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Turbulence Heat and Mass Transfer 5. Proceedings of the International Symposium on Turbulence Heat and Mass Transfer
September, 25-29, 2006, Dubrovnik, Croatia

DOI: 10.1615/ICHMT.2006.TurbulHeatMassTransf


ISBN Print: 978-1-56700-229-4

ISSN: 2377-2816

Experimental investigation of coherent flow structures in a gas-turbine combustor model

pages 279-282
DOI: 10.1615/ICHMT.2006.TurbulHeatMassTransf.510
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ABSTRACT

The isothermal flow field in a gas-turbine combustor model characterised by the injection of secondary air jets into a swirled main flow was experimentally investigated by various non-intrusive measurement techniques. The present paper focuses on coherent structures arising from the swirl nozzles, such as precessing vortex core (PVC), and their impact on the penetrating behaviour of the jets. Results of LDA-measurements and time-resolved imaging revealed a strong periodic fluctuation of the axial velocity component at a frequency proportional to the mass flow, indicating a helix vortex, typical of a swirl flow. A more detailed analysis of this phenomenon revealed another periodic movement of the helix opening angle. This oscillation, which turned out to be in-phase opposition for adjacent swirl nozzles, is also proportional to the mass flow but at a larger period (Tβ ≈ 102*TPVC). Both oscillation frequencies could be observed in the penetration behaviour of the secondary air jets e.g. the penetration angle. A Proper Orthogonal Decomposition (POD) of PIV and QLS (quantitative light sheet) data showed that these phenomena dominate the flow field.

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