Detonation Parameters Research Articles

Impact of nitromethane additive on ANFO performance.

The article presents an evaluation of the detonation performance of a nitromethane-ammonium nitrate fuel oil energetic material. The brisance and relative strength of this material were assessed using the Hess and Trauzl methods. Both methods confirmed that the shattering effect and relative work increase in a polynomial manner with the increasing content of nitromethane. A significant enhancement in detonation parameters was observed with up to 9% nitromethane addition. The results from the Trauzl and Hess tests indicated that at 9% nitromethane content, the average cavity expansion and brisance were 371cm3 and 10.01mm, respectively. The improved detonation performance is attributed to the introduction of additional nitro groups from nitromethane, replacing fuel oil, as well as the increased density of the energetic material.

Simple synthesis of monocyclic pyrimidine-based energetic molecule with “amino–nitro–hydrazino” arrangement

With the constant development of energetic materials, numerous explosive molecules have been synthesized, some of which feature competitive performances. However, energetic materials are directly oriented to application requirements. Therefore, more emphasis is gradually placed on route simplification and cost reduction while designing novel energetic molecules. In this work, monocyclic energetic compound 2,4-diamino-6-hydrazineyl-5-nitropyrimidine (3) was successfully obtained. This compound exhibits an alternating “amino–nitro–hydrazino” arrangement, featuring strong intramolecular hydrogen-bonding interaction. With cheap raw material, the whole reaction comprised only two steps, and exhibited simple post processing, only filtration. This novel energetic molecule possesses excellent mechanical security (IS > 40 J, FS > 360 N), acceptable thermal stability (Td = 225 °C), and good detonation parameters (Dv = 8470 m/s, P = 24.9 GPa), indicating that compound 3 may act as a candidate of insensitive explosives.

Synthesis, Characterization and Energetic Properties of Hydroxymethyl-Bishomocubanone Derivatives.

The present work reports synthesis, characterization and theoretical insights on novel hydroxymethyl-bishomocubanone derivatives. Twelve new bishomocubanes (BHCs) were synthesized and fully characterized by various spectroscopic techniques and single crystal X-ray analysis. The densities of the title compounds were in the range of 1.30-1.59 g/cm3. Density-functional theory (DFT) based calculations at B3LYP/6-311++G(d,p) level of theory were performed on ten selected BHC based cage compounds. Propulsive and ballistic properties of newly synthesized hydroxymethyl-bishomocubanone derivatives in solid and liquid propulsion systems were calculated, and the results suggested that these compounds are superior to conventional fuel RP1 and binder HTPB. The detonation parameters revealed that these compounds are not explosive in nature and safe to use as solid propellants. Furthermore, kinetic and thermal stabilities of the title compounds were determined by HOMO-LUMO energy gap, ESP maps, impact sensitivity (h50) and bond dissociation energies (BDEs) followed by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). Three compounds, a dinitroazide (Isp,vac=310.98 s), a dinitrate (Isp,vac=309.51 s), and a dinitronitrate (Isp,vac=309.20s) were found to be excellent candidates for volume limited applications.

Theoretical investigation of the nitro-and amino-substituted 4-(1H-1,2,4-triazole-1-yl) pyrimidine

The amino- and nitro-groups are introduced into 4-(1H-1,2,4-triazole-1-yl) pyrimidine, and 31 derivatives are constructed to look for high-energy-density compounds. Both the thermal stability and detonation characteristics are considered in detail. The heat of formation (HOF) is calculated by using the G3MP2 method in the framework of the atomisation reaction. Furthermore, bond dissociation energy (BDE) is evaluated by designing the homolytic reaction. To explore the detonation characteristics of title molecules, the detonation pressure (P), crystal density (ρ), heat of detonation (Q), and detonation velocity (D) are calculated based on the Kamlet-Jacobs empirical equation, and the excellent detonation parameters are confirmed. To estimate the sensitivity to impact, the impact sensitivity (H 50) value and the free space in the crystal lattice (ΔV) are also considered. Finally, three derivatives (D2, D5, and E) are screened out as candidates for high-energy-density compounds (HEDCs).

Volume of detonation determination based on gaseous products of energetic materials by time resolved LIPS combined with schlieren image.

The safe and fast measurement of volume of detonation (VoD) is always a hard task for macroscale explosion even though it is one of the important parameters to evaluate the explosion performance. Therefore, a promising technology to determine the VoD is highly desirable for evaluation of energetic materials. Herein, a new method of VoD determination based on gaseous products via small dose energetic materials by time correlated laser induced plasma spectroscopy (LIPS) combined with schlieren image was proposed. Hydrodynamics of products after laser ablation on a time scale ranging from microsecond to millisecond was investigated. Based on the analysis of hydrodynamics of products after laser ablation, the effective spectra of gaseous products of each energetic material are obtained. Subsequently, a high-accuracy quantitative analysis model of VoD based on gaseous products using the method of principal component analysis - partial least squares (PCA-PLS) with small sample modeling algorithm has been developed( R2>0.96). The VOD model accurately predicts the detonation parameters with the average relative error of test set (ARET) < 3% and the maximum relative error of test set (MRET) < 5%. Moreover, the results without spectra selection of the relative error of blind data show the max relative error is less than 7%. The results of variable importance in projection (VIP) identification indicate a robust association between the spectral signatures of carbon (C), nitrogen (N), hydrogen (H), oxygen (O) and VoD. Furthermore, the N lines exert the most substantial influence on the VoD model. This method provides a new safe and fast determination technology for the evaluation of VoD and clarification of the related mechanism.

Effects of typical MH2 (M= Ti, Mg, Zr) on the detonation energy release characteristics of composite charge containing Al/PTFE reactive materials and RDX

To explore the effects of three typical metal hydride powders (TiH2, MgH2, ZrH2) on the detonation energy release characteristics of composite charge containing Al/PTFE reactive materials and RDX, a variety of composite charges containing Al/PTFE/MH2 ternary active materials and RDX were prepared. The effects of metal hydrides on detonation parameters of composite charges were studied by air blast experiments and the temperature distributions of explosion fireball were mapped using colorimetric thermometry technique. The experimental results indicated that the addition of metal hydrides had significantly positive effects on afterburning effect and detonation performance of composite charges, and the enhancement effect of MgH2 was superior to that of TiH2 and ZrH2. The fireball duration, maximum average temperature and shock wave parameters of the composite charges in air blast experiments all changed with the order of Al/PTFE/MgH2+RDX > Al/PTFE/TiH2+RDX > Al/PTFE/ZrH2+RDX > Al/PTFE + RDX. The results could offer theoretical references for the formulation design of high-power explosives.

Effect of mixed carbon phase state on detonation parameters and reaction zone of explosives under extreme condition

A precise description of the thermodynamic states of gaseous and solid detonation products is essential when using thermodynamic calculations to determine the detonation performance and destructive power of explosives. For high oxygen-lean explosives (the oxygen contained in explosives is insufficient to completely oxidize combustible elements and excess solid carbon will be generated in the detonation products), the phase state of solid carbon product affects the Chapman–Jouguet (CJ) detonation performance parameters, reaction zone, and energy release process. However, the recovery of detonation products demonstrates that the actual detonation carbon product is primarily a mixed state of diamond/graphite stack, as opposed to the existing thermodynamic codes, which essentially treat detonation carbon as single-phase carbon. To understand the thermodynamic effect of the mixed carbon phase state on the non-ideal detonation behavior, in this work, the matching relationship among the VINET equation of state parameters, thermodynamic potential parameters of the solid products of the equivalent system and the phase mixed system was constructed by using the nonlinear fitting method. The relationship between the carbon phase composition at the CJ point and the explosive composition structure was researched. Investigations were conducted into how the mixed carbon phase affected the volume and content of gas products as well as the composition at CJ points. Diamond formation in products is good for enhancing explosive's working capacity. Based on mixed-state potential parameters, the correlation mechanism between the mixed carbon phase and the chemical reaction zone was investigated, and it was found that intramolecular carbon/intermolecular carbon and more detonation graphite/diamond products all would lead to the extension of the reaction zone.

A dynamic droplet breakup model for Eulerian-Lagrangian simulation of liquid-fueled detonation

This study proposes a dynamic model to reflect the physical image of the droplet breakup process in two-phase detonation flows. This breakup model is implemented in a two-phase detonation solver developed based on an open-source computational fluid dynamic platform, OpenFOAM, and compared with three prevalent models (TAB, PilchErdman, and ReitzKH-RT model) under different droplet diameters (30–70 μm) in one- and two-dimensional detonation problems. The simulating results show that the present breakup model well predicts experimentally determined detonation parameters such as detonation velocities and post-wave temperature. In addition, the present model has the advantage of being free of the KH breakup time parameter, which the ReitzKH-RT model needs to fit the experimental data. The one-dimensional detonation simulations indicate that different breakup models slightly impact the detonation wave velocity because the droplet breakup process does not significantly affect the total heat release as long as it is sufficiently fast to sustain the detonation. However, the two-dimensional detonation simulations show that the breakup model and the droplet initial diameter significantly affect the detonation cell size due to the different droplet distributions predicted by various models. The breakup length, which is the distance from the shock wave to the location at which sufficiently small child droplets appear, affects the chemical reaction zone thickness and then the detonation cell size. A longer breakup length will result in a larger detonation cell size.

A theoretical method for oblique and curved detonation waves

In this paper, a theoretical solution method for the post-wave parameters of detonation is proposed and developed with a series of analyses and applications. Based on Newton's method, the objective function for shock-coupled chemical reactions is constructed along with its derivative. Two verification examples demonstrate that the method can calculate accurate post-wave parameters quickly and is suitable for single-step and detailed mechanistic chemical reactions. In addition, the method provides sensitivities between various aerodynamic parameters to offer a fresh perspective for detonation, polar analysis with sensitivity is built as a result. Moreover, the method can predict the transition pattern of the detonation, and the validity is supported by the comparison of different examples. Rather than being limited to oblique detonation, the post-wave parameters of the curved detonation can also be calculated correctly, which indicates the excellent applicability of the method. This method can also be applied to the thermodynamic efficiency of detonation combustion and its sensitivity, which demonstrates the unique advantages of this method. Furthermore, the method can be rewritten as a solution for wedge angle under the given wave angle by changing the independent variable. This solution is validated by the simulation results, which implies that the method can be used as a simple inverse design method in oblique detonation engines. In general, the proposed method is an effective theoretical solution, analytical tool, and inverse design method for detonation.

Investigation and mapping of toxic fumes produced by detonation of ANFO explosives in underground space

AbstractPost‐blast fumes are hazardous and known to cause severe health related issues of workers. Further, these harmful gases have a significant impact on the surrounding environment. Thus, it is imperative to have an in‐depth understanding of the real time detonation fume generation in underground space to avoid hazardous health risk of the worker. In this context, the mapping of toxic fume concentrations generated by the detonation of ANFO explosives in the actual field is a fascinating area of research that has a great environmental impact. This article examined the real‐time analysis of toxic fumes generated by ammonium nitrate fuel oil (ANFO) explosives at various locations of a metalliferous underground mine. Furthermore, detonation parameters of various ANFO explosive compositions were also studied at the mining site. On‐site blasting studies were performed with ANFO explosives, and post‐detonation fume measurements enabled us to map the CO and NOx concentrations in underground spaces. Toxic fumes like CO and NOx were analyzed before and after each blasting operation at different intervals, and found within the allowed limit as per the Directorate General of Mines Safety guidelines. Additionally, an empirical correlation has been established to evaluate the maximum detonation velocity based on the alteration of ammonium nitrate and fuel oil composition.

Nonlinear Approach to Jouguet Detonation in Perpendicular Magnetic Fields

The focus of this paper was Jouguet detonation in an ideal gas flow in a magnetic field. A modified Hugoniot detonation equation has been obtained, taking into account the influence of the magnetic field on the detonation process and the parameters of the detonation wave. It was shown that, under the influence of a magnetic field, combustion products move away from the detonation front at supersonic speed. As the magnetic field strength increases, the speed of the detonation products also increases. A dependence has been obtained that allows us to evaluate the influence of heat release on detonation parameters.

Design and evaluation of a kind of polymer-bonded explosives with improved mechanical sensitivity and thermal properties

The emergence of TKX-50, an energetic ionic salt with a high enthalpy of formation and low sensitivity, has opened a new path for the development of high-energetic, insensitive composite explosives. However, due to the poor interfacial binding properties of TKX-50 with conventional binders, there is a lack of effective guidance for the design of TKX-50 based composite explosives. To address the above issues, the interactions between carboxymethyl cellulose acetate butyrate (CMCAB) and other binders with explosives TKX-50/HMX were compared using the molecular dynamics method. Based on the simulations, TKX-50/HMX/CMCAB-based polymer-bonded explosives (PBXs) were prepared with CMCAB as binder, which displays a high binding energy (Ebind) with TKX-50 and high cohesive energy density (CED), and the effect of TKX-50 content on the performance of PBXs was investigated. The physical properties of PBXs, specifically the morphology, mechanical sensitivity, and thermal conductivity, were analyzed by SEM, sensitivity apparatus, and thermal conductivity meter, respectively. The specific heat capacity (Cp) and non-isothermal decomposition temperature of PBXs were tested by DSC, and then the corresponding thermal kinetic parameters were analyzed to evaluate their thermal safety. The adiabatic thermal decomposition processes of PBXs were tested using an ARC instrument. The decomposition mechanism and kinetics were also explored to further analyze their thermal stability and thermal safety under adiabatic conditions. The computer code EXPLO5 was used to predict the detonation parameters of PBXs. The results showed that CMCAB and TKX-50 displayed favorable interfacial bonding properties, and TKX-50 can be bonded with HMX to form a molding powder with a desirable morphology and safety profile. The TKX-50 in PBXs effectively improves the mechanical sensitivity and thermal safety of PBX and has a significant effect on the detonation performance of PBX. This research demonstrates a novel method suitable for screening and investigating high-energetic insensitive explosive systems compatible with TKX-50.

Discovery of high-energy nitro-azolo-pyridine compounds with high-throughput computation and machine learning

The nitro-azolo-pyridine compounds have planar molecular backbones with high nitrogen content, which are considered as a candidate system of insensitive high-energetic explosive (IHE). In this work, 30969 energetic molecules were generated based on 7 kinds of azolo-pyridine backbones; among them 2000 sample molecules were chosen to perform high-throughput calculations (HTC) of detonation velocity and pressure, then the machine learning (ML) models were constructed according to the computed molecular descriptors and detonation parameters; the detonation parameters for the other molecules besides the HTC samples were predicted by the ML models, and the molecular stability for the highest energy molecules were computed using quantum chemistry. Finally, 3 nitroazolo-pyridine compounds with high-energy and low-sensitivity were screened, and their synthetic accessibility were verified.

Comparative study on the equation of state of detonation products

The equation of state (EOS) for detonation products can predict explosive performance with basic information about density, enthalpy of formation, and elemental composition. However, to achieve higher prediction accuracy, it is necessary to select an appropriate EOS for the specific detonation parameters being calculated. To study the applicability of different equations of states for explosive products, five EOSs, Becker–Kistiakowsky–Wilson, Kihara–Hikita–Tanaka, Virial-Wu (VLW), Lennard-Jones–Devonshire (LJD), and Jacobs–Cowperthwaite–Zwisler (JCZ), were used to calculate the Hugoniot curve of nitrogen and the detonation performance of typical explosives. The calculation results show that all five EOSs can provide reasonably accurate predictions of the Hugoniot curve of nitrogen on the relative volume-pressure plane. Moreover, the EOSs can accurately predict the detonation velocity and pressure of explosives within a wide range of initial densities. When it comes to temperature calculations, LJD and JCZ demonstrate higher prediction accuracy. Additionally, the results indicate that VLW may not be suitable for calculating the overdriven detonation of explosives, particularly at higher pressures.

Theoretical exploration of the stabilities and detonation parameters of nitro-substituted 1H-benzotriazole.

The nitro group was introduced into the nitrogen heterocycle of 1H-benzotriazole to design a total of 31 derivatives. To estimate the thermal stability of these derivatives, the heat of formation (HOF) is calculated based on the isodesmic reaction. The bond dissociation energy (BDE) was also predicted based on the homolytic reaction to further evaluate the dynamic stability. To evaluate the possibility of utilizing as high energy density compounds (HEDCs), the detonation parameters including the detonation pressure (P), detonation velocity (D), and explosive heat (Q) are predicted by taking advantage of the Kamlet-Jacobs empirical equation. To measure the sensitivity to impact, both the characteristic height (H50) and free space in crystal (∆V) are considered in this paper. Based on our calculations, D-series and E are found to be the candidates for HEDCs. The Gaussian 09 software package was used in this paper. The B3PW91 hybrid function with the 6-311 + G(d,p) basis set was chosen to perform the structural optimization, frequency analysis, heat of formation, and bond dissociation energy. The detonation parameters were calculated following the Kamlet-Jacobs equation.

Comparative study on detonation parameters of ammonium dinitramide and ammonium perchlorate in composite explosives

ABSTRACT Ammonium dinitramide (ADN) has the advantages of chlorine free, low characteristic signal and high energy compared with ammonium perchlorate (AP), which is the most likely oxidant to replace ammonium perchlorate. Therefore, we conducted theoretical calculations to analyze the influence of oxidant content and RDX content on the detonation parameters of composite explosives. We compared the detonation parameters of ADN-based composite explosives with AP-based composite explosives, then verify the theoretical calculation analysis results through actual testing. The main research conclusions of this paper are as follows: (i) The detonation parameters of ADN based composite explosive are higher than those of AP-based composite explosive, in which the detonation velocity is about 3.3%~17.2% higher, the detonation heat is about 0.65% ~41.8% higher, and the explosion volume is about 1.6% ~11.6% higher; (ii) the average detonation velocity of the ADN-based explosives tested in practice is 20.4% and 3% higher than that of AP-based explosives respectively, which is basically consistent with the theoretical calculation results. However, the work capacity is lower than that of AP-based composite explosive.

Detonation parameters of the mixture of gelled nitromethane/microballoons at high porosity

The detonation properties of mixtures of gelled nitromethane (NM) with hollow glass microballoons (GMBs), the concentration of which varied from 16 to 30 wt. %, have been studied using an optical technique with high temporal and spatial resolution. It is shown that the addition of GMBs up to 30 wt. % does not qualitatively change the reaction zone structure of NM, which is in accordance with the classical detonation theory. However, the detonation parameters of the mixture decrease significantly with increasing GMB concentration—the pressure at the Chapman–Jouguet point drops by more than an order of magnitude at a porosity of 75%. The non-monotonic nature of the change in critical detonation diameter with decreasing mixture density is noted. The dependence of the critical diameter on the porosity of U-shape with the formation of two local minima at 8 and 18 wt. % GMB in the mixture and a local maximum at 13 wt. % GMB is obtained. At a concentration above 20 wt. % GMB, the critical detonation diameter increases dramatically, and at 30 wt. % GMB, the critical diameter becomes comparable to that of gelled NM.

Synthesis and investigation of 5-amino-2,4,6-trinitrobenzene-1,3-diol and its salts

ABSTRACT 5-amino-2,4,6-trinitrobenzene-1,3-diol (ATNBD) was synthesized using an improved literature method. The reactions of ATNBD with different N-bases (e.g., ammonia, hydrazine, hydroxylamine, and guanidine) and metathesis reactions producing energetic salts were reported. Several energetic compounds were synthesized and characterized for the first time using multinuclear NMR spectroscopy, mass spectrometry, elemental analysis, and differential scanning calorimetry (TG-DSC). The crystal structures of ATNBD and three energetic salts were determined using single-crystal X-ray diffraction at room temperature. Heats of formation (HOF) for the metal-free species were calculated using the Gaussian 09 software. Detonation parameters were estimated using the EXPLO5 program. The sensitivities toward impact and friction were also determined. Energetic evaluation indicates that, in addition to the molecular ATNBD, some ionic derivatives, 3, 4, 5, and 9, also have high densities (1.79–1.88 g cm−3), good detonation pressures, and velocities (P, 31.5–38.8 GPa; v D , 8450–9097 m s−1), as well as acceptable impact and friction sensitivities (IS, 5–42 J; FS, 120–360 N). These attractive features highlight the application potential of the salts of 3, 4, and 9.

Experimental study on the effect of titanium hydride content on the detonation performance of emulsion explosives

AbstractIn order to improve the explosion characteristics of emulsion explosives, titanium hydride was added to emulsion explosives to produce a new type of hydrogen storage emulsion explosives. Charges with different contents of titanium hydride were evaluated through underwater explosion experiments and detonation velocity tests. The tests on underwater explosion and detonation velocity reveal that compared to pure emulsion explosives, the detonation parameters of emulsion explosives containing titanium hydride showed a trend of first increasing and then decreasing. When the mass ratio of titanium hydride in the emulsion explosive is 1 % to 3 %, all detonation parameters have been improved to a certain extent. When the mass ratio of titanium hydride in the emulsion explosive is 3 % to 10 %, only part of the detonation parameters (specific impulse, specific shock energy, specific total energy and volume energy density) has been improved. The maximum increase of specific impulse, specific shock energy, specific total energy and volume energy density of emulsion explosive containing titanium hydride is 7.06 %, 8.95 %, 3.97 % and 8.22 %, respectively. Based on the analysis, it is evident that though powdered TiH2 participates in the detonation reaction process of the emulsion explosive, the majority of TiH2′s energy is released during the secondary reaction occurring after the detonation wave front. Therefore, the detonation performance of emulsion explosives can be effectively improved by adding a certain mass ratio of titanium hydride.

Calculation of Thermochemical and Detonation Parameters of Azido-Acetylenic Derivatives of s-Triazine

Calculation of Thermochemical and Detonation Parameters of Azido-Acetylenic Derivatives of s-Triazine