gas turbine engines, the impact parameters being associated with each operating condition of the proposed mission; calculating an optimised set of one or more fuel characteristics for each flight condition of the proposed flight defined in the flight description based on the nvPM impact parameters; and determining a fuel allocation based on the optimised set of one or more fuel characteristics.

A contrail suppression system includes a shell having an exhaust gas inlet, an exhaust gas outlet, a condensate drain and a flow chamber in fluid communication with the exhaust gas inlet, the exhaust gas outlet and the condensate drain. The exhaust gas inlet is in fluid communication with a jet exhaust nozzle of a gas turbine engine. A first tube bundle is disposed within the flow chamber downstream from the exhaust gas inlet. The first tube bundle includes an inlet and an outlet. The inlet of the first tube bundle is fluidly connected to a first cooling medium source. A second tube bundle is disposed within the flow chamber downstream from the first tube bundle and upstream from the exhaust gas outlet. The second tube bundle includes an inlet and an outlet. The inlet of the second tube bundle is fluidly connected to a second cooling medium source.

A gas turbine engine for an aircraft. The gas turbine comprises a staged combustion system having pilot injectors and main injectors, a fuel metering system configured to control fuel flow to the pilot injectors and the main injectors, and a fuel system controller. The controller is configured to identify an atmospheric condition, determine a ratio of pilot fuel flow rate for the pilot injectors to main fuel flow rate for the main injectors in response to the atmospheric condition, and inject fuel by the pilot injectors and the main injectors in accordance with said ratio to control an index of soot emissions caused by combustion of fuel therein.

A gas turbine engine for an aircraft. The gas turbine comprises a staged combustion system having pilot injectors and main injectors, a fuel metering system configured to control fuel flow to the pilot injectors and the main injectors, and a fuel system controller. The controller is configured to identify an atmospheric condition, determine a ratio of pilot fuel flow rate for the pilot injectors to main fuel flow rate for the main injectors in response to the atmospheric condition, and inject fuel by the pilot injectors and the main injectors in accordance with said ratio to control an index of soot emissions caused by combustion of fuel therein.

A gas turbine engine for an aircraft. The gas turbine comprises a combustor, a fuel injection system connected with a source of fuel and configured to inject fuel into the combustor, a water injection system connected with a source of water and which is configured to inject water into the combustor, and a control system. The control system is configured to identify an atmospheric condition; determine a water-fuel ratio for injection into the combustor of the gas turbine engine in response to the atmospheric condition; and control injection of fuel and water by the fuel injection system and the water injection system according to said water-fuel ratio to control an soot emissions caused by combustion of fuel therein.

An assembly including a first turbocharger, the first turbocharger including a first turbine and a first compressor, the first turbine arranged in a turbine flowpath to be driven in rotation by an exhaust gas flowing at a variable flow rate through the turbine flowpath. The first compressor arranged in a compressor flowpath to be driven by the first turbine to urge an intake gas to flow through the compressor flowpath. The first turbine and first compressor being supported for rotation in bearings supplied via an oil flowpath at an oil pressure. The assembly further including a seal arranged between the oil flowpath and the compressor flowpath to resist leakage of the oil into the compressor flowpath and a flow control means configured to control a rotational speed of the first turbine and first compressor by controlling the flow of exhaust gas in the turbine flowpath.

This invention concerns an aircraft propulsion system in which an engine has an engine core comprising a compressor, a combustor and a turbine driven by a flow of combustion products of the combustor. At least one propulsive fan generates a mass flow of air to propel the aircraft. An electrical energy store is provided on board the aircraft. At least one electric motor is arranged to drive the propulsive fan and the engine core compressor. A controller controls the at least one electric motor to mitigate the creation of a contrail caused by the engine combustion products by altering the ratio of the mass flow of air by the propulsive fan to the flow of combustion products of the combustor. The at least one electric motor is controlled so as to selectively drive both the propulsive fan and engine core compressor.

This invention concerns an aircraft propulsion system in which an engine has an engine core comprising a compressor, a combustor and a turbine driven by a flow of combustion products of the combustor. At least one propulsive fan generates a mass flow of air to propel the aircraft. An electrical energy store is provided on board the aircraft. At least one electric motor is arranged to drive the propulsive fan and the engine core compressor. A controller controls the at least one electric motor to mitigate the creation of a contrail caused by the engine combustion products by altering the ratio of the mass flow of air by the propulsive fan to the flow of combustion products of the combustor. The at least one electric motor is controlled so as to selectively drive both the propulsive fan and engine core compressor.

Method for optimizing the limitation of dust emissions from a gas turbine or combustion plant comprising a line for supplying liquid fuel oil, a line for generating fuel oil atomizing air, and a central controller, wherein: a first definition step, starting from a nominal temperature of the fuel oil and a nominal pressure ratio of the atomizing air of the fuel oil, and by controlling the injection of the soot inhibitor, of a nominal operating point corresponding to the maximum permissible level of emitted dust; a second step of controlling a first parameter, taken from the group of the fuel oil temperature and the pressure ratio of the fuel oil atomizing air, in order to reach another operating point; and a third step of controlling the soot inhibitor injection to achieve the maximum permissible level of emitted dust.