摘要 |
A three stage lean burn combustion chamber (28) comprises a primary combustion zone (36), a secondary combustion zone (40) and a tertiary combustion zone (44). Each of the combustion zones (36, 40, 44) is supplied with premixed fuel and air by respective fuel and air mixing ducts (76, 78, 80, 92). Secondary fuel injectors (106) and two secondary fuel manifolds (105A, 105B) supply fuel into different circumferential sectors, halves, of the secondary fuel and air mixing duct (80). The secondary fuel manifolds (105A, 105B) have secondary fuel valves (107A, 107B) which supply a greater proportion of fuel to the secondary fuel manifold (105A) than the secondary fuel manifold (105B) so that there is circumferential biasing of fuel in the secondary combustion zone (40). This circumferential biasing of fuel in the secondary combustion zone (40) reduces the generation of harmful pressure oscillations in the combustion chamber (28). Alternatively the biasing of the fuel may be in the primary or tertiary combustion zones (36, 44).
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