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Publications (4 of 4) Show all publications
Sembian, S., Liverts, M. & Apazidis, N. (2018). Plane blast wave propagation in air with a transverse thermal inhomogeneity. European journal of mechanics. B, Fluids, 67, 220-230
Open this publication in new window or tab >>Plane blast wave propagation in air with a transverse thermal inhomogeneity
2018 (English)In: European journal of mechanics. B, Fluids, ISSN 0997-7546, E-ISSN 1873-7390, Vol. 67, p. 220-230Article in journal (Refereed) Published
Abstract [en]

An alternate mechanism explaining the shock broadening and splitting effects observed during its propagation through an elongated region with transverse thermal inhomogeneity is described. The shock wave is generated by exploding wire technique and its propagation is captured optically using shadowgraph method. Visualizing the flow provided distinct advantage not only for obtaining detailed information on the propagation characteristics but also for validating the numerical scheme used in the analysis. Three physical features namely shock jump, precursor region and vorticity induced flow, are identified to contribute to the shock structure with the latter two being responsible for the pressure profile ‘broadening’. The physical behavior of the incident shock is also analyzed along with other factors like temperature and curvature effects.

Place, publisher, year, edition, pages
Elsevier, 2018
Keywords
Exploding wire, Shock broadening/splitting, Shock curvature, Thermal inhomogeneity, Shock waves, Wave propagation, Blast wave propagation, Exploding wire technique, Physical behaviors, Propagation characteristics, Shadowgraph method, Exploding wires
National Category
Mechanical Engineering
Identifiers
urn:nbn:se:kth:diva-216806 (URN)10.1016/j.euromechflu.2017.09.011 (DOI)000418726900021 ()2-s2.0-85030309669 (Scopus ID)
Funder
Swedish Research Council, 621-2014-5678
Note

QC 20180111

Available from: 2017-12-05 Created: 2017-12-05 Last updated: 2018-05-18Bibliographically approved
Sembian, S., Liverts, M. & Apazidis, N. (2016). Attenuation of strong external blast by foam barriers. Physics of fluids, 28(9), Article ID 096105.
Open this publication in new window or tab >>Attenuation of strong external blast by foam barriers
2016 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 28, no 9, article id 096105Article in journal (Refereed) Published
Abstract [en]

The mitigation of externally generated strong blast waves by an aqueous foam barrier of varying configurations within fixed distance between the explosion origin and the object to be protected is investigated and quantified both experimentally and numerically. The blast waves of shock Mach number 4.8 at 190 mm from the explosion plane are generated using exploding wire technique. The initially cylindrical blast waves are transformed into a plane blast wave in a specially constructed test unit in which the experiments are performed. The shock waves emanating from the foam barrier are captured using shadowgraph technique. A simple numerical model treating the foam by a pseudo-gas approach is used in interpreting and reconstructing the experimental results. The additional contribution of the impedance mismatch factor is analysed with the aid of numerical simulation and exploited for achieving greater blast wave pressure reduction.

Place, publisher, year, edition, pages
American Institute of Physics Inc, 2016
Keywords
Numerical models, Shock waves, A-plane, Aqueous foams, Blast waves, Exploding wire technique, Impedance mismatch factors, Shadowgraph technique, Test unit, Exploding wires
National Category
Applied Mechanics
Identifiers
urn:nbn:se:kth:diva-194875 (URN)10.1063/1.4963243 (DOI)000384878900039 ()2-s2.0-84989361083 (Scopus ID)
Note

QC 20161213

Available from: 2016-12-13 Created: 2016-11-01 Last updated: 2018-05-18Bibliographically approved
Liverts, M. & Apazidis, N. (2016). Limiting Temperatures of Spherical Shock Wave Implosion. Physical Review Letters, 116(1), Article ID 014501.
Open this publication in new window or tab >>Limiting Temperatures of Spherical Shock Wave Implosion
2016 (English)In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 116, no 1, article id 014501Article in journal (Refereed) Published
Abstract [en]

Spherical shock wave implosion in argon is studied both theoretically and experimentally. It is shown that as the strength of the converging shock increases the nonideal gas effects become dominant and govern the evolution of thermal and transport gas properties limiting the shock acceleration, lowering the gas adiabatic index and the achievable energy density at the focus. Accounting for multiple-level ionization, excitation, Coulomb interaction and radiation effects, the limiting equilibrium temperatures to be achieved during the shock implosion are estimated. Focal temperatures of the order of 30 000 K are measured in experiments where converging spherical shock waves are created using a conventional gas-dynamic shock tube facility.

Place, publisher, year, edition, pages
American Physical Society, 2016
Keywords
IONIZATION, ARGON, STABILITY, PLASMA, GASES
National Category
Physical Sciences
Identifiers
urn:nbn:se:kth:diva-181361 (URN)10.1103/PhysRevLett.116.014501 (DOI)000367677300001 ()2-s2.0-84954541374 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20160205

Available from: 2016-02-05 Created: 2016-02-01 Last updated: 2017-11-30Bibliographically approved
Liverts, M., Ram, O., Sadot, O., Apazidis, N. & Ben-Dor, G. (2015). Mitigation of exploding-wire-generated blast-waves by aqueous foam. Physics of fluids, 27(7), Article ID 076103.
Open this publication in new window or tab >>Mitigation of exploding-wire-generated blast-waves by aqueous foam
Show others...
2015 (English)In: Physics of fluids, ISSN 1070-6631, E-ISSN 1089-7666, Vol. 27, no 7, article id 076103Article in journal (Refereed) Published
Abstract [en]

In this work, we implement an exploding wire technique to generate small-scale cylindrical blast waves in aqueous foam. The exploding wire system offers an easy to operate and effective tool for studying blast-wave/foam interaction related phenomena in real explosion scenarios. The mitigation of blast waves as a function of the thickness of the foam barrier is discussed and quantified. A fluid mixture pseudo-gas based numerical approach with the aid of the point explosion theory is used to separate the mitigation mechanisms into the near-and the far-field related groups and to analyze the contribution of each group to the overall losses of the blast wave energy.

National Category
Mechanical Engineering Other Physics Topics
Identifiers
urn:nbn:se:kth:diva-172723 (URN)10.1063/1.4924600 (DOI)000358872200040 ()2-s2.0-84937019630 (Scopus ID)
Note

QC 20150828

Available from: 2015-08-28 Created: 2015-08-27 Last updated: 2017-12-04Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0003-1475-5351

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