Comparison of critical conditions for DDT in regular and irregular cellular detonation systems

The results of an experimental study of DDT in mixtures with regular and ir regular detonation cellular structures are presented. Experiments were carr ied out in a tube 174 mm i. d. with obstacles (blockage ratios were 0.1, 0. 3. and 0.6). Mixtures used were hydrogen-air and stoichiometric hydrogen-ox ygen diluted with N-2, Ar, and He. The critical conditions for DDT are show n to depend on the regularity of the cellular structure of test mixtures. T he critical values of the cell sizes in Ar- and He-diluted mixtures are sho wn to be significantly smaller than those in N-2-diluted mixtures. This mea ns that systems with a highly regular detonation cellular structure have fa r less capacity for undergoing DDT compared to irregular ones with the same values of detonation cell sizes.