Effect of Explosion Source Type on Blast Wave Shielding

2013 ◽  
Author(s):  
Jihui Geng ◽  
J. Kelly Thomas
Keyword(s):  
Blast Wave ◽  
Target Location ◽  
Blast Waves ◽  
Explosion Hazard ◽  
Shape Parameters ◽  
Wave Shape ◽  
Blast Overpressure ◽  
Screening Study ◽  
Vapor Cloud ◽  
The Uk

A key component of explosion hazard evaluations is the determination of standoffs to given blast overpressure values. Many such evaluations use a simplified methodology that assumes that the blast wave propagates from the explosion source to the target location without interacting with intervening buildings or structures (i.e., without blast wave shielding). This is obviously a perfectly acceptable approach for a screening study, but blast wave shielding effects can be significant in certain circumstances (e.g., within a building group). A methodology was proposed by the UK Health & Safety Laboratory (HSL) in 2001 to account for blast shielding due to buildings/structures between the explosion source and target location. The HSL methodology is based on the blast waves generated by high explosives (HE). This paper extends the blast shielding evaluation to blast waves generated from pressure vessel bursts (PVB) and vapor cloud explosions (VCE). The influences of blast wave shape parameters (overpressure, duration and rise time) on blast wave shielding are examined. The results indicate that the degree of blast shielding is strongly dependent on the source of the blast wave (i.e., on the blast wave shape parameters) and that the shielding factors obtained with HE blast waves are not always directly applicable for PVB and VCE blast waves.

Blast Wall Shielding Effectiveness

2017 ◽  
Author(s):  
Jihui Geng ◽  
J. Kelly Thomas
Keyword(s):  
Blast Wave ◽  
High Explosive ◽  
Blast Loading ◽  
Blast Waves ◽  
Shielding Effectiveness ◽  
Wave Shape ◽  
Mitigation Option ◽  
Blast Damage ◽  
Wave Parameters ◽  
Vapor Cloud

Blast walls are frequently considered as a potential mitigation option to reduce the applied blast loading on a building or structure in cases where unacceptably high levels of blast damage are predicted. There are three general explosion types of interest with respect to blast loading: High Explosive (HE), Pressure Vessel Burst (PVB), and Vapor Cloud Explosion (VCE). The blast waves resulting from these explosion types can differ significantly in terms of blast wave shape and duration. The effectiveness of a blast wall depends on these blast wave parameters (shape and duration), as well as the blast wall parameters (e.g., height, width and standoff distance from the protected structure). The effectiveness of a blast wall in terms of mitigating the blast loading on a protected structure depends on the combination of the blast wave and blast wall parameters. However, little guidance is available on the effectiveness of blast walls as a mitigation option for non-HE explosion sources. The purpose of this paper is to characterize the effect of blast wave parameters on the effectiveness of a blast wall and to provide guidance on how to determine whether a blast wall is an effective and practical blast damage mitigation option for a given blast loading.

Shock Tube Design for High Fidelity Blast Wave Simulation

2015 ◽  
Author(s):  
Christopher Ostoich ◽  
Mark Rapo ◽  
Brian Powell ◽  
Humberto Sainz ◽  
Philemon Chan
Keyword(s):  
Shock Tube ◽  
Blast Wave ◽  
Laboratory Data ◽  
Blast Waves ◽  
High Fidelity ◽  
Ongoing Research ◽  
Wave Simulation ◽  
Blast Overpressure ◽  
Blast Exposure ◽  
Significant Pathway

Traumatic brain injury (TBI) has been recognized as the signature wound of the current conflicts and it has been hypothesized that blast overpressure can contribute a significant pathway to TBI. As such, there are many ongoing research efforts to understand the mechanism to blast induced TBI, which all require blast testing using physical and biological surrogates either in the field or in the laboratory. The use of shock tubes to generate blast-like pressure waves in a laboratory can effectively produce the large amounts of data needed for research into blast induced TBI. A combined analytical, computational, and experimental approach was developed to design an advanced shock tube capable of generating high quality out-of-tube blast waves. The selected tube design was fabricated and laboratory tests at various blast wave levels were conducted. Comparisons of tube-generated laboratory data with explosive-generated field data indicated that the shock tube could accurately reproduce blast wave loading on test surrogates. High fidelity blast wave simulation in the laboratory presents an avenue to rapidly and inexpensively generate the large volumes of data necessary to validate and develop theories linking blast exposure to TBI.

Blast Event Recognition Method for Multisensor Data

2012 ◽  
Author(s):  
Mark Rapo ◽  
Chong Whang ◽  
Philemon Chan
Keyword(s):  
Blast Wave ◽  
Pressure Sensors ◽  
Recognition Algorithm ◽  
Blast Waves ◽  
Event Recognition ◽  
Lookup Table ◽  
Sensor Data ◽  
Upright Posture ◽  
Recirculating Flow ◽  
Blast Overpressure

Due to the great concern that blast overpressure can cause mild traumatic brain injury (mTBI), there is strong interest in putting sensors on warfighters to collect theater data for correlation with medical outcomes. One approach is to mount multiple pressure sensors on the warfighter to measure the blast overpressure environment. An event recognition algorithm that is based on the sensor data recordings is needed to reconstruct the incident blast wave that impacts the warfighter. Blast impingement pressure on an object is highly dependent on the angle of incidence at the point of impact; shadowing and recirculating flow effects can complicate the sensor data pattern. Using computational fluid dynamics (CFD) simulation, the present work demonstrates that for a warfighter in an upright posture in an open blast environment, a three-sensor event recognition algorithm can be developed to reconstruct the incident blast wave (generally characterized as a Friedlander wave). Three-dimensional Navier-Stokes’ based CFD simulations were performed to predict pressure recordings at the three sensor locations for a range of horizontal blast waves impacting the warfighter at all angles of incidence. The predicted peak pressures and durations were recorded and stored in a lookup table. Using an inverse problem approach, it was found that based on the three-sensor data recorded for each event, an algorithm exists for reconstructing the blast incident wave. The established event recognition algorithm is limited to warfighters with upright posture in open blast. Work is being continued to generalize and extend the method to include complex blasts involving multiple reflections and other posture orientations.

scholarly journals Guidelines to inform the generation of clinically relevant and realistic blast loading conditions for primary blast injury research

2021 ◽  
pp. bmjmilitary-2021-001796
Author(s):  
J W Denny ◽  
A S Dickinson ◽  
G S Langdon
Keyword(s):  
Blast Wave ◽  
Blast Loading ◽  
Wave Interaction ◽  
Blast Waves ◽  
Experimental Investigations ◽  
Loading Conditions ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Engineering Theory ◽  
Blast Traumatic Brain Injury

‘Primary’ blast injuries (PBIs) are caused by direct blast wave interaction with the human body, particularly affecting air-containing organs. With continued experimental focus on PBI mechanisms, recently on blast traumatic brain injury, meaningful test outcomes rely on appropriate simulated conditions. Selected PBI predictive criteria (grouped into those affecting the auditory system, pulmonary injuries and brain trauma) are combined and plotted to provide rationale for generating clinically relevant loading conditions. Using blast engineering theory, explosion characteristics including blast wave parameters and fireball dimensions were calculated for a range of charge masses assuming hemispherical surface detonations and compared with PBI criteria. While many experimental loading conditions are achievable, this analysis demonstrated limits that should be observed to ensure loading is clinically relevant, realistic and practical. For PBI outcomes sensitive only to blast overpressure, blast scaled distance was demonstrated to be a useful parameter for guiding experimental design as it permits flexibility for different experimental set-ups. This analysis revealed that blast waves should correspond to blast scaled distances of 1.75<Z<6.0 to generate loading conditions found outside the fireball and of clinical relevance to a range of PBIs. Blast waves with positive phase durations (2–10 ms) are more practical to achieve through experimental approaches, while representing realistic threats such as improvised explosive devices (ie, 1–50 kg trinitrotoluene equivalent). These guidelines can be used by researchers to inform the design of appropriate blast loading conditions in PBI experimental investigations.

scholarly journals In silico investigation of biomechanical response of a human subjected to primary blast

2021 ◽  
Author(s):  
Sunil Sutar ◽  
Shailesh Ganpule
Keyword(s):  
White Matter ◽  
Blast Wave ◽  
Rotational Motion ◽  
Blast Waves ◽  
Primary Blast ◽  
Body Model ◽  
The Past ◽  
Biomechanical Response ◽  
The Brain ◽  
Full Body

The response of the brain to the explosion induced primary blast waves is actively sought. Over the past decade, reasonable progress has been made in the fundamental understanding of bTBI using head surrogates and animal models. Yet, the current understanding of how blast waves interact with the human is in nascent stages, primarily due to lack of data in humans. The biomechanical response in human is critically required so that connection to the aforementioned bTBI models can be faithfully established. Here, using a detailed, full-body human model, we elucidate the biomechanical cascade of the brain under a primary blast. The input to the model is incident overpressure as achieved by specifying charge mass and standoff distance through ConWep. The full-body model allows to holistically probe short- (<5 ms) and long-term (200 ms) brain biomechanical responses. The full-body model has been extensively validated against impact loading in the past. In this work, we validate the head model against blast loading. We also incorporate structural anisotropy of the brain white matter. Blast wave human interaction is modeled using a conventional weapon modeling approach. We demonstrate that the blast wave transmission, linear and rotational motion of the head are dominant pathways for the biomechanical loading of the brain, and these loading paradigms generate distinct biomechanical fields within the brain. Blast transmission and linear motion of the head govern the volumetric response, whereas the rotational motion of the head governs the deviatoric response. We also observe that blast induced head rotation alone produces a diffuse injury pattern in white matter fiber tracts. Lastly, we find that the biomechanical response under blast is comparable to the impact event. These insights will augment laboratory and clinical investigations of bTBI and help devise better blast mitigation strategies.

Design Considerations for Compression Gas Driven Shock Tube to Replicate Field Relevant Primary Blast Condition

2013 ◽  
Author(s):  
Aravind Sundaramurthy ◽  
Raj K. Gupta ◽  
Namas Chandra
Keyword(s):  
Shock Tube ◽  
Blast Wave ◽  
Gaseous Product ◽  
Burst Pressure ◽  
Membrane Thickness ◽  
Time Duration ◽  
Primary Blast ◽  
Blast Overpressure ◽  
Direct Exposure ◽  
Positive Time

Detonation of a high explosive (HE) produces shock-blast wave, noise, shrapnel, and gaseous product; while direct exposure to blast is a concern near the epicenter; shock-blast can affect subjects even at farther distances. The latter is characterized as the primary blast with blast overpressure, time duration, and impulse as shock-blast wave parameters (SWPs). These parameters in turn are a function of the strength of the HE and the distance from the epicenter. It is extremely important to carefully design and operate the shock tube to produce a field relevant SWPs. In this work, we examine the relationship between shock tube adjustable parameters (SAPs) and SWPs to deduce relationship that can be used to control the blast profile and emulate the field conditions. In order to determine these relationships, 30 experiments by varying the membrane thickness, breech length (66.68 to 1209.68 mm) and measurement location was performed. Finally, ConWep was utilized for the comparison of TNT shock-blast profiles with the profiles obtained from shock tube. From these experiments, we observed the following: (a) burst pressure increases with increase in the number of membrane used (membrane thickness) and does not vary significantly with increase in the breech length; (b) within the test section, overpressure and Mach number increases linearly with increase in the burst pressure; however, positive time duration increases with increase in the breech length; (c) near the exit of the shock tube, there is a significant reduction in the positive time duration (PTD) regardless of the breech length.

Blast Wave Mitigation from the Straight Tube by Using Water Part II - Numerical Simulation

2018 ◽  
Vol 910 ◽  
pp. 78-83 ◽  
Author(s):  
Yuta Sugiyama ◽  
Tomotaka Homae ◽  
Kunihiko Wakabayashi ◽  
Tomoharu Matsumura ◽  
Yoshio Nakayama
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Energy Transfer ◽  
Numerical Simulations ◽  
Blast Wave ◽  
Blast Waves ◽  
Straight Tube ◽  
Water Interface ◽  
Effect Of Water ◽  
Air Water Interface

This paper investigates explosions in a straight square tube in order to understand the mitigation effect of water on blast waves that emerge outside. Numerical simulations are used to assess the effect of water that is put inside the tube. The water reduces the peak overpressure outside, which agrees well with the experimental data. The increases in the kinetic and internal energies of the water are estimated, and the internal energy transfer at the air/water interface is shown to be an important factor in mitigating the blast wave in the present numerical method.

scholarly journals GRB 030329: 3 years of radio afterglow monitoring

2007 ◽  
Vol 365 (1854) ◽  
pp. 1241-1246 ◽  
Author(s):  
A.J van der Horst ◽  
A Kamble ◽  
R.A.M.J Wijers ◽  
L Resmi ◽  
D Bhattacharya ◽  
...  
Keyword(s):  
Blast Wave ◽  
Gamma Ray ◽  
Ambient Medium ◽  
Low Frequency ◽  
Blast Waves ◽  
Physical Parameters ◽  
Late Time ◽  
Wave Band ◽  
Radio Telescopes ◽  
Relativistic Phase

Radio observations of gamma-ray burst (GRB) afterglows are essential for our understanding of the physics of relativistic blast waves, as they enable us to follow the evolution of GRB explosions much longer than the afterglows in any other wave band. We have performed a 3-year monitoring campaign of GRB 030329 with the Westerbork Synthesis Radio Telescopes and the Giant Metrewave Radio Telescope. Our observations, combined with observations at other wavelengths, have allowed us to determine the GRB blast wave physical parameters, such as the total burst energy and the ambient medium density, as well as to investigate the jet nature of the relativistic outflow. Further, by modelling the late-time radio light curve of GRB 030329, we predict that the Low-Frequency Array (30–240 MHz) will be able to observe afterglows of similar GRBs, and constrain the physics of the blast wave during its non-relativistic phase.

scholarly journals Vortex structures and turbulence emerging in a supernova 1987a configuration: Interactions of “complex” blast waves and cylindrical/spherical bubbles

2003 ◽  
Vol 21 (3) ◽  
pp. 471-477 ◽  
Author(s):  
SHUANG ZHANG ◽  
NORMAN J. ZABUSKY ◽  
KATSUNOBU NISHIHARA
Keyword(s):  
Blast Wave ◽  
Flow Instability ◽  
Supernova Explosion ◽  
Blast Waves ◽  
High Density ◽  
Supernova 1987A ◽  
Planar Shock ◽  
Spherical Bubbles ◽  
Inhomogeneous Flow ◽  
Piecewise Parabolic

We examine the interaction of both cylindrical and spherical bubbles (2D) and acomplexblast wave, which consists of an approaching shock/contact discontinuity/shock (Kanget al., 2001a, 2001b). Such configurations may arise following a supernova explosion, for example, SN 1987A, where a complex blast wave is presently approaching a high density “circumstellar ring” (CR) (Borkowskiet al., 1997). Using simulations with the piecewise parabolic method algorithm (Colella & Woodward, 1984), we emphasize the appearance of vortex bilayers, vortex projectiles, and turbulent domains on the downstream and upstream sides of the bubble. We believe that the interfacial deformation of the CR is associated with astrong blast-wave driven accelerated inhomogeneous flow instabilityin ahigh densitymedium and thus will have a different character than the more common planar shock-driven Richtmyer–Meshkov instability.

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