The role of explosion limit chemical kinetics in H2-CO-O2 detonations

Abstract

The role of explosion limit kinetics is explored by applying three different explc, sion limits to detonation waves traveling at a critical Mach number in stoiehiometrie mixture of H:-COO 2. Such waves are achieved by subjecting normal Chapman-Jouguet waves to a gaseous boundary and bringing them to a critical veloeit~t below which quenching would re/mlt. It is found that the critical velocities can be explained by the explos:on limit adv,~nced by Minkoff and Tipper when recent applicable rate constants (slightly modified) are used. In addition, this explosion limit seems to give a reasonable prediction of the lean detonation limit of CO-H,-O,, mixtures, although it fa~ls to agree with the experimental evidence at the rich detonation limit end found in the literature,

A Simple Model for the Detonation Limits of Gas Mixtures

“…In fact the velocity of limit detonations can be substantially different from the C-J value and need not be constant even in the same mixture-however, the mean velocity is usually only slightly lower than the C-J value within a few per cent of the limit, as can be seen from measurements quoted by Lewis and von Elbe (1961), and so this assumption should only lead to slightly narrower predicted than measured limits, the discrepancy depending on the definition of a detonation. Further support for this comes from Lu et al (1971) who showed that detonations in stoichiometric CO-H.-O. mixtures failed if the velocity was reduced by more than 10% which is a similar reduction to that predicted by Zeldovich (1940) when considering losses to the tube walls.…”

“…Kinetic data on the explosion limit is not available for most mixtures but Lu et al (1971) have applied the same criteria for H.-CO-O. mixtures to select the best reaction scheme and rates by comparison with the results of Laffitte (1938) and Lewis and von Elbe (1961).…”