Gas turbine flow modulation

Abstract

Gas Turbine Flow Modulation A method of operating a gas turbine engine, the gas turbine engine comprising: an engine core comprising a turbine, a compressor, a combustor for burning 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 for supporting the fan shaft; an oil loop system for supplying oil to the at least one bearing; and a heat exchange system comprising: an air-to-oil heat exchanger through which oil in the oil loop system flows; a fuel-to-oil heat exchanger through which oil in the oil loop system and fuel flow such that heat is transferred between the oil and the fuel;and a temperature sensor for providing an indication of fuel temperature downstream of the fuel-oil heat exchanger; and at least one valve for varying at least one of an oil flow rate and an air flow rate through at least one of the fuel-oil heat exchanger and the air-oil heat exchanger, the method comprising: determining whether the fuel temperature has increased above a set threshold at cruise conditions, based on an output of 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. Figure for abstract: Fig. 17;