Transition to detonation in corn starch dust-oxygen and -air mixtures
Combustion and Flame, 86 (1-2):
21--32 (July 1991)DOI: http://dx.doi.org/10.1016/0010-2180(91)90053-E
Abstract
In the transition to detonation of some organic dust-gas oxidizer
mixtures four stages can be distinguished: (1) initial particle ignition;
(2) compression wave amplification by coherent energy release; (3)
unsteady reaction shock; and (4) spin detonation. By decreasing the
initiation energy the monotonous acceleration of the whole process
turns into a multistage one. Within the stage of the reaction shock
the symmetrical smooth wavefront structure is transformed into a
three-dimensional one, and the spin detonation forms. The transition
with an abrupt onset of detonation and retonation wave formation,
as observed normally in gaseous mixtures, exists in dust mixtures
too, since propagation of dust detonations is also dominated by transverse
waves. For detonations in lean corn starch dust-oxygen mixtures at
initial pressure $p_0$ = 0.4 bar, the minimum tube diameter is dmin
= 0.14 m. But for corn starch dust-air mixtures, the same value of
$d_min$ holds only at $p_0$ = 2-2.5 bar.