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Comparison of a spectral model for premixed turbulent flame propagation to DNS and experiments

 

作者: Mark Ulitsky,   Chaouki Ghenaï,   Iskender Gökalp,   Lian-Ping Wang,   LanceR Collins,  

 

期刊: Combustion Theory and Modelling  (Taylor Available online 2000)
卷期: Volume 4, issue 3  

页码: 241-264

 

ISSN:1364-7830

 

年代: 2000

 

DOI:10.1088/1364-7830/4/3/302

 

出版商: Taylor & Francis

 

数据来源: Taylor

 

摘要:

A recently developed spectral model for premixed turbulent combustion in the flamelet regime (based on the EDQNM turbulence theory) has been compared with both direct numerical simulations (DNS) and experimental data. The 1283DNS is performed at a Reynolds number of 223 based on the integral length scale. Good agreement is observed for both single- and two-point quantities (i.e. ratio of the turbulent to laminar burning velocities, scalar autocorrelation, dissipation and scalar-velocity cross correlation spectra) for the two different values ofu′/sL0considered. The model also predicts the rapid transient behaviour of the flame at early times. An experimental set-up is then described for generating a lean methane-air flame and measuring two-point spatial correlations along the midpoint of the flame brush (i.e. along the C¯=0.5 contour). The experimental measurements in the flamelet regime take the form of a discontinuous or ‘telegraph’ signal. The EDQNM model, in contrast, describes an ‘ensemble’ of flames, and thus is based solely on continuous variables. A theoretical relationship between the correlation obtained from the EDQNM model and the equivalent correlation for a discontinuous (experimental) flame is derived. The relationship is used to enable a meaningful comparison between experimentally observed and model correlations. In general, the agreement is good for the three different cases considered in this study, with most of the error occurring at the lowest Reynolds number (ReL=22). Furthermore, it is shown that considerably more error would result if no attempt is made to convert the ensemble representation in the model to an equivalent single-flame or ‘telegraph’ signal.

 

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