Water shocks

Detonation Parameters Chapman-Jouguet Pressure, Energy, and Isentropic Exponent from Water Shock Measurements 11... 

A. Sakurai, "Water Shock Waves from Above -Water Explosions , Rept AEWES-Misc Paper-1 -808, Army Engineers Waterways ExptI Sta,... 

C. Subsurface Burst. A subsurface burst weapon is detonated beneath the surface of land or water. Cratering will generally result from an underground burst, just as for a surface burst. If the burst does not penetrate the surface, the only other hazard will be from ground or water shock. If the burst is shallow enough to penetrate the surface, blast, thermal, and initial nuclear radiation effects will be present, but will be less than for a surface burst of comparable yield. Local fallout will be very heavy if penetration occurs. 

Figure 13 gives selected frames from another sequence in which the confinement medium is water. This has the advantage that the products are slowed and the reaction front can be followed. The sequence also shows the important result that initiation can take place away from the interface when the water shock meets a discontinuity in the crystal. 

That such an event is not an isolated example and occurs with other azides has been shown in recent work by Chaudhri and Field [28]. They obtained a sequence in which crystals of silver and jS-lead azides were mounted side by side. In both cases initiation occurred at the interface, but also later when the water shock interacts with discontinuities near the ends of the crystals. Since the reaction fronts in the crystals were subsonic it was possible for the shocks in the crystals, as well as stress waves produced by reaction, to travel ahead. The waves were capable of fracturing the crystals (by, for example, a spall-type mecha-... 

Figure 13. A silver azide crystal in water is shocked from below. Reaction starts at the barrier interface and also at defect sites, A, when the water shock reaches them. Length of crystal 11.9 mm, diameter 120 urn frame interval, 0.7 Msec [76].

Results were obtained for crystals in air, in water confinement, and in a furnace heated to 373°K. Water confinement had various advantages since it prevented products from obscuring the reaction front, allowed the water shock and its strength to be observed, and changed the confinement conditions. The results of Table XIII show that reaction in lead and silver azides propagates in thin crystals as a deflagration (subsonic) with a velocity that increases with crystal thickness (minimum dimension). 

Initial velocity of Strength of initial of water shock water shock (m/sec) (kbar)... 

Figure 2.46 shows that the pressure drops faster when it is close to the explosion center while the pressure drop slows down once it is far from the explosion center. In addition, in the explosion of liquid explosives under/in water, the positive impact time of shock waves is longer following the distance increasing, but it is much shorter than that of air shock waves. The impact time in water is only about 1/100 of that in air because the speed difference between fronts and tails is smaller in water. For example, when the pressure of water shock waves is P = 500 MPa, the velocity/rate of water shock waves is 2,040 m/s (when the pressure of water shock waves is 5 MPa (1/100 of water), the velocity of air shock waves is 2,230 m/s). When the pressure drops down to 25 MPa, the propagation velocity of water shock waves is close to sound rate (about 1,450-1,500 m). Now the fronts and waves have similar propagation rate. 

Like the explosion on the ground, explosion in water increases the pressure of water shock waves. For rigid water bottom, it equals two times of explosion power. In fact, the water bottom is not absolutely rigid, and it absorbs part of energy. Experiments indicate that in the water bottom with sandy soils, shock wave pressure increases up 16 % and impulse goes up 35 %. 

In summary, the explosion of explosives in/under water generates water shock waves, bubble impulse, and pressure waves. All of these can cause serious damage for the targets. 

Storage Keep away from heat and flame keep container closed when not in use Uses Fragrance in cosmetics, perfumes Features Normally stable even elevated temps, and pressures nonpyrophoric nonreactive with water shock-stable does not form explosive mixts. with org. materials Regulatory SARA 313 nonreportable Manuf./Distrib. Firmenich... 

Andrieu, Sykes), which can generate a shallow water shock (Buguin, Vorelle). On a liquid substrate, viscous dissipation no longer takes place in the rim, but rather in the substrate, and in a much reduced form. If the substrate has low viscosity, the behaviour resembles that in suspended films (Martin, Buguin) (see Fig. 1.30). 

Inside a cell, a thiol might form a stable complex with a particular cellular constituent. Cystamine- S does not seem to form any particularly marked complexes with the cell nuclei, mitochondria and microsomes of liver and spleen , while cysteamine- S forms a very tight complex with the dinucleoprotein, which cannot be disrupted by repeated water shock and extraction . 

Hyndman, D. A. and Gaffney, E. S, "Development of PVDF Water Shock Gauges," Ktech Corp., Albuquerque, NM, Rept. TR-89-19, July 1989. 

Using BKW one can program additional reaction of the remaining ammonium nitrate along the isentrope to approximate the additional energy release that the aquarium data requires. Several rates of additional ammonium nitrate reaction were therefore programmed into BKW and the isentropes were used to calculate the position of the interface and water shock. Several of the rates could reproduce the observations one such rate is shown in Figure 2.18. The observed detonation velocity of about 0.35 cm/)usec can be reproduced if 55% of the ammonium nitrate is assumed to not react at the C-J point. 

Figure 2.17 Calculated and experimental water shock and explosive-water interface profiles for a 5-cm-radius cylinder of ANFO confined by water. Fifty-five percent of the aluminum nitrate is assumed to remain unreacted. The experimental profile is shown by circles. The isobar interval is 1 kbar.

To further test the weak detonation model, S. Goldstein measured the water shock velocity in the aquarium test after the detonation wave interacted with the water above the top of the X0233 cylinder. Her experimental water shock velocities, as a function of distance above the top of the explosive cylinder, are shown in Figure 2.28 along with the calculated water shock velocities. They are consistent with a flat top Taylor wave characteristic of a weak detonation and a detonation front pressure of 160 kbars. The initial water shock velocities exhibit behavior characteristic of irregular decomposition of the explosive near the shock front. The 2DL calculated aquarium pressure contours are shown in Figure 2.29. 

The displaced BKW isentrope that will describe the observed plate dent, aquarium water shock profiles, explosive interface, and the detonation velocity of X0233 exhibits a weak detonation behavior. 

The SIN code described in Appendix A was used to study the flow resulting from detonation of a 3.27 cm radius sphere of Tetryl in water at various initial pressures and densities. The calculation model used 1000 cells with the explosive initially resolved to 0.1 cm and the first 10 cm of water resolved to 0.25 cm. For the low initial pressure calculations, the water cell width was then increased to allow sufficient distance to follow the water shock during the time of interest. 

Numerical calculations of underwater detonations have been performed by many investigators the work of Sternberg and Walker is an example. Using the proper method for burning the explosive results in lower initial water shock pressures than reported in reference 13, which used the Taylor self-similar solution to describe the explosive that was shown to be incorrect in Chapter 2. 

Figure 5.6 Water shock and Tetryl water interface pressure as a function of time for a 3.27 cm radius Tetryl sphere in water at 4660 bars.

Figures 5.15 and 5.16 show early time profiles for several of the cases studied. Note that higher hydrostatic pressure systems have nearly the same pressure-time profiles as do the lower hydrostatic pressure systems until the Tetryl-water interface pressure drops to near the hydrostatic pressure. The pressure gradient behind the water shock becomes less steep for the higher hydrostatic pressure systems and determines when the bubble will collapse. At lower hydrostatic pressures, many reverberations occur during expansion and collapse of the bubble. The pressure-time and pressure-distance profiles become very complicated.

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