Measurements of the structure of sooting laminar diffusion flames at elevated pressures

Soot measurements by two angle scattering and extinction in an N2-diluted ethylene/air counterflow diffusion flame from 2 to 5 atm

“…For example, McCrain and Roberts [8] studied methane-air and ethylene-air coflow flames at pressures up to 25 atm and 16 atm, respectively, and found that the local peak soot volume fraction scales with pressure as P 1.2 for methane and P 1.7 for ethylene flames. Flower and Bowman [12] studied ethylene/air flames in Wolfhard-Parker burner up to 2.5 atm using light scattering/extinction technique. The results showed that primary particle diameter and number density of primary particles increased with pressure.…”

Structure of incipiently sooting ethylene–nitrogen counterflow diffusion flames at high pressures

“…To estimate a chemical time, on the other hand, we can roughly approximate the overall soot production rate with an overall reaction rate dcs dt ¼ kc 1þb p , where k is a temperaturedependent rate constant, c s is the soot concentration, c p is the concentration of some critical soot precursor. b can be assumed to satisfy the inequality 1 > b > 0 in the first approximation, as suggested by the pressure dependence of (mature) soot volume fraction in laminar flames [20,52]. As a result, number for soot formation increases with pressure.…”

“…We also note that some of the leveling-off effect in soot increase with pressure that was reported in the literature and attributed to an increase in coagulation rate with resulting decrease in surface available for growth [36] would not apply to incipient sooting of the type we are considering here. Equally inapplicable are any concerns of the coupling of the soot with the temperature field via radiative losses [20] for the same reasons. However we do notice a leveling off of the benzene growth with pressure at least at the highest pressures in Series 1.…”

“…The thin reacting environments at high pressures because of the low thermal and mass diffusivity makes probe-based studies more difficult to implement. Among the directly relevant flame work at high pressure are the study of co-flow diffusion flames to measure ''mature'' soot particles [20][21][22] and two contributions with a focus on PAH and soot precursor concentration [19,23]. For completeness, we also list the work in premixed flames at high pressure on ethylene up to 7 MPa [24], and in the range 0.1-0.5 MPa with ethylene, propene and toluene [25].…”

CARS Temperature Measurements in Sooting, Laminar Diffusion Flames

“…They used thermocouples for temperature and results presented here represent a contribution to needed comparisons under similar experimental conditions. Flower and Bowman (1984) and Farrow et al (1984) at Sandia have been performing soot formation, CARS and thermocouple measurements in a two-dimensional ethylene-air diffuson flame. Excellent agreement was found in non-sooting and sooting regions between CARS data and their rapid-insertion thermocouple measurements.…”