Analytical study of an effect of gas compressibility on a burning accident in an obstructed passage

Abstract

The incompressible analytical formulation describing a burning accident in an obstructed passage [F. Kodakoglu et al., “Towards descriptive scenario of a burning accident in an obstructed mining passage: An analytical approach,” in 27th International Colloquium on the Dynamics of Explosions and Reactive Systems (ICDERS), Beijing, China, July 28–Aug 2, 2019, Paper 369] is extended to account for gas compression, which cannot be ignored as soon as the flame velocity starts approaching the speed of sound. The analysis combines the theories of globally spherical, self-accelerating premixed expanding flames with that of ultrafast flame acceleration in obstructed conduits. It is shown that while the entire acceleration scenario may promote the flame velocity up to near-sonic values, the effect of gas compressibility moderates flame acceleration, and such an impact depends strongly on various thermal-chemical properties of the combustible premixture. Starting with gaseous combustion, the formulation is subsequently widened to the gaseous-dusty environments with combustible (coal) and inert (sand) dusts, and their combinations. In particular, it is quantified how the flame evolution and its locus and velocity depend on the type and size of the dust particles.