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Accession Number:
ADA530872
Title:
Deflagration-to-Detonation Transition Control by Nanosecond Gas Discharges
Descriptive Note:
Final rept. 1 Apr 2007-1 Apr 2008
Corporate Author:
MOSCOW INST OF PHYSICS AND TECHNOLOGY DOLGOPRUDNYI (RUSSIA)
Report Date:
2008-04-07
Pagination or Media Count:
79.0
Abstract:
During the current project, an extensive experimental study of detonation initiation by highvoltage nanosecond gas discharges has been performed in a smooth detonation tube with different discharge chambers and various discharge cell numbers. The chambers were constructed on the basis of our previous studies and introduced analogous cell geometries. The discharge study performed in all the chamber has shown that three modes of discharge development are realized under the experimental conditions a spark mode with high temperature channel formation, a streamer mode with nonuniform gas excitation, and a transient mode. The mechanisms of deflagration to detonation transition DDT under different discharge modes have been proposed and confirmed experimentally. Under spark and transient initiation, simultaneous ignition inside the discharge channel occurs, forming a shock wave and leading to a conventional deflagration to detonation transition DDT via an adiabatic explosion. Using a singlecell discharge chamber, the DDT length and time at 1 bar of initial pressure in the square smooth tube with a 20 mm transverse size amounts to 50 mm and 50 microseconds, respectively. The streamer mode of discharge development in the singlecell chamber at an initial pressure of 1 bar results in nonuniform mixture excitation and a successful DDT via a gradient mechanism, which has been confirmed by high-speed time-resolved ICCD imaging. The gradient mechanism implies a longer DDT time of 150 microseconds, though under significantly lower initiation energy of 1 J and a short DDT run-up distance of 50 mm. The gradient mechanism has been studied in more detail in a fourcell discharge chamber. The governing parameters have been established and a significantly higher efficiency in terms of detonation initiation has been achieved due to the enhanced geometry.
Distribution Statement:
APPROVED FOR PUBLIC RELEASE
