ID#: 154
Abstract Title: The Influence of Detonation Cell Size and Regularity on the Propagation of Gaseous Detonations in Granular Materials
Session Title: Cellular Structure III
Session Date: 7/30/01
Session Start Time: 3:40 PM
Contributing Author: Slungaard, T.
Organization: Norwegian University of Science and Technology
Country: Norway
Authors: Torbjorn Slungaard, Tom Engebretsen, Otto K. Sonju
Short Abstract: Filters consisting of granular materials can be used to transform a detonation wave into a fast deflagration wave or to totally extinguish the flame of a detonation wave. Whether a detonation wave fails or not by a given filter type can depend both on detonation cell size and regularity. A research project for finding the limits for transmission of a detonation wave through a granular filter is completed. Both spherical glass beads and crushed rock were tested. Varying the initial pressure of the detonating gas mixture in the range 0.02 - 1 bara, controlled the cell size. Adding of argon was used to vary the detonation cell regularity. Eight piezoelectric pressure transducers recorded the pressure-time profile of the detonation wave. These pressure signals were used to calculate the detonation wave speed upstream, inside and downstream of the granular filter. To detect whether the flame of the detonation wave was extinguished or not, an ionisation probe was used in some experiments. The results are used to establish the conditions for total flame extinction in a granular filter. In addition it is found an approximate range for direct transmission of a detonation wave with irregular cell structure. For argon dilution resulting in regular detonation cells this range is changed. In the direct transmission range, the detonation wave regains full velocity immediately downstream of the granular filter. The range producing a fast deflagration downstream of the granular filter with the possibility of deflagration to detonation transition (DDT) is also found.