Investigation of Soot Formation in Diesel Combustion Using Forward Illumination Light Extinction (FILE) Technique 2004-01-1411

In this paper, a new-developed forward illumination light extinction (FILE) soot measurement technique is introduced. This technique has the capability to give two-dimensional time-resolved quantitative soot measurements. Applying the light extinction theory, the line-of-sight soot volume fraction is determined by the ratio of reflected light intensities with and without a soot cloud. The advantages of this technique include its non-intrusiveness, ease of application, requirement of only one optically accessible window, and suitability for the study of transient cycle-to-cycle variations. The application of the FILE technique for diesel combustion in a constant volume chamber demonstrates the applicability and advantages of this technique. Three stages of soot formation during diesel combustion were determined using this technique. The rapid soot generation at the later time of the premixed combustion period is followed by a stable period with balanced generation and oxidation before the end of injection. Oxidation controls the burning of the latest injected fuel.