Smokes, droplets, flames and electric fields

Abstract

The paper summarises recent results on the influence of electric fields on carbon, silica and lead oxide smokes, as well as on suspensions of fuel droplets, in flame systems. The object, in each case, is to cause the particles to acquire charge for their subsequent manipulation by fields. Examples of using this as a method of controlling the trajectories of particles—either to remove them or to affect the process of their growth or consumption in the reaction zone—are discussed. The latter includes a measure of control over the reaction, by varying particle sizes and concentrations and by transposing charged nuclei. Mechanisms of charge acquisition are considered theoretically and it is shown that, in the absence of other charging mechanisms (such as thermionic emission or electrical breakdown of the gas), chemi-ionization in the flame may be used for this purpose. On the supposition that diminishing resources of fossil fuels and increasing concern about pollution will allow consideration of more complex combustion systems in future, a theoretical assessment of the maximum effects attainable in practice is carried out for the variety of effects observable in the laboratory.