Michael James B, Venkateswaran Prabhakar, Shaddix Christopher R, Meyer Terrence R
Appl Opt. 2015 Apr 10;54(11):3331-44. doi: 10.1364/AO.54.003331.
Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals are observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10-50 kHz. Guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.
据报道，使用脉冲模式激光系统以高达100kHz的重复频率进行平面激光诱导白炽（LII）成像，从而能够研究高度湍流火焰中碳烟形成动力学。为了量化相对碳烟体积分数测量的准确性和不确定性，在各种激光操作条件下检查了层流火焰和湍流火焰中LII场的时间演化。在高速重复探测下，发现在碳烟汽化区域内以高激光通量运行时，LII信号对碳烟物理特性的变化敏感。对于这些激光条件，在高达100kHz的测量速率下观察到强烈的平面LII信号，但主要用于定性跟踪碳烟结构动力学。然而，在较低通量下收集的LII信号允许在10 - 50kHz的重复频率下以足够的信噪比顺序进行平面相对碳烟体积分数测量。讨论了识别和避免LII信号中重复探测效应出现的指导方针，以及其他潜在的测量误差和不确定性来源。
