CUED Publications database

Spatial correlation of heat release rate and sound emission from turbulent premixed flames

Liu, Y and Dowling, AP and Swaminathan, N and Dunstan, TD (2012) Spatial correlation of heat release rate and sound emission from turbulent premixed flames. Combustion and Flame, 159. pp. 2430-2440. ISSN 0010-2180

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Abstract

The two-point spatial correlation of the rate of change of fluctuating heat release rate is central to the sound emission from open turbulent flames, and a few attempts have been made to address this correlation in recent studies. In this paper, the two-point correlation and its role in combustion noise are studied by analysing direct numerical simulation (DNS) data of statistically multi-dimensional turbulent premixed flames. The results suggest that this correlation function depends on the separation distance and direction but, not on the positions inside the flame brush. This correlation can be modelled using a combination of Hermite-Gaussian functions of zero and second order, i.e. functions of the form (1-Ax2)e-Bx2 for constants A and B, to include its possible negative values. The integral correlation volume obtained using this model is about 0.2δL3 with the length scale obtained from its cube root being about 0.6δ L, where δ L is the laminar flame thermal thickness. Both of the values are slightly larger than the values reported in an earlier study because of the anisotropy observed for the correlation. This model together with the turbulence-dependent parameter K, the ratio of the root-mean-square (RMS) value of the rate of change of reaction rate to the mean reaction rate, derived from the DNS data is applied to predict the far-field sound emitted from open flames. The calculated noise levels agree well with recently reported measurements and show a sensitivity to K values. © 2012 The Combustion Institute.

Item Type: Article
Uncontrolled Keywords: Combustion noise from open flames Correlation volume and length scale DNS V-flames Heat release rate fluctuation Two-point correlation
Subjects: UNSPECIFIED
Divisions: Div A > Fluid Mechanics
Div A > Energy
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:27
Last Modified: 08 Dec 2014 02:40
DOI: 10.1016/j.combustflame.2012.03.003