Perspective—Aerodynamic Control of Combustion

Abstract

To do useful work, the exothermic process of combustion should be carried out in an enclosure, as is typically the case with i.c. engines—the subject of this paper’s particular concern. To meet the requirements of high efficiency and low pollutant production, this process should be executed at a relatively low temperature—a condition attainable by the use of lean air-fuel mixtures. For this purpose it has to be distributed in space upon multipoint initiation and kept away from the walls to minimize their detrimental effects. In principle, all this can be accomplished by a system referred to as fireball combustion that takes advantage of entrainment and spiral mixing associated with large scale vortex structures of jet plumes. As demonstrated in this paper, the success in such an endeavor depends crucially upon the utilization of the essential elements of classical aerodynamics: the properly distributed sources, expressed in terms of velocity divergences prescribed by the thermodynamic process of combustion and of the vorticity field generated by shear between the jets and the fluid into which they are injected.