Spontaneous Ignition of an Inflammable Gaseous Mixture on Release from Compression

Abstract

THE ‘shock-tube’ method of producing one-dimensional shock waves has found many applications in recent years. It was first used by Vieille¹ to study the establishment and propagation of discontinuous waves in columns of air. Payman and Shepherd² applied the method—in their ‘bursting-diaphragm apparatus’—to examine, by means of schlieren photography, the nature and spread of the discontinuous disturbance in the expansion chamber. Their results³ linking shock-wave speed and air flow with the initial pressure in the compression chamber fitted accepted theory. The theory of shock tubes has since been more deeply considered, for example, by Hertzberg⁴ in the United States, and by Lukasiewicz⁵ in Canada. A shock tube has also been used by Perry and Kantrowitz⁶ for demonstrating the luminosity caused by an intense shock wave being propagated in air. Recent developments have been directed towards the use of the shock tube for the generation of shock waves of high Mach number, and for this purpose gases of high acoustic speed have been used in the compression end as the driver agent, the high speed and pressure being obtained by exploding inflammable mixtures of low density behind the diaphragm. Hertzberg and Smith⁷ describe some anomalous results in such experiments, and it is to offer perhaps an explanation of these that this communication is made.