Caltech Library System

About | Browse | Search | Caltech Student Instructions

Type of Document	Dissertation
Author	Bergthorson, Jeffrey Myles
Author's Email Address	jeffb AT tyrvos.caltech.edu
URN	etd-05242005-165713
Persistent URL	http://resolver.caltech.edu/CaltechETD:etd-05242005-165713
Title	Experiments and modeling of impinging jets and premixed hydrocarbon stagnation flames
Degree	PhD
Option	Aeronautics
Advisory Committee	Advisor Name Title Paul E. Dimotakis Committee Chair Aron Kuppermann Committee Member Daniel I. Meiron Committee Member David G. Goodwin Committee Member J.E. Shepherd Committee Member
Keywords	PLIF Planar Laser Induced Fluorescence modeling combustion stagnation flow chemical kinetics ethylene ethane methane CH PSV Particle Streak Velocimetry
Date of Defense	2005-05-06
Availability	unrestricted
Abstract To model the combustion of long-chain hydrocarbon fuels, an accurate kinetics mechanism must first be developed for the oxidation of small hydrocarbons, such as methane, ethane, and ethylene. Even for methane, a generally accepted mechanism is still elusive due to a lack of kinetically independent experimental data. In this work, a combined experimental and modeling technique is developed to validate and further optimize these mechanisms. This technique relies on detailed measurements of strained flames in a jet-wall stagnation flow using simultaneous Particle Streak Velocimetry (PSV) and CH Planar Laser Induced Fluorescence (PLIF). Stagnation flames are simulated using an axisymmetric, one-dimensional model with accurate specification of the requisite boundary conditions. Direct comparisons between experiment and simulation allow for an assessment of the various models employed, with an emphasis on the chemistry model performance. The flow field for a cold 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 laminar 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. Mechanism performance is found to be relatively insensitive to both the mixture dilution and the imposed strain rate, while exhibiting a stronger dependence on the fuel type and flame stoichiometry. The approach and diagnostics presented here permit an assessment of the predictions of strained-hydrocarbon flames for several combustion chemistry mechanisms. The data presented in this thesis are made available to kineticists looking for optimization targets, with the goal of developing a predictive kinetics model for hydrocarbon fuels. The methodology described here can allow new optimization targets to be rapidly measured, reducing the experimental burden required to fully constrain the chemistry models.
Files	Filename       Size       Approximate Download Time (Hours:Minutes:Seconds)     28.8 Modem   56K Modem   ISDN (64 Kb)   ISDN (128 Kb)   Higher-speed Access    Bergthorson_JM_2005_thesis.pdf 4.97 Mb 00:22:59 00:11:49 00:10:20 00:05:10 00:00:26