Characterization of Temperature and Soot Volume Fraction in Laminar Premixed Flames: Laser Absorption/Extinction Measurement and Two-Dimensional Computational Fluid Dynamics Modeling

Abstract

We performed a comprehensive laser absorption/extinction study of temperature and soot volume fraction (SVF) in C2H4/air premixed sooting flames. Laser-absorption two-line thermometry at 2.5 μm provided a temperature uncertainty of 50 K compared with that of 90 K using conventional thermocouples. Laser extinction of soot at 633 nm was first validated against the previous measurements using laser-induced incandescence. All of the measurements were conducted at four representative C2H4 flame conditions (equivalence ratio Φ = 1.78, 1.95, 2.14, and 2.38). In addition, a CFD (computational fluid dynamics) framework coupling a skeletal mechanism (56 species and 428 reactions) with the Moss–Brookes model was developed for interpreting the experimental data. The current CFD simulations well predicted the temperature and SVF distribution along the centerline of flame. It is of interest to observe that the SVF depends on the Reynolds number of reactants by investigating the SVFs at different heights above the burner for the varied flow rates and equivalence ratios.

Simultaneous Inversion of Particle Size Distribution, Thermal Accommodation Coefficient, and Temperature of In-Flame Soot Aggregates Using Laser-Induced Incandescence

“…From Figure 9 d, it is evident that LII-based particle sizing is sensitive to flame temperature bias. To obtain satisfactory results for both μ d and σ d (with relative errors <±10%), the tolerable bias in the prior flame temperature is approximately within the range of ±50 K. In light of this, when the independent measurement error of flame temperature is within ±50 K (achievable through various methods, including thermocouple [ 44 ], laser absorption spectroscopy [ 45 ], and spectral soot emission-based two-color pyrometry [ 46 ]), it is still preferable to treat LII-based particle sizing of in-flame soot as a binary inverse problem. Due to the ill-posed nature of inverse problems, simultaneously inverting fewer parameters aids in obtaining solutions with higher confidence and precision.…”

Soot Particle Size Distribution, Regulated and Unregulated Emissions of a Diesel Engine Fueled with Palm Oil Biodiesel Blends

“…This is mainly because the oxygen contained in biodiesel improves diffusion combustion and promotes the post-flame oxidation of smoke during later expansion and exhaust processes. Additionally, soot formation is also associated with temperature and the soot volume fraction (SVF) [42,43]; the oxygen contained in biodiesel can also improve local anoxic conditions caused by fuel-rich zones. The biodiesel has a higher cetane number than diesel, which also can increase fuel combustion efficiency and reduce smoke opacity [41].…”

Numerical and Experimental Investigation of Soot Suppression by Acoustic Oscillated Combustion

“…In this study, numerical simulations were conducted using the finite-rate detailed chemistry model , and the DES turbulence model with a low Reynolds number correction. The soot formation was predicted by the Moss-Brookes model ,− with the modification in that the effect of soot formation on the chemical species was considered by using user-defined functions (UDF). Comparisons were made between the experiments and simulations, and the soot formation was analyzed in detail.…”