Thermoacoustic resonance is a difficult technical problem that is experienced by almost all lean-premixed combustors. The Industrial Trent combustor is a novel dry-low-emissions (DLE) combustor design, which incorporates three stages of lean premixed fuel injection in series. The three stages in series allow independent control of two stages—the third stage receives the balance of fuel to maintain the desired power level—at all power conditions. Thus, primary zone and secondary zone temperatures can be independently controlled. This paper examines how the flexibility offered by a 3-stage lean premixed combustion system permits the implementation of a successful combustion noise avoidance strategy at all power conditions and at all ambient conditions. This is because at a given engine condition (power level and day temperature) a characteristic “noise map” can be generated on the engine, independently of the engine running condition. The variable distribution of heat release along the length of the combustor provides an effective mechanism to control the amplitude of longitudinal resonance modes of the combustor. This approach has allowed the Industrial Trent combustion engineers to thoroughly “map out” all longitudinal combustor acoustic modes and design a fuel schedule that can navigate around regions of combustor thermoacoustic resonance. Noise mapping results are presented in detail, together with the development of noise prediction methods (frequency and amplitude) that have allowed the noise characteristics of the engine to be established over the entire operating envelope of the engine. [S0742-4795(00)00802-4]

Hubbard, S, and Dowling, A. P., 1998, “Acoustic Instabilities in Premix Burners,” AIAA Paper 98-2272, presented at the 4th AIAA/CEAS Aeroacoustics Conference, June 1998, Toulouse, France.
Paschereit, C. O., and Polifke, W., 1998, “Investigation of the Thermoacoustic Characteristics of a Lean Premixed Gas Turbine Burner,” ASME Paper 98-GT-582, presented at the International Gas Turbine & Aeroengine Congress & Exhibition, Stockholm, Sweden.
Williams, F. A., 1985, Combustion Theory, Benjamin/Cummings, Menlo Park, CA, USA.
Chu, B. T., 1953, “Mechanism of Generation of Pressure Waves at Flame Fronts,” Technical Note 3683, National Advisory Committee for Aeronautics.
Candel, S., 1992, “Combustion Instabilities Coupled by Pressure Waves and their Active Control,” 24th Symposium (International) on Combustion, The Combustion Institute, pp. 1277–1296.
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Adv. Appl. Mech.
, pp.
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