A Study on the Local Flame Displacement Velocity of Premixed Turbulent Flames

The aim of this work is to examine the state-of-the-art turbulent flame speed (ST) correlations and optimize their adjustable parameters to best match a wide range experimental turbulent premixed combustion results. Four correlations based on previous works by Zimont, Kobayashi, Ronney and Muppala have been selected for the present study. Using a Matlab-based Nelder-Mead simplex direct search method, each correlation's adjustable parameters are optimized such that their mean absolute percentage error (MAPE) is minimized. In addition to the literature correlations, a new empirical correlation is developed using the same search method to define constants and powers in the expression. Two sets of optimized parameters are proposed to account for atmospheric and elevated (0.2-3.0 MPa) pressure flames. Each correlation is tested further, examining their ability to match ST trends for varying equivalence ratio (ϕ) and turbulent velocity ratio (u'/SL). It was found that a minimum of two correlations and two sets of adjustable parameters are required to accurately account for the entire range of data, thus showing that there is currently no turbulent flame speed correlation that is applicable across all engine-relevant conditions.

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A Comparison of Turbulent Flame Speed Correlations for Hydrocarbon Fuels at Elevated Pressures

Burke

Güthe²,

Monaghan

2016

Volume 4B: Combustion, Fuels and Emissions

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The aim of this work is to provide insight into the state-of-the-art turbulent flame speed (ST) correlations and to determine the most appropriate correlations to use under different turbulent premixed combustion conditions. The accuracies of 16 correlations for ST are determined using a large volume of data over a range of conditions. Accuracy is based on a mean absolute percentage error (MAPE). The comparison is completed once using the original authors’ adjustable parameters and a second time using parameters proposed by the current work that minimize MAPE for four different groups of data. Based on the results of the analysis using the newly-suggested parameters, the five most accurate correlations are then further examined to evaluate their respective abilities to predict trends under various turbulent conditions. While many correlations perform well over the range of data (MAPE < 33%), no single correlation can predict all experimentally-observed trends for methane flames under these conditions. Further issues are found when predicting trends for larger hydrocarbons; ethane and propane. Although low errors are again found (MAPE < 25%), correlations are not generally able to replicate the observed trends of experimental data for C2H6 and C3H8. While it is commonly accepted that no single correlation can accurately predict ST, this work has shown that the correlation derived by Muppala provides the closest overall agreement to the data examined. However it cannot be defined as a general correlation. For this reason the authors have proposed to continue development of an ST modeling tool based on a modified version of the Cantera 1D freely propagating laminar flame speed (SL) code. Greater cooperation in the ST research community to expand the range of available experimental data and better enable direct comparison of data and correlations from different experiments is also recommended.

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A Study on the Local Flame Displacement Velocity of Premixed Turbulent Flames

Cited by 12 publications

References 25 publications

Experimental and analytical investigation of the turbulent burning velocity of two-component fuel mixtures of hydrogen, methane and propane

Experimental and analytical investigation of the turbulent burning velocity of two-component fuel mixtures of hydrogen, methane and propane

An Optimized Correlation for Turbulent Flame Speed for C1–C3 Fuels at Engine-Relevant Conditions

A Comparison of Turbulent Flame Speed Correlations for Hydrocarbon Fuels at Elevated Pressures

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