Abstract: An aircraft turbofan gas turbine engine includes a fan assembly, a compressor module, and a turbine module. An electric machine is positioned downstream of the fan assembly and is connected to the turbine module. The fan assembly includes a highest pressure fan stage having a plurality of fan blades defining a fan diameter. The turbine module includes a lowest pressure turbine stage having a row of rotor blades. The gas turbine engine has a fan tip axis that joins a radially outer tip of the leading edge of one of the plurality of fan blades of the highest pressure fan stage, and the radially outer tip of the trailing edge of one of the rotor blades of the lowest pressure turbine stage. The fan tip axis lies in a longitudinal plane which contains a centreline of the gas turbine engine. The fan axis angle is between 11 and 20 degrees.

Abstract: A cooling system for an aircraft comprises a gas turbine engine, an ancillary apparatus, and a heat exchanger. The gas turbine engine comprises, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate an electrical power PEM1 (W). The heat exchanger is configured to transfer a total waste heat energy Q (W) generated by the gas turbine engine and the ancillary apparatus, to an airflow passing through the heat exchanger, and a ratio S of: S = ( Total ? Electrical ? Power ? Generated = P EM ? 1 ) ( Total ? Heat ? Energy ? Rejected ? to ? Airflow = Q ) is in a range of between 0.50 and 5.00.

Abstract: An gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, together with a first electrical machine rotationally connected to the turbine module. The combustor module has a combustor volume V (cm3). In use, at a full power condition, the gas turbine engine has a maximum corrected core flow Q (m3/sec), and a ratio T of: T = ( Maximum ? Corrected ? Core ? Flow = Q ) ( Combustor ? volume = V ) is in a range of between 450 and 2,500.

Abstract: An aircraft gas turbine engine includes a heat exchanger module, and a core engine including an intermediate-pressure compressor, a high-pressure compressor, a high pressure turbine, and a low-pressure turbine. The high-pressure compressor is connected to the high-pressure turbine by a first shaft, and the intermediate-pressure compressor is connected to the low-pressure turbine by a second shaft. The heat exchanger module includes a central hub and heat transfer elements extending radially from the central hub and spaced in a circumferential array, for transferring heat energy from a fluid within the heat transfer elements to an inlet airflow passing over the heat transfer elements prior to entry of the airflow into an inlet to the core engine. The gas turbine engine further includes a first electric machine connected to the first shaft and positioned downstream of the heat exchanger module, and a second electric machines connected to the second shaft.

Abstract: An aircraft turbofan gas turbine engine includes a fan assembly, a compressor module, and a turbine module. An electric machine positioned downstream of the fan assembly is rotationally connected to the turbine module. The fan assembly is in fluid communication with the compressor module by an intermediate duct and includes a highest pressure fan stage having a plurality of fan blades defining a fan diameter. The compressor module includes a lowest pressure compressor stage having a row of rotor blades. An intermediate flow axis is defined joining a radially outer tip of a trailing edge of one of the fan blades of the highest pressure fan stage, and a radially outer tip of a leading edge of one of the rotor blades of a leading edge of a lowest-pressure compressor blade. An intermediate flow axis angle and the intermediate flow axis angle is from ?20 to ?30 degrees.

Abstract: A gas turbine engine for an aircraft includes, in axial flow sequence, a compressor module, a combustor module, and a turbine module, with a first electric machine being rotationally connected to the turbine module. The first electrical machine is configured to generate a total electrical power PEM1 (W), and the gas turbine engine is configured to generate a total shaft power PSHAFT (W); and a ratio R of: R = Total Shaft Power = P S H A F T Total Electrical Power Generated = P E M 1 is in a range of between 0.005 and 0.020.

Abstract: An aircraft turbofan gas turbine engine includes a fan assembly, a compressor module, and a turbine module. An electric machine is positioned downstream of the fan assembly and is connected to the turbine module. The fan assembly includes a highest pressure fan stage having a plurality of fan blades defining a fan diameter. The turbine module includes a lowest pressure turbine stage having a row of rotor blades. The gas turbine engine has a fan tip axis that joins a radially outer tip of the leading edge of one of the plurality of fan blades of the highest pressure fan stage, and the radially outer tip of the trailing edge of one of the rotor blades of the lowest pressure turbine stage. The fan tip axis lies in a longitudinal plane which contains a centreline of the gas turbine engine. The fan axis angle is between 11 and 20 degrees.

Abstract: A gas turbine engine (10) comprising: a high pressure turbine (17); a low pressure turbine (19); a high pressure compressor (15) coupled to the high pressure turbine (17) by a high pressure shaft (27); a propulsor (23) and a low pressure compressor (14) coupled to the low pressure turbine (19) via a low pressure shaft (26) and a reduction gearbox (30); wherein the low pressure compressor (14) consists of four compressor stages (14) and defines a cruise pressure ratio of between 2.4:1 and 3.3:1; the high pressure compressor (15) defines a cruise pressure ratio of less than 17:1; and the high pressure compressor (15) and low pressure compressor (14) together define a cruise core overall pressure ratio of greater than 36:1.

Abstract: A gas turbine engine has a cycle operability parameter ? in a defined range to achieve improved overall performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined range of cycle operability parameter ? may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A gas turbine engine (10) comprising: a high pressure turbine (17); a low pressure turbine (19); a high pressure compressor (15) coupled to the high pressure turbine (17) by a high pressure shaft (27); a propulsor (23) and a low pressure compressor (14) coupled to the low pressure turbine (19) via a low pressure shaft (26) and a reduction gearbox (30); wherein the low pressure compressor (14) consists of four compressor stages (14) and defines a cruise pressure ratio of between 2.4:1 and 3.3:1; the high pressure compressor (15) defines a cruise pressure ratio of less than 17:1; and the high pressure compressor (15) and low pressure compressor (14) together define a cruise core overall pressure ratio of greater than 36:1.

Abstract: A method of controlling electrical power supplied to a component of a vehicle, the method comprising: receiving a signal comprising information associated with an operating condition of a gas turbine engine; determining whether a parameter exceeds a predetermined threshold value using the information in the received signal; and controlling a reduction in electrical power supplied to a component of a vehicle from a generator of the gas turbine engine if the parameter exceeds the predetermined threshold value.

Abstract: A control system for use in controlling a cabin blower system. The cabin blower system includes a gas turbine engine spool, a cabin blower compressor powered by the spool and arranged in use to compress fluid used in a cabin of an aircraft, and one or more control mechanisms via which the control system controls the power extracted by the cabin blower compressor from the spool. The control system is arranged in use to control the power extracted from the spool by the cabin blower compressor in accordance with one or more primary control parameters. The control system is arranged in use to alter the spool power extracted by the cabin blower compressor by comparison with the power that would have been extracted in accordance with the primary control parameters alone, in response to modifications in a secondary control parameter indicative of the commencement or occurrence of an engine transient.

Abstract: A gas turbine engine has a quasi-non-dimensional mass flow rate in a defined range and a specific thrust in a defined range to achieve improved over all performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined ranges of quasi-non-dimensional mass flow rate and specific thrust may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A gas turbine engine has a cycle operability parameter ? in a defined range to achieve improved overall performance, taking into account fan operability and/or bird strike requirements as well as engine efficiency. The defined range of cycle operability parameter ? may be particularly beneficial for gas turbine engines in which the fan is driven by a turbine through a gearbox.

Abstract: A method of controlling electrical power supplied to a component of a vehicle, the method comprising: receiving a signal comprising information associated with an operating condition of a gas turbine engine; determining whether a parameter exceeds a predetermined threshold value using the information in the received signal; and controlling a reduction in electrical power supplied to a component of a vehicle from a generator of the gas turbine engine if the parameter exceeds the predetermined threshold value.

Abstract: A control system for use in controlling a cabin blower system. The cabin blower system includes a gas turbine engine spool, a cabin blower compressor powered by the spool and arranged in use to compress fluid used in a cabin of an aircraft, and one or more control mechanisms via which the control system controls the power extracted by the cabin blower compressor from the spool. The control system is arranged in use to control the power extracted from the spool by the cabin blower compressor in accordance with one or more primary control parameters. The control system is arranged in use to alter the spool power extracted by the cabin blower compressor by comparison with the power that would have been extracted in accordance with the primary control parameters alone, in response to modifications in a secondary control parameter indicative of the commencement or occurrence of an engine transient.

Abstract: A flow modulating device comprises flow modulating elements 8 of a shape memory alloy, which are acted upon by resilient elements 10. The flow modulating elements 8 and resilient elements 10 are mounted on a common support ring 6. At one temperature, the flow modulating elements 8 overcome the resilient force of the resilient elements 10 to lie against the wall of a duct 4 in which the device is situated. The flow modulating elements 8 thus offer a relatively low resistance to flow in the duct 4. At a second temperature, the force of the resilient elements 10 overcomes that of the flow modulating elements 8 to deflect them inwardly of the duct 4, so increasing the flow resistance of the device.

Abstract: A flow modulating device comprises flow modulating elements 8 of a shape memory alloy, which are acted upon by resilient elements 10. The flow modulating elements 8 and resilient elements 10 are mounted on a common support ring 6. At one temperature, the flow modulating elements 8 overcome the resilient force of the resilient elements 10 to lie against the wall of a duct 4 in which the device is situated. The flow modulating elements 8 thus offer a relatively low resistance to flow in the duct 4. At a second temperature, the force of the resilient elements 10 overcomes that of the flow modulating elements 8 to deflect them inwardly of the duct 4, so increasing the flow resistance of the device.