| CPC F02C 7/14 (2013.01) [F02C 7/36 (2013.01); F05D 2260/213 (2013.01); F05D 2260/4031 (2013.01); F05D 2260/83 (2013.01)] | 20 Claims |
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1. A method of operating a gas turbine engine, the 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 so as to drive the fan at a lower rotational speed than the core shaft;
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 in the oil loop system flows;
a fuel-oil heat exchanger through which the oil in the oil loop system and the fuel flow such that heat is transferred between the oil and the fuel;
a temperature sensor arranged to provide an indication of fuel temperature downstream of the fuel-oil heat exchanger;
a fuel composition determination module arranged to determine at least one fuel characteristic of the fuel and
at least one valve arranged to allow at least one of oil flow rate and air flow rate through at least one of the fuel-oil heat exchanger and the air-oil heat exchanger to be varied, the method comprising:
after refueling, determining in the fuel composition determination module the at least one fuel characteristic of the fuel;
determining a set threshold based on the at least one fuel characteristic of the fuel;
determining if the fuel temperature has increased above the set threshold at cruise conditions, based on an output from the temperature sensor; and
in response to determining that the fuel temperature has increased above the set threshold at cruise conditions, controlling the at least one valve so as to change the at least one flow rate through the at least one heat exchanger, wherein
the at least one fuel characteristic is at least one of:
percentage of sustainable aviation fuel in the fuel:
heteroatomic species concentration of the fuel' aromatic hydrocarbon content of the fuel;
multi-aromatic hydrocarbon content of the fuel;
percentage of nitrogen-containing species in the fuel;
presence or percentage of a tracer species or trace element in the fuel;
hydrogen to carbon ratio of the fuel:
hydrocarbon distribution of the fuel;
level of non-volatile particulate matter emissions on combustion;
naphthalene content of the fuel;
sulphur content of the fuel;
cycloparaffin content of the fuel:
an indication that the fuel is a fossil fuel; and
at least one of density, viscosity, calorific value, and heat capacity.
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