Can laser-induced incandescence calibrated by laser extinction method be used for quantitative determination of soot volume fraction in laminar flames?

This review is conducted to assess the effectiveness of the laser extinction method (LEM) calibrated laser-induced incandescence (LII) to quantitatively determine the soot volume fraction in flames. This article mainly focuses on the discussion and analysis of the existing experimental results in typical co-flow laminar diffusion flames. Initially, a brief introduction of the background and application of sooting tendency in co-flow laminar diffusion flames by using the combination of LII and LEM is presented. Then, the general theoretical backgrounds of LII and LEM techniques used for soot diagnostics is introduced. This is followed by a detailed summary and comparison of the maximum soot volume fraction in laminar diffusion flames obtained by a combination of LII and LEM techniques as well as the various optical methods. The maximum soot volume fraction in flames measured by the combined technique of LII and LEM exhibits high consistency with those of other optical methods, but the uncertainty derived from this approach is relatively large in soot concentration measurement. Minimizing the measurement uncertainty of soot volume fraction obtained by the combination of LII and LEM is still an important and non-negligible issue. The determination of the soot refractive index function E(m) for mature soot is one of the major sources of measurement uncertainty when using the combined technique of LII and LEM. Whereas it is of great challenge to confirm an accurate E(m) for mature soot of flames in the visible and nearinfrared spectrum, and it still needs a large number of experimental investigations to reveal the accurate value of E(m). Finally, the conclusion and perspective for investigating sooting tendency in flames by the LEMcalibrated LII technique are presented.