Hydrogen-air detonations

The Three Mile Island nuclear plant accident has triggered renewed interest in fundamental combustion studies in hydrogen-air mixtures. The present study is concerned with the problem of detonation of atmospheric, hydrogen-air mixtures and reports new experimental results on cell sizes lambda and critical tube diameters d/sub c/. The results confirm the empirical correlation d/sub c/ = 13lambda. Comparison of the critical tube diameter of stoichiometric hydrogen-air mixtures (d/sub c/ = 20 cm) with that of stoichiometric acetylene-air mixtures (d/sub c/ = 12 cm) indicates that hydrogen is slightly less sensitive than acetylene. The relatively slow increase in d/sub c/ for H2-rich mixtures (as compared to lean mixtures) indicates that fuel-rich mixtures are more hazardous from the detonation point of view than fuel-lean mixtures. Regarding the detonability limits, the present paper formally defines limit criteria for different boundary conditions based on the cell size of the mixture. For fully confined detonations in tubes, limits are set by the onset of single-headed spin