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Instability Control by Actuating the Swirler in a Lean Premixed Combustor

Mahesh, S and Gopakumar, R and Rahul, B V and Dutta, A K and Mondal, S and Chaudhuri, S (2018) Instability Control by Actuating the Swirler in a Lean Premixed Combustor. In: JOURNAL OF PROPULSION AND POWER, 34 (3). pp. 708-719.

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Official URL: http://dx.doi.org/10.1088/1538-3873/aaab3e

Abstract

A detailed study concerning a novel, dynamic control strategy for mitigating thermoacoustic instability in a swirl-stabilized lean premixed, laboratory combustor configuration is presented in this paper. The mitigation strategy is realized by rotating the otherwise static swirler, which is primarily meant for stabilizing the lean premixed flame. The proposed strategy is tested over a range of bulk flow velocities, mixture equivalence ratios, and swirler rotation rates for validating the robustness of this concept. A prominent reduction in the fundamental acoustic mode amplitude by about 25dB is observed with this control technique for the cases that are studied. The physical mechanism responsible for the instability mitigation due to the rotating swirler is investigated by observing the distinct changes associated with the reacting flowfield using particle image velocimetry. An attempt is made to probe into the self-excited flame dynamics using high-speed intensified, chemiluminescence imaging and identifying the instability driving source locations from a spatial Rayleigh indices map. The rotating swirler induces vortex breakdown and increased turbulence intensity to decimate strongly positive Rayleigh indices regions (and eventually the acoustic energy source) to render quiet instability mitigated swirling flames.

Item Type: Journal Article
Additional Information: Copy right for this article belong to AMER INST AERONAUTICS ASTRONAUTICS, 1801 ALEXANDER BELL DRIVE, STE 500, RESTON, VA 22091-4344 USA
Department/Centre: Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Depositing User: Id for Latest eprints
Date Deposited: 08 May 2018 19:04
Last Modified: 23 Oct 2018 14:47
URI: http://eprints.iisc.ac.in/id/eprint/59811

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