US 12,241,421 B1
Method of operating a gas turbine engine
Andrea Minelli, Derby (GB); Craig W Bemment, Derby (GB); Benjamin J Keeler, Chesterfield (GB); David M Beaven, Nottingham (GB); and Kevin R McNally, Derby (GB)
Assigned to ROLLS-ROYCE plc, London (GB)
Filed by ROLLS-ROYCE PLC, London (GB)
Filed on Jun. 25, 2024, as Appl. No. 18/753,264.
Claims priority of application No. 2319140 (GB), filed on Dec. 14, 2023.
Int. Cl. F02C 7/14 (2006.01); F02C 7/06 (2006.01); F02C 7/36 (2006.01)
CPC F02C 7/36 (2013.01) [F02C 7/06 (2013.01); F02C 7/14 (2013.01); F05D 2260/213 (2013.01); F05D 2260/4031 (2013.01)] 15 Claims
OG exemplary drawing
 
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; and
at least one valve arranged to allow a proportion of the oil sent via at least one of the heat exchangers to be varied,
the method comprising controlling the at least one valve such that, under cruise conditions, an oil flow ratio of:

OG Complex Work Unit Math
is in the range from 0 to 0.2 provided that the fuel temperature on entry to the combustor is at least 160° C.