An Experimental Study on the Effects of Burst Pressure on Air Blast Development in a Blast Wave Simulator

2021 ◽  
Author(s):  
Parker Zieg ◽  
John Benson ◽  
Yang Liu
Keyword(s):  
Blast Wave ◽  
High Speed ◽  
Imaging System ◽  
Blast Waves ◽  
Burst Pressure ◽  
Schlieren Image ◽  
Membrane Thickness ◽  
Pressure Sensing ◽  
Point Pressure ◽  
Driver Section

Abstract Due to the extensive use of explosive devices in military conflicts, there has been a dramatic increase in life-threatening injuries and resultant death toll caused by explosive blasts. In an attempt to better understand the blast waves and mitigate the damages caused by such blast waves, various devices/systems have been developed to replicate the field blast scenarios in laboratory conditions. The East Carolina University Advanced Blast Wave Simulator (i.e., ECU-ABWS) is one such facility that can reproduce blast waves of various shapes and profiles. The peak overpressure of a blast is the key factor that causes the greatest number of damages, and it is essentially determined by the burst pressure of the blast. Therefore, a better understanding of the effects of burst pressure on blast generation and development is strongly desired to develop safer and more effective blast mitigation technologies. In the present study, a series of experiments were carried out in the ECU-ABWS to characterize the blast waves generated under different burst pressure conditions. While the incident (side-on) pressures at multiple locations along the blast propagation direction were measured using a temporally-resolved multi-point pressure sensing system, the time-evolutions of blast wave profiles were also qualitatively revealed by using a high-speed Schlieren imaging system. The synchronization of pressure sensing and Schlieren image acquisition enables us to extract more physical details of the dynamic blast wave development under different burst pressure conditions by associating the incident pressures and shock wave morphologies. In this study, the different burst pressures were achieved by altering the thickness of the membrane separating the driver section of pressurized gas and the driven section of air at atmospheric pressure. It is found that there is a linear relationship between the burst pressure and the peak overpressure. As the burst pressure increases (by increasing the membrane thickness), more clearly defined shock wavefronts are also observed along with the peak overpressure increase.

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.

Plane blast wave interaction with an elongated straight and inclined heat-generated inhomogeneity

2018 ◽  
Vol 851 ◽  
pp. 245-267 ◽  
Author(s):  
S. Sembian ◽  
M. Liverts ◽  
N. Apazidis
Keyword(s):  
Blast Wave ◽  
High Speed ◽  
Quadratic Function ◽  
Wave Interaction ◽  
Numerical Data ◽  
Ambient Air ◽  
Blast Waves ◽  
Incident Plane ◽  
Gradual Loss ◽  
Two Factors

The unstable evolution of an elongated elliptically shaped inhomogeneity that is embedded in ambient air and aligned both normal and at an angle to an incident plane blast wave of impact Mach number 2.15 is investigated both experimentally and numerically. The elliptic inhomogeneities and the blast waves are generated using gas heating and exploding wire technique and their interaction is captured optically using shadowgraph method. While two symmetric counter-rotating vortices due to Richtmyer–Meshkov instability are observed for the straight interaction, the formation of a train of vortices similar to Kelvin–Helmholtz instability, introducing asymmetry into the flow field, are observed for an inclined interaction. During the early phase of the interaction process in the straight case, the growth of the counter-rotating vortices (based on the sequence of images obtained from the high-speed camera) and circulation (calculated with the aid of numerical data) are found to be linear in both space and time. Moreover, the normalized circulation is independent of the inhomogeneity density and the ellipse thickness, enabling the formulation of a unique linear fit equation. Conversely, the circulation for an inclined case follows a quadratic function, with each vortex in the train estimated to move with a different velocity directly related to its size at that instant. Two factors influencing the quadratic nature are identified: the reduction in strength of the transmitted shock thereby generating vortices with reduced vorticity, along with the gradual loss of vorticity of the earlier-generated vortices.

Some Consideration on the Aerodynamic Design of Blast Wave Simulator Using a Shock Tube System

2019 ◽  
Author(s):  
Suguru Kushida ◽  
Kengo Asada ◽  
Kozo Fujii ◽  
Tomoaki Tatsukawa ◽  
Kazuyuki Sakamoto
Keyword(s):  
Shock Tube ◽  
Blast Wave ◽  
Nozzle Exit ◽  
Jet Flow ◽  
Blast Waves ◽  
Aerodynamic Design ◽  
Computational Simulations ◽  
Tube System ◽  
Reduction Methods ◽  
Driver Section

Abstract Reduction methods of the jet flow associated with simulated blast waves by blast wave simulators are investigated by computational simulations. First, the cause of the jet flow is discussed. After that, the influence of the nozzle angle and the volume of the driver section on the jet flow are investigated. The obtained results show that the jet flow is caused by vortices which are generated at the edge of the nozzle and that the jet can be reduced by decreasing the driver section. Furthermore, the nozzle with the moderate angle reduces the jet flow near the nozzle exit and the nozzle with the widest angle reduces the jet flow far from the nozzle exit. These results indicate reducing the driver section and using the proper nozzle angle according to the distance from the nozzle exit are effective for reducing the jet flow.

The properties of a blast wave obtained from an analysis of the particle trajectories

1971 ◽  
Vol 324 (1558) ◽  
pp. 275-299 ◽  
Keyword(s):  
Blast Wave ◽  
High Speed ◽  
Time Derivative ◽  
Blast Waves ◽  
High Speed Photography ◽  
Flow Properties ◽  
Particle Trajectories ◽  
Adiabatic Flow ◽  
First Time ◽  
Shock Fronts

It is shown that all of the flow properties within an unsteady shock wave of intermediate strength can be determined by an analysis of the experimentally observed particle trajec­tories. The analysis has been applied to the blast waves from two large trinitrotoluene (t. n. t.) explosions. The particle trajectories were observed by high-speed photography of smoke tracers formed close to the charges immediately before detonation. The density throughout the flow was determined by application of the Lagrangian conservation of mass equation. This was then used to calculate the pressure, assuming adiabatic flow for each air element between shock fronts. The temperature and sound speed throughout the flow were found from the pressure and density, assuming a perfect gas equation of state. The particle velocity within the flow was obtained from the time derivative of the observed particle trajectories. The results have been compared with other blast measurements and with theoretical calcula­tions. It is estimated that the technique gives the flow properties to an accuracy comparable with that for other forms of measurement, namely, 5 to 10%. This is the first time that it has been possible to describe all the properties of a blast wave based on experimental measurements, only.

Betadine has a ciliotoxic effect on ciliated human respiratory cells

2014 ◽  
Vol 129 (S1) ◽  
pp. S45-S50 ◽  
Author(s):  
J H Kim ◽  
J Rimmer ◽  
N Mrad ◽  
S Ahmadzada ◽  
R J Harvey
Keyword(s):  
Epithelial Cells ◽  
High Speed ◽  
Imaging System ◽  
Beat Frequency ◽  
Ciliary Beat Frequency ◽  
Positive Control ◽  
Clinical Dose ◽  
Significant Difference ◽  
Sinonasal Mucosa ◽  
Ciliary Beat

AbstractObjective:This study investigated the effect of Betadine on ciliated human respiratory epithelial cells.Methods:Epithelial cells from human sinonasal mucosa were cultured at the air–liquid interface. The cultures were tested with Hanks' balanced salt solution containing 10 mM HEPES (control), 100 µM ATP (positive control), 5 per cent Betadine or 10 per cent Betadine (clinical dose). Ciliary beat frequency was analysed using a high-speed camera on a computer imaging system.Results:Undiluted 10 per cent Betadine (n = 6) decreased the proportion of actively beating cilia over 1 minute (p < 0.01). Ciliary beat frequency decreased from 11.15 ± 4.64 Hz to no detectable activity. The result was similar with 5 per cent Betadine (n = 7), with no significant difference compared with the 10 per cent solution findings.Conclusion:Betadine, at either 5 and 10 per cent, was ciliotoxic. Caution should be applied to the use of topical Betadine solution on the respiratory mucosal surface.

Optical diagnostics and multi-point pressure sensing on the knocking combustion with multiple spark ignition

2022 ◽  
Vol 236 ◽  
pp. 111802
Author(s):  
Hao Shi ◽  
Qinglong Tang ◽  
Kalim Uddeen ◽  
Gaetano Magnotti ◽  
James Turner
Keyword(s):  
Optical Diagnostics ◽  
Spark Ignition ◽  
Pressure Sensing ◽  
Point Pressure
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