| Autor: |
D. Desbordes, F. Joubert, F. Virot, B. Khasainov, H.-N. Presles |
| Předmět: |
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| Zdroj: |
Shock Waves; Sep2008, Vol. 18 Issue 4, p269-276, 8p |
| Abstrakt: |
Abstract We present experimental results on the detonability of the H2/NO2 mixture whose detonation exhibits a single cellular structure (λ1) for the lean mixtures and a double cellular structure (fine cells of size λ1 inside larger cells of size λ2) for stoichiometric and rich mixtures. Whatever the equivalence ratio $${\phi}$$ , the chemical energy is released in two successive exothermic steps of heat of reaction Q 1 and Q 2 (Q 1 + Q 2 = Q, the total heat release) and characterised (for $${\phi > 1}$$) by two chemical lengths. The detonability is evaluated on the basis of critical conditions of self-sustained detonations transmission from a cylindrical tube of i.d. d to free space. Results show that for the critical tube diameter relationship d/λ1 = k, with respect to the equivalence ratio $${\phi}$$ ranging from 0.5 to 1.3 at ambient temperature, k is higher than the classical value 13 and its variation is rather complex. Indeed, d/λ1 increases with $${\phi}$$ from 17–18 for $${\phi = 0.5}$$ to 45–50 for $${\phi = 1}$$ and to 90–100 for $${\phi = 1.3}$$ . The highest detonability obtained for $${\phi = 0.6}$$ is explained on the basis of the highest relative contribution of the first exothermic step to the total energy Q. We conclude that, as d/λ1 drops with Q 2 decreasing, it should tend to 13 with the vanishing second exothermic reaction. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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