Explosive Behavior Research Articles

Multiscale understanding of structural effect on explosive dispersal of granular media

Explosive dispersal of granular media widely occurs in nature across various length scales, enabling engineering applications ranging from commercial or military explosive systems to the loss prevention industry. However, the correlation between the explosive dispersal behaviour and the structure of dispersal system is far from completely understood, thereby compromising the prediction of the explosive dispersal outcome resulting from a specific dispersal system. Here, we investigate the dispersal behaviours of densely packed particle rings driven by the enclosed pressurized gases using coarse-grained computational fluid dynamics–discrete parcel method. Distinct dispersal modes emerge from the dispersal systems with vastly varying sets of the macro- and micro-scale structural parameters in terms of the dispersal completeness and the spatial uniformity of the dispersed mass. Further investigation reveals the variation in the dispersal modes arises from the collective effects of multiscale gas–particle coupling relationships. Specifically, the macroscale coupling dictates the cyclic momentum/energy transfer between gases and particle ring as an entirety. The mesoscale coupling relates to the inter-pore gas filtration through the thickness of the particle ring, leading to the mass/energy reduction of the explosive source. The microscale coupling involves the individual particle dynamics influenced by the local flow parameters. A persistent macroscale coupling results in an incomplete dispersal which takes the form of an aggregated annular band, whereas the meso- and micro-scale couplings alter the macroscale coupling to a different extent. By incorporating the effects of the variety of structural parameters on the multiscale gas–particle coupling relationships, a non-dimensional parameter referred to as the modified mass ratio is constructed, which shows an explicit correlation with the dispersal mode. We proceed to establish a dispersal ring model in the continuum frame which accounts for the macro and meso-scale coupling effects. This model proves to be capable of successfully predicting the ideal and validated failed dispersal modes.

Influence of Contaminated Ammonium Nitrate on Detonation Behaviour of Bulk Emulsion Explosives and Numerical Analysis of Detonation‐Induced Damage Zone

AbstractBulk emulsion explosives are widely used industrial explosives for mining and civil infrastructure work. Ammonium nitrate is an important ingredient for bulk emulsion explosives and plays an important role in the detonation behaviour. Considering the growing demand for bulk emulsion explosives, an in‐depth investigation is necessary to understand how the impurities in ammonium nitrate can affect the detonation behaviour and safe handling of bulk emulsion explosives. Herein, we have demonstrated the influence of contaminated ammonium nitrate on the detonation behaviour and characteristics of bulk emulsion explosive. Furthermore, the particle size of the internal phase of the all prepared bulk emulsion explosives was analyzed using optical microscopy to confirm the effect of contaminated ammonium nitrate. Time dependent chemical‐induced gassing behaviour and detonation velocity of prepared bulk explosive samples were also studied. Importantly, numerical modeling was used to stimulate the detonation‐induced rock damage zone and assess the impact of ammonium nitrate contamination. Additionally, a real‐time rock damage pattern of different prepared samples was further investigated to understand the impact of contamination on the detonation induced crack development phenomena of different bulk emulsion samples.

A modified phosphorus-based inhibitor for dry water inhibitor and its chemical mechanisms in preventing benzoyl peroxide explosion

Dust explosions caused by benzoyl peroxide (BPO) pose a significant risk to the chemical industry, making the development of high-performance inhibitors essential. The effect of a novel inhibitor on the explosion behavior of BPO dust was studied through experiments and simulations. The chemical mechanism behind the suppressed BPO dust explosion was clarified. The primary explosion hazard of BPO stems from the instability of the oxygen–oxygen bond. To address this, a novel phosphorus-based dry water powder inhibitor, MAP-DW, was prepared which effectively captures key reactive radicals involved in the chain reaction. At the optimal explosion concentration of BPO, a concentration of 400 g/m3 of MAP-DW reduced the maximum explosion pressure and the maximum explosion pressure rise rate by 96.48 % and 99.58 %, respectively. The suppression effects of MAP-DW on the explosion of BPO dust include heat absorption, oxygen dilution, thermal insulation, and capture of key free radicals. The kinetic simulation results showed that the suppression cycle between phosphorus-containing substances captured key chain reaction radicals, and the coupled suppression among NH3, H2O, and phosphorus-containing substances dominated the suppression mechanism of MAP-DW on BPO dust explosion. This study provides new insights into the characterization and suppression of BPO dust explosion, while also supplying crucial data for the safe utilization of peroxides.

Unravelling eruption dynamics at El Reventador, Ecuador: linking the physiochemical properties of volcanic ash with geophysical, geochemical and satellite remote sensing data

The physiochemical properties of volcanic ash are determined by magma ascent and eruption dynamics and provide important insights into controls on the timing and style of volcanic eruptions. However, linking petrological observations to monitoring parameters remains challenging. Here we investigate the relationships between geophysical, geochemical and satellite remote sensing data with the physiochemical properties of volcanic ash to better understand eruptive dynamics at El Reventador volcano, Ecuador. Between 2016 and 2019, eruptive activity at El Reventador was characterised by frequent explosions interspersed with effusive activity from two summit vents. We found that: (1) periods of predominantly effusive behaviour were defined by ash samples with the lowest proportions of juvenile grains, frequent, more intense thermal anomalies and frequent (ca. every 25 min) but low-energy explosions that produced lower average ash column heights (< 1200 m above the summit) and; (2) periods of predominantly explosive behaviour were defined by ash samples with the highest proportions of juvenile grains and also vesicular juvenile grains, low thermal anomalies and less frequent (ca. every 70 min), higher-energy explosions that produced higher average eruption column heights (> 1500 m above the summit). Our study shows that there are strong correlations between the physiochemical properties of erupted material and the multiparametric monitoring data which in turn link to the type of surface activity observed. As a result, the development of physical conduit models and interpretations of eruptive dynamics are made more robust combining both monitoring data and the physical properties of eruptive products.

Study on the jetting characteristics of an underwater explosion bubble collapsing near a floating body

This study explores the dynamic behavior and jet characteristics of underwater explosion (UNDEX) bubble oscillating near a rigid floating body using the arbitrary Lagrangian–Eulerian (ALE) method. Experiments on UNDEX bubble oscillating in a free field or oscillating near a rigid floating body in an explosion tank are used to validate the effectiveness of the ALE method in simulating the behaviors of high pressure bubble oscillating near a boundary in water. The numerical results are in good agreement with the experimental data. On this basis, the distribution of the field pressure and velocity of the oscillating bubble are further analyzed in detail. The evolution characteristics of the bubble jets are discussed for various values of the stand-off distance and explosion attack angle. The results reveal that a bubble produces two jet patterns for close stand-off distances (from γD=0.800 to γD=1.336) and attack angles of 0°, 45°, 75°, and 90°. The first bubble jet results in an annular splitting of the bubble, while the second jet is pointed toward the floating body. The aim of this study is to provide a reference for further understanding the jet dynamics of UNDEX bubble collapsing near a structure and the effective attack on ship sides.

Investigation on the inhibition effect and mechanism of hydrogen explosion by 2-bromo-3,3,3-trifluoropropene

This study investigated the effect of 2-bromo-3,3,3-trifluoropropene (2-BTP, C3H2BrF3) on hydrogen explosion behavior through a combination of experiments and simulations. The maximum explosion pressure (pmax), maximum pressure rise rate ((dp/dt)max), and critical inhibition concentration (CIC), across different equivalence ratios (Φ) and inhibitor concentrations (V), were obtained via experiments. The changes in adiabatic flame temperature, mole fraction of active radicals and sensitivity coefficient throughout the reaction were analyzed using CHEMKIN. The fuel-like properties of 2-BTP and the carbon monoxide (CO) produced by decomposition led to a promoting effect on the lean hydrogen explosion, primarily due to the elementary reactions R31, R806 and R882. When Φ≥1.0, the capture of active radicals via elementary reactions such as R908, R1507, and R88 was enhanced, resulting in the dominance of inhibition and a corresponding inhibitory effect. Notably, 2-BTP exhibited an inhibitory effect for (dp/dt)max at any equivalence ratio. The CIC decreased from 10% to 4% when increasing equivalence ratios from 0.6 to 2.0. This work provides crucial data and a theoretical foundation for the prevention and control of hydrogen explosions.

Absorbable and biodegradable enzyme-crosslinked gelatin/alginate semi-IPN hydrogel wound dressings containing curcumin

Effective wound management presents a substantial financial and time-related obstacle for healthcare institutions. Enhancing healthcare involves implementing innovative wound treatment methods to minimize healing time and expenses. This study is centered on the development of a non-toxic wound dressing using only two natural polymers and an enzyme. By adding 10 % wt microbial transglutaminase, the mechanical properties of the dressing were improved. This formulation increased the swelling rate by 70 %, deswelling rate by 15 %, conversion rate by 9 %, and networking rate by 20 %. Additionally, the non-toxic dressing showed a cell viability rate of 106 %. In drug delivery tests, explosive release behavior was observed, which is advantageous for open wounds. Cell staining experiments were also carried out to evaluate wound behavior in terms of collagen formation, granulation, and inflammation. The results suggest that the optimized hydrogel has great potential as a wound dressing. Its excellent absorption, antioxidant, and biocompatibility characteristics enhance tissue granulation rate and reduce wound treatment time by half compared to conventional methods, while also minimizing scarring risk. This innovative treatment, which eliminates the need for frequent changes, is beneficial for both secondary intentions and severe open wounds requiring bottom-up healing.

Generalized visible curvature: An indicator for bubble identification and price trend prediction in cryptocurrencies

We propose a novel curvature-based indicator constructed on log-price time series that captures an interplay between trend, acceleration, and volatility found relevant to quantify risks and improve trading strategies. We apply it to diagnose explosive bubble-like behaviors in cryptocurrency price time series and provide early warning signals of impending market shifts or increased volatility. This improves significantly on standard statistical tests such as the Generalized Supremum Augmented Dickey–Fuller (GSADF) and the Backward SADF tests. Furthermore, the incorporation of our curvature-based indicator as a feature into the Light Gradient Boosting Machine enhances its predictive capabilities, as measured by classification accuracy and trading performance.

Effects of position layout and length gradient of two side ducts of on methane/air explosion in a tube

ABSTRACT In order to examine how two side ducts affect the dynamic behavior of a gas explosion in a tube, two side ducts were added to a tube containing a mixture of 9.5% methane and air. An experiment was conducted to release the explosion pressure and study how the position and length gradient of the side ducts influence the explosion’s overpressure and the speed at which the flame spreads. Based on the data, it was found that the most effective pressure release occurred at a length of 0.2 m for the front side duct and 0.1 m for the end side duct. Additionally, the greatest explosive overpressure recorded was 2.54 kPa. A double driving effect was created between the two side ducts when they were put in the front and middle and the middle and end locations. This increased the flame propagated speed. The greatest acceleration effect on the flame front occurred at 0.2 m of side duct length. When the two side ducts were placed at the front and end of the tube, the length gradient did not have any impact on flame propagation. Instead, it was predominantly the length of the front side duct that controlled flame propagation. The pressure relief effect was more pronounced when the two side ducts had a downward gradient; however, it was affected by the length of the end side duct. A relationship equation was established between the lengths of the two side ducts (d 1 and d 2), positioned at the front and end locations, and the maximum flame velocity (Vmax). The analysis results of the impact of different positioning layouts and length gradients of two side ducts on flame propagation and pressure release within the tube were instrumental in ensuring the safety of personnel, equipment, and environment during energy utilization processes.

Investigation on structural feature and bonding performance of Hastelloy foil/steel explosive welding composites under different explosive loads

Hastelloy foil/steel composite is of most interest in many industrial fields, as it has competitive advantages of excellent corrosion resistance and low cost. Due to the low thermal conductivity and thermal hardening property, traditional fusion-based connection methods fail to provide high-quality Hastelloy/steel composites. Here an improved explosive welding was introduced to prepare this composite, and the effect of the explosive amount was carefully investigated. The characterizations (including optical microscopy (OM), electron backscatter diffraction (EBSD), bending, nanoindentation, and electrochemical corrosion) were conducted to understand the bonding properties, and Smoothed Particle Hydrodynamics (SPH) simulation was used to investigate transient interface behavior. It was found that the self-developed explosive welding was a suitable method to produce superior Hastelloy/steel composites. Under reasonable welding parameters, both the surfaces of Hastelloy and Hastelloy/steel interface exhibited ideal welding patterns without defects, and the composite remained intact under 90° bending loading. The explosive load is a crucial factor determining bonding properties, and the undesirable features like wrinkles and melting area were found to be positively correlated with the explosive load, which reduced the corrosion resistance. This comprehensive research enabled to provide a new perspective for Hastelloy/steel preparation and improve the understanding of explosive welding process behavior.

Flame propagation mechanism of methanol fuel spray explosion in a square closed vessel

Methanol, as an important chemical raw material and clean energy source, easily forms explosive droplet clouds during its production, processing, and usage. Therefore, understanding the evolution and propagation mechanisms of methanol spray explosion flames is crucial for its widespread use and the design of safety measures. This paper studies the flame propagation behavior of methanol spray explosions using a 16.2-L visualized enclosed vessel. The results indicate that the flame structure of methanol spray explosions is similar to that of premixed gas explosions but significantly differs from traditional fossil fuels. It demonstrates homogeneous combustion characteristics primarily governed by the kinetics-controlled regime. As the methanol spray concentration increases, both the maximum flame propagation speed and the maximum explosion pressure initially increase and then decrease, reaching their peak at a concentration of 224.68 g/m3, with values of 9.96 m/s and 0.72 MPa, respectively. The heat losses during combustion exhibit a trend opposite to that of explosion pressure. Numerical simulation results indicate that the concentrations of key radicals such as O, H, and OH vary significantly between lean and rich combustion states. The increase in H radical concentration enhances the elementary reactions that suppress flame temperature and promotes chain-terminating reactions.

Ignition mechanism and chemical reaction of the micro-damage polymer-bonded explosives under different inertial loading conditions

Understanding the impact-induced ignition properties and energy release behavior of polymer-bonded explosives (PBXs) is critical for the safety of explosive systems. In this study, a new impact test component was designed using a light gas gun to quantify the ignition mechanism and chemical reaction of micro-damaged PBXs under different inertial loading conditions. A constitutive model was developed to describe the mechanical-thermal-chemical response of the PBXs. This model was employed to further investigate the correlation between microcracks, debonding, hot spots, and chemical reactions. The results show that the stress state of the material is not uniformly distributed due to the micro-inhomogeneities and structural defects of PBXs. The shear friction of the microcracks contributes to localized hot spots, thereby inducing ignition. The critical loading condition for ignition is the length of the steel pillar is 32 mm. The damage and hotspot temperatures of the anterior lateral and posterior lateral regions are greater than those of other locations. The ignition response is accentuated with longer steel pillars, resulting in a more violent release of energy.

Investigation on the explosion of ammonia/hydrogen/air in a closed duct by experiments and numerical simulations

In this paper, the evolution of an explosion of hydrogen/ammonia/air flames is studied by experiments and numerical simulations. A two-dimensional (2D) model is utilized, employing the detached eddy simulation (DES) method along with the thickened flame model. Stoichiometric hydrogen/ammonia/air with ∂ = 25% and 50% (ammonia blending ratio in fuel) is considered. The results indicate that the numerical simulations accurately replicate the experimental findings. Both the experimental observations and numerical simulations reveal the formation process of the “tulip” flame. With increasing ∂, both the flame front speed and overpressure decrease. A change in ∂ can alter the contribution of intermediate reactions, thereby influencing the explosion behavior.

Transition of dome formation to sudden explosive eruptions at Popocatépetl, Mexico: magnetic indicators

Transitions from effusive to explosive activity can increase hazards making it crucial to define early indicators such as changes in the magnetic signals. After more than 80 cycles of crater-dome extrusion and destruction from 1996 on, Popocatépetl volcano (Mexico) experienced changes in its behavior from March 15 to 18 July 2019, when no lava domes were observed. Some of the domes behaved as contained lava flows within the crater floor (pancakes) while others were more irregular-shaped. Activity decreased considerably over this 2019 interval except for the unexpected explosions in March and June, that produced ash plumes reaching up to 14,000 m a.s.l. In order to investigate the causes of the transition from effusive to explosive behavior in March and June, we analyzed the time series from the magnetic monitoring network at Popocatépetl volcano between October 2018 and December 2019. The raw signals were analyzed by weighted differences (WD) based on the elimination of non-local changes from the total intensity values of the geomagnetic field and the discrete-time continuous wavelet transform was used to evaluate the local variations of energy within the time series. The high energy periods (linked to negative magnetic anomalies) are induced by magma ascent associated with movement within the conduit. They indicate that the sudden explosions were due to the ascent of several magma batches that were slowed during ascent and were not able to reach the surface. Changes in the rheology of the lava are linked to the influx of several batches of magma with different compositions as well as to compaction by gas loss when ascending andesitic magma pushed out overlying more viscous degassed magma clearing the conduit, which can explain why these sudden explosions were more energetic. Several geophysical data sets as well as tephra compositions were integrated to support this conclusion. The correlated multiparameters also confirm that geomagnetic volcano monitoring has been essential in understanding the processes that drive the observed changes in eruptive behavior. We present new evidence for the detection of transient events produced by magma ascent and changes in the feeding system of Popocatépetl volcano with wavelet analysis. Detailed vulcanomagnetic processing, especially when it is correlated with other monitoring parameters, provides information on ascending magma and several conduit processes that would otherwise be camouflaged. Ascending batches may precede an eruption but they can also ascend in several pulses indicating how dome growth occurs.

Explosion behaviors of aviation kerosene in a 20-L spherical vessel

Aviation kerosene is the main fuel in aerospace industry. In order to investigate the explosion behaviors of aviation kerosene, the explosion experiments were conducted using the 20-L liquid explosion testing system. The influence factors, including mist concentration CAV, ignition delay time td, liquid injection pressure Pi, and ignition energy E were discussed, and the explosion mechanism of aviation kerosene droplet was analyzed as well. Experimental results showed that minimum explosible concentration (MEC) of aviation kerosene mist was 140 g/m³. The maximum explosion pressure (Pex), maximum pressure rise rate ((dP/dt)ex), explosion index (KSt) and average flame propagation velocity (VAF) first rose and then declined, while combustion time (tc) showed the opposite trend with increasing CAV. 600 g/m3 was the optimal concentration. Pex, (dP/dt)ex, KSt and VAF showed an inverted “U-shaped” trend, while tc presented a positive “U-shaped” trend with td. The optimal ignition delay time was 100 ms. Pex, (dP/dt)ex, KSt, and VAF all gave a linear positive correlation, while tc presented a linear negative correlation with both Pi and E. The influence of Pi and E on (dP/dt)ex, KSt, and VAF was greater than that on Pex and tc. VAF could be used to approximate the flame propagation velocity in simplifying calculations. The relationship between KSt, VAF and CAV, td, Pi and E was also concluded. The mass evaporation rate m¯, the trend of the diameter over time dr/dt and the trend of the temperature over time dT/dt of aviation kerosene droplet were obtained. The evaporation model and multizone combustion model of aviation kerosene vapor-liquid two-phase mixture was discussed in detail.

Do infectious diseases explain Bitcoin price Fluctuations?

This study examines Bitcoin price movements from an infectious disease perspective. The author compares the outbreak of the COVID-19 pandemic with the Bitcoin price explosion and adopts the SIR epidemiological model. The SIR model operates by categorizing the population of individuals into susceptible (S), infected (I), and removed (R). In the case of Bitcoin, open wallets represent the susceptible population, and the infection starts with a single individual. After conducting four estimation trials, the model that uses the recovery rate derived from the Bitcoin price downtrend and the infection rate from the upward trend has the highest accuracy. The estimation deviates from the Bitcoin price explosions by only three days. Previous studies commonly use faster-than-exponential growth or stationarity tests to identify bubble formations. This paper introduces a novel approach that employs epidemiological models to analyze Bitcoin’s explosive price behavior.

Experimental Evidence of Primary Permeability at Very Low Gas Content in Crystal‐Rich Silicic Magma

AbstractEruptive dynamics is influenced by gas escape from the ascending magma. Gas pathways form in the magma via bubble coalescence, leading to gas channeling. Magmatic crystals play a key role in gas channel formation. This work constrains experimentally decompression‐induced coalescence in high‐crystallinity silicic magmas without external deformation, focusing on low gas content and bimodal crystal size (microlites and phenocrysts). All percolating samples have permeabilities of 10−14 m2 at bulk porosities of 7–10 vol% and bulk crystallinities up to 75 vol%. Our results demonstrate the possibility of coalescence‐related outgassing at high pressure (120–350 MPa) and without external strain, which corresponds to magma stagnating deep in a volcanic conduit. Channeling at such low gas content implies that bimodal crystallinity favors effusive over explosive volcanic behavior. It may also be the missing physical mechanism explaining gas transfer across magmatic systems despite high melt viscosity and low or absent magma extrusion.

Methodological proposal to determine explosive tourism growth: a warning for unsustainable development?

ABSTRACT Sustainability is a crucial aspect of tourism growth and development. This paper suggests the adaptation of a methodology originally designed for analysing explosive behaviour in financial market time series to assess the explosive behaviour of demand pressure in tourist destinations. The proposed methodology could function as an early warning system for potential issues such as over-tourism by identifying further unsustainable growth in destinations. The methodology is exemplified by examining the long-term evolution of tourism pressure in both Spain as a whole, and in Barcelona, which is a destination frequently scrutinised in the literature and media due to perceived over-tourism. The findings suggest explosive behaviour in tourism pressure, especially in the case of Barcelona, from which valuable lessons can be learned and meaningful conclusions drawn.

The effect of open-end ignition at different positions on the explosion behaviors of H2/CO/Air in variable cross-section pipe

This work is focused on the explosion performance of syngas/air premixed gas in a self-designed variable cross-section pipe under varying ignition positions (IP1, IP2) and hydrogen volume fraction (α(H2)). Results show that α(H2) has a great influence on the propagation of the flame as well as the maximum flame front velocity (FFVmax) and the maximum overpressure (Pmax). As α(H2) in the syngas increases, the time the flame stays in the pipe is gradually reduced, the FFVmax as well as the Pmax increase regardless of the ignition position. Differently, when α(H2) < 50%, the tclosed at IP1 is shorter than that at IP2. The opposite is true when α(H2) ≥ 50%. This is attributed to the difference in flame velocity and the effect of film breakage. Both α(H2) and variable cross-section chamber structure all affect the evolution of the flame morphology. When ignition at IP2, a “M” flame is observed for the first time at α(H2) = 20%, and a flame resembling a “T” shape appears at α(H2) = 70%. Ignition positions have a great influence on overpressure oscillation. In the case of α(H2) = 15%, the Fourier transform is performed for the pressure curve. When ignited at IP1, secondary unstable oscillations occur during the later stage of flame propagation. However, when ignition at IP2, primary instability oscillations occur in both the early and late stages of flame propagation. The variable cross-section chamber structure plays a role in the flame front velocity (FFV) and overpressure. After the flame front enters the variable section chamber, the FFV reduces, and when the flame front leaves the variable section chamber, due to the sudden decrease of the cross-sectional area, the FFV increases significantly, and FFVmax and Pmax are obtained at this moment.

Effects of H2/CO ratio and CO2 dilution on the explosion behavior and flame evolution of syngas/air mixtures

Syngas, which is used as both a fuel and a raw material, presents numerous safety risks during its utilization. In this paper, the effects of H2/CO ratio (R = 0%, 30%, 50%, 70% and 100%) and CO2 dilution ([CO2] = 0%–20%) on the explosion behaviors of syngas/air mixtures with different equivalence ratios (φ = 0.8, 1.0, 1.6, and 2.5) are examined via experiments and numerical calculations. The results show that the peaks of explosion pressure and OH* spectral intensity are significantly influenced by the H2 percentage in the syngas. The introduction of CO2 notably decreases these parameters in oxygen-rich and severe oxygen-poor states. Additionally, the flame propagation speed noticeably increases with increasing H2 proportion in the syngas. The influence of CO2 on the buoyancy instability of the spherical flame of syngas is considered negligible when compared to that of other combustible gases, such as CH4. Nevertheless, the presence of CO2 decreases the density ratio between the unburned gas and burned gas and increases the flame thickness of syngas/air mixtures. This trend reduces the cellular instability of the spherical flame, particularly in severe oxygen-poor states. Notably, there is a definite correlation between the formation of cellular flames and the rise rate of explosion pressure. The cellular structure on the flame surface becomes more pronounced when the rise rate of explosion pressure increases. Conversely, it develops later or is noticeably inhibited. Furthermore, the main reaction pathways are H2 → ∙OH → H2O2 → H2O and H2 → ∙OH → CO → CO2 during the syngas explosion process. ∙OH is critical in the entire chain reaction because it promotes the conversion of H2 to H2O and acts as a vital connection between the reactants H2 and CO in the explosion process.