Instability Suppression in a Swirl-Stabilized Combustor Using Microjet Air Injection

Type
Conference Paper

Authors
LaBry, Zachary
Shanbhogue, Santosh
Speth, Raymond
Ghoniem, Ahmed

KAUST Grant Number
KUS-110-010-01

Online Publication Date
2012-06-25

Print Publication Date
2010-01-04

Date
2012-06-25

Abstract
In this study, we examine the effectiveness of microjet air injection as a means of suppressing thermoacoustic instabilities in a swirl-stabilized, lean-premixed propane/air combustor. High-speed stereo PIV measurements, taken to explore the mechanism of combustion instability, reveal that the inner recirculation zone plays a dominant role in the coupling of acoustics and heat release that leads to combustion instability. Six microjet injector configurations were designed to modify the inner and outer recirculation zones with the intent of decoupling the mechanism leading to instability. Microjets that injected air into the inner recirculation zone, swirling in the opposite sense to the primary swirl were effective in suppressing combustion instability, reducing the overall sound pressure level by up to 17 dB within a certain window of operating conditions. Stabilization was achieved near an equivalence ratio of 0.65, corresponding to the region where the combustor transitions from a 40 Hz instability mode to a 110 Hz instability mode. PIV measurements made of the stabilized flow revealed significant modification of the inner recirculation zone and substantial weakening of the outer recirculation zone.

Citation
LaBry Z, Shanbhogue S, Speth R, Ghoniem A (2010) Instability Suppression in a Swirl-Stabilized Combustor Using Microjet Air Injection. 48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition. Available: http://dx.doi.org/10.2514/6.2010-1524.

Acknowledgements
The authors would like to acknowledge the King Abdullah University of Science and Technology for their support of this research. This work was funded by the KAUST grant, number KUS-110-010-01.

Publisher
American Institute of Aeronautics and Astronautics (AIAA)

Journal
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition

DOI
10.2514/6.2010-1524

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