科研之友
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摘要
The present numerical and experimental study aims at enhancing the quantitative accuracy of soot formation predictions in atmospheric pressure, laminar, sooting, coflow diffusion flames of jet fuel, improving upon a previously published study that used a polycyclic aromatic hydrocarbon (PAH) nucleation based soot model. That model used a conventional acetylene-based PAH growth reaction scheme to calculate PAH concentrations in a Jet A-1 surrogate flame. Its results were compared to the experimental data for a real Jet A-1 flame. In the central region of the flame, that model, similar to many soot models in the literature, underpredicted soot concentration by more than one order of magnitude. The following improvements are made in the present work: (1) flame temperature and soot volume fraction profiles are experimentally measured in a flame using surrogate Jet A-1 rather than real Jet A-1, so that more direct comparisons can be made, (2) a novel reaction scheme for PAH growth (mechanism 2 in the present work), with a more comprehensive set of pathways for aromatic ring formation and growth, is used to model soot formation, and (3) the empirical soot surface growth parameter, a, is updated. The simulation data, using mechanism 2, are compared to the measurement results and another set of computational data, using the less detailed acetylene-based mechanism (mechanism 1). It is shown that only mechanism 2 can predict the correct order of magnitude of the centerline soot concentrations, reproducing them within a factor of one to five. Soot particles are shown to be exposed to similar temperatures and acetylene concentrations with both mechanisms. Hence, this improvement on the centerline is because of the enhanced PAH growth model, which produces higher levels of pyrene and increases the soot particle nucleation rate.
- 出版日期2013
