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TECHNICAL PAPERS: Gas Turbines: Combustion and Fuels

Unsteady Aerodynamics of an Aeroengine Double Swirler Lean Premixing Prevaporizing Burner

[+] Author and Article Information
Edward Canepa

 DIMSET—Università di Genova, I-16145 Genova, Italyedward.canepa@unige.it

Pasquale Di Martino

 Avio S.p.A—R.&D., I-80038 Pomigliano d’Arco, Napoli, Italypasquale.dimartino@aviogroup.com

Piergiorgio Formosa

 DIMSET—Università di Genova, I-16145 Genova, Italyformosap@libero.it

Marina Ubaldi

 DIMSET—Università di Genova, I-16145 Genova, Italyzunmp@unige.it

Pietro Zunino

 DIMSET—Università di Genova, I-16145 Genova, ItalyPietro.zunino@unige.it

J. Eng. Gas Turbines Power 128(1), 29-39 (Mar 01, 2004) (11 pages) doi:10.1115/1.1924720 History: Received October 01, 2003; Revised March 01, 2004

Lean premixing prevaporizing (LPP) burners represent a promising solution for low-emission combustion in aeroengines. Since lean premixed combustion suffers from pressure and heat release fluctuations that can be triggered by unsteady large-scale flow structures, a deep knowledge of flow structures formation mechanisms in complex swirling flows is a necessary step in suppressing combustion instabilities. The present paper describes a detailed investigation of the unsteady aerodynamics of a large-scale model of a double swirler aeroengine LPP burner at isothermal conditions. A three-dimensional (3D) laser Doppler velocimeter and an ensemble-averaging technique have been employed to obtain a detailed time-resolved description of the periodically perturbed flow field at the mixing duct exit and associated Reynolds stress and vorticity distributions. Results show a swirling annular jet with an extended region of reverse flow near to the axis. The flow is dominated by a strong periodic perturbation, which occurs in all the three components of velocity. Radial velocity fluctuations cause important periodic displacement of the jet and the inner separated region in the meridional plane. The flow, as expected, is highly turbulent. The periodic stress components have the same order of magnitude of the Reynolds stress components. As a consequence the flow-mixing process is highly enhanced. Turbulence acts on a large spectrum of fluctuation frequencies, whereas the large-scale motion influences the whole flow field in an ordered way that can be dangerous for stability in reactive conditions.

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Copyright © 2006 by American Society of Mechanical Engineers
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Figures

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Figure 2

Measuring-point locations

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Figure 3

LDV measurement chain

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Figure 4

Velocity time trace and power spectrum

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Figure 5

Auto- and cross-correlations of signals of probes 1 and 2 at the premixer duct outlet (x∕D=0.1)

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Figure 6

Time-averaged velocity components distributions

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Figure 7

Time-averaged rms of turbulent and periodic fluctuations

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Figure 8

Time-averaged turbulent and periodic shear stresses

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Figure 9

Vector plots superimposed to ensemble-averaged axial velocity in the meridional plane

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Figure 10

Instantaneous distribution of ensemble-averaged axial velocity in cross-sectional planes

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Figure 11

Time evolution of ensemble-averaged tangential vorticity in the meridional plane

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Figure 12

Instantaneous distribution of ensemble-averaged axial vorticity in cross-sectional planes

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