A numerical and experimental study of a laminar sooting coflow Jet-A1 diffusion flame

Abstract

A numerical and experimental study of a laminar sooting coflow jet-A1 diffusion flame Saffaripour, M.; Zabeti, P.; Dworkin, S. B.; Zhang, Q.; Thomson, M. J.; Guo, H.; Liu, F.; Smallwood, G. J. Proceedings of Combustion Institute -Canadian SectionSpring Technical Meeting Carleton University, Ottawa IntroductionDeveloping multidimensional flame models for blended liquid fuels, such as jet fuel, is challenging, mainly due to the very large chemical kinetic mechanisms and the associated computational resources required. Numerous researchers use a surrogate mixture to approximate the chemical and thermophysical properties of complex multicomponent blends. Honnet et al.[1] performed detailed calculations of an opposed jet diffusion flame using a surrogate mixture (80% n-decane and 20% 1,2,4-trimethylbenzene, by mass) and measured the soot volume fraction, autoignition, and extinction properties of both aviation kerosene and the surrogate. The results of the experiments for the surrogate and the actual jet fuel were reasonably close. The agreement between the numerical calculations using the detailed chemical kinetic mechanism of the surrogate, and the experiments were also satisfactory. Moss et al.[2] implemented a flamelet-based two-equation soot model for a simple Jet-A surrogate, comprising 77% ndecane and 23% 1,3,5-trimethylbenzene by liquid volume, in a laminar coflow diffusion flame, and measured soot volume fraction, mixture fraction, and temperature. The radial soot volume fraction profiles and location of the peak concentration were predicted reasonably well. Wen et al. [3] modeled soot formation in a turbulent coflow nonpremixed kerosene flame using a kerosene surrogate (20% toluene and 80% decane by liquid volume), a laminar flamelet approach, and the 141-chemical species mechanism of Dagaut et al. [4]. Comparisons were made for soot volume fraction and soot number density. After unsatisfactory initial comparisons, improvements were obtained in the results with a Polyaromatic Hydrocarbon (PAH)-based soot inception model as compared to an acetylene-based model.Numerically solving multidimensional flames with detailed chemistry and transport proves to be a computationally intensive task, especially when complex fuels, such as jet fuel, are considered. Due to the inherently high computational cost of such models, parallel implementation has seen significant development in the last two decades. In 1991, Smooke and Giovangigli [5] presented a numerical simulation of a laminar coflow methane/air diffusion flame with 6 processors, using strip-domain decomposition. Since that time, numerous researchers have utilized a similar strip-domain decomposition strategy wherein subdomain boundaries are placed perpendicular to the axial flow direction. Zhang et al. [6,7] developed a detailed model for an ethylene/air coflow flame using a semi-implicit scheme and divided the computational domain into 16 subdomains. Flame temperatures, species concentrations, soot volume fraction, and soot number density compared well to exp...

Application of an enhanced PAH growth model to soot formation in a laminar coflow ethylene/air diffusion flame

“…In the last few years, Zhang and coworkers have extended the sectional aerosol dynamics model to track both particle diameter and number of primary particles per aggregate in each section so as to yield information on particle size distribution and structure. This model was first applied to ethylene/air diffusion flames [28,29,30], and more recently to a jet fuel flame [31]. These studies used the chemical kinetic mechanism, pyrene-based inception, soot surface chemistry, and surface condensation models from [11].…”

Toward finite-rate chemistry large-eddy simulations of sooting swirl flames

“…Previous soot CFD simulations of real scale aero-engine combustors (Blacha et al, 2011;Eberle et al, 2014;Lecocq et al, 2014;Mueller and Pitsch, 2013) lacked a rigorous model validation, because the experiments were limited to smoke number measurements at the combustor exit. So far detailed soot measurements were performed mainly for academic test cases like laminar flames (Arana et al, 2004;Figura and Gomez, 2014;Geigle et al, 2005;McEnally and Pfefferle, 2000;Saffaripour et al, 2011;Santoro et al, 1987;Tsurikov et al, 2005;Zhao et al, 2005) or turbulent jet flames (Gu et al, 2017;Köhler et al, 2012;Qamar et al, 2009). Such simple validation test cases are not representative for real scale devices, however.…”

Soot modeling of counterflow diffusion flames of ethylene-based binary mixture fuels

“…In previous PAH-based soot models, for example in [26,63,64], soot nucleation typically takes place when two pyrene molecules collide. It is expected that only a portion of these collisions could result in successful soot nucleation by forming a dimer while the rest of colliding molecules may simply fall apart due to the high collision energy required or the unfavorable colliding angle.…”