Blast Wave Overpressure Research Articles

Estimation the blast wave pressure effecters by apply Remote Sensing (RS) and Geographic Information System (GIS) techniques

After the year 2003 terrorist attacks knock Baghdad city capital of Iraq using bomb explosion various, shook the nation, and made public resident of Baghdad aware of the need for better ways to protect occupants, assets, and buildings cause the terrorist gangs adopt style burst of blast to injury vulnerability a wider range form, and many structures will suffer damage from air blast when the overpressure concomitant the blast wave, (i.e., the excess over the atmospheric pressure 14.7 pounds per square inch at standard sea level conditions are about one-half pound per square inch or more(to attainment injury. Then, the distance to which this overpressure level will extend depends primarily on the energy yield (§1.20) of the burst of blast. Accordingly, must been have adopted a changing philosophy to provide appropriate and effective protection for preservation of psyche and building occupants, by establishment of a protected perimeter and the design of a debris mitigating facade, the isolation of internal explosive threats that may to dodge detection through the screening stations or may enter the public spaces prior to screening and the protection of the emergency evacuation, rescue and recovery systems. By reason of this above-mentioned, the study simple contribution of determined phenomena risk containment. Moreover, in this study may be applied remote sensing (RS) and geographic information system (GIS) techniques to estimation the blast wave overpressure of bomb explosive effecters for damage that building of materials (i.e., facade, building glass, secondary of roof, fashioning tools and furniture), and how avoid this problem, therefore, selection justice ministry of Iraq building in Salehyiea region at Baghdad city, it destroyed at 28/10/2009 by motocar bombs explosion.

Consequence assessment of high-pressure hydrogen storage tank rupture during fire test

This paper deals with the consequences assessment associated with the accidental catastrophic explosion in the case of high-pressure tank (165 L, 35 MPa) rupture during fire test. Two catastrophic explosion accidents caused by the thermally activated pressure relief device (TPRD) failure in activating in time were reported. The detailed explosion processes were recorded and analyzed, providing a valuable study case for improving the hazard identification. A method was developed for calculating the explosion energy stored in high-pressure hydrogen tank based on the real-gas state equation of the hydrogen. Three kinds of damage patterns were analyzed synthetically considering the intensity of the blast wave, thermal radiation, and flying fragments. It is found that for the overpressure of blast wave, the slight injury for human and minor damage for equipment are expected in the radius range of within 14.0 m and 65.4 m, respectively. Similarly, the safe radius distances of thermal radiation for human and equipment are 140 m and 52.1 m. The flying distance of the destructed tank increases with the increment of projection angle. The theoretical results are in good agreement with the data collected from the accidents. The proposed method provides a theoretical support for taking enough safety measures in advance to prevent dangerous consequences of high-pressure storage hydrogen tank during fire test.

Numerical investigation of particle–blast interaction during explosive dispersal of liquids and granular materials

Experiments show that when a high-explosive charge with embedded particles or a charge surrounded by a layer of liquid or granular material is detonated, the flow generated is perturbed by the motion of the particles and the blast wave profile differs from that of an ideal Friedlander form. Initially, the blast wave overpressure is reduced due to the energy dissipation resulting from compaction, fragmentation, and heating of the particle bed, and acceleration of the material. However, as the blast wave propagates, particle–flow interactions collectively serve to reduce the rate of decay of the peak blast wave overpressure. Computations carried out with a multiphase hydrocode reproduce the general trends observed experimentally and highlight the transition between the particle acceleration/deceleration phases, which is not accessible experimentally, since the particles are obscured by the detonation products. The dependence of the particle–blast interaction and the blast mitigation effectiveness on the mitigant to explosive mass ratio, the particle size, and the initial solid volume fraction is investigated systematically. The reduction in peak blast overpressure is, as in experiments, primarily dependent on the mass ratio of material to explosive, with the particle size, density, and initial porosity of the particle bed playing secondary roles. In the near field, the blast overpressure decreases sharply with distance as the particles are accelerated by the flow. When the particles decelerate due to drag, energy is returned to the flow and the peak blast overpressure recovers and reaches values similar to that of a bare explosive charge for low mass ratios. Time–distance trajectory plots of the particle and blast wave motion with the pressure field superimposed, illustrate the weak pressure waves generated by the motion of the particle layer which travel upstream and perturb the blast wave motion. Computation of the particle and gas momentum flux in the multiphase flow generated during explosive particle dispersal indicates that the particle momentum flux is the dominant term in the near field. Both the gas and particle loading must be taken into account when determining the damage to nearby structures following the detonation of a high-explosive charge surrounded by a material layer.

Experimental investigation of blast mitigation and particle–blast interaction during the explosive dispersal of particles and liquids

The attenuation of a blast wave from a high-explosive charge surrounded by a layer of inert material is investigated experimentally in a spherical geometry for a wide range of materials. The blast wave pressure is inferred from extracting the blast wave velocity with high-speed video as well as direct measurements with pressure transducers. The mitigant consists of either a packed bed of particles, a particle bed saturated with water, or a homogeneous liquid. The reduction in peak blast wave overpressure is primarily dependent on the mitigant to explosive mass ratio, M/C, with the mitigant material properties playing a secondary role. Relative peak pressure mitigation reduces with distance and for low values of M/C (< 10) can return to unmitigated pressure levels in the mid-to-far field. Solid particles are more effective at mitigating the blast overpressure than liquids, particularly in the near field and at low values of M/C, suggesting that the energy dissipation during compaction, deformation, and fracture of the powders plays an important role. The difference in scaled arrival time of the blast and material fronts increases with M/C and scaled distance, with solid particles giving the largest separation between the blast wave and cloud of particles. Surrounding a high-explosive charge with a layer of particles reduces the positive-phase blast impulse, whereas a liquid layer has no influence on the impulse in the far field. Taking the total impulse due to the blast wave and material impact into account implies that the damage to a nearby structure may actually be augmented for a range of distances. These results should be taken into consideration in the design of explosive mitigant systems.

Study of blast wave overpressures using the computational fluid dynamics

ABSTRACT The threats of bomb attacks by criminal organizations and accidental events involving chemical explosives are a danger to the people and buildings. Due the severity of these issues and the need of data required for a safety design, more research is required about explosions and shock waves. This paper presents an assessment of blast wave overpressures using a computational fluid dynamics software. Analyses of phenomena as reflection of shock waves and channeling effects were done and a comparison between numerical results and analytical predictions has been executed, based on the simulation on several models. The results suggest that the common analytical predictions aren’t accurate enough for an overpressure analysis in small stand-off distances and that poorly designed buildings may increase the shock wave overpressures due multiple blast wave reflections, increasing the destructive potential of the explosions.

A methodology to predict shock overpressure decay in a tunnel produced by a premixed methane/air explosion

A methodology for estimating the blast wave overpressure decay in air produced by a gas explosion in a closed-ended tunnel is proposed based on numerical simulations. The influence of the tunnel wall roughness is taken into account in studying a methane/air mixture explosion and the subsequent propagation of the resulting shock wave in air. The pressure time-history is obtained at different axial locations in the tunnel outside the methane/air mixture. If the shock overpressure at two, or more locations, is known, the value at other locations can be determined according to a simple power law. The study demonstrates the accuracy of the proposed methodology to estimate the overpressure change with distance for shock waves in air produced by methane/air mixture explosions. The methodology is applied to experimental data in order to validate the approach.

The spatial distribution patterns of condensed phase post-blast explosive residues formed during detonation

The continued usage of explosive devices, as well as the ever growing threat of ‘dirty’ bombs necessitates a comprehensive understanding of particle dispersal during detonation events in order to develop effectual methods for targeting explosive and/or additive remediation efforts. Herein, the distribution of explosive analytes from controlled detonations of aluminised ammonium nitrate and an RDX-based explosive composition were established by systematically sampling sites positioned around each firing. This is the first experimental study to produce evidence that the post-blast residue mass can distribute according to an approximate inverse-square law model, while also demonstrating for the first time that distribution trends can vary depending on individual analytes. Furthermore, by incorporating blast-wave overpressure measurements, high-speed imaging for fireball volume recordings, and monitoring of environmental conditions, it was determined that the principle factor affecting all analyte dispersals was the wind direction, with other factors affecting specific analytes to varying degrees. The dispersal mechanism for explosive residue is primarily the smoke cloud, a finding which in itself has wider impacts on the environment and fundamental detonation theory.

Experimental study of blast mitigating devices based on combined construction

A robust blast inhibiting bin is the most often used device for damage blast effects suppression. In particular, a top open cylindrical bin significantly reduces a fragmentation effect resulted from a detonation of an explosive device placed inside the bin. However, reduction of blast wave overpressure and impulse by such cylindrical bins is not sufficient [1].A reasonable alternative to endless increase of height and thickness of robust blast inhibiting bins is a development of destructible inhibitors having no solid elements in their structure and, therefore, excluding secondary fragmentation. So, the family of “Fountain” inhibitors [2,3] localizes and suppresses damaging blast effects due to multiphase working system.The present study is analyzing data obtained in testing of prototypes of new combined inhibitors. Their structure combines robust elements (bottoms, side surfaces) with elements responsible for blast loads reduction due to multi-phase working system (top and low transverse embeddings) and fairings impeding wave propagation in undesirable directions.

Simulation and Measurements of Small Arms Blast Wave Overpressure in the Process of Designing a Silencer

Abstract Simulation and measurements of muzzle blast overpressure and its physical manifestations are studied in this paper. The use of a silencer can have a great influence on the overpressure intensity. A silencer is regarded as an acoustic transducer and a waveguide. Wave equations for an acoustic dotted source of directed effect are used for physical interpretation of overpressure as an acoustic phenomenon. Decomposition approach has proven to be suitable to describe the formation of the output wave of the wave transducer. Electroacoustic analogies are used for simulations. A measurement chain was used to compare the simulation results with the experimental ones.

Analytic computations of nonideal corrections to blast wave overpressure predictions at high altitudes

AbstractIn this paper, the effects of temperature, pressure, winds, moisture, and molecular content on the propagation of blast waves at high altitudes are investigated. These cause refractions and attenuations which modify the recorded ground overpressures from the ideal predictions. By coupling these effects together, the nonideal corrections to the overpressures are estimated by applying approximations which are dependent on the angle of propagation of the blast wave.

Analysis of vacuum chamber suppressing gas explosion

In order to suppress the harm of gas explosion, the current study researched on the body of vacuum chamber. The previous studies verified that it could obviously lower the explosion overpressure by reasonably arranging vacuum chamber on pipe. That is to say, the vacuum chamber has the effect of absorbing wave and energy. To further deeply analyze the vacuum chamber suppressing gas explosion, this research designed the L-type pipe of gas explosion, and compared the experimental results of gas explosion with vacuum chamber and without vacuum chamber. Besides, using the gas chromatograph, this study also investigated the gas compositions in the pipe before and after explosion. The results show that: (1) without vacuum chamber, the maximum value of explosion overpressure is 0.22MPa, with 60ms duration, and after explosion, the concentration of oxygen drops to 12.07%, but the concentration of carbon monoxide increases to 4392.3×10−6, and the concentration of carbon dioxide goes up to 7.848%, which can make the persons in danger suffocate and die; (2) with vacuum chamber, explosion overpressure drops to 0.18MPa, with 20ms duration or less, and after explosion, the concentration of oxygen still remains 12.07%, but the concentration of methane is 7.83%, however the concentration of carbon monoxide is only 727.24×10−6, and the concentration of carbon dioxide is only 1.219%, at the this moment the concentration ratio of toxic gas drops by more than 83% in comparison to be that without vacuum chamber. Consequently, the vacuum chamber can guarantee that most methane does not take part in chemical reaction, and timely quenches the deflagration reaction of gas and oxygen. Because of the two points mentioned above, it reduces the explosion energy, and lowers that the overpressure of blast wave impacts and damages on the persons and facilities, and also decreases the consumption of oxygen and the production of the toxic gas. Therefore, it is safe to conclude that the vacuum chamber not only absorbs wave and energy, but also prevents and suppresses explosion.

Simplified Analysis of Blast Wave Overpressure Functions in Air

Though analysis of the blast wave changing law and the basic equation of blast wave overpressure functions in air,blast wave overpressure functions have been simplified. A simplified form of blast wave overpressure function is acquired,and experimental certificated. The results show that the simplified function curve correctly reflects the characteristics of the experimental curve. The blast wave created to simplify the function is reasonable.

The Application and Analysis of the Risk Assessment Model about BLEVE Accident

The flammable vapor pressure inside the combustible liquid storage tanks in the fire environment elevates, and the of the tank wall the yield strength of enduring the heat decreases, which cause the collapse to occur soon, resulting in the happen of BLEVE. BLEVE is an incident form of great harm, and the study of its formation mechanism and hazard model is of great significance for the safety of the chemical enterprise. In this paper, the physical and chemical characteristic of dichloropropane and BLEVE in a dichloropropane tank area is analyzed, and the accident analysis model is built. According to TNT equivalent method, the vapor cloud fire and explosion models and the blast wave overpressure injury criteria, we calculated the accident consequence of BLEVE in different filling levels. The calculation and analysis shows that, if the BLEVE occurred, the entire tank area and adjacent buildings will be severely affected and the affect area will be up to 50.35 meter; the people less than 7.43 meter from the explosion tank will be subject to serious injury or death. Based on the above substance hazardous characteristics analysis in dichloro propane tank storage area and the corresponding qualitative and quantitative analysis, and according to the relevant requirements of the specification, the fire safety prevention and control measures in the tank area should be further strengthened.

Development of uniform harm criteria for use in quantitative risk analysis of the hydrogen infrastructure

This paper discusses the preliminary results of the Risk Management subtask efforts within the International Energy Agency (IEA) Hydrogen Implementing Agreement (HIA) Task 19 on Hydrogen Safety to develop uniform harm criteria for use in the Quantitative Risk Assessments (QRAs) of hydrogen facilities. The IEA HIA Task 19 efforts are focused on developing guidelines and criteria for performing QRAs of hydrogen facilities. The performance of QRAs requires that the level of harm that is represented in the risk evaluation be established using deterministic models. The level of harm is a function of the type and level of hazard. The principle hazard associated with hydrogen facilities is uncontrolled accumulation of hydrogen in (semi) confined spaces and consecutive ignition. Another significant hazard is combustion of accidentally released hydrogen gas or liquid, which may or may not happen instantaneously. The primary consequences from fire hazards consist of personnel injuries or fatalities, or facility and equipment damage due to high air temperatures, radiant heat fluxes, or direct contact with hydrogen flames. The possible consequences of explosions on humans and structures or equipment include blast wave overpressure effects, impact from fragments generated by the explosion, the collapse of buildings, and the heat effects from subsequent fire balls. A harm criterion is used to translate the consequences of an accident, evaluated from deterministic models, to a probability of harm to people, structures, or components. Different methods can be used to establish harm criteria including the use of threshold consequence levels and continuous functions that relate the level of a hazard to a probability of damage. This paper presents a survey of harm criteria that can be utilized in QRAs and makes recommendations on the criteria that should be utilized for hydrogen-related hazards.

Analysis of blast wave propagation inside tunnel

The explosion inside tunnel would generate blast wave which transmits through the longitudinal tunnel. Because of the close-in effects of the tunnel and the reflection by the confining tunnel structure, blast wave propagation inside tunnel is distinguished from that in air. When the explosion happens inside tunnel, the overpressure peak is higher than that of explosion happening in air. The continuance time of the blast wave also becomes longer. With the help of the numerical simulation finite element software LS-DYNA, a three-dimensional nonlinear dynamic simulation analysis for an explosion experiment inside tunnel was carried out. LS-DYNA is a fully integrated analysis program specifically designed for nonlinear dynamics and large strain problems. Compared with the experimental results, the simulation results have made the material parameters of numerical simulation model available. By using the model and the same material parameters, many results were adopted by calculating the model under different TNT explosion dynamites. Then the method of dimensional analysis was used for the simulation results. As overpressures of the explosion blast wave are the governing factor in the tunnel responses, a formula for the explosion blast wave overpressure at a certain distance from the detonation center point inside the tunnel was derived by using the dimensional analysis theory. By comparing the results computed by the formula with experimental results which were obtained before, the formula was proved to be very applicable at some instance. The research may be helpful to estimate rapidly the effect of internal explosion of tunnel on the structure.

Evaluation of the blast-wave overpressure and fragments initial velocity for a BLEVE event via empirical correlations derived by a simplified model of released energy

When a pressure vessel filled with a liquid is involved in a fire, a variety of effects are to be expected. If the vessel is filled with LPG, a boiling liquid expanding vapour explosion (BLEVE) is one of the possible effects, although it does not always happen. Actually BLEVE is a complex phenomenon resulting from many factors which are hard to summarize into mathematical formulations or models. Nevertheless it could be useful in order to assess the consequences of a BLEVE, to have access to simplified models lying on physical basis. In this paper empirical correlations for blast-wave overpressure and fragments initial velocity are presented. The basic hypothesis that BLEVE is a phenomenon driven by the excess heat stored in the liquid (overheated liquid) is assumed and some thermodynamic approximations are introduced. Despite these approximations and the empirical formulation simplicity, the results accuracy is good.

Microstructural Effects in Face-Centered-Cubic Alloys after Small Charge Explosions

Effects on metal targets after an explosion include the following: fracture, plastic deformation, surface modifications, and microstructural crystallographic alterations with ensuing mechanical properties changes. In the case of small charge explosions, macroscopic effects are restricted to small charge-to-target distances, whereas crystal alterations can still be observed at moderate distances. Microstructural variations, induced on gold-alloy disk samples, as compared to previous results on AISI 304Cu steel samples, are illustrated. The samples were subjected to blast-wave overpressures in the range of 0.5 to 195 MPa. Minimum distances and peak pressures, which could still yield observable alterations, were especially investigated. Blast-related microstructural features were observed on the explosion-exposed surface and on perpendicular cross sections. Analyses using X-ray diffraction (XRD) were performed to identify modifications of phase, texture, dislocation density, and frequency of mechanical twins, before and after the explosions. Optical metallography (OM) and scanning electron microscopy (SEM) observations evidenced partial surface melting, zones with recrystallization phenomena, and crystal plastic deformation marks. The latter marks are attributed to mechanical twinning in the stainless steel and to cross-slip (prevalent) and mechanical twinning (possibly) in the gold alloy.

Vented confined explosions in Stramberk experimental mine and AutoReaGas simulation

Research Mining Institute, Inc., Ostrava-Radvanice, in cooperation with Dept. of Theory And Technology of Explosives of University of Pardubice and Klokner Institute of CTU in Prague, has performed three series of experiments examining methane–air mixture explosions and their impact on 14 and 29 cm thick wall. The project was named ‘Modeling Pressure Fields Effects on Engineering Structures During Accidental Explosions of Gases in Buildings’ and was sponsored by Grant Agency of Czech Republic (project No. 103/01/0039). The project is aimed at deeper understanding of pressure field effect upon the structures. Methane-air mixture explosion was used to generate the blast wave. The geometrical configuration of the environment resembled a room of an average size, such as larger kitchen. Preliminary simulations were made by AutoReaGas code (Century Dynamics and TNO). The design phase was followed by tests in an experimental mine in Stramberk. Two masonry dams were build in the mine, with cross-section areas of 10.2 m 2 and longitudinal distance of 5.7 m, creating an explosion chamber with a volume of 58 m 3. Two vent openings with an adjustable free cross-section were used to control the maximum overpressure inside the chamber. The concentration of methane-air mixture was approximately 9.5% (vol.) and the volumes of the clouds were 5.25, 10.2 and 15.3 m 3 respectively. The generated blast wave overpressures inside the chamber ranged between 1 and 150 kPa. According to experimental results a calibration of the code was performed. After the calibration it is possible to make relatively accurate simulations in similar geometry and to calculate the pressure loading of the structure at any spot in the simulated space. This paper describes the experiments performed and compares experimental and computational results.

Application of shock wave research to geophysics

Abstract This is a report describing an ambitious application of shock wave research to volcanology. In the explosive eruption of a volcano, a shock wave or a blast wave is created, which as it propagates, exhibits characteristics related to the nature of the pressure release at the mouth of the volcano. Hence, it was decided that it would be worthwhile to measure its overpressure in situ via a pressure transducer installed at a point not very far away from its mouth and then to use the measured data to validate a numerical scheme which, to identify the initial energy release of the eruption, was constructed for shock wave propagation over the three-dimensional geometry. The Shock Wave Research Center, Institute of Fluid Science, Tohoku University began a project in 1995 to study the shock wave dynamics of volcanic eruption, by measuring the time variation of blast wave overpressures in situ at Mount Aso near Kumamoto. This paper describes the preparation of the overpressure measurement, still awaiting an eruption, and the result of a three-dimensional fine numerical simulation, which is ready to be compared with the measured data.

Observed high‐altitude pressure waves from an underground and a surface explosion

Measurements of high‐altitude pressure waves from underground and surface explosions are of interest, as these waves can affect ionospheric electron density and be a source of infrasonic signals. Canisters, equipped with parachutes, were dropped from aircraft to determine time histories of pressure waves radiated by the ground surface above an underground nuclear explosion and a surface chemical explosion. These canisters contained transducers to document pressure and acceleration histories as well as a transmitter to relay information to ground receiver stations. We found observed pressure histories from the underground explosion to be consistent with histories calculated from surface ground motion records. The peak blast wave overpressures from the chemical explosion agreed with predicted scaled values. Observed time histories, however, had shorter positive phase duration than predicted with scaling.