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Laser Diagnostics of Detonation Waves

#1250


Experimental Study of Detonation Wave Structure of Condensed High Explosives in Nanosecond and Subnanosecond Range by Laser Velocimeters

Tech Area / Field

  • PHY-NGD/Fluid Mechanics and Gas Dynamics/Physics

Status
3 Approved without Funding

Registration date
14.04.1998

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Collaborators

  • Los-Alamos National Laboratory, USA, NM, Los-Alamos\nLawrence Livermore National Laboratory, USA, CA, Livermore

Project summary

The aim of the project is to experimentally study detonation wave (nonideal also) structure of condensed (solid and liquid) high explosives (HE) by means of laser interferometry with nanosecond and subnanosecond resolution, as well as to analyze and interpretate the available and newly obtained data of front structure and detonation wave propagation mechanism.

Scientific value of the studies is motivated by: insufficient and contradictory nature of experimental data available; absence of complete updated detonation theory, explaining and considering small – scale 3D detonation wave (DW) structure.

There is still no precise data in available literature about Von Neumann spike values in powerful condensed HE.

The expected results include accumulation of experimental data on detonation wave structure and experimental confirmation Zeldovitch-Neumann-During theory.

This Project intends the solution of the following experimental problems:

Recording with the help of laser velocimeters Fabry – Perot and ORVIS (Optically Recording Velocity Interferometer System) the dependence of particle velocity on time in chemical reaction zone. The experiments will be carried out with the help of the precision – window method.

Thin foil (6-10 mm) or covering ~1 mm made of aluminium is placed between HE and window. Crystals LiF, CaF2, NaCl, KCl, water and other materials will be used as windows. This will allow to determine Von Neumann spike parameters for basic powerful condensed HE. Experiments with different charge length will allow to define chemical reaction duration and Chapman – Jouget state parameters.

The works will be fulfilled using powerful narrow – band ruby and iodine lasers and high – sensitive electronic optical registrators, interferometer systems Fabry– Perot, ORVIS and RFNC – VNIIEF software.

The basis for this task solution is available in VNIIEF:


· explosive loading devices;
· modern measuring units to record detonation development;
· laser interferometer systems Fabry – Perot and ORVIS;
· computation center;
· codes to solve continuum mechanics problems;
· experimental data, obtained by A.V.Fedorov’s team during recent years where Von Neumann spike parameters, chemical reaction zones, and Chapman – Jouget state are defined for two plastifired HE on the basic of PETN (Von Neumann spike state exceeds Chapman – Jouget state in pressure and particle velocity 78%, chemical reaction zone duration is 10±3 ns) and HMX (Von Neumann spike state exceeds Chapman – Jouget state in pressure and particle velocity up 63%, chemical reaction zone duration is @40 ns).

The problem solution includes:


· development of experimental procedure;
· experimental activities and results analysis;
· computation and theoretical study of detonation propagation.

Project realisation will allow to reveal DW structure, to simulate physical and chemical processes taking place in detonation wave front, to determine Von Neumann spike values in the basic HE (HMX, RGX, PETN, TNT, tetrinintomethane, etc.) and dependence of chemical reaction zone width on HE charge structure. The Project realization will allow to refine specific value of dynamic parameters for HE reacted and unreacted in the area of detonation front experimentally confirm ZND theory, to obtain equation of state of unreacted HE in the wide range of pressures. The Project realization can be used also at solving many practical tasks. For example, detonation wave parameters acknowledgment (Von Neumann spike state, Chapman – Jouget, chemical reaction zone, etc.) will allow to make modern detonation model and applied hydrocodes, to simulate different physical processes and mechanisms in detonation front. This will allow to switch the efforts of scientists and specialists, involved into weapons area to solving fundamental problems of detonation theory.


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