The development of a predictive chemical-kinetic model to describe the combustion of hydrocarbon fuels is one of the most im portant research areas in combustion. The key to understanding and modeling the combustion of hydrocarbon fuels is to obtain an accurate chemical-kinetic model for the oxidation of C₁ and C₂ hydrocarbons. As longer hydrocarbon chains are investigated, all of the reactions associated with smaller hydrocarbons must be included, as well as reactions th at account for the breaking up of these chains into C₁ and C₂ fragments. In order to model the combustion of gasoline, kerosene, or other long-chain hydrocarbon fuels, the combustion chemistry of methane, ethane, ethylene, etc., must first be accurately modeled. Unfortunately, due to a lack of kinetically independent experimental data, a generally accepted mechanism for m ethane is still elusive.

This experimental study is aimed at developing a technique th at can quickly and accurately obtain measurements to further constrain and validate these mechanisms, towards the eventual development of a fully constrained kinetics mechanism for small hydrocarbons. The approach presented here relies on detailed measurements of strained flames in a jet-wall stagnation flow. This setup yields a flow with boundary conditions that can be accurately specified, facilitating simulation and comparisons with experiment. The diagnostics are optimized for accuracy, minimal flame disturbance, and rapid simultaneous recording of flow velocity and CH radical profiles. Flam e simulations utilize a one-dimensional hydrodynamic model, a multicomponent transport formulation, and various detailed-chemistry models. Direct comparisons between experiment and sim ulation allow for an assessment of the various models employed, with an emphasis on the chemistry model performance.

Cold impinging jets are an im portant flow in many contexts and are utilized to stabilize premixed stagnation flames. Particle Streak Velocimetry (PSV) is used to measure axial velocity profiles for lam inar impinging jets as a function of the nozzle-to-plate separation distance and Reynolds number. The velocity profiles for impinging jets are modeled using empirical fits, a one-dimensional streamfunction model, an axisymmetric potential-flow model, and direct numerical simulation. The flow field for an impinging laminar jet is found to be independent of the nozzle-to-plate separation distance if velocities are scaled by the Bernoulli velocity. The one-dimensional formulation is found to accurately model the stagnation flow if the velocity boundary conditions are appropriately specified. The boundary-layer-displacement-thickness corrected diameter is found to be an appropriate scale for axial distances and allows the identification of an empirical, analytical expression for the flow field of the impinging lam inar jet.

Strained methane-air flame experiments confirm that the reacting flow is also independent of the nozzle-to-plate separation distance. Methane, ethane, and ethylene flames are studied as functions of the applied strain rate, mixture dilution, and mixture fraction. The model performance is found to be relatively insensitive to both the m ixture dilution and the imposed strain rate, while exhibiting a stronger dependence on the flame stoichiometry. The approach and diagnostics presented here permit an assessment of the numerical simulation predictions of strained-hydrocarbon flames. While GRI-Mech 3.0 and the C3 -Davis models accurately predict experiment in some cases, the 2005 revision of the San Diego mechanism is found to give the best agreement with experiment for methane, ethane, and ethylene flames. The data presented in this thesis are made available to kineticists looking for optim ization targets, with the goal of developing a fully constrained, predictive, kinetics model for hydrocarbon fuels. The methodology described here can allow new optim ization targets to be rapidly measured, reducing the experimental burden required to fully constrain the chemistry models.