The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

The ability to accurately measure solid particulate levels in various applications ranging from engines to laboratory flames has become very important in the past few decades. A new approach to measuring soot levels called laser-induced incandescence was investigated. An apparatus was designed and built in order to measure soot levels in an atmospheric laminar diffusion flame with the intent of conducting proof-of-concept measurements. The apparatus utilized highly focussed optics while collecting time-resolved data using fast PMTs which allowed measurement of both time and spatial domains. Although noise and other technical problems proved to be a concern, measurements with reasonable agreement with published results for temperature (2800 K) and the primary particle soot size (6.3 +/- 2.5 nm) were achieved within the flame. Noise issues with the apparatus prevented accurate soot volume fraction measurements from being obtained. Numerous suggestions have been made as to how to improve the experiment for future use, potentially in a high pressure environment.

Accurate determination of soot emissions from combustion is of interest in both fundamental research and industries that rely on combustion. Laser-induced incandescence of soot particles is a young technique that allows unobtrusive measurements of both soot volume fraction and particulate size. An apparatus utilizing this technique has been brought to function for both atmospheric and high pressure measurements. Proof of concept measurements of an atmospheric ethylene-air laminar diffusion flame at 35, 42, and 47 mm above the burner exit correlate well with literature findings. Profile trends of a methane-air diffusion flame at 10, 20, and 40 atm at 6 mm above the burner are similar to reports in literature and are compared to trends from spectral soot emission measurements. Particle size is found to be roughly proportional to pressure. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus are herein.

Combustion-generated carbon black nano particles, or soot, have both positive and negative effects depending on the application. From a positive point of view, it is used as a reinforcing agent in tires, black pigment in inks, and surface coatings. From a negative point of view, it affects performance and durability of many combustion systems, it is a major contributor of global warming, and it is linked to respiratory illness and cancer. Laser-Induced Incandescence (LII) was used in this study to measure soot volume fractions in four steady and twenty-eight pulsed ethylene diffusion flames burning at atmospheric pressure. A laminar coflow diffusion burner combined with a very-high-speed solenoid valve and control circuit provided unsteady flows by forcing the fuel flow with frequencies between 10 Hz and 200 Hz. Periodic flame oscillations were captured by two-dimensional phase-locked LII images and broadband luminosity images for eight phases (0°- 360°) covering each period. A comparison between the steady and pulsed flames and the effect of the pulsation frequency on soot volume fraction in the flame region and the post flame region are presented. The most significant effect of pulsing frequency was observed at 10 Hz. At this frequency, the flame with the lowest mean flow rate had 1.77 times enhancement in peak soot volume fraction and 1.2 times enhancement in total soot volume fraction; whereas the flame with the highest mean flow rate had no significant change in the peak soot volume fraction and 1.4 times reduction in the total soot volume fraction. A correlation (ƒv Reˉ1 = a+b· Str) for the total soot volume fraction in the flame region for the unsteady laminar ethylene flames was obtained for the pulsation frequency between 10 Hz and 200 Hz, and the Reynolds number between 37 and 55. The soot primary particle size in steady and unsteady flames was measured using the Time-Resolved Laser-Induced Incandescence (TIRE-LII) and the double-exponential fit method. At maximum frequency (200 Hz), the soot particles were smaller in size by 15% compared to the steady case in the flame with the highest mean flow rate.

This study is dedicated to investigation of soot formed during combustion in diesel engine. Measurements were performed in a high speed direct injection optical diesel engine. Initially soot particle size, size distribution and soot volume fraction were investigated using time resolved laser induced incandescence (TR-LII) technique. For this study standard diesel fuel was used and measurements were performed for various injection timing and two different engine loads. Investigation showed that TR-LII is a powerful tool that can be used for characterization of in-cylinder soot in the engines. Subsequently TR-LII technique was developed to measure in-cylinder soot in two dimensional plane (planar laser induced incandescence PLII) and technique was combined with high speed imaging to investigate soot processes for ultra-low sulfur diesel (ULSD) and bio-fuel (RME). Two injection strategies of single and double injection were applied during these measurements. A high speed imaging technique was used to study the soot formation and oxidation during the combustion process within the cylinder and PLII was applied later in the stroke to study qualitatively the relative amount of un-oxidised soot that was left in the combustion chamber. In addition to PLII, TR-LII technique was used simultaneously to explore crank angle resolved variation of primary soot particle size and their size distribution during the expansion stroke. The same measurements were repeated for fuels with different composition investigating the relationship between the fuel properties and soot emission. Finally mathematical model for soot particle size and distribution width was modified by introducing assumption of multi-lognormal in-cylinder soot particle size distribution.

Measurements of soot emission properties are of interest in both fundamental research and combustion-based industries. Laser-induced incandescence of soot particles is a novel technique that allows unobtrusive measurements of both soot volume fraction and particulate size with significant advantages. An apparatus utilizing this technique has been customized and used to provide measurements of soot concentration and particle sizing of a laminar, diffusion methane/air flame at pressures of 10, 20 and 40 atm at 6~mm above the burner. Soot volume fraction measurements correlate well with literature findings at all pressures. Despite similar trends, particle size values are found to be consistently larger than values reported in literature. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus and results are herein.

Measurements of soot emission properties are of interest in both fundamental research and combustion-based industries. Laser-induced incandescence of soot particles is a novel technique that allows unobtrusive measurements of both soot volume fraction and particulate size with significant advantages. An apparatus utilizing this technique has been customized and used to provide measurements of soot concentration and particle sizing of a laminar, diffusion methane/air flame at pressures of 10, 20 and 40 atm at 6~mm above the burner. Soot volume fraction measurements correlate well with literature findings at all pressures. Despite similar trends, particle size values are found to be consistently larger than values reported in literature. Discussion on the errors of laser-induced incandescence as well as recommendations for improving the apparatus and results are herein.

The current study represents the first application of commercial laser-induced incandescence (LII) instrumentation at the University of Toronto Combustion Research Laboratory, for the characterization of soot in atmospheric laminar co-flow diffusion flames. An experimental apparatus was designed to accommodate the optical diagnostic, and to provide the means to probe various regions of the flames. An experiment with a well-characterized non-smoking ethylene-air diffusion flame was carried out to validate the performance of the LII instrument. Three measurement heights were analyzed; those at 40, 50, and 60 mm above the fuel exit. The soot volume fraction results were found to be in good agreement with those from the literature. The highest value was found to be 8.3 ppm at a height of 40 mm. While the instrumentation could report primary particle diameters, it was determined from the validation trial that the results were still premature. Further work is needed to validate the results of the instrument, especially for the particle size data.

The current study represents the first application of commercial laser-induced incandescence (LII) instrumentation at the University of Toronto Combustion Research Laboratory, for the characterization of soot in atmospheric laminar co-flow diffusion flames. An experimental apparatus was designed to accommodate the optical diagnostic, and to provide the means to probe various regions of the flames. An experiment with a well-characterized non-smoking ethylene-air diffusion flame was carried out to validate the performance of the LII instrument. Three measurement heights were analyzed; those at 40, 50, and 60 mm above the fuel exit. The soot volume fraction results were found to be in good agreement with those from the literature. The highest value was found to be 8.3 ppm at a height of 40 mm. While the instrumentation could report primary particle diameters, it was determined from the validation trial that the results were still premature. Further work is needed to validate the results of the instrument, especially for the particle size data.