A Study of the Effect of Free-Radical Generation by Flourine and Fluorine Producers on Hydrocarbon Combustion.

摘要

It is proposed to adapt hydrocarbon fuels to the ignition requirements of supersonic combustion by injecting small quantities of fluorine or active fluorine compounds into the air stream. Ignition limits and ignition lags of mixtures of fluorine,oxygen and inert gas with propane and butane have been determined experimentally and the chemical -kinetic theory of these systems has been substantially resolved. Methane has been included in this work in a different frame of experimentation and theoretical analysis,corresponding to the fact that the various free-radical reactions associated with the break-up of the higher hydrocarbon molecules do not occur with methane. Some data on ignition of mixtures of fluorine,oxygen and hydrocarbons including methane,butane and cyclohexadiene have been interpreted. Several previously unknown elementary reactions have been identified,including a reaction of alkyl peroxide radicals with oxygen that appears to play a cardinal role in the so-called 'cool flame'regime of the reaction of oxygen with higher hydrocarbons. The effect of small concentrations of free radicals on the ignition process is illustrated by the example of propane-air ignition in the temperature field of a reflected shock wave and a combustion wave. The fluorine effect is further demonstrated by an investigation of the effect of fluorine on the ignition temperature in methane-air combustion waves,and the mechanism of ignition or explosion of mixtures of fluorine,oxygen and higher hydrocarbons is studied.