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This study aims to present computational technology that can be used to evaluate numerically the harmful environmental consequences caused by an accidental hydrogen release from failed high-pressure dispensing cylinders and its explosion at a vehicle hydrogen filling station. A coupled problem of a hydrogen explosion products expansion in the atmospheric ground layer and a harmful explosion pressure wave shock impact on service personnel and infrastructure buildings at an accident site is solved by means of computer experiment simulation series. A spatial time-dependent model of compressible hydrogen-air mixture flow is used to obtain pressure history in calculation area in order to assess maximum overpressure in control points of human possible locations and on building surfaces exposed to hydrogen blast wave impact. A deterministic impact consequences model is based on comparing maximum overpressure values extracted from the mathematical model with threshold ranges corresponding to certain degrees of human damage and infrastructure destruction. The presented computer technology allows safety experts to identify potentially dangerous zones by means of mathematical modelling and recommend effective protection measures to mitigate negative consequences of explosions.

The January 2022 Hunga Tonga–Hunga Ha’apai eruption was one of the most explosive volcanic events of the modern era, producing a vertical plume that peaked more than 50 km above the Earth. The initial explosion and subsequent plume triggered atmospheric waves that propagated around the world multiple times. A global-scale wave response of this magnitude from a single source has not previously been observed. Here we show the details of this response, using a comprehensive set of satellite and ground-based observations to quantify it from surface to ionosphere. A broad spectrum of waves was triggered by the initial explosion, including Lamb waves propagating at phase speeds of 318.2 ± 6 m s^(−1) at surface level and between 308 ± 5 to 319 ± 4 m s^(−1) in the stratosphere, and gravity waves propagating at 238 ± 3 to 269 ± 3 m s^(−1) in the stratosphere. Gravity waves at sub-ionospheric heights have not previously been observed propagating at this speed or over the whole Earth from a single source. Latent heat release from the plume remained the most significant individual gravity wave source worldwide for more than 12 h, producing circular wavefronts visible across the Pacific basin in satellite observations. A single source dominating such a large region is also unique in the observational record. The Hunga Tonga eruption represents a key natural experiment in how the atmosphere responds to a sudden point-source-driven state change, which will be of use for improving weather and climate models.

In blasting engineering, the location and number of detonation points, to a certain degree, regulate the propagation direction of the explosion stress wave and blasting effect. Herein, we examine the explosion wave field and rock breaking effect in terms of shock wave collision, stress change of the blast hole wall in the collision zone, and crack propagation in the collision zone. The produced shock wave on the collision surface has an intensity surpassing the sum of the intensities of the two colliding explosion shock waves. At the collision location, the kinetic energy is transformed into potential energy with a reduction in particle velocity at the wave front and the wave front pressure increases. The expansion form of the superposed shock wave is dumbbell-shaped, the shock wave velocity in the collision area is greater than the radial shock wave velocity, and the average propagation angle of the explosion shock waves is approximately 60°. Accordingly, a fitted relationship between blast hole wall stress and explosion wave propagation angle in the superposition area is plotted. Under the experimental conditions, the superimposed explosion wave stress of the blast hole wall is approximately 1.73 times the singleexplosion wave incident stress. The results of the model test and numerical simulations reveal that large-scale radial fracture cracks were generated on the blast hole wall in the superimposed area, and the width of the crack increased. The width of the large-scale radial fracture cracks formed by a strong impact is approximately 5% of the blast hole length. According to the characteristics of blast hole wall compression, the mean peak pressures of the strongly superimposed area are approximately 1.48 and 1.84 times those of the weakly superimposed and nonsuperimposed areas, respectively.

To address the issue of peak overpressure distribution of shock wave fronts during propagation in rectangular tunnels, three-dimensional simulation models of explosion at the tunnel entrance were established using AUTODYN. The model’s validity was verified through conducted experiments. Initially, a comparative analysis of peak overpressure differences at various positions within the tunnel cross-section was performed. Results indicate that for explosions occurring outside the rectangular tunnel entrance, the shock wave overpressure on the tunnel roof and floor exhibits significant relative deviations. Therefore, measurement points should not be placed at these locations during tunnel shock wave testing but rather near the midpoint of the side walls. Subsequently, the relative average deviation of the peak overpressure of the shock wave front in the tunnel was introduced and calculated to characterize the uniformity of the overpressure distribution of the wave front. Finally, the effects of explosive distance X and explosive mass Q on this deviation were examined. The results indicate that these two factors have different impacts on explosions inside and outside the tunnel entrance. For external explosions, a decrease in X and an increase in Q both increase the relative average deviation and the proportional distance λ required to form a uniform plane wave. In the case of internal explosions, changes in X have negligible effects on the relative average deviation and the position required to form a uniform plane wave, while an increase in Q raises the λ needed to achieve a uniform plane wave. These findings provide significant reference for the accurate characterization of tunnel shock wave loads and the design of related experimental tests.

Blasting and shaped charges are the main forms of underwater weapons, and their near-field underwater explosions (UNDEX) can severely damage structures. Therefore, it is of great importance to study underwater explosive load characteristics of different forms of charges. The full physical process of a typical underwater explosion of a sphere/column blasting charge and a shaped charge was simulated using the Eulerian method. The loading characteristics of the underwater blast shock wave and bubble, as well as the projectile, were studied. The results show that the shock wave loads of spherical, cylindrical, and polygonal charges propagate outward in spherical, ellipsoidal–spherical and ellipsoidal–spherical wavefronts, respectively. When the shock wave reaches 16 times the distance-to-diameter ratio, its surface is approximately spherical. In addition, in the shaped charge underwater explosion, the shaped charge liner cover absorbs 30°–90© of the shock wave energy and some of the bubble energy to form a high-speed shaped penetrator. Spherical, ellipsoidal, and ellipsoidal bubbles are generated by underwater explosions of spherical, cylindrical, and shaped charges, respectively. The obtained results provide a reference for evaluating the power of underwater weapons.

The propagation characteristics of the overpressure waves and flame fronts of methane explosions in complex pipe networks under realistic conditions were studied. A custom-designed experimental platform was used, the propagation characteristics of overpressure wave and flame wave in complex pipe network were characterized by overpressure attenuation coefficient and flame mutation coefficient. The results showed that the overpressure wave propagation characteristics in complex pipe networks were more complicated and disordered than those in straight or simple branched pipes. The overpressure wave attenuation and superposition occurred many times in the propagation process, the explosion shock wave attenuation in the beveled branch pipe was faster. When the flame wave passed through all the branch tubes, the flame wave velocity increased significantly. When the flame wave passed through the same tube at different times, the flame wave mutation coefficient was different, the change of flame wave temperature had a certain lag compared with the change of flame velocity, resulting in the peak of flame wave temperature and flame wave velocity appearing in different branch tubes. The experimentally obtained data were fit to functional relationships using nonlinear multiple regression analysis, and good agreement between the functional relationships and the data was obtained.

The main aims of this study are to assess numerically the mitigation effects caused by the solid wall installed at the fueling station in order to protect personnel from the consequences of the emergent gas explosion, evaluate the optimal location of the wall and choose the appropriate material the wall have to be made of in order not to be destructed. A three-dimensional mathematical model of an explosion of hydrogen-air cloud is used. A computer technology how to define the personnel damage probability fields on the basis of probit analysis of the explosion wave is developed. The mathematical model takes into account the complex terrain and three-dimensional non-stationary nature of the shock wave propagation process. The model allows obtaining time-spatial distribution of damaging factors (overpressure in the shock wave front and the compression phase impulse) required to determine the three-dimensional non-stationary damage probability fields based on probit analysis. The developed computer technology allows to carry out an automated analysis of the safety situation at the fueling station and to conduct a comparative analysis of the effectiveness of different types of material the protective facilities made of.

The coupled Eulerian–Lagrangian (CEL) method has shown good capability to simulate large deformation behavior in the blast response of complex structural and multi-physics systems. However, the published literature has not addressed blast wave characteristics in free open-air space or directly compared the results of such studies with experiments. In this study, the authors performed three-dimensional (3-D) non-linear finite element (FE) analysis of CEL model utilizing ABAQUS/Explicit finite element software to estimate blast wave parameters, peak overpressure (Pso), time of arrival (ta), positive phase duration ( to+ ), and blast shock wave front velocity (U) in comparison to empirical Kingery–Bulmash free air-blast predictions and recently published small-scale blast field test results. The height of spherical and cubical TNT charges (HOE) is 5.0-m inside a Eulerain domain (ED). The air and trinitrotoluene (TNT) charge are modeled using (C3D8R) continuum solid elements and the Eulerian domain is modeled as a volume element using (EC3D8R). The CEL model results show good agreement with Kingery–Bulmash predictions and experimental data for incident peak-overpressure, time of arrival, and blast shock wave velocity of considered scaled distances. However, the CEL model outcomes of positive phase duration showed a difference from Kingery–Bulmash model as high as 55% due to secondary shock waves moving inward and reflected toward the source of burst. Despite the extensive validation of the Kingery–Bulmash empirical model, direct measurements in open-space indicate that incorporating blast wave propagation phenomena is critical in different explosion scenarios, especially when reflection phenomena are probable. As a practical model of the CEL model, the blast response and damage evolution of a X70 steel pipe subjected to contact pipe bomb charge is investigated. This grade of steel pipe is a reliable material and used in oil and gas transmission pipelines. The post-damage simulation showed wall thickness has significant contribution to improve the response of the pipe and blast-post damage evolution. This study aims to highlight the efficiency of coupled Eulerian–Lagrangian (CEL) technique to simulate blast for a better understanding of wave propagation in free space and wave-structure interaction phenomena when blast waves interact with structures.

The article covers the problem of determination of loads of blast wave on aboveground and underground structures. In industrial production, the chemical sources of explosion occur, for which the environment is air. The most common and typical source of explosion is solid products of the explosion (PE) in the form of a packed charge. In a chemical explosion, highly compressed and heated gaseous products of the explosion (PE) are formed in the volume of the charge. The main parameters of the shock wave that determine its effect on the structure, i.e., excess pressure on the wave front, time of the wave's actionτ, and the impulse of the wave have been determined according to the empirical formulas obtained by experiment for each explosion source. Therefore, in this work, the formulas for determining the incident wave in large-scale experimental studies are presented. It has been found that loads on the structure of barriers of buildings are increase significantly as a result of secondary returning waves superimposing the first incident wave.

This article considers the generation of pressure waves during the combustion of hydrogen–air clouds in various modes. The problem of the combustion of spherical clouds, in which the inner spherical volume burns with an apparent velocity of 240 m/s, and the remaining outer layer with an apparent velocity of 100 m/s, is considered. Also, for comparison, two limiting cases are considered: the combustion of the entire cloud with constant velocities of 100 and 240 m/s. The problem is solved numerically in a one-dimensional formulation, with the combustion front clearly identified. As a result, using precise numerical simulation, it is shown that the deflagration of secondary volumes of hydrogen–air mixtures in an open space at a slow speed (up to 100 m/s) does not lead to an increase in pressure in the waves generated earlier during the deflagration of the primary volume at a fast speed corresponding to deflagration in an obstructed space. Such a situation is observed for the inner region of various sizes (the portion of the cloud that burns at a high rate).