Modelling combustion in spark ignition engines with special emphasis on near wall flame quenching

Abstract

A flame front is quenched when approaching a cold wall due to excessive heat loss. Accurate computation of combustion rate in such situations requires accounting for near wall flame quenching. Combustion models, developed without considering wall effects, cannot be used for wall bounded combustion modelling, as it leads to wall flame acceleration problem. In this work, a new model was developed to estimate the near wall combustion rate, accommodating quenching effects. The developed correlation was then applied to predict the combustion in two spark ignition engines in combination with the famous Bray–Moss–Libby (BML) combustion model. BML model normally fails when applied to wall bounded combustion due to flame wall acceleration. Results show that the proposed quenching correlation has significantly improved the performance of BML model in wall bounded combustion. As a second step, in order to further enhance the performance, the BML model was modified with the use of Kolmogorov–Petrovski–Piskunov analysis and fractal theory. In which, a new dynamic formulation is proposed to evaluate the mean flame wrinkling scale, there by accounting for spatial inhomogeneity of turbulence. Results indicate that the combination of the quenching correlation and the modified BML model has been successful in eliminating wall flame acceleration problem, while accurately predicting in-cylinder pressure rise, mass burn rates and heat release rates.

Flame Surface Density based mean reaction rate closure for Reynolds averaged Navier Stokes methodology in turbulent premixed Bunsen flames with non-unity Lewis number

“…However, the findings of the current paper are not possible to extract from those studies. The model limitations identified in this paper contributed to the disagreements between the previous RANS results [ [55][56][57][58][59][60][61][62][63] and experimental data. The present work is limited to a-priori analysis and consequently does not…”

“…The BML modelling methodologies discussed in this paper are still frequently used in the context of explosions or internal combustion engines [55][56][57][58][59][60][61][62][63]. However, the findings of the current paper are not possible to extract from those studies.…”

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

“…10,11,12,16 experimentally investigated the influence of the ring pack geometry on the uHC production. The flame wall quenching was examined in dedicated studies, 17,18 where empirical or theoretical correlations for the quenching distance were proposed. Some simplified approaches for the description of the fuel adsorption/desorption from the oil layer were proposed in Dent and Lakshminarayanan 19 and Min and Cheng.…”

“…In light of the above considerations, the main aim of this work is the development of a phenomenological model for the quantification of the unburned hydrocarbons, able to sense the most important engine operating parameters and some geometrical features (ring pack geometry, engine compression ratio, bore). Conversely to other works available in the current literature, 11–23 the model is developed and validated concerning engines fueled with natural gas, instead of gasoline. Moreover, the considered engines are also characterized by different ignition devices, specifically dual fuel mode and pre-chamber.…”