Two-dimensional laser-induced incandescence (LII) measurements were used for quantitative soot volume fraction ($f_v$) measurements in methane-air diffusion flames at pressures ranging from 0.1 to 0.5 MPa. Additionally, laser-induced fluorescence (LIF) was used for visualization of polycyclic aromatic hydrocarbons (PAHs) considered as important soot precursors. A heat and mass transfer-based LII model was used for the analysis of experimental LII fluence curves to evaluate soot absorption functions, $E\left(m\right),$ at various spatial positions in the flames. Based on previous work, variations in the evaluated $E\left(m\right)$ was assumed to be related to soot maturity. Generally, the most mature soot was found at the spatial position of maximum $f_v$ along the central axis and at the flame edges. Also, the soot maturity at the position of maximum $f_v$ at each pressure was found to increase from the flame at 0.1 MPa to 0.5 MPa. A critical examination of the assumptions and uncertainties in the $E\left(m\right)$ analysis was made. The present study emphasizes the limitation of assigning soot a constant $E\left(m\right)$ in the overall flame for temperature and soot concentration evaluation using the optical methods spectral soot emission (SSE) and line-of-sight attenuation (LOSA), which are commonly used non-intrusive optical diagnostic techniques in sooting high-pressure flames. The study also demonstrates the critical choice of fluence in quantitative imaging LII measurements of $f_v$ when the $E\left(m\right)$ of soot spans over large range of values.

二维激光诱导白炽度（LII）测量用于定量烟灰体积分数（$F_v$）在压力为0.1至0.5 MPa的甲烷-空气扩散火焰中进行测量。此外，激光诱导荧光（LIF）用于可视化为重要烟灰前体的多环芳烃（PAH）。基于传热和传质的LII模型用于分析实验性LII能量密度曲线，以评估烟灰吸收功能，$Ë（米），$在火焰中的各个空间位置。根据以前的工作，评估$Ë（米）$被认为与烟灰的成熟有关。通常，最成熟的烟灰位于最大烟灰的空间位置。$F_v$沿中心轴和火焰边缘。另外，最大位置的烟灰成熟度$F_v$发现在每个压力下，火焰在0.1MPa下的最大压力增加到0.5MPa。批判性地考察了假设中的假设和不确定性$Ë（米）$分析。本研究强调了为烟灰分配常数的局限性$Ë（米）$使用光谱方法的光谱烟尘发射（SSE）和视线衰减（LOSA）评估整体火焰中的温度和烟灰浓度，这是在高压烟灰中常用的非侵入式光学诊断技术。该研究还证明了定量成像LII测量中注量的关键选择$F_v$ 当。。。的时候 $Ë（米）$ 烟尘跨度很大。