Investigation of the detonation regimes in gaseous mixtures with suspended starch particles |
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Authors: | B Veyssiere BA Khasainov P Arfi |
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Institution: | (1) Laboratoire de Combustion et de Detonique, UPR 9028 CNRS – ENSMA Poitiers, F-86960 Futuroscope cedex, France , FR;(2) Institute of Chemical Physics, Russian Academy of Sciences, Oulitsa Kossiguina 4, 117977 Moscow, V334 Russia , RU |
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Abstract: | The existence of a secondary discontinuity at the rear of a detonation front shown in experiments by Peraldi and Veyssiere
(1986) in stoichiometric hydrogen-oxygen mixtures with suspended 20-m starch particles has not been explained satisfactorily. Recently Veyssiere et al. (1997) analyzed these results using a
one-dimensional (1-D) numerical model, and concluded that the heat release rate provided by the burning of starch particles
in gaseous detonation products is too weak to support a double-front detonation (DFD), in contrast to the case of hybrid mixtures
of hydrogen-air with suspended aluminium particles in which a double-front detonation structure was observed by Veyssiere
(1986). A two-dimensional (2-D) numerical model was used in the present work to investigate abovementioned experimental results
for hybrid mixtures with starch particles. The formation and propagation of the detonation has been examined in the geometry
similar to the experimental tube of Peraldi and Veyssiere (1986), which has an area change after 2 m of propagation from the
ignition point from a 69 mm dia. section to a 53 mm 53 mm square cross section corresponding to a 33% area contraction. It is shown that the detonation propagation regime in
these experiments has a different nature from the double-front detonation observed in hybrid mixtures with aluminium particles.
The detonation propagates as a pseudo-gas detonation (PGD) because starch particles release their heat downstream of the CJ
plane giving rise to a non-stationary compression wave. The discontinuity wave at the rear of the detonation front is due
to the interaction of the leading detonation front with the tube contraction, and is detected at the farthest pressure gauge
location because the tube length is insufficient for the perturbation generated by the tube contraction to decay. Thus, numerical
simulations explain experimental observations made by Peraldi and Veyssiere (1986).
Received 5 July 1997 / Accepted 13 July 1998 |
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Keywords: | :Detonation Two-phase flow Solid particle-gas mixture Numerical simulation |
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