A flamelet-based a priori analysis on the chemistry tabulation of polycyclic aromatic hydrocarbons in non-premixed flames
- Creators
- Xuan, Yuan
- Blanquart, Guillaume
Abstract
In this paper, the chemical response of different species to turbulent effects is investigated in the context of one-dimensional laminar non-premixed flamelets. Turbulent effects are modeled as abrupt changes in the scalar dissipation rate. One-dimensional unsteady flamelet calculations assuming unity-Lewis number for all species are performed for an ethylene/air configuration. From the time-evolution of the species mass fractions, it is found that transient effects are not substantial for radicals such as OH and H, and species such as CO; CO_2 and C_2H_2, consistent with their small characteristic chemical time scales. The steady state flamelet assumption for these species is well justified and their mass fractions can be pre-tabulated using the steady state flamelet solutions legibly. On the other hand, aromatic species are characterized by relatively slow chemistry, and substantial transient effects are observed for these species. The evolution of their mass fractions and chemical source terms are studied through a reaction flux analysis. Specifically for Polycyclic Aromatic Hydrocarbons (PAH), the chemical production terms are found to be linearly proportional to the mass fraction of smaller aromatic species, and the chemical consumption terms are found to be linearly proportional to their own mass fractions. Based on the unsteady flamelet results, the validity of various existing flamelet-based pre-tabulation methods is examined, and a new linear relaxation model is proposed for PAH. The proposed relaxation model is validated through the unsteady flamelet formulation, and results are compared against full chemistry calculations.
Additional Information
© 2013 The Combustion Institute. Published by Elsevier Inc. Received 1 September 2013; Received in revised form 16 November 2013; Accepted 17 November 2013; Available online 16 December 2013. The authors gratefully acknowledge funding from the US Department of Energy-Basic Energy Sciences (DE-SC006591).Attached Files
Supplemental Material - mmc1.zip
Supplemental Material - mmc2.zip
Supplemental Material - mmc3.zip
Files
Additional details
- Eprint ID
- 43217
- DOI
- 10.1016/j.combustflame.2013.11.022
- Resolver ID
- CaltechAUTHORS:20140106-094049321
- DE-SC006591
- Department of Energy (DOE)
- Created
-
2014-01-07Created from EPrint's datestamp field
- Updated
-
2021-11-10Created from EPrint's last_modified field