combustion chemistry - American Chemical Society

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SYMPOSIUM

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Densitometer Tracing of Oxyacetylene Bame Spectrum

COMBUSTION CHEMISTRY Presented before the Divisions of Petroleum Chemistry and Gas and Fuel Chemistry at the 119th Meeting of the American Chemical Society, Cleveland, O h i o

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NTEREST in combustion has undoubtedly been widespread since it

was first observed by prehistoric man. However, the beginning of any modern study of combustion must start with Lavoisier's observations on combustion in 1772 when he gathered enough facts to show definitely that flame combustion took place b y absorbing a substance from the air. Prior to this time the phlogiston theory of combustion was popular, a theory which, of course, could contribute little to the study of combustion. Since that time the advance i n understanding of the over-all thermodynamic and stoichiometric aspects ofcombustion has been accelerating, until it is now possible to predict the composition of combustion products and their enthalpy with sufficient accuracy to provide engineers with the data needed for preliminary design of various heat engines. The engineer, however, in addition to the necessity for understanding what i s available in the way of working fluids and energy, must also design the equipment for converting the air and fuel into the hot combustion products. To be truly effective, this step involves the mechanics and kinetics of a combustion system end in this respect the designer has not had available to him any substantial mass of fundamental information which could guide him in the detailed design of his equipment. The recent demand for and development of high power output for automobile and aircraft engines has made it necessary to liberete the heat in as smell a volume es possible. Furthermore, since high r.p.m. of pistons or turbines i s essential i f size and weight are to be kept low, the combustion must be carried out i n as short a time as possible. In the attempt to design these types of apparatus, important limitations relating to combustion as we now know it have been encountered and these shortcomings have given a great deal of impetus to combustion research aimed at their solution. In other words, the power plant engineer needs all the scientific help that can be mustered. Recently, the problems incident to obtaining satisfactory combustion in the very small volume allowed in rockets and other jet en-

gines have aroused great interest in the minds of scientific people, as the rapid strides made by empirical methods in just the past ten years of effort- in this field have been phenomenal. Accomplishment of advances which will bridge the gap of interplanetary transportation, perhaps within the span of life of the youngest here, are not beyond realization. The governments of many nations have had a major interest in research of this kind, because of the ,military and economic implicetions of superior developments i n ' propulsion units which will allow faster and longer flights carrying heavier loads. Because combustion is such a complex process, and because it involves homogeneous and heterogeneous types, a great variety of interesting phenomena are observed and it would appear to b e possible to do great amounts of research without contributing appreciably to the solution of a given practical problem. It would, therefore, seem that more immediately useful results may be obtained b y basing a good proportion of research studies on phenomena that are observed in actual equipment of interest. Recent fundamental work on ignition energy and the mechanism of quenching have done much to contribute to a quantitative understanding of the relationship between these phenomena, and i s a good example of the way i n which basic research on a simple and moderately well-understood system can be applied to more complex b practical systems. Since neither the reaction kinetics nor the hydrodynamics of a turbulent burning gas are adequately understood, i t i s obvious that a formidable task faces those who try to describe quantitatively hydrocarbon combustion, and that i t will require the combined and harmonious efforts of chemists, physicists, and engineers to make the most of the propulsion engines we now have and to invent and develop new one that are even better.

w. 1. SWEENEY