INTERPRETATION OF A CHARACTERISTIC TIME MODEL FOR PERFORMANCE OF A PREVAPORIZED/PREMIXED COMBUSTOR
Abstract
The flow field, flame structure, and overall combustion process occurring within a prevaporizing/premixing type combustor is analyzed. Numerical, experimental and semi-empirical techniques are used to examine a simplified axisymmetric burner configuration possessing the fundamental characteristics found in real prevaporizing/premixing combustion systems. Numerical analysis of the non-reacting flow field of the prevaporizing/premixing combustor configuration was done using an elliptic finite-difference computer code utilizing the k - (epsilon) turbulence model. Calculations were performed for a variety of geometries and inlet flow conditions to the combustor. Gas samples were extracted from within the prevaporizing/premixing combustor for the two flames examined, propane and jet-A, and analyzed for gaseous components. Temperature and combustion efficiency calculations were made using this information. Examination of the numerical and experimental information reveals the invariant behavior of the fundamental flow field with respect to operating conditions. Furthermore, the type of combustion (i.e., single or two-phase fuel input into the combustor) does not significantly alter the flow field, but it does change the relative intensities of combustion within established combustion zones. Data representing overall combustion efficiency of the combustor are examined in conjunction with numerical and experimental information. Severe un-mixed behavior of the combustor is established. Suggestions are made for the development of a characteristic time correlation for modeling combustion inefficiency in a prevaporized/premixed combustor.
Degree
Ph.D.
Subject Area
Mechanical engineering
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