AN ANALYSIS ON THE BLAST INITIATION OF SPRAY DETONATIONS

When a strong blast wave passes through a mixture of fuel droplets and oxidizing gas, the droplets are ignited by a hot and highly compressed convective flow behind the shock wave. Under appropriate conditions, the blast wave becomes a ″spray detonation″ which is sustained by the heat of the droplet combustion. In the present analysis, the blast initiation of the spray detonation in a uniformly dispersed fuel spray is treated by using the perturbation method of blast waves due to Sakurai. The rate-controlling process is the gasification of the droplets and its depends on the initial diameter, the volatility and the heat of combustion of the droplets. Here, the decrease rate of the diameter of a burning droplet is assumed to be inversely proportional to the diameter itself, the proportionality constant being treated as a parameter. The results are restricted to the early stage of the process, but they show that the blast wave decays to a steady wave whose velocity depends on the droplet size.