Abstract:
An underwater hydro-reactive explosive system includes a pressure vessel with a central section of water disposed between identical sections of a material selected from the group consisting of thermites, intermetallics, nano-sized metallic particles, and micro-sized metallic particles. The water is provided in a stoichiometric quantity that provides a complete reaction with the material following simultaneous detonation of the sections thereof.

Description:
ORIGIN OF THE INVENTION 
     The invention described herein was made in the performance of official duties by employees of the Department of the Navy and may be manufactured, used, licensed by or for the Government for any governmental purpose without payment of any royalties thereon. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to underwater explosives, and more particularly to a hydro-reactive explosive system for generating an explosion in an underwater environment. 
     BACKGROUND OF THE INVENTION 
     Underwater explosive devices include hydro-reactive devices in which elements of the device react exothermically to form a hot reaction mass that produces an explosion when the reaction mass comes into contact with water. The explosion produces shock energy, bubble energy, and impulse. Ideally, the explosion is generated with little or no waste energy production and little or no material waste in the form of unreacted elements. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an object of the present invention to provide an underwater hydro-reactive explosive system. 
     Another object of the present invention is to provide a hydro-reactive explosive system that efficiently generates explosion products. 
     Other objects and advantages of the present invention will become more obvious hereinafter in the specification and drawings. 
     In accordance with the present invention, an underwater hydro-reactive explosive system includes a pressure vessel with a hydro-reactive explosive stack confined therein. The stack includes a central section of water disposed between identical sections of a material selected from the group consisting of thermites, intermetallics, nano-sized metallic particles, and micro-sized metallic particles. The water is provided in a stoichiometric quantity that provides a complete reaction with the material following simultaneous detonation of the sections thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other objects, features and advantages of the present invention will become apparent upon reference to the following description of the exemplary embodiments and to the drawings, wherein corresponding reference characters indicate corresponding parts throughout the several views of the drawings and wherein: 
         FIG. 1  is a schematic view of an underwater hydro-reactive explosive system in accordance with an embodiment of the present invention; and 
         FIG. 2  is a schematic view of an underwater hydro-reactive explosive system in accordance with another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring now to the drawings and more particularly to  FIG. 1 , an underwater hydro-reactive explosive system in accordance with the present invention is shown and is referenced generally by numeral  10 . Explosive system  10  can be a stand-alone system or could be incorporated into a delivery vehicle (e.g., a torpedo) without departing from the scope of the present invention. Further, the term “underwater” as used herein refers to seawater and fresh water environments. 
     Explosive system  10  includes an outer housing  12 , and two sections  14  and  16  of explosively-activated reactive material sandwiching a chamber of water  18 . Identical detonators  30  and  32  are coupled to the outermost and opposing end regions of sections  14  and  16 , respectively, and a single detonation signal trigger device  34  is coupled to detonators  30  and  32 . Housing  12  can completely envelope/encase sections  14 / 16  and water  18  therein up to detonators  30  and  32  as shown. However, the present invention is not so limited as housing  12  could also encase detonators  30  and  32  without departing from the scope of the present invention. Still further, housing  12  can be defined by a portion of a delivery vehicle designed to transport explosive system  10  to a desired underwater detonation location. As will be explained further below, housing  12  is generally constructed to operate as a pressure vessel that temporarily confines an explosion generated when sections  14 / 16  react with water  18 . Such pressure vessel construction and materials used to construct the pressure vessel are well understood in the art. 
     In general, sections  14  and  16  are identically configured in terms of an exothermic reaction mass generated when they are explosively driven into water  18 . Prior to activation of system  10 , sections  14  and  16  include a reactive material that is kept isolated from water  18 . The reactive material for this embodiment is a material that generates hot products when detonated. The detonation also drives the hot products into water  18  where they react therewith to form an explosion. Such reactive materials include thermites, intermetallics (e.g., titanium/boron), or metallic particles mixed with a high explosive such as TNT, RDX, HMX, etc. 
     When, system  10  is activated by means of a simultaneous detonation of detonators  30  and  32  (via trigger device  34 ), the reactive material in each of sections  14  and  16  is simultaneously converted to hot products and is driven in opposing fashion into water  18 . By explosively driving the hot products into water  18  from opposing locations/directions, fast mixing and heating of the reactive material and water  18  occurs. At the same time, the opposing shock waves from the simultaneous detonation occurring in sections  14  and  16  creates a mach stem in water  18  thereby increasing the temperature, pressure and turbulent mixing occurring in water  18 . As mentioned above, housing  12  is designed to briefly confine and inwardly direct the shockwaves associated with the simultaneous detonations and then fragment and disperse radially outward when the shockwaves impact housing  12 . 
     Water  18  can be fresh water (e.g., tap water, distilled water, environmental water, etc.) or seawater without departing from the scope of the present invention. The amount of water  18  provided in system  10  should be a stoichiometric amount necessary for water  18  to form a complete reaction with the hot products driven therein from sections  14  and  16  upon the simultaneous detonation thereof. 
     Another embodiment of the present invention is illustrated in  FIG. 2  and is referenced generally by numeral  20 . Explosive system  20  includes a cylindrical housing  22  containing a layered arrangement of elements in accordance with the present invention. Starting at one axial end of housing  22 , explosive system  20  has the following: an explosive  23  fitted in and sealed against one axial end of housing  22 ; a pure-fuel reactive material  24  (e.g., micro or nano-sized metallic particles such as aluminum or magnesium that react/explode in the presence of water) adjacent explosive  23  and spanning a section of housing  22 ; a liquid-impervious barrier  25  adjacent reactive material  24  and spanning the diameter of housing  22  and sealed thereto; water  26  adjacent barrier  25  and filling a section of housing  22 ; a liquid-impervious barrier  27  that (i) is adjacent water  26 , (ii) spans the diameter of housing  22  and sealed thereto, and (iii) opposes barrier  25 , where the combination of housing  22  and barriers  25 / 27  contains water  26 ; a pure-fuel reactive material  28  adjacent barrier  27  and spanning a section of tube  22  where material  28  is identical to material  24  in terms of type, amount, etc.; and an explosive  29  fitted in and sealed against an opposing axial end of housing  22 . 
     As in the previous embodiment, identical detonators  30  and  32  are coupled to explosives  23  and  29 , respectively, and a single detonation signal trigger device  34  is coupled to detonators  30  and  32 . Also as in the previous embodiment, housing  22  can be sealed against detonators  30  and  32  (as shown) or could completely encase same. Explosives  23  and  29  should be identically configured (i.e., type, amount, etc.), as should reactive materials  24  and  28 . When explosives  23  and  29  are simultaneously detonated, reactive materials  24 / 28  are heated, dispersed and driven into water  26  where materials  24  and  28  react therewith to generate an explosion. The stoichiometric amount of water  26  should be sufficient to ensure that water  26  forms a complete reaction with reactive materials  24  and  28  as they are simultaneously explosively-driven into water  26 . 
     By explosively driving the hot and dispersed reactive materials  24  and  28  into water  26  from opposing locations/directions, fast mixing and heating of the dispersed reactive materials  24 / 26  and water  26  occurs. At the same time, the opposing shock waves from the simultaneous detonation creates a mach stem in water  26  thereby increasing the temperature, pressure and turbulent mixing occurring in water  26 . Similar to housing  12 , housing  22  is designed to briefly confine and inwardly direct the shockwaves associated with the simultaneous detonations. 
     The advantages of the present invention are numerous. The simultaneous and opposing driving of reactive materials into a confined section of water generates fast and efficient mixing of the fuel/oxidizer to improve both the efficiency and intensity of the explosion. 
     Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described. 
     Finally, any numerical parameters set forth in the specification and attached claims are approximations (for example, by using the term “about”) that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, and not as an attempt to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be construed in light of the number of significant digits and by applying ordinary rounding.