Abstract: A method of controlling turbine tip clearance includes measuring turbine speed; measuring turbine temperature; measuring parameters indicative of current operating conditions; determining limits for the turbine speed and turbine temperature; calculating target tip clearance from the turbine speed, turbine temperature and parameters, to optimise turbine efficiency within the turbine speed and turbine temperature limits; and controlling turbine tip clearance apparatus to the calculated target tip clearance.

Abstract: An engine that has, in axial flow series, booster compressor, core compressor, combustion equipment, core turbine, and low-pressure turbine. Core turbine drives core compressor via an interconnecting high-pressure shaft. Low-pressure turbine drives booster compressor via an interconnecting low-pressure shaft. Low-pressure turbine also drives external load having a defined speed characteristic that dictates speed of the low-pressure turbine and booster compressor. Booster compressor has one or more rows of variable stator vanes. The method includes: scheduling variation in the angle of variable stator vanes as a function of speed of the booster compressor wherein the vanes open as booster compressor speed increases; measuring or setting one or more operational parameters which are determinative of temperature at entry to core turbine; and biasing scheduling of angle variation of variable stator vanes as a function of operational parameter(s) to reduce variation in temperature at entry to core turbine.

Abstract: A method of controlling turbine tip clearance includes measuring turbine speed; measuring turbine temperature; measuring parameters indicative of current operating conditions; determining limits for the turbine speed and turbine temperature; calculating target tip clearance from the turbine speed, turbine temperature and parameters, to optimise turbine efficiency within the turbine speed and turbine temperature limits; and controlling turbine tip clearance apparatus to the calculated target tip clearance.

Abstract: A method to detect shaft break includes monitoring first and second parameters and defining a two-dimensional parameter space that is a function of the first and second parameters, the two-dimensional parameter space includes integration regions. The method also includes defining an integration function for each integration region. For measured values of the first and second parameters, the method determines the applicable integration region and applies the integration function to the first parameter to give an integration result; and then sets a shaft break signal to TRUE when the integration result exceeds a predetermined threshold. The present invention also provides a shaft break detection system.

Abstract: A method to determine shaft stiffness of a rotating shaft, the shaft coupling a turbine to drive the rotation and a load to be driven by the rotation. For a given operational temperature and rotational speed of the shaft, the method including steps to determine polar moments of inertia of the load and the turbine. Determine natural torsional vibration frequency of the shaft. Determine the shaft stiffness by calculation using the inertias and vibration frequency.

Abstract: An engine that has, in axial flow series, booster compressor, core compressor, combustion equipment, core turbine, and low-pressure turbine. Core turbine drives core compressor via an interconnecting high-pressure shaft. Low-pressure turbine drives booster compressor via an interconnecting low-pressure shaft. Low-pressure turbine also drives external load having a defined speed characteristic that dictates speed of the low-pressure turbine and booster compressor. Booster compressor has one or more rows of variable stator vanes. The method includes: scheduling variation in the angle of variable stator vanes as a function of speed of the booster compressor wherein the vanes open as booster compressor speed increases; measuring or setting one or more operational parameters which are determinative of temperature at entry to core turbine; and biasing scheduling of angle variation of variable stator vanes as a function of operational parameter(s) to reduce variation in temperature at entry to core turbine.

Abstract: A shaft break detection system and a method of detecting shaft break for a gas turbine engine. A first indication is calculated from measured rotational speed of a shaft. A second indication is calculated from the rotational speed. A shaft break signal is generated if both indications are true.

Abstract: A turbine fuel supply system is disclosed as including a first sub-system having: a first nozzle for injecting fuel into a combustor of a turbine engine; a first valve controllable to communicate fuel to the first nozzle; and a first fuel manifold for communicating fuel to the first valve from a fuel source; the system further including a controller assembly for raising the pressure of fuel in the first fuel manifold; and the system being characterized in that the first valve is adapted to open in response to a predetermined pressure difference between the first fuel manifold and the pressure in the combustor, thereby allowing fuel to be communicated from the first fuel manifold to the first nozzle. The system may include a first recirculating conduit in fluid communication with the first fuel manifold and the fuel source, the first recirculating conduit allowing fuel not communicated by the first valve to be returned to the fuel source.

Abstract: A shaft break detection system and a method of detecting shaft break for a gas turbine engine. A first indication is calculated from measured rotational speed of a shaft. A second indication is calculated from the rotational speed. A shaft break signal is generated if both indications are true.

Abstract: A method of detecting an ice shedding event in a gas turbine engine, the engine having a rotor comprising a compressor drivingly connected via a shaft to a turbine; the method for detecting an ice shedding event comprising the steps of measuring the temperature at regular intervals and where a temperature drop of at least 20 degrees per second is recorded, producing a signal indicative of an ice shedding event and sending the signal to an indicator device. Advantageously, the engine may then be inspected for damage associated to an ice impact rather than other foreign object ingestion event or fuel flow irregularity. Alternatively, instead of temperature, pressure may be measured and a pressure drop of at least 20 kPa per second is indicative of an ice shedding event.

Abstract: A turbine fuel supply system is disclosed as including a first sub-system having: a first nozzle for injecting fuel into a combustor of a turbine engine; a first valve controllable to communicate fuel to the first nozzle; and a first fuel manifold for communicating fuel to the first valve from a fuel source; the system further including a controller assembly for raising the pressure of fuel in the first fuel manifold; and the system being characterized in that the first valve is adapted to open in response to a predetermined pressure difference between the first fuel manifold and the pressure in the combustor, thereby allowing fuel to be communicated from the first fuel manifold to the first nozzle. The system may include a first recirculating conduit in fluid communication with the first fuel manifold and the fuel source, the first recirculating conduit allowing fuel not communicated by the first valve to be returned to the fuel source.