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Heat release rate correlation and combustion noise in premixed flames

Swaminathan, N; Xu, G; Dowling, AP; Balachandran, R; (2011) Heat release rate correlation and combustion noise in premixed flames. J FLUID MECH , 681 80 - 115. 10.1017/jfm.2011.232. Green open access

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Abstract

The sound emission from open turbulent flames is dictated by the two-point spatial correlation of the rate of change of the fluctuating heat release rate. This correlation in premixed flames can be represented well using Gaussian-type functions and unstrained laminar flame thermal thickness can be used to scale the correlation length scale, which is about a quarter of the planar laminar flame thermal thickness. This correlation and its length scale are observed to be less influenced by the fuel type or stoichiometry or turbulence Reynolds and Damkohler numbers. The time scale for fluctuating heat release rate is deduced to be about tau(c)/34 on an average, where tau(c) is the planar laminar flame time scale, using direct numerical simulation (DNS) data. These results and the spatial distribution of mean reaction rate obtained from Reynolds-averaged Navier-Stokes (RANS) calculations of open turbulent premixed flames employing the standard (k) over tilde-(epsilon) over tilde model and an algebraic reaction rate closure, involving a recently developed scalar dissipation rate model, are used to obtain the far-field sound pressure level from open flames. The calculated values agree well with measured values for flames of different stoichiometry and fuel types, having a range of turbulence intensities and heat output. Detailed analyses of RANS results clearly suggest that the noise level from turbulent premixed flames having an extensive and uniform spatial distribution of heat release rate is low.

Type: Article
Title: Heat release rate correlation and combustion noise in premixed flames
Open access status: An open access version is available from UCL Discovery
DOI: 10.1017/jfm.2011.232
Publisher version: http://dx.doi.org/10.1017/jfm.2011.232
Language: English
Additional information: © 2011 Cambridge University Press
Keywords: acoustics, reacting flows, turbulent reacting flows, INLET VELOCITY OSCILLATIONS, ACOUSTIC RADIATION, NONLINEAR RESPONSE, SOUND GENERATION, VALIDATION, TURBULENCE, SPEED, MODEL, JET
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Mechanical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/1332314
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