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Atomization and Sprays, Vol.16, No.5, 475-491, 2006
Optical measurements of the reacting two-phase flow in a realistic gas turbine combustor at elevated pressures
A rectangular sector of a realistic axially staged gas turbine combustor of Rolls-Rayce Deutschland was operated at elevated pressures. Optical measurements of the reacting two-phase flow were performed using phase Doppler anemometry (PDA) and two planar light sheet techniques, laser-induced fluorescence (LIF) and Mie scattering. Beside the interpretation of the results of the measurements, the experience gathered with the techniques is analyzed with respect to the applicability, the accuracy, and the kind of information they deliver. ne constraints, e.g., limited optical access, combustor with several injectors in line, and strong soot luminescence, affecting the optical setup for PDA measurements are. discussed. ne PDA measurements were conducted at a combustor inlet pressure of p = 6 bar. With an estimated error in the size measurement of up to Delta = 10% caused by the change of the reactive index, it was still possible to obtain quantitative results of the mean diameter. The error of the liquid volume concentration is higher and difficult to assess. Beside the unknown refractive index of the droplets, the constantly changing size and shape of The measurement volume due to beam steering effects contributed significantly to the measuring error. images of the planar Mie scattering are used as a consistency check of the PDA data. The light sheet techniques deliver supplementary information. Imaging of kerosene LIP of an isothermal spray at atmospheric pressure was used to calculate the liquid volume concentration. A comparison with results from PDA measurements revealed a good agreement. Under reacting conditions, kerosene LIF was limited to qualitative information on the distribution of liquid and vaporized fuel mainly because of the temperature dependency of the fluorescence quantum yield. At higher pressure, the applicability of LIF was limited by the absorption of the UV laser light in the dense spray. Imaging of the planar Mie scattered light was possible at combustor inlet pressures up to p = 20 bar, giving qualitative information on the distribution of the liquid fuel.