Combustion Instability and Blowout Characteristics of Fuel Flexible Combustors
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چکیده
Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. " 3 1. ABSTRACT Under this program, Georgia Institute of Technology investigated the blowout characteristics of fuel-flexible combustors. Particular attention was given to coal-derived and high hydrogen gaseous fuels which are of interest to the DOE. The program consists of three main focuses. Under the first research focus, we performed extensive chemical kinetic analyses of such quantities as flame speeds and stretch sensitivities of syngas fuels in order to develop the mixture characteristics information needed to correlate test data. In addition, we developed and distributed a software utility that utilizes these calculations, determines other basic mixture properties, and has such features as outputting all fuel mixture combinations with a given flame speed, adiabatic flame temperature, or heating value within some given tolerance. Under the second research focus, we made extensive measurements of the combustor's blowout characteristics as a function of fuel composition. We designed and fabricated a gas-mixing facility to blend syngas-type fuels of arbitrary compositions of H 2 , CO, CO 2 , N 2 , and CH 4. We then measured the equivalence ratios at lean blow off for a large number of H 2 /CO/CH 4 mixtures at different inlet temperatures and combustion pressures. Consistent with prior studies, these results indicate that the percentage of H 2 in the fuel dominates the mixture blowout characteristics. It is shown that standard well stirred reactor based correlations, based upon a Damköhler number with a diffusivity ratio correction, can capture the effects of fuel composition variability on blowoff limits. Under the third research focus, we performed more detailed diagnostics of near blowoff flames in order to characterize the blowoff phenomenology better and to provide further insight into how fuel composition (particularly H 2 levels in the fuel) …
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