The objectives of the present program are to develop detailed and simplified chemical kinetics model for hydrocarbon combustion, and to understand and quantify the dynamics of flames. During the reporting period progress were made in the following projects: (1) Laminar flame speeds of mixtures of ethylene and n-butane were studied. Results suggest the dominant influence of the adiabatic flame temperature in assessing the mixture flame speed. (2) A theory of complex CSP (computational singular perturbation) for chemistry reduction and analysis was developed. An algorithm was derived through which detailed mechanisms can be systematically reduced to simpler ones without compromising the comprehensiveness of the original mechanism. (3) Stretch effects on premixed flame pulsation were computationally and analytically studied. Results show that positive (negative) stretch promotes (retards) the development of pulsating instability, which is completely opposite to the influence of stretch on cellular instability. (4) Pulsating instability of near-limit diffusion flames were computationally studied. Results show that the instability and the subsequent extinction of methane and hydrogen flames assume the characteristics of diffusion and premixed flames respectively.
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