Intense Explosion Research Articles

Investigation of battery safety states based on thermal propagation and expansion analysis: Experimental studies on different packaging forms

Lithium-ion batteries are highly susceptible to thermal runaway under harsh conditions, posing significant safety risks for electric vehicles. The differences in thermal runaway propagation across battery systems with varying manufacturing methods (including packaging and internal stacking) and the study of changes in expansion force within battery modules are crucial for improving safety and developing early warning systems for battery systems. This study investigates the thermal runaway and propagation behavior of lithium-ion batteries under various conditions, focusing on state of charge (SOC), internal manufacturing processes (electrode stacking and winding), and packaging types (pouch and prismatic) through a series of novel experiments. The results show that batteries at high SOC levels are at a greater risk of thermal runaway propagation, with winding pouch cells displaying more severe runaway behavior. In contrast, prismatic cells, despite experiencing intense explosions with an equivalent force of up to 42.3 g of TNT, exhibit relatively milder propagation. Furthermore, the study incorporates heat transfer analysis during thermal runaway propagation, identifying key phenomena such as the formation of negative pressure zones before explosions and changes in expansion forces at the module level. Based on these findings, a new safety evaluation method is proposed to assess the risk, hazards, and severity of thermal runaway, offering valuable insights for enhancing battery safety management and fire prevention strategies.

Kinematic Differences between Gradual and Impulsive Coronal Mass Ejections: The Role of Flares

Coronal Mass Ejections (CMEs) are significant solar events that involve intense explosions of magnetic fields and mass particles out from the corona. These events are known to be the main driver of space weather and other disturbances experienced by the Earth. Generally, there are two types of CMEs – gradual and impulsive, and each type has different properties which is important to be studied on as they have potential to cause breakdowns in our systems. This study is aimed to analyze and differentiate the kinematic behavior of gradual and impulsive CME with the association of weak and strong flares. Data collection is made through SOHO LASCO catalogues and STEREO database which include velocity, acceleration and angular width as well as images. At the end of this study, it can be deduced that impulsive CME (specifically associated with strong flare) is the most prominent event that has greatest angular width and average velocity. The associated flare has contributed more heat energy to speed up the magnetic energy conversion which results to high velocity of plasma discharge. Since fast CME carries huge amount of momentum during the ejection, impulsive CMEs also experience decelerations due to loss of momentum that has been transferred to background solar wind.

Ultraviolet laser-induced fragmentation of hydrocarbon fuel droplets

The present study aims to understand droplet fragmentation due to instabilities from the radiative heating process. We focus on the plasma-induced breakup mechanism of iso-octane and n-hexane droplets from the nucleation of holes through sheets and instabilities. The plasma generation inside the droplets leads to an intense explosion followed by fragmentation of the droplets. A droplet is suspended in the air using an acoustic levitator and exposed to ultraviolet nanosecond laser pulses. The droplet sizes used are in the range of 0.5–2 mm in diameter, and laser energies are 10–20 mJ per pulse. Initially, plasma formation followed by shock wave emission is observed during the impact of the laser pulse. Afterward, the droplet opens at one side and is stretched vertically to form a liquid sheet. The hole formation and its rapid growth result in the breaking of the thin liquid sheet. Small droplets and ligaments emerge from the circular edge of the sheet, which follows the well-known ligament distribution. This study reveals the detailed analysis of expansion dynamics, evolution of single and multiple holes, and instabilities associated with the liquid sheet. The results observed are categorized into four different mechanisms: (1) plasma formation followed by shock wave propagation, (2) droplet deformation, (3) sheet breakup through nucleation of holes followed by rapid growth, and (4) complete atomization.

Damage assessment method of clay brick masonry load-bearing walls under intense explosions with long duration

The vulnerability of clay brick masonry load-bearing (CBML) walls under low-intensity explosions has been extensively investigated. In recent years, large-scale explosions have raised wide concerns about the destructive effect of intense explosions. Intense explosions induced by large TNT equivalent explosives usually cause severe damage to building structures within several kilometers. Although the damage of building structures under intense explosions and normal low-intensity explosions might be different, the differences have yet received any attention in previous studies. Therefore, this study numerically investigates the dynamic performance of CBML walls under intense explosions with long duration (IELD). Firstly, the numerical model is validated by reproducing experimental records. Then the verified model is utilized to investigate the dynamic response and dynamic modes of CBML walls under IELD. Based on the identified failure mechanism, the effects of several parameters such as axial compression ratio, compressive strengths of masonry materials and wall geometry on the damage degrees of CBML walls are analyzed in detail. The damage index based on the residual axial loading capacity of CBML wall is proposed for damage evaluation. The damage assessment method is established for CBML walls under IELD, which can help to evaluate the damage level of clay brick masonry structures under far-field intense explosive scenarios.

Search for anomalies in Stromboli's pre-paroxysm activity through an automatic hybrid method of time series analysis

Stromboli (Italy) is an open-vent volcano with persistent explosive activity producing up to five hundred mild explosions per day. Fluctuations in explosion intensity, varying even by orders of magnitude in terms of emitted volume and their subsequent impact on the surrounding regions, sometimes occur abruptly. Consequently, identifying precursors of larger eruptive activities, particularly for more intense (paroxysmal) explosions, is challenging. In order to search for anomalies in the pre-paroxysm activity related to the summer 2019 eruption, we applied a hybrid method to the automatic analysis of geophysical and geochemical time series. This approach is based on the combination of two methods: 1. the Empirical Mode Decomposition (EMD) and 2. the Support Vector Regression (SVR). The aggregation of these two methods allowed us to identify anomalies in the patterns of the geophysical and geochemical parameters measured on Stromboli in a ten-month period including the July–August 2019 eruption. The results of this study are encouraging for an improvement of the monitoring systems and for volcano early warning applications.

Explosive Leidenfrost-Droplet-Mediated Synthesis of Monodispersed High-Entropy-Alloy Nanoparticles for Electrocatalysis.

High-entropy-alloy nanoparticles (HEA NPs) exhibit promising potential in various catalytic applications, yet a robust synthesis strategy has been elusive. Here, we introduce a straightforward and universal method, involving the microexplosion of Leidenfrost droplets housing carbon black and metal salt precursors, to fabricate PtRhPdIrRu HEA NPs with a size of ∼2.3 nm. The accumulated pressure within the Leidenfrost droplet triggers an intense explosion within milliseconds, propelling the carbon support and metal salt rapidly into the hot solvent through explosive force. The exceptionally quick temperature rise ensures the coreduction of metal salts, and the dilute local concentration of metal ions limits the final size of the HEA NPs. Additionally, the explosion process can be fine-tuned by selecting different solvents, enabling the harvesting of diverse HEA NPs with superior electrocatalytic activity for alcohol electrooxidation and hydrogen electrocatalysis compared to commercial Pt (Pd) unitary catalysts.

Simple Model for Temporal Variations of Hα Spectrum by an Eruptive Filament from a Superflare on a Solar-type Star

Flares are intense explosions on the solar and stellar surfaces, and solar flares are sometimes accompanied by filament or prominence eruptions. Recently, a large filament eruption associated with a superflare on a solar-type star EK Dra was discovered for the first time. The absorption of the Hα spectrum initially exhibited a blueshift with the velocity of 510 km s−1, and decelerated in time probably due to gravity. Stellar coronal mass ejections (CMEs) were thought to occur, although the filament eruption did not exceed the escape velocity under the surface gravity. To investigate how such a filament eruption can occur and whether CMEs are associated with the filament eruption or not, we perform a one-dimensional hydrodynamic simulation of the flow along an expanding magnetic loop emulating a filament eruption under adiabatic and unsteady conditions. The loop configuration and expanding velocity normal to the loop are specified in the configuration parameters, and we calculate the line-of-sight velocity of the filament eruption using the velocities along and normal to the loop. We find that (i) the temporal variations of the Hα spectrum for EK Dra can be explained by a falling filament eruption in the loop with longer time and larger spatial scales than that of the Sun, and (ii) the stellar CMEs are also thought to be associated with the filament eruption from the superflare on EK Dra, because the rarefied loop unobserved in the Hα spectrum needs to expand faster than the escape velocity, whereas the observed filament eruption does not exceed the escape velocity.

New evidence of multiple channels for the origin of gamma-ray bursts with extended emission

ABSTRACT Gamma-ray bursts (GRBs) are the most intense explosions in the Universe. GRBs with extended emission (GRBs EE) constitute a small subclass of GRBs. GRBs EE are divided into EE-I GRBs and EE-II GRBs, according to the Amati empirical relationship rather than duration. We test here if these two types of GRB have different origins based on their luminosity function (and formation rate). Therefore, we use Lynden-Bell’s c− method to investigate the luminosity function and formation rate of GRBs with EE without any assumption. We calculate the formation rate of two types of GRBs. For EE-I GRBs, the fitting function can be written as ρ(z) ∝ (1 + z)−0.34 ± 0.04 for z < 2.39 and ρ(z) ∝ (1 + z)−2.34 ± 0.24 for z > 2.39. The formation rate of EE-II can describe as ρ(z) ∝ (1 + z)−1.05 ± 1.10 for z < 0.43 and ρ(z) ∝ (1 + z)−8.44 ± 1.10 for z > 0.43. The local formation rate is $\rho (0) = 0.03\, {\rm Gpc}^{-3} \, {\rm yr}^{-1}$ for some EE-I GRBs and $\rho (0) = 0.32 \, {\rm Gpc}^{-3} \, {\rm yr}^{-1}$ for EE-II GRBs. Based on these results, we provide new evidence that the origins of EE-I GRBs are different from EE-II GRBs from the perspective of event rate. The EE-I GRB could be produced from the death of the massive star, but EE-II GRB may come from other processes that are unrelated to the star formation rate. Our findings indicate that the GRBs with EE could have multiple production channels.

Statistical Insights on the Eruptive Activity at Stromboli Volcano (Italy) Recorded from 1879 to 2023

Stromboli is an open-conduit active volcano located in the southern Tyrrhenian Sea and is the easternmost island of the Aeolian Archipelago. It is known as “the lighthouse of the Mediterranean” for its continuous and mild Strombolian-type explosive activity, occurring at the summit craters. Sometimes the volcano undergoes more intense explosions, called “major explosions” if they affect just the summit above 500 m a.s.l. or “paroxysms” if the whole island is threatened. Effusive eruptions are less frequent, normally occurring every 3–5 years, and may be accompanied or preceded by landslides, crater collapses and tsunamis. Given the small size of the island (maximum diameter of 5 km, NE–SW) and the consequent proximity of the inhabited areas to the active craters (maximum distance 2.5 km), it is of paramount importance to use all available information to forecast the volcano’s eruptive activity. The availability of a detailed record of the volcano’s eruptive activity spanning some centuries has prompted evaluations on its possible short-term evolution. The aim of this paper is to present some statistical insights on the eruptive activity at Stromboli using a catalogue dating back to 1879 and reviewed for the events during the last two decades. Our results confirm the recent trend of a significant increase in major explosions, small lava flows and summit crater collapses at the volcano, and might help monitoring research institutions and stakeholders to evaluate volcanic hazards from eruptive activity at this and possibly other open-vent active basaltic volcanoes.

Characteristics of Different Groups of Flare-CME in the Minimum to Rising Phase of Solar Cycle 24

Coronal Mass Ejections are significant solar events that involve intense explosions of magnetic fields and mass particles out from the corona. As the hot plasma are brought by the solar wind into the Earth’s magnetosphere, geomagnetic storm is generated and causing malfunctions in telecommunication and power systems. This study is aimed to investigate the distribution of flare-CMEs characteristics which occurred at the beginning phase of solar cycle 24, from Dec. 2008 until Dec. 2013. In the analysis, all events are classified according to their class of flares associated with the CMEs. The CMEs that are accompanied by A, B, and C flares are categorized as low group flare-CME, while CMEs with M and X flares are placed under high group flare-CME. Afterwards, they are analyzed to observe the distribution of their main CME properties; velocity, acceleration and angular width. At the end of the study, we found that velocity and angular width are the two properties that have high influential for high and low groups, with R value of 0.36 and 0.67, respectively. Most of high group flare-CMEs showed up in 360° as well as low group flare-CMEs if the associated minor flares lasted longer than 30 min. Furthermore, the speed range of 360° high and low class flare-CME cannot be defined from the results since all of them propagated at fluctuating velocity. Hence, it is believed that full halo CMEs have no velocity boundary as they can travel from 500 km/s and go beyond 2500 km/s.

Attenuation of blast waves from an intense explosion in dusty gases: a case study

An intense explosion in dusty gas is analyzed considering the Beirut ammonium nitrate explosion of 2020 as a case study. The data available from various sources for the Beirut explosion are used to determine the energy released and the possible reduction in damage radius if there were additional dust particles in the atmosphere. The relationship derived in our previous article ( Proc. R. Soc. A 476 , 2020) between the blast radius and the time of arrival of the shock seems quite accurate, and here the energy released by the explosion and the mass of trinitrotoluene (TNT) equivalent based on energy considerations and blast damage are estimated for dusty gases. These estimates depend on Γ , the ratio of specific heats of the dusty gas mixture. The hydrostatic overpressure and dynamic pressure are calculated from previous results by using the data available. The variation of the three dust parameters in the atmosphere, i.e. (i) mass concentration of dust particles ( k p ) , (ii) specific heat ratio ( β ) , and (iii) density ratio ( G ) , gives the estimated TNT equivalence as ≈ 0.1 kt to 2.5 kt up to a distance of 500 m. Enhanced decay and reduced pressure is evident for dusty gases with appropriate dust parameters.

Blast Waves in Two and Three Dimensions: Euler Versus Navier–Stokes Equations

The exact solution of the Euler equation, which describes the time evolution of a blast wave created by an intense explosion, is a classic problem in gas dynamics. However, it has been found that the analytical results do not match with results from molecular dynamics simulation of hard spheres in two and three dimensions. In this paper, we show that the mismatch between theory and simulations can be resolved by considering the Navier–Stokes equation. From the direct numerical simulation of the Navier–Stokes equation in two and three dimensions, we show that the inclusion of heat conduction and viscosity terms is essential to capture the results from molecular dynamics simulations.

An analysis of shock wave propagation in a dusty gas

The present work uses a power series method to investigate the propagation of shock waves with generalized geometries generated by an intense explosion in a dusty gas. A mathematical model using a system of partial differential equations (PDEs) is presented for the considered problem. The density of the undisturbed medium is assumed to be constant. Approximate analytic solutions to the considered problem are obtained using the power series method by extending the power series of the flow variables. This work discusses the first‐order and second‐order approximate solutions and provides closed‐form solutions for the first‐order approximation. The behavior of the flow variables is depicted via figures behind the shock front for the first‐order approximation. Furthermore, the effects of geometry factor α, adiabatic exponent γ, and various dusty gas parameters such as Kp (the mass fraction of the dust particles), G0 (the ratio of the density of the dust particles to the initial density of the gas), and σ (the relative specific heat) are analyzed on the flow variables and total energy of disturbance J0 for the first‐order approximation. It is observed that an increase in any of the parameters Kp or σ causes the fluid velocity to increase and density and pressure to decrease. Increase in the parameter G0 causes the density and pressure to increase, whereas the fluid velocity does not get affected. An increase in the value of α results in a decrease in the density and pressure, while the fluid velocity remains the same. An increase in the value of γ results in a decrease in the fluid velocity; however, it has opposite effect on the pressure. The density decreases near the shock front and increases as we move towards the axis/center of symmetry with an increase in γ. Also, it is observed that J0 increases on increasing the value of G0 or σ, while it decreases on increasing the value of Kp, γ or α.

A different etiology of pneumothorax: Truck tire explosion!

A Pneumothorax (PNX) is the accumulation of air in the pleural space. PNX, which occurs due to the blast effect of an intense explosion, is a rare and important cause in etiology, as it is generally seen as spontaneous PNX. Blast injuries have become more common in the last century causing by terrorist attack events like bomb explosions and home-related or industrial accidents. While repairing or servicing a large tire, the explosion of the tire may result in high mortality and morbidity. In this case report, we present a 37-year-old male truck driver with barotraumatic PNX and rib fractures that developed due to a truck tire explosion.

Inhibition of hydrogen–oxygen/air gaseous detonations using CF3I, H2O, and CO2

The ignition of hydrogen-air mixtures can cause intense explosions. To ensure the safe utilization of hydrogen fuel and prevent catastrophic explosion accidents, the inhibiting effect of flame inhibitors must be understood since they have important consequences for hazard analyses. In the present study, the detonability of hydrogen mixtures diluted with CF3I, H2O, CO2, and N2 is investigated using numerical computations. The inhibiting effect of chemically active (CF3I, H2O, and CO2) and chemically inert (N2) diluents on the chemical length and time scales of a ZND detonation structure was studied using a detailed chemical kinetic mechanism for hydrogen oxidation. The inhibition efficiency of a halogenated compound, CF3I, towards quenching of hydrogen-air/oxygen gaseous detonations was also studied. As an additive, CF3I was found to promote detonation at lower concentrations. However, at higher concentrations, CF3I suppresses gaseous detonations by acting as a radical-scavenging agent. In the present study, a given retardant's effectiveness for suppressing a given detonation wave was evaluated for CF3I, H2O, CO2, and N2. The combined suppression effects of CF3I, H2O, and CO2 were also investigated. The efficacy of a composite inhibitor towards the quenching of a detonation wave was also evaluated and compared.

Shock Propagation in the Hard Sphere Gas in Two Dimensions: Comparison Between Simulations and Hydrodynamics

We study the radial distribution of pressure, density, temperature and flow velocity fields at different times in a two dimensional hard sphere gas that is initially at rest and disturbed by injecting kinetic energy in a localized region through large scale event driven molecular dynamics simulations. For large times, the growth of these distributions are scale invariant. The hydrodynamic description of the problem, obtained from the continuity equations for the three conserved quantities—mass, momentum, and energy—is identical to those used to describe the hydrodynamic regime of a blast wave propagating through a medium at rest, following an intense explosion, a classic problem in gas dynamics. Earlier work showed that the results from simulations matched well with the predictions from hydrodynamics in two dimensions, but did not match well in three dimensions. To resolve this contradiction, we perform large scale simulations in two dimensions, and show that like in three dimensions, hydrodynamics does not describe the simulation data well. To account for this discrepancy, we check in our simulations the different assumptions of the hydrodynamic approach like local equilibrium, existence of an equation of state, neglect of heat conduction and viscosity.

The reflection of a blast wave by a very intense explosion.

We demonstrate that the geometric similarity of Taylor’s blast wave persists beyond reflection from an ideal surface. Upon impacting the surface, the spherical symmetry of the blast wave is lost but its cylindrical symmetry endures. As the flow acquires dependence on a second spatial dimension, an analytic solution of the Euler equations becomes elusive. However, the preservation of axisymmetry, geometric similarity and planar symmetry in the presence of a mirror-like surface causes all flow solutions to collapse when scaled by the height of burst (HOB) and the shock arrival time at the surface. The scaled blast volume for any yield, HOB and ambient air density follows a single universal trajectory for all scaled time, both before and after reflection.

From Formation to Disruption: Observing the Multiphase Evolution of a Solar Flare Current Sheet

Abstract A current sheet, where magnetic energy is liberated through reconnection and converted to other forms, is thought to play the central role in solar flares, the most intense explosions in the heliosphere. However, the evolution of a current sheet and its subsequent role in flare-related phenomena such as particle acceleration is poorly understood. Here we report observations obtained with NASA’s Solar Dynamics Observatory that reveal a multiphase evolution of a current sheet in the early stages of a solar flare, from its formation to quasi-stable evolution and disruption. Our observations have implications for the understanding of the onset and evolution of reconnection in the early stages of eruptive solar flares.

Shock Propagation Following an Intense Explosion: Comparison Between Hydrodynamics and Simulations

The solution for the radial distribution of pressure, density, temperature and flow velocity fields in a blast wave propagating through a medium at rest, following an intense explosion, starting from hydrodynamic equations, is one of the classic problems in gas dynamics. However, there is very little direct verification of the theory and its assumptions from simulations of microscopic models. In this paper, we compare the results and assumptions of the hydrodynamic theory with results from large scale event driven molecular dynamics simulations of a hard sphere gas in three dimensions. We find that the predictions for the radial distribution of the thermodynamic quantities do not match well with the numerical data. We improve the theory by replacing the ideal gas law with a more realistic virial equation of state for the hard sphere gas. While this improves the theoretical predictions, we show that they still fail to describe the data well. To understand the reasons for this discrepancy, the different assumptions of the hydrodynamic theory are tested within the simulations. A key assumption of the theory is the existence of a local equation of state. We validate this assumption by showing that the local pressure, temperature and density obey the equation of state for a hard sphere gas. However, the probability distribution of the velocity fluctuations has non-gaussian tails, especially away from the shock front, showing that the assumption of local equilibrium is violated. This, along with neglect of heat conduction, could be the possible reasons for the mismatch between theory and simulations.

Eksplozija graničnog sloja po ulasku svemirske letelice u guste slojeve Zemljine atmosfere

Introduction/purpose: A supersonic flow around a sphere with a radius of 1m at altitudes of 80 to 40 km was analysed. Methods: The descent trajectory at the first cosmic velocity, similar to that of the Soyuz spacecraft with a duralumin structure without thermal protection, was taken into consideration. Results: For the gas between the shock wave front and the surface of the descending spacecraft, data were obtained on the increase in density, pressure, and temperature behind the shock wave front as well as the shift of the shock wave from the surface of the descending spacecraft. The effective temperature of the shock-heated gas reaches its maximum value of 7340 K at an altitude of 60 km. At altitudes of 80 and 40 km, the effective temperature is 7000 K and 6400 K, respectively. Based on the obtained data on the thermodynamic state of the gas behind the shock wave every 10 km, calculations were made of energy fluxes to the surface of the spacecraft for convective and radiative heat transfer, as well as for the impact of electrons produced due to ionization of negative ions. Radiative heat transfer has proven to be the most significant. The burning mechanism of negative ions of triatomic molecules of aluminium with the formation of AlO molecules was determined, and data on pressure rise in the boundary layer on the spacecraft surface were obtained. At all considered altitudes, the pressure rises instantly: to 1.06*1010 Pa at an altitude of 80 km, 5.3*10 Pa at an altitude of 60 km, and reaches the maximum value of 5.5*1010 Pa and an altitude of 40 km. A pressure of 109 to 1010 Pa arises during explosion of various explosives. The energy flux reaches the spacecraft surface between explosions. At the moment of explosion, shock waves develop in the atmosphere surrounding the surface of the descending spacecraft, and compressive waves develop in the entire structure of the spacecraft. The descending spacecraft cracks, and its entire structure breaks down into parts. The area of interaction increases sharply, and each subsequent explosion has a greater intensity and size. As a result, the last most intense explosion occurs at an altitude of approx. 40 km, after which individual fragments of the spacecraft fall to Earth. Conclusion: The exploration of space with flight to other planets is possible only after a thorough study of explosive processes taking place on the surface of the spacecraft descending on other planets, and especially on Earth.