UC Irvine

Combustion is expected to remain one of the main sources of power in the world. Therefore, the understanding of the underlying physical and chemical processes needs to continue improving, to increase efficiency and to reduce emissions of combustion systems. In order to study the steady-state characteristics of complex flame configurations, laminar surrogate models can aid significantly in the description of more complicated systems. One valuable class of surrogate configurations is the nonpremixed laminar flame, in which fuel and oxidizer are initially separated. In nonpremixed flames the mixing process is a necessary part of the flow to be investigated and the chemical process can be represented by a global reaction mechanism. Such simplification allows the conservation equations to be treated with analytical or semi-analytical methods, while still capturing the critical physical characteristics of the system. The dissertation describes and analyzes three laminar nonpremixed stagnation flow models based on canonical flame configurations: a coflow impinging flame, a water-laden counterflow flame, and a tubular counterflow burning condensed fuels. The performance of the theoretical models is validated with experimental data available in the literature. In addition, the nonpremixed swirl-type tubular flame configuration is presented for the case of a liquid fueled porous wall fed system. The experimental system and the mathematical model that describes theoretically the configuration are evaluated. To this end, a novel analytical solution based on asymptotic methods is presented.