Numerical study on three-dimensional flow field of continuously rotating detonation in a toroidal chamber

Gaseous detonation propagating in a toroidal chamber was numerically studied for hydrogen/oxygen/nitrogen mixtures. The numerical method used is based on the three-dimensional Euler equations with detailed finiterate chemistry. The results show that the calculated streak picture is in qualitative agreement with the picture recorded by a high speed streak camera from published literature. The three-dimensional flow field induced by a continuously rotating detonation was visualized and distinctive features of the rotating detonations were clearly depicted. Owing to the unconfined character of detonation wavelet, a deficit of detonation parameters was observed. Due to the effects of wall geometries, the strength of the outside detonation front is stronger than that of the inside portion. The detonation thus propagates with a constant circular velocity. Numerical simulation also shows three-dimensional rotating detonation structures, which display specific feature of the detonation- shock combined wave. Discrete burning gas pockets are formed due to instability of the discontinuity. It is believed that the present study could give an insight into the interest- ing properties of the continuously rotating detonation, and is thus beneficial to the design of continuous detonation propulsion systems.

Influence of Accelerated Aging on Detonation Performance of Explosives

To understand the aging effects on detonation performances of explosives,an accelerated aging mechanism and effect of explosives were analyzed.Based on the thermo-gravimetric(TG) curves of explosives under the heat rate of 5,10 and 20 K·min-1,the thermal decomposition activation energy,pre-exponential factor,mechanism function and kinetic equation of the explosives were calculated by Ozawa's equation and decomposition extents.Then,according to the derived kinetic equation,the density,composition and heat of formation of GI-1,PBX-1 and PBX-2 explosive in different decomposition extents were calculated at accelerated aging temperatures of 70 ℃ and 75 ℃,respectively.Furthermore,the detonation parameters of GI-1,PBX-1 and PBX-2 explosives were found out by means of VLWR code.The results show that after accelerated aging,the density are decrease,the detonation velocity and pressure are all decreased slightly.

Numerical calculation of JWL EOS parameters for explosives

JWL equation of state（EOS） parameter for most energetic materials is blank,that makes it impossible for the numerical simulation of the explosive dynamic response and damage effects.In this paper,the numerical calculation of JWL EOS parameters for the gaseous,liquid and condensed source of the explosion was performed,the numerical simulation for the bottleneck problem of the dynamic response and damage effects for the aluminized explosives and some other non-ideal explosion source was solved,the visualization software for the detonation parameters and numerical parameters of JWL equation was developed.The results were relatively consistent with the experimental data.

Synthesis and properties of novel nitro-based thermally stable energetic compounds

This paper reviews the achievements in the field of synthesis of new thermally resistant explosive compounds in the years 2009 through 2019. The performance characteristics of these compounds(sensitivity, thermal decomposition parameters, and detonation parameters) were compared with those of 1,3,5-triamino-2,4,6-trinitrobenzene, which still seems to be an unrivalled model of a thermally resistant and generally low-sensitivity explosive material. New thermally stable explosives(TSEs) were found among macromolecular compounds with tri-and dinitrophenyl groups, nitro and amine-nitro derivatives of azoles, and polynitro derivatives of calixarenes. Some of them match TATB in terms of thermal resistance and additionally have higher detonation parameters.

A quasi-isentropic model of a cylinder driven by aluminized explosives based on characteristic line analysis

A quasi-isentropic study on the process of driving a cylinder with aluminized explosives was carried out to examine the influence of the aluminum(Al) reaction rate on cylinder expansion and the physical parameters of the detonation products. Based on the proposed quasi-isentropic hypothesis and relevant isentropic theories, the characteristic lines of aluminized explosives driving a cylinder were analyzed,and a quasi-isentropic model was established. This model includes the variation of the cylinder wall velocity and the physical parameters of the detonation products with the Al reaction degree. Using previously reported experimental results, the quasi-isentropic model was verified to be applicative and accurate. This model was used to calculate the physical parameters for cylinder experiments with aluminized cyclotrimethylenetrinitramine explosives with 15.0 % and 30.0 % Al content. The results show that this quasi-isentropic model can be used not only to calculate the cylinder expansion rule or Al reaction degree, but also to calculate the physical parameters of the detonation products in the process of cylinder expansion. For explosives with 15.0 % and 30.0 % Al, 24.3 % and 18.5 % of the Al was found to have reacted at 33.9 μs and 34.0 μs, respectively. The difference in Al content results in different reaction intensity, occurrence time, and duration of two forms of reaction(diffusion and kinetic) between the Al powder and the detonation products;the post-detonation burning reaction between the Al powder and the detonation products prolongs the positive pressure action time, resulting in a continuous rise in temperature after detonation.

Synthesis and characterization of functionalized 1,3-bis(2-alkyltetrazol-5-yl)triazenes

A series of 1,3-bis（2-alkyltetrazol-5-yl）triazenes have been synthesized in high yields by treatment of sodium nitrite and hydrochloric acid with substituted-5-aminotetrazoles. All compounds were fully characterized using IR spectroscopy,~1H NMR and^（13） C NMR spectroscopy and high resolution mass spectrometer（HRMS）. Most of these triazenes exhibit good detonation performance comparable with TNT and low melting points ranging from 81°C to 106°C, which are suitable for melt-cast explosives.Among these compounds, 1,3-bis（2-azidoethyltetrazol-5-yl）triazene（2g） displays a low melting point（106°C）, moderate onset decomposition temperature（183°C） and good detonation performance（D：7087 m/s; P： 17.6 GPa）.