Detonation Theory Research Articles

One-step synthesis and characterization of Y2O3 nanoparticles via emulsion detonation method

Yttrium oxide (Y2O3) nanoparticles have critical applications in many industries, including ceramics, optics, and biomedicine. However, conventional synthesis methods are typically cumbersome and time-consuming. Herein, a novel emulsion detonation method successfully achieved the one-step synthesis of Y2O3 nanoparticles. In this method, yttrium nitrate hexahydrate was uniformly dispersed in the emulsion explosive as a precursor and an auxiliary oxidizer. After the emulsion explosive was detonated in a detonation chamber, the detonation products were collected, purified and characterized by X-ray diffraction, Fourier transform infrared spectrometer, Raman spectrometer, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, field emission transmission electron microscopy, and ultraviolet spectrophotometer. The results show that the as-synthesized powders are high-purity cubic phase yttrium oxide nanoparticles with a spherical-like morphology and an average particle size of approximately 30 nm. These Y2O3 nanoparticles have a wide (5.53 eV) energy band gap, close to the conventional methods. Based on detonation theory, thermochemical theory, and characterization results, this text discussed the mechanism of the Y2O3 nanoparticles synthesized by the emulsion detonation method. During detonation, the formation of the Y2O3 nanoparticles underwent three stages: the formation of the Y2O3 molecules by the collision of Y and O ions, the formation of the crystal nucleus at supersaturation concentration, and crystal growth. This study provides a novel, cost-effective method for efficiently synthesizing Y2O3 nanoparticles.

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.

Study on copper-stainless steel explosive welding for nuclear fusion by generalized interpolated material point method and experiments

The thick copper stainless steel composite plate is an important component of the cooling coil terminal box of international nuclear fusion reactors. The composite rate, tensile strength, shear strength, and interface waveform of the metal plate are also far higher than the requirements of conventional explosive welding technology. It is difficult to obtain the best technical process parameters in a short time solely relying on conventional explosive welding tests. In order to solve the above-mentioned technical difficulties in explosive welding, this article applies the generalized interpolation material point method (GIMP) based on the explosive welding window, metal elastic-plastic mechanics, and explosive detonation theory to conduct macroscopic three-dimensional and microscopic two-dimensional numerical simulations of the copper stainless steel explosive welding process and the composite interface wave formation process, respectively. The experimental results demonstrate that the GIMP has significant advantages in numerical calculation and analysis for the explosive welding problem of high-speed impact collision of metal plates driven by explosive detonation, and it can effectively solve the technical problems of high technical specifications, low explosive processing composite rate, and low interface strength of large thickness copper stainless steel composite plates used in nuclear fusion.

Анализ параметров ударных волн на стенке взрывной полости при преломлении детонационных волн через воздушную и водную среду

Анализ параметров ударных волн на стенке взрывной полости при преломлении детонационных волн через воздушную и водную среду

Study on direct initiation process and initiation mechanism of acetylene/oxygen premixed gas detonation

Studying the process and mechanism of direct initiation of gas detonation is the basis for preventing serious gas explosion disasters and developing detonation propulsion power devices. This article utilizes a combustible gas combustion and explosion experimental system to achieve direct spherical acetylene/oxygen mixture detonation through a high-energy ignition system. The detonation velocity and flame structure evolution process in direct detonation were studied through schlieren images, and a critical detonation model was established to explain the direct detonation process. The critical detonation wave velocity for direct detonation was determined to be half of the CJ detonation velocity. Revealed the mechanism of detonation cell formation during the direct initiation process. The basic criterion for achieving direct initiation of spherical detonation has been obtained: to achieve direct detonation, when the overdrive detonation wave formed by the detonation source attenuates to half the detonation velocity of CJ, the propagation radius must not be less than a full detonation cell size. This article conducts in-depth research on the direct initiation process of acetylene/oxygen mixture detonation. The results obtained have essential value for developing and applying the detonation theory of acetylene fuel. At the same time, they have important practical significance for preventing gas fire and explosion accidents.

Characterization and synthesis mechanism of Co3O4 nanoparticles synthesized by the emulsion detonation method

Tricobalt tetraoxide (Co3O4) nanoparticles have excellent applications in the fields of electricity, photocatalysis, and ceramics, whereas conventional synthesis methods require sophisticated equipment, strictly controlled conditions, and long duration. Herein, a new method for the synthesis of Co3O4 nanoparticles was proposed. In this emulsion detonation method, the precursor cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was added during the production of the explosives and was therefore more uniformly dispersed than in other detonation methods. The preparation and detonation durations of the explosives were on the scale of minutes and microseconds, respectively, which are much shorter than those in other nanomaterial synthesis methods. The collected products were briefly purified and characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectrometer, field emission scanning electron microscopy, and field emission transmission electron microscopy. Cyclic voltammetry and galvanostatic charge–discharge measurements were performed. The results show that the synthesized products were of high purity and consisted mainly of sphere-like particles with a dimensional distribution of approximately 50 nm. The electrochemical properties of these Co3O4 nanoparticles were similar to those synthesized by conventional methods. Combined with the detonation theory and the initial composition of the products, the analysis showed that the synthesis mechanism is mainly divided into two stages: formation and polymerization. Therefore, this approach could provide a new and effective synthesis method for the low-cost production of Co3O4 nanoparticles.

Model of a stationary thermal detonation wave in the “liquid lead – water” system for safety analysis of NPP with the reactor BREST-OD-300 during heat exchanger tube break accident

This paper presents a mathematical model of a stationary wave of thermal detonation in the “liquid lead - water” system, which can occur after the rupture of a steam generator tube of the reactor BREST-OD-300. The model is based on the mechanics of multiphase fluid flows. The system under study includes a continuous phase of liquid lead, in which drops of water surrounded by a steam film are dispersed. Heat exchange between high-temperature molten lead and water drops is carried out in the film boiling mode. A shock wave propagating in this multiphase system causes all phases in motion. Due to the significant difference in density between liquid lead and water, a difference in velocities arises between dispersed water drops and liquid lead, which cause the fragmentation of water droplets. The shock wave velocity and amplitude are determined by constructing the shock adiabat and the Hugoniot adiabat for the parameters of the studied multiphase mixture. To describe the fragmentation of water droplets, heat transfer between phases, and interfacial friction, the empirical correlations of the thermal detonation theory are used. The obtained numerical solutions describe the distributions of parameters in the zone of melt – water interaction.

Numerical modeling of charge diameter effect on detonation properties of emulsion explosives using Wood-Kirkwood detonation model

ABSTRACT Emulsion explosives exhibit strong nonideal detonation behavior, which provides a challenge for accurate numerical modeling. We present a nonideal detonation model based on the Wood–Kirkwood detonation theory and EXPLO5, capable of modeling the effect of the charge diameter on steady-state detonation velocity. The elements of the model are calibrated based on experimental data for four different emulsion explosives. It was demonstrated that both simple pressure-dependent and Kirby and Chan’s two-step reaction rate models can satisfactorily reproduce the detonation velocity–charge diameter data of unconfined charges. In addition, the reaction rate parameters are found to be a function of the density of explosives.

Continuous rotating detonation engine fueled by ammonia

As a carbon-free fuel, ammonia has attracted increasing interests while the corresponding utilizations are still limited. In this paper, ammonia-oxygen continuous rotating detonation (CRD) was firstly proposed and realized in the hollow chamber with Laval nozzle. The formation process and propagation characteristics were investigated through pressure measurement and optical observation. The CRD wave formation time increased with the nozzle contraction ratio, which was mainly attributed to the slower injection recovery process under the higher chamber pressure. The operation range was large, and the CRD wave propagated in single-wave mode with the velocity of 1806 m/s in the chosen test. The propagation velocity did not increase continuously as the equivalence ratio increased, which could be attributed to the changeable reaction mechanisms and the slow heat release of ammonia. The coupling of ammonia injection and CRD wave propagation was analyzed under both supersonic and subsonic injection conditions. The synchronous fluctuations of the pressure in ammonia plenum and the intensity of detonation waves proved that the coupling was very tight under subsonic injection condition. This paper was beneficial to the improvement of the detonation theory, and it provided an efficient approach to the utilization of ammonia.

Estimation of detonation front curvature radius by empirical equations

ABSTRACT Numerical modeling of detonation by the Wood-Kirkwood detonation theory requires the detonation front curvature radius to be specified as an input parameter. In this work we present two empirical equations for the estimation of the curvature radii of various explosives. The equations are derived based on a large number of literature-reported experimental data on the detonation front curvature radii as a function of charge radii and failure radii. The proposed equations predict the front curvature radii with the root mean square error of about 30%, which is a significant improvement compared to previously proposed empirical equations.

Detonation waves in melt-coolant interaction

Abstract Making use of the detonation theory presented in part 1 for melt-water interaction, detonation solutions for different meltwater pairs at different conditions are compared to each other. Discussion is provided on the existence of detonation solutions for water droplet – melt droplet – gas systems. The conclusion is made that even if such solutions can be realized in the nature, which is highly questionable, the resulting detonation pressures will be below 200 bar. This is an important result for judging the risk of the melt-water disperse mixtures in nuclear safety analysis. In addition, the detonation pressures for alumnacontinuous water systems have been found to be stronger then those for urania-continuous water systems, in agreement with the experimental observations and seems to give finally the searched for a long time explanation why alumna-water systems detonate much more violent than urania-water systems.

DETERMINATION OF DETONATION FRONT CURVATURE RADIUS OF ANFO EXPLOSIVES AND ITS IMPORTANCE IN NUMERICAL MODELLING OF DETONATION WITH THE WOOD-KIRKWOOD MODEL

Nitratebased commercial explosives, such as ANFO (ammonium nitrate/fuel oil mixture) and emulsion explosives, are characterized by a curved detonation front. The curvature is directly related to the rate of radial expansion of detonation products in the detonation driving zone and the rate of chemical reactions, and it is one of the characteristics of nonideal explosives. The detonation theories used to model the nonideal behaviour of explosives require both reaction rate and rate of radial expansion to be known/specified as input data. Unfortunately, neither can be measured and what is mostly used is a link between these rates and parameters which can be more easily measured. In this paper, the Wood-Kirkwood approach of determination of radial expansion through the radius of detonation front curvature and the electro-optical technique for experimental determination of detonation front curvature of ANFO explosives is applied. It was shown that an experimentally determined radius of detonation front curvature vs charge diameter, incorporated in the Wood-Kirkwood detonation theory, can satisfactorily reproduce experimental detonation velocity-charge diameter data for ANFO explosives, especially when the pressure-based reaction rate law is also calibrated (D=1.3 and k=0.06 1/(μs/GPaD)).

Analysis on stationary window of oblique detonation wave in methane-air mixture

In order to obtain the standing conditions and stationary range of oblique detonation wave in methane-air combustible mixture, we use the Newton-Raphson iteration method to solve the perfect gas flow conservation equations of oblique detonation wave based on detonation theory. We investigate the variation laws of the oblique detonation stationary window and internal mechanism under different methane-air equivalence ratio, incoming flow velocity, initial pressure and initial temperature. The oblique detonation polar curve can be separated into three sections, each of which has different flow characteristics corresponding to different wave morphology. Among them, a stationary oblique detonation wave can be formed when the wedge angle is larger than the wedge angle of Chapman-Jouguet state oblique detonation wave, and smaller than the maximum wedge angle corresponding to the oblique detonation wave without detached. The wedge angle range is called the stationary window of the oblique detonation wave. We found that the oblique detonation is more easily formed when the methane-air mixture is under the oxygen-enriched condition, and the range of oblique detonation wave stationary window becomes larger as the incoming velocity increases. The changes of initial pressure and temperature have little influence on the stationary window. The change law of the stationary window of oblique detonation wave corresponds to the change law of Mach number behind CJ oblique detonation wave. In addition, the standing conditions are mainly related to the coupling of the incoming mixture kinetic energy and heat release.

Multiscale physics of rotating detonation waves: Autosolitons and modulational instabilities.

Proposed is a phenomenological modeling framework that is capable of reproducing the diverse experimental observations of the nonlinear, combustion wave propagation in a rotating detonation engine (RDE), specifically the nucleation and formation of combustion pulses, the soliton-like interactions between these combustion fronts, and the fundamental, underlying Hopf bifurcation to time-periodic modulation of the waves. In this framework, the mode-locked structures are classified as autosolitons or stably propagating nonlinear waves where the local physics of nonlinearity, gain, and dissipation exactly balance. We find that the global dominant balance physics in the RDE combustion chamber are dissipative and multiscale in nature: The fast combustion physics provide the energy input to form the fundamental mode-locked autosoliton state, while the slow physics of exhaust and propellant recovery shape the waveform and dictate the number of autosolitons. In this manner, the global multiscale balance physics give rise to the stable structures-not exclusively the frontal dynamics prescribed by classical detonation theory. Experimental observations and numerical models of the RDE combustion chamber are in strong qualitative agreement. Moreover, numerical continuation (computational bifurcation tracking) of the RDE analog system indicates that a Hopf bifurcation of the steadily propagating pulse train leads to the fundamental instability of the RDE, or time-periodic modulation of the waves. Along branches of Hopf orbits in parameter space exist a continuum of wave-pair interactions that exhibit solitonic interactions of varying strength.

Химическая теория флогистона в культурной экономике огня: от Просвещения к современности

The article focuses on how the chemical concept of phlogiston functions in the so-called economy of fire from the eighteenth to twenty-first centuries, in view of a shift in “pyropolitics” (politics of fire) in their relation to the economic paradigms (cameralism, industrial capitalism, postindustrial digital economy), and theories of chemical flame processes (phlogistics, oxygen theory,theory of detonation and deflagration). The phlogiston concept is explored as the key substantial notion of the phlogictic chemical theory of the Enlightenment (regarded also as a natural “cameralistic science” in terms of metallurgy), the epistemological metaphor of ignorance in nineteenth-century Marxist discourse. Phlogiston circulates in the economics of fire discourse as a signifier for surplus value (and some other Marxist terms). “Fire as equivalent to money” becomes, in petropolitical studies, a means for turning petropolitics into pyropolitics with the radical metaphor of “PyroGaia” (Nigel Clark) in the Anthropocene period.

NUMERICAL INVESTIGATION ON THE SPACE-TIME CORRELATION BETWEEN OBLIQUE DETONATION AND NORMAL DETONATION PROPAGATION

The propagation theory of one-dimensional detonation is complete and accurate, while prediction of two-dimensional oblique detonation propagation with large scale and high accuracy is still difficult primarily due to the treatment of wedge wall during the calculation and the modelling of viscosity. In this paper, the space-time correlation between two-dimensional steady oblique detonation induced by finite wedge and one-dimensional unsteady detonation supported by piston is investigated by numerical simulations of multi-species Euler equations with H2-Air detailed chemical kinetics. The initiation and propagation process of detonation wave, together with its interaction with rarefaction waves are numerically analyzed from the perspective of both space and time. The results show that under the same overdriven degree, the wave structure, wall parameters and profile variation calculated from one-dimensional case fit well both qualitatively and quantitatively with two-dimensional case after a certain space-time transformation, which validates the space-time correlation between one- and two-dimensional detonation waves. The difference mainly lies in the transition process between different stages of detonation development, such as the transition from over-driven oblique detonation wave to near Chapman-Jouguet (CJ) oblique detonation wave under the effect of rarefaction waves. Since most features of oblique detonation waves over finite wedge can be obtained efficiently by one-dimensional numerical calculation of piston-driven detonation and space-time transformation, the present work provides a feasible way to understand the spatial structure of oblique detonations waves, including detonation initiation, formation of over-driven oblique detonation and cellular structure downstream. Besides, this paper also provides a novel method to distinguish the effect of wall compression and boundary layer by comparing one- and two-dimensional numerical results. Moreover, the results imply that two-dimensional flow field over wedges of different shapes can be obtained with satisfying accuracy by altering the velocity of piston, which greatly reduces the time, cost and complexity of numerical simulation during the design of combustion chamber in an oblique detonation wave engine.

An improved Kirkwood–Bethe model for calculating near-field shockwave propagation of underwater explosions

To calculate the near-field shockwave propagation of underwater explosions for different explosives quickly and accurately, an improved calculation model, based on the Kirkwood–Bethe theory, is proposed. Based on the detonation theory and shock jump conditions, the model establishes initial equilibrium conditions and an initial shockwave-front state of the explosion bubble interface. By incorporating a second-order Mach-precision bubble dynamics equation, the model determines the physical parameters and enthalpy change functions at the initial expanding stage in real time. By solving the isentropic flow of the enthalpy change function G at varying delay times, a functional relation was established between the enthalpy change function and the pressure at arbitrary flow points and times. The model obtained the near-field shockwave-front peak-pressure spatial distributions of underwater explosions and the pressure decay time constants at arbitrary flow points. The results indicated that the proposed method can quickly and accurately determine the near-field shockwave propagation of underwater explosions for different explosives, with satisfactory agreement with experimental data. The proposed method relates the explosive detonation, explosion bubble expansion, and shockwave propagation, thus connecting the explosive parameters with the shockwave front state parameters.

Detonation wave of condensation

In a number of recent studies by the authors, a new physical phenomenon has been discovered and investigated in detail — the formation of a detonation wave during the condensation of highly supersaturated carbon vapor. The essence of the phenomenon is that an initiating shock wave propagating through an exothermic carbon compound (for example, carbon suboxide C3O2 or acetylene C2H2), as a result of its rapid dissociation, yields a highly supersaturated carbon vapor; the energy released during its condensation forms and maintains a detonation wave. This review describes in detail the results of experimental studies and their analysis based on the detailed kinetics and thermodynamics of the processes occurring and the one-dimensional Zeldovich–Neumann–Döring (ZND) theory of detonation. The potential to practically use the discovered phenomenon is discussed.

Prediction of Cylinder Wall Velocity Profiles for ANFO Explosives Combining Thermochemical Calculation, Gurney Model, and Hydro‐Code

AbstractTheoretical prediction of performance indicators of explosives plays an important role in the development of new explosives and explosive formulations. Of particular interest is the possibility to estimate the velocity of metal liner driven by an explosive charge. We present a theoretical model for estimation of metal cylinder wall velocity profiles of non‐ideal ANFO explosives. The model is based on thermochemical calculations using EXPLO5 code, expressing the Gurney energy in terms of JWL equation of state, and using hydro‐code simulation. The Wood‐Kirkwood detonation theory, incorporated in EXPLO5, is applied for calculation of detonation parameters of non‐ideal ANFO explosives. It was found that this approach enables prediction of cylinder wall velocity for ANFO explosives, with the error at V/V0=7 expansion ratio not exceeding 100 m/s.

Modeling and Simulation of the Effects of Steel Casing Confinements on Formation of Explosively Formed Projectile

LS-DYNA software is used to model and simulate the effects of thickness and length of steel casing on the forming status of EFP specifically, and then a theoretical model is established to explain the forming mechanism and calculate the velocity of EFP. The following conclusion can be obtained. (1) The thicker steel cased charge can provide more impulse to the liner in EFP’s forming process. A formula of f(M/C) is fitted to estimate the steel casing effect on the velocity of EFP; (2)In order to get an EFP with higher solidity it is not necessary for the casing to fully cover the liner and charge, and when L C/L 0 reaches to 35%, the obtained value of η can be as much as that when the casing fully cover the liner and charge with acceptable velocity range. And 65% of the casing mass can be lightened to reduce the weight of EFP charge structure; (3) A theoretical model to calculate the velocity of cased EFP based on the theory of instantaneous detonation is put forward to explain the mechanism of EFP’s forming process and calculate the velocity of EFP. The research results are significant in the design of light weight EFP warhead, and the theoretical model is easy and convenient of calculate the velocity of EFP with different steel cased charge structure, which can be used to provide reference for researchers in the design of EFP.