Role of Buoyancy Induced Vortices in a Coupled-Mode of Oscillation in Laminar and Turbulent Jet Diffusion Flames

Nayak, Guguloth Mahesh and Kolhe, Pankaj and Balusamy, Saravanan (2022) Role of Buoyancy Induced Vortices in a Coupled-Mode of Oscillation in Laminar and Turbulent Jet Diffusion Flames. Flow, Turbulence and Combustion, 108 (4). pp. 1069-1087. ISSN 1386-6184

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Abstract

The unsteady effects of buoyancy-induced instabilities on jet diffusion flames are investigated experimentally under normal gravity conditions. Methane and propane are used as test fuels that are lighter and heavier than ambient air, respectively. A similar Froude (Fr) and Reynolds (Re) number relationship is realized in both hydrocarbon fuels with different tube diameters ranging from 6 to 24.2 mm. The Schlieren visualization technique and high-speed imaging synchronized with chemiluminescence signal measurement are used to identify changes in global flame shape and dominant frequency. Buoyancy-induced instabilities generate two forms of diffusion flames with varying frequencies in space. Both laminar and turbulent jet flames exhibit natural and subharmonic frequencies, as well as a shift between them. The methane-propane Re–Fr relationship confirms the instability mode transition. In addition, Strouhal (St) and Froude number relations are obtained as St∝Fr-0.50, with a slope difference between natural and subharmonic modes in both fuels. © 2021, The Author(s), under exclusive licence to Springer Nature B.V.

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IITH Creators:

IITH Creators	ORCiD
Kolhe, Pankaj	https://orcid.org/0000-0002-7930-5987
Balusamy, Saravanan	https://orcid.org/0000-0002-3418-4915

Item Type:

Article

Additional Information:

The Science and Engineering Research Board (SERB) funds this research with grant number ECR/2015/000343. Mahesh Nayak is grateful to the Ministry of Education in India for providing a Ph.D. fellowship. The authors would like to express their gratitude to the central workshop staff at IIT Hyderabad for their assistance with fabrication work.

Uncontrolled Keywords:

Buoyancy-induced vortex; Coupled-mode oscillation; Diffusion flame; Strouhal-Froude number; Subharmonic frequency; Vortex merging

Subjects:

Physics > Mechanical and aerospace

Divisions:

Department of Mechanical & Aerospace Engineering

Depositing User:

. LibTrainee 2021

Date Deposited:

22 Jul 2022 09:12

Last Modified:

22 Jul 2022 09:12