Gas turbine reheat combustor including a fuel injector for delivering fuel into a gas mixture together with cooling air previously used for convectively cooling the reheat combustor

A gas turbine engine, comprising:

• a low pressure compressor;
• a high pressure compressor;
• a primary combustor;
• a high pressure turbine for expanding combustion gases produced by the primary combustor;
• a reheat combustor for reheating the combustion gases following expansion through the high pressure turbine;
• and
• a low pressure turbine for expanding the reheated combustion gases wherein the reheat combustor comprises:
• a fuel/gas mixer for mixing fuel with combustion gases that have been produced by the primary combustor and expanded through the high pressure turbine;
• a plurality of fuel injectors for injecting fuel into the fuel/gas mixer;
• an annular combustion chamber downstream of the fuel/gas mixer, in which the mixture of injected fuel and combustion gases is combusted prior to expansion through a low pressure turbine;
• wherein a wall of the fuel/gas mixer defines at least one convective cooling path through which cooling air flows, in use, to convectively cool the fuel/gas mixer;
• and the fuel injectors are arranged to inject the cooling air previously used for convective cooling of the fuel/gas mixer into mixing zones of the fuel/gas mixer together with the fuel.

A method of cooling a reheat combustor in a gas turbine engine, comprising:

• injecting cooling air previously used for convectively cooling at least a part of the reheat combustor by fuel injectors into mixing zones of the reheat combustor together with fuel;
• convectively cooling a combustion chamber downstream of the mixing zones;
• convectively cooling mixing zones with cooling air therefrom;
• convectively cooling low pressure turbine inlet guide vanes (LP IGV's) downstream of the combustion chamber;
• and
• convectively cooling the combustion chamber with cooling air therefrom.