Technical Report 29, c4e-Preprint Series, Cambridge

Numerical simulation and sensitivity analysis of detailed soot particle size distribution in laminar premixed ethylene flames

ref: Technical Report 29, c4e-Preprint Series, Cambridge

Associated Theme: Nanoparticles

Abstract

In this paper, the prediction of a soot model [Appel et. al, Combustion and Flame, 121(2000)] is compared to recently a published set of highly de- tailed soot particle size distributions [Zhao et. al, Proceedings of Combustion Institute, 30(2005)]. A stochastic approach is used to obtain soot particle size distributions (PSDs). The key features of the measured and simulated particle size distributions are identified and used as a simple way of comparing PSDs. The sensitivity of the soot PSDs to the parameters defining parts of the soot model, such as soot inception, particle and PAH collision efficiency and enhancement, and surface activity is investigated. Incepting soot particle size is found to have a very significant effect on the lower end of the PSDs, especially the position of the trough for a bimodal soot PSDs. A new model for the decay in the surface activity is proposed in which the activity of the soot particle depends only on the history of that particle and the local tem- perature in the flame. This is a first attempt to use local flame variables to define the surface ageing which has major impact on the prediction of high end of the PSDs. Using these modifications to the soot model it is possible to improve the agreement between some of the points of interest in the simulated and measured PSDs. The paper achieves the task to help advance the soot models to predict soot PSD in addition to soot volume fraction and number density, which has been the focus of the literature.

Material from this preprint has been published in: Combustion and Flame 145, 117-127, (2006)

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