Numerical simulation and experimental studies of highly-loaded valveless pulsed combustors
LccTJ 254.5 O44 1985
Heat - Transmission
Pulse techniques (Electronics)
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AbstractThe main objectives of the work were to develop a numerical model that simulates the operation of valveless pulsed combustors and to study the effects of flow pulsations on heat transfer rate in such a combustor through experimental measurements which would also provide results for assessing the validity of the model. Dynamic pressure, time-average heat flux, wall and gas temperatures were measured at six ports in the propane-fuelled combustor. The convective heat transfer coefficients in the combustion chamber were slightly less than steady flow values in most cases whereas they were mostly between 1.5 to 3 times as high as steady flow values, in the tail pipe. The effects of wall friction, heat transfer and composition changes due to chemical reaction were considered in the numerical simulation. Application of the conservation principles of fluid mechanics to the one-dimensional flows in the inlet and tail pipe yielded a system of first order hyperbolic partial differential equations which were integrated by a numerical method of characteristics. For the combustion chamber which was treated as a large reservoir, the conservation principles gave a set of ordinary differential equations since the gas mixture in it was assumed to have negligible kinetic energy and uniform thermodynamic properties. The agreement between theoretically predicted results and experimental measurements were good within the limits of experimental error in some cases orily but the predicted trends agreed with experimental measurements in all the comparisons. Since the flow pulsations enhance heat transfer considerably in the tail pipe, it is necessary to divert sufficient cool secondary air flow past the tail pipe for the combustor to have a long service life in jet drying, thrust generation and gas turbine applications. Using the numerical model, modifications to the tail pipe geometry that would give the experimental unit improved performance were suggested. From the results predicted with the model, it was concluded that intermittent combustion occurs in the combustion chamber through variations in the concentrations of carbon-dioxide and oxygen.
Bibliography: p. 226-241.
CitationOlorunmaiye, J. A. (1984). Numerical simulation and experimental studies of highly-loaded valveless pulsed combustors (Unpublished doctoral thesis). University of Calgary, Calgary, AB. doi:10.11575/PRISM/22105
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