US 12,352,210 B2
Gas turbine fuel temperature
Andrea Minelli, Derby (GB); Craig W Bemment, Derby (GB); Benjamin J Keeler, Chesterfield (GB); Kevin R McNally, Derby (GB); and Martin K Yates, Derby (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE plc, London (GB)
Filed on Jun. 25, 2024, as Appl. No. 18/753,121.
Claims priority of application No. 2319128 (GB), filed on Dec. 14, 2023.
Prior Publication US 2025/0198333 A1, Jun. 19, 2025
Int. Cl. F02C 7/14 (2006.01); F02C 7/224 (2006.01); F02C 7/232 (2006.01); F02C 7/06 (2006.01)
CPC F02C 7/14 (2013.01) [F02C 7/224 (2013.01); F02C 7/232 (2013.01); F02C 7/06 (2013.01); F05D 2260/213 (2013.01)] 18 Claims
OG exemplary drawing
 
1. A method of operating a gas turbine engine of an aircraft, 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 fan shaft;
at least one bearing arranged to support the fan shaft;
at least one auxiliary system arranged to use some of the fuel;
an oil loop system arranged to supply oil to the at least one bearing; and
a heat exchange system comprising:
a primary fuel-oil heat exchanger through which the oil in the oil loop system and at least substantially all the fuel flow such that heat is transferred between the oil and the fuel; and
a secondary fuel-oil heat exchanger through which the oil in the oil loop system and a portion of the fuel flow, such that heat is transferred between the oil and the fuel, the secondary fuel-oil heat exchanger being arranged to supply fuel to the at least one auxiliary system;
a fuel pump arranged to pump the fuel, wherein the fuel pump is located downstream of the primary fuel-oil heat exchanger and upstream of the secondary fuel-oil heat exchanger along a fuel flow path;
a fuel bypass pipe arranged to allow a proportion of the fuel to bypass at least one of the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger;
a fuel bypass valve arranged to allow the proportion of the fuel sent through the fuel bypass pipe to be varied;
an oil bypass pipe arranged to allow a proportion of the oil to bypass at least one of the primary fuel-oil heat exchanger and the secondary fuel-oil heat exchanger; and
an oil bypass valve arranged to allow the proportion of the oil sent through the oil bypass pipe to be varied, wherein
the method comprises controlling the heat exchange system such that, under cruise conditions, the fuel temperature on leaving the secondary fuel-oil heat exchanger is in the range from 120° C. to 200° C., wherein controlling the heat exchange system comprises
determining at least one fuel characteristic of the fuel, the at least one fuel characteristic being other than the fuel temperature and being selected from the group consisting of:
i. a percentage of sustainable aviation fuel in the fuel:
ii. a heteroatomic species concentration of the fuel;
iii. an aromatic hydrocarbon content of the fuel;
iv. a multi-aromatic hydrocarbon content of the fuel:
v. a percentage of nitrogen-containing species in the fuel:
vi. a presence or percentage of a tracer species or trace element in the fuel;
vii. a hydrogen to carbon ratio of the fuel;
viii. a hydrocarbon distribution of the fuel;
ix. a level of non-volatile particulate matter emissions on combustion;
x. a naphthalene content of the fuel;
xi. a sulphur content of the fuel;
xii. a cycloparaffin content of the fuel;
xiii. a thermal stability of the fuel; and
xiv. a level of coking of the fuel, and
controlling, based on the determined at least one fuel characteristic, at least one of the fuel bypass valve and the oil bypass valve so as to adjust the proportion of the fuel and/or the oil sent via at least one of the primary and secondary fuel-oil heat exchangers at cruise conditions.