Fundamental Aspects of Unconfined Explosions
Final rept. 20 Jan 1971-19 Jan 1972,
MICHIGAN UNIV ANN ARBOR DEPT OF AEROSPACE ENGINEERING
Pagination or Media Count:
The theoretical aspects of cylindrical strong blast waves and Chapman-Jouguet C-J detonations are treated in detail. A critical radius is discussed which divides the cloud into an inner blast wave zone and an outer detonation zone. Expressions for the evaluation of ground and dynamic impulse are presented, and the propagation of a C-J detonation through a cloud of fuel drops, the initiation problem, and deviations from the ideal cylindrical blast model are considered. A modified computer program for calculating detonation velocity of complex hydrocarbon fuels is discussed. The design and operation of an experimental facility to study the propagation of two-phase detonations in a cylindrical segment of a cloud is described. Experiments conducted with kerosene drops in air showed that at small radius the cylindrical wave decayed as a shock wave, but beyond a critical radius the wave becomes a constant velocity two- phase Chapman-Jouguet detonation. The experimentally determined critical radius agreed quite well with the theoretical predictions. The results lend encouragement to the prediction of threshold energy levels required for detonation initiation in various geometries.