Rolls-royce Corporation

Kevin R McNally

Craig W Bemment

Benjamin J Keeler

Andrea Minelli

Martin Kenneth Yates

Paul William Ferra

Alastair G Hobday

David Michael Beaven

A method of operating an aircraft gas turbine engine including: a core including a turbine, a compressor, a combustor, and a core shaft connecting the turbine to the compressor; a fan upstream of the core; a fan shaft; at least one bearing supporting the fan shaft; at least one auxiliary system using some of the fuel; an oil loop system to supply oil to the bearing; and a heat exchange system including: a primary fuel-oil heat exchanger through which oil in the oil loop system and substantially all the fuel flow to transfer heat between the oil and the fuel; and a secondary fuel-oil heat exchanger through which oil in the oil loop system and a portion of the fuel flow, to transfer heat between the oil and the fuel; and a fuel pump; wherein, under cruise conditions, fuel temperature on leaving the second heat exchanger is 120° C. to 200° C.

Gas turbine fuel temperature

A method of operating a gas turbine engine including: an engine core with a turbine, compressor, a fuel combustor, and a core shaft connecting the turbine to the compressor; a fan; a gearbox that receives an input from the core shaft and outputs drive to the fan; an oil loop system arranged to supply oil to the gearbox; and a heat exchange system including: an air-oil heat exchanger through which the oil flows; a fuel-oil heat exchanger through which the oil and the fuel flow; a temperature sensor downstream of the fuel-oil heat exchanger; and a valve arranged to allow oil or air flow rate through at least one heat exchanger to be varied, the method including: determining if the fuel temperature has increased above a set threshold at cruise conditions; and in response, controlling the valve so as to change the flow rate through the heat exchanger.

Gas turbine temperature sensor

A method of determining at least one fuel characteristic of a fuel provided to a gas turbine engine of an aircraft includes making an operational change, the operational change being effected by a controllable component of a propulsion system of which the gas turbine engine forms a part, and being arranged to affect operation of the gas turbine engine, sensing a response to the operational change; and determining the at least one fuel characteristic based on the response to the operational change.

Aircraft operation

A method of refuelling an aircraft comprising a gas turbine engine and a fuel tank arranged to provide fuel to the gas turbine engine comprises obtaining an amount of energy required for an intended flight profile; obtaining a calorific value of fuel available to the aircraft for refuelling; calculating the amount of the available fuel needed to provide the required energy; and refuelling the aircraft with the calculated amount of the available fuel. The calculating the amount of the available fuel needed to provide the required energy may comprise obtaining an energy content of fuel already in the fuel tank and subtracting that from the determined amount of energy required for the intended flight profile.

Aircraft refuelling

A method of operating a gas turbine engine comprising an engine core comprising a turbine, a compressor, a combustor arranged to combust a fuel, and a core shaft connecting the turbine to the compressor; a fan located upstream of the engine core; a gearbox that receives an input from the core shaft and outputs drive to the fan; an oil loop system arranged to supply oil to the gearbox; and a heat exchange system comprising an air-oil heat exchanger through which the oil flows, a fuel-oil heat exchanger through which the oil and the fuel flow; and a valve arranged to allow a proportion of the oil sent via at least one of the heat exchangers to be varied, is disclosed, the method comprising controlling the valve such that, under cruise conditions, an oil flow ratio of: is in the range from 0 to 0.59.

Method of operating a gas turbine engine

A method of operating an aircraft gas turbine engine including: a core including a turbine, a compressor, a combustor to combust fuel, and a core shaft connecting the turbine to the compressor; a fan upstream of the core; a fan shaft; a bearing supporting the fan shaft; an oil loop system supplying oil to the bearing; and a heat exchange system including: an air-oil heat exchanger through which oil in the oil loop system flows; and a fuel-oil heat exchanger through which oil in the oil loop system and fuel flow to transfer heat between the oil and the fuel; and a bypass pipe to allow a proportion of the oil to flow past one of the air-oil and the fuel-oil heat exchanger; and a bypass valve to allow the proportion of the oil sent through the bypass pipe to be varied.

Operating a gas turbine engine

A method of operating a gas turbine engine is disclosed, the gas turbine engine comprising a fuel delivery system arranged to provide fuel; a combustor arranged to combust at least a proportion of the fuel; a primary fuel-oil heat exchanger arranged to have up to 100% of the fuel provided by the fuel delivery system flow therethrough; and a secondary fuel-oil heat exchanger arranged to have a proportion of the fuel from the primary fuel-oil heat exchanger flow therethrough. Fuel is arranged to flow from the primary fuel-oil heat exchanger to the secondary fuel-oil heat exchanger and oil is arranged to flow from the secondary fuel-oil heat exchanger to the primary fuel-oil heat exchanger. The method comprises transferring 200-600 KJ/mof heat to the fuel from the oil in the primary fuel-oil heat exchanger at cruise conditions.

Fuel oil heat exchange

The present application discloses a method of determining one or more fuel characteristics of an aviation fuel suitable for powering a gas turbine engine of an aircraft, the gas turbine engine having a combustor supplied with fuel from a fuel system, the method comprising: determining a mass of the fuel being supplied to the combustor; determining a corresponding volume of the fuel being supplied to the combustor; and determining one or more fuel characteristics based on the determined mass and volume. Also disclosed is a fuel characteristic determination system, a method of operating an aircraft, and an aircraft.

Fuel delivery

A method of checking refuelling of an aircraft comprising a gas turbine engine and a fuel tank arranged to provide fuel to the gas turbine engine comprises: receiving an input of calorific value data for fuel provided to the aircraft on refuelling; independently determining at least one of: (i) the calorific value of fuel supplied to the gas turbine engine in use; and (ii) the calorific value of the fuel provided to the aircraft on refuelling; and providing an alert if the determined calorific value is inconsistent with the calorific value data input received.

Method of determining the calorific value of fuel provided to a gas turbine engine

A method of operating a gas turbine engine, the engine including an engine core with a turbine, a compressor, a combustor arranged to combust a fuel, and a core shaft connecting the turbine to the compressor; a fan upstream of the engine core; a fan shaft; a main gearbox that receives an input from the core shaft and outputs drive to the fan via the fan shaft; a primary oil loop system to supply oil to lubricate the main gearbox; and a heat exchange system to transfer heat between the oil and the fuel, the oil having an average temperature of at least 180° C. on entry to the heat exchange system at cruise conditions. The method includes transferring heat from the oil to the fuel to lower the fuel viscosity to a value of less than or equal to 0.58 mm/s on entry to the combustor at cruise conditions.

Combustion of fuel

A gas turbine engine including a fuel delivery system arranged to provide fuel; a combustor arranged to combust at least a proportion of the fuel; a primary fuel-oil heat exchanger arranged to have up to 100% of the fuel provided by the fuel delivery system flow therethrough; and a secondary fuel-oil heat exchanger arranged to have a proportion of the fuel from the primary fuel-oil heat exchanger flow therethrough. Fuel is arranged to flow from the primary fuel-oil heat exchanger to the secondary fuel-oil heat exchanger whereas oil is arranged to flow from the secondary fuel-oil heat exchanger to the primary fuel-oil heat exchanger. The method includes using at least one of the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger to heat the fuel so as to adjust the fuel viscosity to a maximum of 0.58 mm/s on entry to the combustor at cruise conditions.

Gas turbine operation

A gas turbine engine includes: a combustor that combust the fuel and having an exit, a combustor exit temperature (T40) is the average temperature of flow and a combustor exit pressure (P40) is the total pressure there; a turbine including a rotor having a leading edge and a trailing edge, and wherein a turbine rotor entry temperature (T41) is an average temperature of flow at the leading edge and a turbine rotor entry pressure (P41) is the total pressure there; and a compressor having an exit, wherein a compressor exit temperature (T30) is the average temperature of flow at the exit from the compressor and a compressor exit pressure (P30) is the total pressure there (all at cruise conditions). A method of determining at least one fuel characteristic includes changing a fuel supplied to the engine; and determining a change in a relationship between T30 or P30, T40 and T41, or of P40 and P41, respectively.

A propulsion system for an aircraft includes a gas turbine engine and a fuel tank, wherein the fuel includes at least a proportion of a sustainable aviation fuel&#x2014;SAF&#x2014;having a density between 90% and 98% of the density, &#x3c1;, of kerosene and a calorific value between 101% and 105% the calorific value CV, of kerosene. The engine includes a combustor; and a fuel pump arranged to supply a fuel thereto at an energy flow rate, C, the pump being arranged to output fuel at a volumetric flow rate, Q, the percentage of fuel passing through the pump not provided to the combustor being referred to as a spill percentage. The fuel include X % SAF, where X % is in the range from 5% to 100%, and has a density, &#x3c1;, and a calorific value CV. The propulsion system is arranged so:  

Aircraft fuel system for gas turbine engine

A method of determining a calorific value of fuel supplied to a gas turbine engine of an aircraft comprises sensing at least one engine parameter during a first time period of aircraft operation during which the gas turbine engine uses the fuel; and, based on the at least one sensed engine parameter, determining a calorific value of the fuel. The sensing may be repeated such that the at least one engine parameter is monitored over time. The gas turbine engine may be a propulsive gas turbine engine of the aircraft or a gas turbine engine of an auxiliary power unit of the aircraft.

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Derby, United Kingdom

Kevin R McNally