Abstract:
A concealment that covers all or a main part of naval vessels and their surroundings and crew, by making provision for coupling a flow of air with an injection of fluid to cause formation of a cloud and to orient the cloud to optimize coverage of the vessel and the surroundings to be protected. A concealment apparatus includes a gas turbine coupled to a conduit discharging a flow of smoke composed of a combustion gas loaded with droplets of fluid in suspension. The conduit includes two branches that emerge on each lateral half-hull of the hull of the vessel. The branches are symmetrical with respect to a vertical symmetry plane of the ship and, through their curvature, have roughly a direction oriented towards the rear of the ship. In this way, the flow of smoke is also oriented towards the rear of the ship.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a method and to an apparatus for concealing a naval vessel such as a ship, a pleasure boat or a watercraft, as well as to a naval vessel equipped with at least one such apparatus. 
         [0002]    The context of the invention is the protection of a naval vessel, at rest or in movement, and its surroundings by a cloud for concealing the vessel at least in the visible radiation range. This concealment aims to prevent any act of aggression or boarding of this vessel. 
         [0003]    The field concerns the production of an opaque environment formed in general from particles, for example liquid particles, in suspension in the air in order to form a cloud, or, for example, solid particles also in suspension in the air in order to generate smoke. 
         [0004]    In the case where the vessel to be protected is moving on the water, the production of an opaque environment must be able to coincide with the movement of the vessel. The installation of means for producing such an environment on or in the vessel is therefore to be provided. In addition, since the concealment is intended to cover all or at the very least the main part of the vessel, it is necessary to ensure that the environment allows such coverage in space and over time. 
       PRIOR ART 
       [0005]    The use of smoke-generating cartridges is known for creating smoke screens. However, these screens remain of small size and are effective only for a short period and provide only a small output. In addition, the efficacy of concealment is not sufficient since the opaque coverage is not uniform. 
         [0006]    In general, pyrotechnics provide smoke that cannot conceal a vessel satisfactorily (dimensions, duration, efficacy) and which gives rise to high cost as well as a degree of not insignificant level of risk in handling. 
       DISCLOSURE OF THE INVENTION 
       [0007]    The invention aims to dispense with these drawbacks by proposing the production of an effective, long-lasting concealment which covers all or the main part of vessels and their surroundings and crew. The aim is also to disorientate and disturb any aggressors in order to dissuade them from any attempt at boarding. To do this, the invention makes provision for coupling an airflow with an injection of fluid able to cause the formation of a cloud and to orient this cloud in order to optimise coverage of the vessel to be protected over time and in space. 
         [0008]    More precisely, the present invention relates to a method for concealing a naval vessel, preferably in movement, comprising at least one deck and a hull. The method consists in integrating in the vessel at least one smoke generator, this integration being able to be achieved on the deck and/or in the vessel, in particular substantially at or above the waterline, injecting a fluid at the output of the smoke generator and guiding the gas flow thus loaded with fluid in suspension, referred to as the flow of smoke, to at least one outlet formed in the hull of the vessel, so as to direct said flow, for example, towards the rear or towards to the front of the vessel, preferably from a position substantially at or above the waterline of the vessel. The smoke generator or generators can be integrated at any point on the vessel such as for example at the bow, amidships or at the stern of the vessel. 
         [0009]    According to preferred embodiments: 
         [0010]    an injection of coloured, powdery, odorous and/or smoke-generating additives is also effected at the gas outlet or downstream of the gas outlet; 
         [0011]    an injection of graphite powder is also effected at the outlet of the smoke generator so as to cause concealment in the infrared radiation range; 
         [0012]    the guidance of the flow is broadened at the outlet of the smoke generator in order to substantially reduce the speed of the smoke; 
         [0013]    the guidance of the flow of smoke is configured so that the guidance outlet out of the hull is implemented between the middle and the front of the naval vessel and at or above the flotation line; 
         [0014]    the guidance is of adaptable orientation, at the outlet from the hull of the naval vessel, by orientation in a reference plane parallel to the deck or decks of the vessel and/or in a plane perpendicular to the reference plane, in order to orient the flow of smoke discharged at the waterline according to the movement of the vessel and the sailing conditions so that the flow of smoke discharged is directed between the deck or decks and the waterline; 
         [0015]    the guidance is of variable length so that the guidance is suited to the dimensions of the hull of the vessel; 
         [0016]    the flow of smoke is cooled and made denser by humidification before leaving the hull of the vessel in order to cause vaporisation at the discharge and to keep the smoke placed over the stretch of water that surrounds the vessel; 
         [0017]    the flow of smoke is regulated so that its discharge speed is almost zero. 
         [0018]    The invention also relates to an apparatus for concealing a naval vessel, intended to implement the method. This apparatus comprises a gas turbine composed of a gas generator and a gas exhaust pipe connected to a reservoir of fuel. The exhaust pipe is equipped with at least one fluid injector connected to at least one reservoir, for injecting this fluid, in particular oil, into the exhaust gases of the gas turbine and to form a flow of gas with fluid in suspension (F 3 ), referred to as a flow of smoke, and is coupled to at least one conduit for guiding the flow of smoke. 
         [0019]    According to advantageous embodiments: 
         [0020]    the or each conduit comprises at least one frustoconical divergent portion, connected to the pipe in order to substantially reduce the speed of the flow of smoke; 
         [0021]    the or each conduit or branch is equipped with an orientable grille in a region of a conduit end, the grille being able to direct and/or mix the flow of smoke that passes through the conduit or branch; 
         [0022]    an external flow injector in the flow of gas is arranged in an end region of the or each conduit or branch in order to cool and make denser the flow of smoke, the external fluid being in particular sea water, at a temperature substantially less than that of the flow of gas in said region; 
         [0023]    the or each conduit or branch is equipped at the end with a nozzle that can be oriented in at least one plane, for example in any direction, in order to direct the flow of smoke at the outlet of the conduit or branch, so that the concealment is as effective as possible according to the conditions (meteorological, movement, attack, etc.) imposed on the vessel; 
         [0024]    the or each conduit comprises a portion fitted in the conduit or branch, with telescopic adjustment means in order to vary and adapt the length of the or each conduit or branch; 
         [0025]    the or each conduit is sized and configured so as to adjust the pressure drops in the flow below a given ceiling, in order to avoid overpressure at the turbine; 
         [0026]    the or each conduit can comprise means for regularising the flow of gas (frustoconical divergent exit cones, valves, shutters, etc.) in order to reduce the speed of the flow of gas and to make it tend towards an almost zero value at the discharge from the conduit; 
         [0027]    an opening flap is arranged at the end of the conduit and controlled so that said flap opens at the start-up of the gas turbine, this flap preventing sea water from entering the conduit as far as the gas turbine and preventing problems of corrosion, watertightness, etc.; 
         [0028]    the gas generator, the pipe and the reservoirs are integrated in a protective chamber, the reservoirs preferably being separated from the gas generator and the pipe by at least one protective partition; 
         [0029]    the apparatus comprises at least one additive injector arranged so as to effect an injection of coloured, powdery, odorous and/or smoke-generating additives at the gas outlet or downstream of the gas outlet. 
         [0030]    The invention also relates to a naval vessel equipped with at least one deck, a hull and at least one such apparatus. The apparatus or apparatuses can be arranged on a deck or in a hold, at any place in the vessel. The lengths of the conduits and branches are then determined so as to emerge out of the hull of the vessel through preformed openings. 
         [0031]    Advantageously, the apparatus is arranged at the front of the vessel centrally, and comprises a conduit with two branches having a common end for coupling to the pipe of the gas turbine and ends emerging on each of the half hulls. The conduit may be arranged downstream or upstream of the gas turbine, preferably with branches roughly oriented towards the rear of the vessel in both cases. 
         [0032]    When the vessel comprises at least two apparatuses, each apparatus may be arranged laterally close to a half hull and comprise only one conduit with an end that emerges out of the half hull. 
         [0033]    The or each apparatus may be integrated in a chamber when this apparatus is installed on the deck of the vessel, in order to protect the apparatus from waves and spray and to facilitate traffic on the deck. 
         [0034]    In addition, the conduit or conduits of the apparatuses are arranged so that the flow of smoke emerges at the front of the vessel, for example as close as possible to the waterline. Preferably the conduit or conduits of the apparatuses comprise at least one horizontal portion and/or one vertical portion. 
         [0035]    The means for orienting the end nozzle of the or each conduit may make it possible to adjust the outlet angle of the flow of smoke, for example according to the movement of the vessel and the sailing conditions so that the smoke discharged is directed for example between the deck or decks and the waterline, in a given direction. 
     
    
     
       PRESENTATION OF THE FIGURES 
         [0036]    Other information, features and advantages of the present invention will emerge from reading the following non-limiting description with reference to the accompanying schematic drawings, in which: 
           [0037]      FIG. 1  is a diagram of an auxiliary engine such as for example a gas turbine of a concealment apparatus according to the invention; 
           [0038]      FIG. 2  is a partial side view of a ship equipped with a concealing apparatus in a chamber installed on the deck of this vessel; 
           [0039]      FIG. 3  is a side view of a short ship equipped with a concealing apparatus in a forward hold of the ship; 
           [0040]      FIGS. 4   a  and  4   b  are partial top views of the ship according to  FIG. 3  with a double conduit of the concealment apparatus installed in a forward hold of the vessel, upstream and downstream of the gas turbine, respectively; 
           [0041]      FIG. 5  is an enlarged partial view of the apparatus according to  FIG. 4  detailing the structure elements at the end of a branch of the double conduit; and 
           [0042]      FIGS. 6   a  and  6   b  are a side view and a top view of a long tanker equipped with four concealment apparatuses according to the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0043]    Throughout the text, the qualifiers “upstream” and “downstream” relate to relative locations of elements of the naval vessels in the direction of standard sailing of these vessels. The front of such a vessel is upstream and corresponds to the bow, whereas the rear is downstream and corresponds to the stern of the vessel. In addition, “horizontal” means parallel to the deck or decks of the vessel and “vertical” means perpendicular to this deck or these decks. 
         [0044]    With reference to the schematic diagram in  FIG. 1 , an engine of the gas turbine type, such as for example an engine of the GPU (ground power unit) type, is modified in order to serve as a “smoke turbine” in the concealment apparatus  10  according to the invention. A GPU is a fixed or movable gas turbine for starting the main engines and generating non-propulsive power (pneumatic, electrical or hydraulic power) of a vehicle or aircraft. 
         [0045]    The GPU  1  is composed mainly of a gas generator  2  and a gas exhaust pipe  3  connected to a fuel reservoir  41  and at least one reservoir  42  for fluid, oil H 1  in the example, which is able to remain in the exhaust gases in the form of suspended droplets. The gas generator  2  comprises: an air compressor  21 —the air (arrows F 1 ) entering, axially or radially, through a sleeve  5 ; a combustion chamber  22  for a mixture of air and fuel, the fuel coming from the reservoir  41  being introduced into the chamber  22  through fuel injectors  23 ; as well as a turbine  24  for expansion of the burnt gases and driving of the compressor  21  via a shaft  25 . The burnt gases (arrows F 2 ) are ejected through the pipe  3 . These components are generally enclosed in a casing  6  open at the inlet  5   a  of the sleeve  5  and at the outlet  3   s  of the pipe  3 , which is at the same time the outlet for the GPU  1 . 
         [0046]    In order to form a smoke turbine, the GPU  1  is modified by adding, at the outlet of the exhaust pipe  3 , an annular ring  7  coupled to the casing  6  and equipped with fluid injectors  71 , for example, for oil, coming from the reservoir  42 . This injection of fluid is propelled by a pump  72  and atomised by the injector  71  in the hot fast-moving exhaust gases emerging through the pipe  3 . 
         [0047]    Such an atomisation forms a gas flow loaded with droplets of fluid in suspension (arrows F 3 ), referred to as “loaded gas flow” or “flow of smoke”. The annular ring  7  is coupled to a conduit  11  for discharging smoke gas to the outside in order to conceal the ship. The conduit  11  is made from stainless steel in the example. The length of this conduit  11  and its configuration are then adapted so as to emerge in the hull of the naval vessel for which the apparatus  10  is intended. This adaptation is in particular dependent on the dimensions of the vessel and the planned location—on the deck or in a hold—for this apparatus.  FIGS. 2 and 3 , which follow, illustrate the installation, on the deck and in the bottom of a hold of a ship, of such apparatuses, which comprise conduits, smoke turbines  1  and reservoirs  41 ,  42 . 
         [0048]    Advantageously, apart from oil, coloured, powdery, odorous and/or smoke-generating additives may also be injected through the injectors  71  or any other injection manifold, in order to create or reinforce the surprise and dissuasive effect of the flow of smoke. It is also advantageous to inject graphite powder, which affords concealment in the infrared radiation range. Alternatively, it is necessary to refrain from injecting graphite powder if the aim is to be able to direct the ship using infrared binoculars through the flow of smoke after it has formed around the ship. 
         [0049]      FIG. 2  is a partial side view of a ship  100  equipped with a concealment apparatus  10  according to the invention comprising a smoke turbine  1 , for example the GPU described with reference to  FIG. 1 , the reservoirs  41  and  42 , and the conduit  11 . The smoke turbine  1  and the reservoirs  41  and  42  are arranged in a protective chamber  8  installed on the deck  10 P of this ship  100 . 
         [0050]    The conduit  11  comprises a frustoconical divergent portion  12 —referred to as a “divergent exit cone”—connected to the pipe  3  at the discharge from the smoke turbine  1 . This divergent exit cone  12  substantially reduces the speed of the gas flow F 3  so that, at the end of the outlet  14  of the conduit  11  through an orifice  13  formed in the hull  101  of the vessel  100 , this speed is almost zero. The conduit  11  has elbows C 1  to C 3 , a horizontal portion P 1  and a vertical portion P 2 . 
         [0051]    The horizontal portion P 1  makes it possible to move the outlet  14  of the conduit  11  towards the front AV of the ship  100 , and the vertical portion P 2  emerges at the outlet  14  close to the waterline LF of the ship  100 . It is in fact sought to have an outlet  14  upstream—in order to enable the smoke to cover the whole of the ship  100  because of the relative speed of the ship—and close to the waterline LF since the smoke remains “attached” to the stretch of water and then rises over time. The outlet  14  remains above this waterline LF in order to prevent the entrance of waves or spray. 
         [0052]    The conduit  11  is sized and configured so that the number of elbows, here three elbows C 1  to C 3 , is reduced to a minimum in order the minimise the pressure drops in the flow of smoke F 3  below a ceiling, determined in advance for the purpose of avoiding overpressures at the smoke turbine  1 . 
         [0053]    Advantageously, a flap  16  for opening/closing the outlet  14  of the conduit  11  on the hull  103  is arranged at the end of the conduit. This flap  16  is controlled from the control centre (not shown) of the ship  100  so that said outlet  14  opens when the smoke turbine  1  starts up. It would in fact be detrimental to allow waves and spray to enter the conduit  11  via this open outlet  14  when the concealment apparatus is not operating. Problems of corrosion, watertightness or the like, caused by the presence of sea water, are thus avoided. 
         [0054]      FIGS. 3 and 4   a  illustrate, in side and (partial) top views of a short ship  102 , another example of installation in a forward hold  31  of the smoke turbine  1  already described. A ship is said to be “short” when, for example, it does not exceed 50 m in length. 
         [0055]    The concealment apparatus  10 ′ comprises, in this case, the smoke turbine  1  already described, and a conduit  11 ′ with two branches  11 ′ a  and  11 ′ b  having a common portion connected at the outlet of the smoke turbine  1 . In this example, the conduit  11 ′ is installed downstream of the smoke turbine  1 . The fact that the ship  102  is short makes it possible to limit the number of apparatuses to only one, arranged at the front AV of the ship  102  so that the flow of smoke F 3  leaves the conduit  11 ′ also from the front of the ship  102 . 
         [0056]    As illustrated by the top view in  FIG. 4   a , the two conduit branches  11 ′ a  and  11 ′ b  emerge on each lateral half-hull  103   a  and  103   b  of the hull  103 . The branches  11 ′ a  and  11 ′ b  are symmetrical with respect to a vertical symmetry plane Pv of the ship  102  and, through their curvature, have roughly a direction oriented (arrow F 4 ) towards the rear AR of the ship  102 . In this way, the flow of smoke F 3  is also oriented mainly towards the rear AR of the ship  102 . 
         [0057]    In a variant of  FIG. 4   a , the partial side view of  FIG. 4   b  shows a conduit  11 ″ of the same type as in  FIG. 4   a  but connected upstream of the smoke turbine  1 . In this case, the symmetrical branches  11 ″ a  and  11 ″ b  are also oriented towards the rear AR of the vessel  102  so that the flow of smoke F 3  is set up along the vessel, from upstream to downstream. 
         [0058]      FIG. 5  details the structure elements in the end region  15  of the branch  11 ′ a  of the conduit  11 ′ improving the directivity and quality of concealment of the flow of smoke at the outlet of the branches  11 ′ a  and  11 ′ b . The partial view in  FIG. 5  is an enlarged view of the apparatus according to  FIG. 4   a . As in  FIG. 1 , the GPU  1  is connected to a ring  7  which is equipped with fluid injectors  71  and itself connected to the conduit  11 ′. 
         [0059]    The end region  15  of each branch  11   a  and  11   b  (only the end of the branch  11   a  is visible in  FIG. 5 ) is equipped with an orientable grille  17   g  with shutters  17   c . The shutters  17   c  of the grille  17   g  have a set of rotation spindles  17   a  controlled remotely at the control centre (not shown). The grille  17   g  is more precisely installed in this example at the outlet end  14  of the branch  11 ′ a . The flow of smoke F 3  is thus finely oriented in the horizontal plane of  FIG. 5 . 
         [0060]    In addition, water injectors  18  are arranged in said region  15 , upstream of the grille  17   g . Water, sea water in the example, at low temperature (10 to 20° C.) substantially below the temperature of the flow of smoke (above 40° C.) is thus injected via these injectors  18 . This injection cools the flow of smoke F 3  and makes it denser in order to make it heavier and “attach” it to the stretch of water that surrounds the ship  102 . The flow of smoke F 3  then detaches from the stretch of water and conceals the whole of the ship  102 . 
         [0061]    In addition, each branch  11 ′ a  is advantageously equipped, at the outlet end  14 , with a nozzle  19  that can be oriented in the horizontal plane of the figure and in a vertical plane perpendicular to the horizontal plane. To do this, twin-axis articulation means  19   a  are integrated in the nozzle  19 , close to the end  19   e  thereof. The flow of smoke is thus oriented in order to be able to attach to the stretch of water that surrounds the ship  102 . In addition, the nozzle  19  fits telescopically in the branch of the conduit  11   a . The fitting is adjusted by rack-type adjustment means  19   c , also controlled from the control centre. It is thus possible to vary and adapt the length of the branch  11 ′ a  (and, in a similar manner, the branch  11   b ). 
         [0062]      FIGS. 6   a  and  6   b  are schematic side and top views of a long tanker  104  (for example with a length greater than  300  m) equipped with four concealment apparatuses installed at the bottom of a forward hold  32  and a hold at the middle  33  of the tanker  104 . Two apparatuses  10 ″ a  are installed close to the lateral half-hull  105   a  of the hull  105  of the ship  104  and two apparatuses  10 ″ b  are installed close to the half-hull  105   b  of the hull  105 . Close to each lateral half-hull  105   a  and  105   b , the apparatuses  10 ″ a  and  10 ″ b  are arranged substantially at the middle MI and towards the front AV of the ship  105 . 
         [0063]    The apparatuses  10 ″ a  and  10 ″ b  are composed of smoke turbines  1 , such as those described previously, connected to conduits  11 ″ a  and  11 ″ b , corresponding respectively to the branch  11 ′ a  and to the branch  11 ′ b  described above with reference to  FIG. 4   a  or  FIG. 5 . The lengths of the conduits  11 ″ a  and  11 ″ b  are determined so that they can emerge out of the hull  105  of the ship through preformed orifices  13 . 
         [0064]    The invention is not limited to the embodiments described and depicted. Thus it is possible to add means for regularising the flow of smoke: valves, shutters, etc. The fluid added to the exhaust gas to serve as a load in suspension and to form the smoke may be any liquid of organic or aqueous nature, suited to the production of such a suspensive effect. 
         [0065]    In addition, in the case of a ship of average length, for example greater than or approximately equal to 100 m, it is possible to limit the number of concealment apparatuses to two installed towards the upstream end of the vessel. 
         [0066]    Moreover, means other than gas turbine compressors may be used as a smoke generator, for example fans of suitable size and output. 
         [0067]    Furthermore, it is advantageous to use the existing pipework of naval vessels to serve as smoke-discharge conduits according to the invention, at least partly.