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Detonation cell size

Figure 1. Detonation cells in tests

In Figure 1 of the article Detonation front structure a diamond-shaped form demonstrates a typical track of triple points from intersecting shock waves. Such track is called detonation cell and can be easily obtained experimentally on sooted surfaces located in detonating gases. These cells form a cellular structure observed experimentally, and are characterized by their two lengths: longitudinal size L and transverse size S. These two lengths are varying depending on type of burnable gase and initial conditions, how-ever the relation S ≈ 0.6 L are kept usually constant.

In Figure 1 an example of detonation cell in stoichiometric hydrogen-air mixture is shown. In the figure a soot track of irregular detonation cellular structure in stoichiometric H2-air mixture is shown (KuznetsovMS:2000), (KuznetsovM:2002c). Average transverse cell size of the test shown in the figure S ≈ 1 cm. The detonation cell size is kept constant for the given components for the same initial condition and depends only on the mixture composition, and therefore is often used as a mesure of mixture reactivity.

Figure 2. Detonations cell sizes

Usually the detonation cell size reaches its minimum at the stoichiometry composition and grows for leaner and richer mixtures. In Figure 2 a dependence of the detonation cell size for H2-air mixtures on initial H2 concentration and mixture temperature ((CiccarelliG:1994) (KaneshigeM:1997) is shown.

Kuznetsov M.S., Alekseev V.I. and Dorofeev S.B. (2000) Comparison of critical conditions for DDT in regular and irregular cellular detonation systems. Shock Waves, 10:217-224.(BibTeX)
Kuznetsov M., Cicarelli G., Dorofeev S., Alekseev V., Yankin Yu. and Kim T.H. (2002) DDT in methane-air mixtures. Shock Waves, 12:215-220.(BibTeX)
Ciccarelli G., Ginsberg T., Boccio J., Economos C., Sato K. and Kinoshita M. (1994) Detonation cell size measurements and predictions in hydrogen-air-steam mixtures at elevated temperatures. Combustion and Flame, 99:212-220.(BibTeX)
Kaneshige M. and Shepherd J.E. (1997) Detonation Database. Technical report Explosion Dynamics Laboratory Report FM-97-8, Graduate Aeronautical Laboratries, California Institute of Technology.(BibTeX)

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