Blast Mitigation by Water Mist (2) Shock Wave Mitigation Using Glass Particles and Water Droplets in Shock Tubes

Schwer, Douglas A.; Kailasanath, K.

doi:10.21236/ada411687

Cited by 9 publications

(15 citation statements)

References 17 publications

(24 reference statements)

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“…For a singledroplet, the high velocity correction term is based on Clift [21], and the vaporization and heat-transfer convective corrections are based on a Ranz-Marshall correlation [22]. Calculation of the source terms is described in detail in [12]. The resulting source terms for transfer of mass from sectionj to sectionj-1 from droplet vaporization is…”

Section: J=lmentioning

confidence: 99%

“…Our simulations have all focused on TNT explosions; however, other explosives could easily be substituted using this initialization procedure. Data for other explosives is provided in Appendix A. Verification and validation of the solution procedure for blasts and particle interactions has been reported in [11,12].…”

Section: Solution Proceduresmentioning

confidence: 99%

“…Our group has had extensive involvement in simulating the ability of water mist to suppress both gas jet flames [8,9] and liquid pool fires [10] using a multiphase simulation technique, and extension of these techniques to blast mitigation scenarios has been straight forward [11,12].…”

Section: Introductionmentioning

confidence: 99%

“…The first report [ 11] discussed modeling of confined and unconfined blasts without mitigation. The second report [ 12] discussed in depth the modeling of the dispersed-phase, and applied this model to predict characteristics of shock waves impinging on particles or droplets. The shock waves were generated by a shock tube and presented an ideal environment to study different fundamental characteristics of particle and droplet-shock wave interaction.…”

Section: Introductionmentioning

confidence: 99%

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Blast Mitigation by Water Mist, (3) Mitigation of Confined and Unconfined Blasts

Schwer¹,

Kailasanath²

2006

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. REPORT DATE (DD-MM-YYYY)2. REPORT TYPE 3. DATES COVERED (From -To) SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES)10. SPONSOR / MONITOR'S ACRONYM(S) SPONSOR/ MONITOR'S REPORT NUMBER(S)12. DISTRIBUTION /AVAILABILITY STATEMENT Approved for public release; distribution is unlimited. SUPPLEMENTARY NOTES ABSTRACTThis is the third in a series of reports focusing on numerical simulations of blasts and blast mitigation. This report uses the models developed in the first two to specifically examine the effect of water mists consisting of sub-50-micron droplets on blast shock-fronts and the development of quasi-static overpressure in enclosed spaces. In unconfined blasts, results showed that the water mist does not directly suppress the secondary reactions. Mitigation of the shock-front is accomplished mainly through momentum extraction and not vaporization. Quantitative results determined the exact effect of 5 to 50 micron sized droplets on the shock-front. Droplet size was found to play a secondary role compared to mass loading. Smaller droplets were less effective close to the explosive, while further downstream, the optimum droplet size depended on mass loading. The total amount of water mass between the observer and explosive was the most important factor in determining the amount of mitigation seen by the observer. Simulations were also conducted to determine the effectiveness of water mist to mitigate quasi-static pressure build-up in enclosures. Comparisons with experiments conducted at NSWC were used to validate the models and showed that the models could predict the overall mitigation efficiency to within a few percent. Absolute values of the simulation quasi-static overpressure tended to be slightly higher than experimental values, most likely because various loss mechanisms (incomplete combustion, absorption of energy by walls, and venting) were not incorporated into the model. Results also suggested that multi-dimensional simulations were required compared with simple thermodynamic and one-dimensional computations. Finally, additional needed computational work is summarized in the report. Many of the...

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Section: J=lmentioning

confidence: 99%

Section: Solution Proceduresmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Blast Mitigation by Water Mist, (3) Mitigation of Confined and Unconfined Blasts

Schwer¹,

Kailasanath²

2006

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“…There are modeling data that show the ability of mist to reduce overpressure and therefore limit shipboard damage caused by an explosion from a combat or terrorist attack [4][5][6]. Water mist, water-walls, and active and passive water deluge systems as a blast mitigating techniques have proven to be quite effective in reducing the effects caused by condensed-phase explosions and vapor-cloud explosions [7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

Blast Mitigation Using Water Mist: Test Series II

Willauer¹,

Ananth²,

Farley³

et al. 2009

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Standard Form 298 (Rev. 8-98)Prescribed by ANSI Std. Z39.18Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. The effects water mist has on the overpressures produced by the detonation of 50 lb equivalent of high explosives (HE) TNT, Destex, and PBXN-109 in a chamber is reported. The overpressures for each charge density were measured with and without mist preemptively sprayed into the space. The impulse, initial blast wave, and quasi-static overpressure measured in the blast mitigation experiments were reduced by as much as (40%, 36%, and 35%) for 50 lbs TNT, (43%, 25%, and 33%) for 50 lbs TNT equivalent Destex, and (49%, 39%, and 41%) for 50 lbs TNT equivalent PBXN-109 when water mist was sprayed 60 seconds prior to detonation at a concentration of 70 g/m 3 and droplet Sauter Mean Diameter (SMD) of 54 mm. These results suggest that current water mist technology is a potentially promising concept for the mitigation of overpressure effects produced from the detonation of high explosives. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S ACRONYM(S) 9. SPONSORING / MONITORING AGENCY NAME(S) AND ADDRESS(ES) SPONSOR / MONITOR'S REPORT NUMBER(S)

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Effects of Fine Water Mist on a Confined Blast

et al. 2010

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A computational, multi-phase, model has been developed to study the interactions between water droplets and radial expansion of a gas cloud in a spherical chamber. Initial conditions for the gas cloud are specified based on chemical equilibrium calculations for the detonation of a high explosive (RDX). Mono-dispersed water droplets are injected at uniform concentration into the chamber prior to the expansion. A Lagrangian model is used to track the breakup of the parent drops near the shock front to form child drops, which are extremely small. The NavierStokes solutions show that the child droplets accumulate near the shock front and evaporate at 100 times higher rate than the parent droplets. Latent heat absorption is the dominant mechanism followed by the sensible heat absorption by the water vapor (and droplets), and momentum absorption from the high velocity gases by the child droplets. The simulations also show that the water vapor formed by the evaporation increases the gas density at the shock front. The increased density and reduced gas temperature (cooling) have opposite effects on the pressure at the shock front. This leads to only a modest suppression in the pressure. At realistic droplet concentrations (0.08 kg droplets/m 3 of air), the water mist is shown to evaporate completely in a short time (2.42 ms) prior to shock reflection at the chamber wall mainly due to the breakup at the shock front. High concentrations of mist may be desirable, but are difficult to achieve in practice at the total flooding conditions.

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Blast Mitigation by Water Mist (2) Shock Wave Mitigation Using Glass Particles and Water Droplets in Shock Tubes

Cited by 9 publications

References 17 publications

Blast Mitigation by Water Mist, (3) Mitigation of Confined and Unconfined Blasts

Blast Mitigation by Water Mist, (3) Mitigation of Confined and Unconfined Blasts

Blast Mitigation Using Water Mist: Test Series II

Effects of Fine Water Mist on a Confined Blast

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