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A comprehensive investigation of the uncertainties associated with the experimental and numerical evaluation of the extinction strain rate in hydrogen/oxygen/nitrogen nonpremixed flames is presented in this work. The reported new experimental uncertainties of the extinction strain rate include several sources of uncertainties that typically affect the characterisation of velocity and boundary conditions of counterflow flames via particle image velocimetry. The uncertainties associated with the numerical determination of the extinction strain rate not only depend upon the selected chemical kinetics parameters but also on the binary diffusion coefficients. In order to identify the major sources of uncertainties in the chemical and diffusion models, a Monte Carlo based high-dimensional model representation analysis of the extinction curve was performed. Independent and simultaneous perturbations of relevant chemical kinetics and diffusion parameters have shown that the uncertainties associated with the binary diffusion coefficients are about a factor of 10 smaller than the uncertainty due to chemical kinetics parameters. Since the experimentally well known binary diffusion coefficient for hydrogen and nitrogen, D H 2 ,N 2 , accounts for most of the propagated uncertainty of the diffusion model, it is shown here that only a reduction of the uncertainty of chemical kinetics parameters will have a significant impact in improving the accuracy of the extinction strain rate predictions.

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Numerous studies have reported the adverse health, environmental, and climatic effects of aerosol or soot particulate emissions from the combustion of hydrocarbon fuels in boilers, furnaces, gas turbines and other internal combustion engines. Considering the significant dependence that our modern society places on hydrocarbon fuels, it is of ethical interest to reduce or mitigate the resulting pollutants. With advanced laser based diagnostic techniques under development, the potential for future regulation on particulate emissions provides further motivation. While production of some pollutant species is well understood, knowledge of soot particulate nucleation and growth remains in its infancy. Precise synthesis of flame generated carbon nanoparticles may also prove useful as an industrial and technical commodity to increase efficiency and reduce cost for a variety of applications. One of the most elementary and important effects on soot formation and growth relevant to modern combustion engines is that of pressure. Utilizing the simple laminar, steady counterflow burner configuration, the goal of this work is to investigate the effect of elevated pressure on the soot nucleation, growth, and oxidation mechanisms of hydrocarbon combustion over a wide range of flow residence times. An absolute irradiance calibrated two-color time resolved Laser Induced Incandescence (LII) technique was developed and utilized to collect quantitative soot incandescence data for determination of soot particle temperature, primary particle size, soot volume fraction, and number density. The approach requires a comprehensive LII nano-scale heat transfer model with coupled extinction and elastic light scattering submodels. Thermophoretic soot