Aircraft power systems

Abstract

A gas turbine engine 10 for an aircraft. The gas turbine engine comprises a combustor 16 comprising a combustion chamber 120 and a plurality of fuel spray nozzles 124 wherein the plurality of fuel spray nozzles comprises a first subset 124A of fuel spray nozzles and a second subset 128B of fuel spray nozzles wherein the combustor is operable in a condition in which each of the fuel spray nozzles of the first subset is supplied with fuel at a greater fuel flow rate than each of the fuel spray nozzles of the second subset. The ratio of the number of fuel spray nozzles in the first subset of fuel spray nozzles to the number of fuel spray nozzles in the second subset of fuel spray nozzles is in the range of 1:2 to 1:5. The engine operation is characterised by specific non-volatile particulate emission ratio of sustainable aviation fuel and fossil fuel at different engine operating conditions. The gas turbine engine is configured to provide fuel comprising a sustainable aviation fuel to the plurality of fuel spray nozzles. A corresponding method is also claimed. Fig 6