Device for generating a jet of two-phase fluid

Abstract

The present invention relates to a device for generating a jet of two-phase fluid, comprising a nozzle having a main duct (1) that is fed by a pressurized gaseous fluid and opens into a mixing chamber (400), and at least one secondary duct (301 to 305) that is fed by at least one pressurized fluid and opens into the mixing chamber (400) in a direction forming a non-zero angle with the axis of the main duct. The mixing chamber (400) has a convergent-divergent cylindrical wall having a constriction (430) defining an opening in the plane perpendicular to the axis of the main duct. The convergent part (410) of the wall has a frustoconical region in the continuation of the axis of the at least one secondary duct (301 to 305) so as to form a fragmentation chamber for the liquid phase.

Description

DESCRIPTION TITLE: DEVICE FOR GENERATING A TWO-PHASE FLUID JET Field of invention

[0001] The present invention relates to the field of producing and propelling a two-phase mixture of at least one gas and one liquid, in particular for extinguishing a fire, cooling equipment, forming a fog. The mixing takes place in a nozzle where the interaction of a high-speed stream of gas with a water jet atomizes water droplets in the water jet to form a fog of very small or minute droplets, thus forming a two-phase mixture of water mist droplets entrained and transported by the gas stream.

[0002] Such two-phase mixtures have remarkable cooling performance and limit damage caused by water and fumes by causing low and localized wetting, the absence of any nuisance in the surrounding area. These mixtures are produced either by fixed installations placed for example on the ceiling of an industrial, tertiary or residential building, a tunnel, the cabin of an aircraft or a ship, or in the overalls of an aircraft pilot or an industrial equipment operator, or by installations installed on industrial sites or in forest areas, or by portable equipment in the form of fire hoses operated by a firefighter or by an autonomous motorized vehicle.

[0003] The finer the mist, the higher the droplet speed and the higher the kinetic energy of the droplets, the greater their ability to penetrate deep into the fire. As the heat exchange surface increases, cooling and inerting are even more important. large. High-pressure water mist also blocks radiant heat. Thus, for example, the temperature can remain bearable just a few meters from a fire heated to 800°C, and attenuates shock waves caused, for example, by an explosion. In addition, this mist produces a dilution of gases and can also produce a dissolution, adsorption or solubilization reaction limiting the explosive nature of a gas.

[0004] The gas supplying the nozzle can be an inert gas, such as nitrogen, carbon dioxide, argon, or simply air, or even oxygen. State of the art

[0005] French patent FR2376384 describes a snow cannon intended to spray water particles into sufficiently cold air so that they freeze before even touching the ground. This device consists of a convergent-divergent fairing open at the rear for the admission of ambient air. Inside this fairing is positioned an olive device intended to regulate the flow rate of a primary air-water mixture. This flow control device has a convergent-divergent mixer supplied with an air flow and a peripheral water flow, opening coaxially into the convergent part of the mixer. The water conduit opens into a tubular conduit coaxial with the air conduit, with an angular orientation, such that the liquid flow is directed towards the outer surface of the air supply conduit.This liquid flow is then deflected into a coaxial tubular section with the air supply duct opening into the mixer to form two substantially laminar and coaxial phases.

[0006] Patent DE10004534 describes a device for implementing the method in which the flow direction of the massage jet that can be emitted by the hydromassage nozzle is influenced without moving components of the hydromassage nozzle are required for this purpose, object, in which preferably the discharge duration and the time between two delivery times, the pause time which is influenced by massage jets which can be emitted from the massage nozzle in different flow directions.

[0007] French patent FR2766108A1 describes a device for generating a two-phase fluid comprising a wall delimiting a chamber generating this fluid, provided with a first end intended to be connected to a source of supply of pressurized liquid and a second end for distributing the two-phase fluid extended by an accelerating nozzle, this wall being perforated by at least one opening through which a pressurized gas enters, device characterized in that it comprises means for dividing the chamber, over all or part of its length, into at least two channels.

[0008] Patent GB865434 relates to the field of guns for projecting grinding or polishing material in a jet or spray, of the type comprising a gun body having a nozzle at the front and passages longitudinally along it respectively for the abrasive material and air or other gas under pressure for projecting the abrasive material from the nozzle and this invention relates to an efficient form of spray gun and to a spray gun in which wear by the abrasive material is minimized.

[0009] Patent GB951589A describes a powder spray extinguisher comprising a barrel carrying a circular cylindrical rubber discharge nozzle engaged at diametrically opposed positions by a pair of transverse rods carried by radially outwardly angled rocker arms. The two arms are engaged by a lip of a flared sleeve which is slidably guided on the barrel to adjust the jet velocity.

[0010] Patent DE90013 describes an adjustable nozzle in the form of a narrow slit, the purpose of which is to give the emerging propellant jet a thin and flat shape, thus achieving a larger contact surface with the liquid. to be treated in relation to the cross-section. The tube or nozzle into or through which the liquid to be treated is drawn or forced is suitably chosen to be of flat, rectangular, or approximately such cross-section. However, this cross-section must be shaped or curved longitudinally (i.e., in the direction of flow) in such a way that changes in cross-section or shape or direction occur gradually, so that the liquid to be displaced offers little resistance to its passage, while being brought into contact with the propellant jet. Disadvantages of the prior art

[0011] The solutions of the prior art are not suitable for the formation of mists with very small droplets, presenting a high efficiency of extinguishing a flame.

[0012] The prior art patent FR2376384, for example, produces artificial snow formed by large frozen flakes, several millimeters or even one or more centimeters, which are absolutely not suitable for extinguishing a fire.

[0013] Prior art solutions are particularly sensitive to the gas phase flow rate / liquid phase flow rate ratio, and when the ratio deviates from the optimal value, the droplets are not correctly micronized. It is therefore not possible to modulate the flow rate and dilution ratio without losing efficiency. Furthermore, prior art solutions generally require high pressure and therefore a high flow rate for the gas phase, which limits the possibilities of use for portable equipment that does not allow the transport of a gas reserve that is too large and bulky. Solution provided by the invention

[0014] To overcome these drawbacks, the present invention relates, in its most general sense, to a device for generating a jet of two-phase fluid in accordance with claim 1. Detailed description of non-limiting examples of implementation

[0015] The present invention will be better understood on reading the following description, referring to non-limiting examples of embodiment, illustrated by the appended drawings where:

[0016] [FIGURE 1] Figure 1 represents a view along a first longitudinal sectional plane of a nozzle according to the invention

[0017] [FIGURE 2] Figure 2 represents a view along a second longitudinal section plane, perpendicular to the previous one, of a nozzle according to the invention

[0018] [FIGURE 3] Figure 3 represents a cutaway sectional view of a nozzle according to the invention

[0019] [FIGURE 4] Figure 4 represents a perspective view of a deformable nozzle according to a variant of the invention

[0020] [FIGURE 5] Figure 5 represents a perspective view of the deformable sleeve in the deployed position according to the variant of the invention

[0021] [FIGURE 6] Figure 6 represents a perspective view of the deformable sleeve in the pinched position according to the variant of the invention

[0022] [FIGURE 7] Figure 7 represents a sectional view of the deformable sleeve and the movable adjustment jaws according to the variant of the invention

[0023] [FIGURE 8] Figure 8 shows a perspective view of the deformable nozzle without the movable jaws

[0024] [FIGURE 9] Figure 9 represents a perspective view of the deformable nozzle in the open position without the fixed jaws

[0025] [FIGURE 10] Figure 10 shows a perspective view of the deformable nozzle in the pinched position without the fixed jaws and with a single movable jaw

[0026] [FIGURE 11] Figure 11 represents a perspective view of a multifunction control handle of a lance according to another variant of the invention

[0027] [FIGURE 12] Figure 12 shows a cross-sectional view of said multi-function control handle. General note

[0028] It is specified that the complete system comprises a nozzle, which can optionally be extended by a variable geometry ejection nozzle, with a multifunction control handle and possibly peripheral elements to form, for example, portable equipment. The aim is to form a mist of water droplets with a cross-section of less than 400 micrometers and preferably less than 90 micrometers. For a fire extinguisher, the water mist in finely divided droplet form constitutes a two-phase extinguishing agent produced "in situ" at the nozzle.

[0029] The action of water mist is based on several mechanisms, often combined: a) Cooling of the flame resulting from the large exchange surface and the high speed of vaporization. Water is a very good heat trap. Raising one kilogram of liquid water from 20°C to 100°C requires 335 kJ / kg and its vaporization requires an additional 2257 kJ / kg, for a total of 2592 kJ / kg. The fineness of the water mist droplets implies a large exchange surface to exploit its potential of evaporation and absorption of calories. By evaporating, the droplets, in contact with hot areas (near the flame) generate a volume of vapor which contributes to locally depleting the oxygen concentration. Cooling the flame contributes to its extinction. It should also be noted that cooling a cloud of smoke can prevent its ignition when it comes into contact with fresh air (Flash over) b) Cooling of combustible solids (materials): Water-solid contact (materials) is limited by the surface area of ​​the burning combustible (material). The fineness of the water mist is not essential but can be used to advantage to limit thermal shocks. Effective cooling, however, requires a sufficient water flow rate and good liquid-solid coverage. If, for example, one wishes to optimize the cooling of a hot atmosphere, a very fine water mist is preferable.On the other hand, if we want to maximize the cooling of a solid fuel, a water mist with a greater proportion of large droplets will give better results. c) The reduction of the global or local oxygen concentration: Depletion of the oxygen content in two cases:. - In the vicinity of the fire, water droplets transform into steam, which contributes to locally reducing the oxygen concentration. In rooms, the formation of water vapor similar to inert gas mechanically contributes to lowering the oxygen concentration in the air of enclosed spaces. In the case of large fires in a small volume, the water mist can vaporize and the action of the vapor produces a smothering effect that can lead to extinction. A sufficient minimum ambient temperature (65°C-75°C) is necessary to observe this effect linked to water vapor because, for a volume saturated with water (under the action of the mist), the proportion by volume for water in vapor form is limited by the saturated vapor pressure of the water in the air. d) Attenuation of thermal radiationj. influence of propagation energy. Like conduction and convection, thermal radiation is a mode of heat transfer. It contributes to the propagation of a fire. A suitably sized water mist can significantly attenuate thermal radiation. The predominant mechanisms in attenuation are absorption, reflection and diffraction. The main parameters involved in the effectiveness of attenuation are: ® The density of water mist; » The thickness of the water mist screen; » The water mist class; "The homogeneity of the distribution of water mist An overall attenuation rate of 50% can be easily achieved.

[0030] The description of one of these elements naturally extends to sub-assemblies including this element combined with another element, even if the first element is not repeated in detail in the part concerning the detailed description of this other element. The non-repeated characteristics must be considered as included in the detailed description, except for the characteristics which would be manifestly technically impossible. Similarly, each of the elements can be used with a complementary element other than that described or even the subject of this patent: the nozzle which is the subject of the patent can be extended by a nozzle other than that proposed by this patent, just as the nozzle described can be used with nozzles other than those which are the subject of this patent. The same applies to all the elements which are the subject of a detailed description. Description of an example of the nozzle's construction

[0031] Figures 1 to 3 represent views of an exemplary implementation of the invention for producing a nozzle intended in particular for extinguishing fires, from a fire hose supplied by a two-phase supply pipe or by a water supply pipe, the gas phase coming from a portable compressed gas bottle connected by a second conduit, or from an autonomous robot equipped with such a nozzle, or from fixed equipment, for example a support placed on the ground in a forest area, in an industrial site, or a building or even a ship or an airplane.

[0032] The nozzle is composed, in the non-limiting example described, of several parts connected by screwing or any other mechanical connection with sealing joints: a connection plate (100), a control body (200), an intermediate body (300) and a mixing chamber (400).

[0033] The nozzle is crossed by a main axial channel (1), opening into the coaxial mixing chamber (400). This main channel (1) extends from an eccentric threaded connection (101) to a ring (301) opening into the mixing chamber (400). It passes through a gas flow control ball valve (201) provided with a spherical body (202) actuated by a rod not visible in figures 1 and 2 actuated by a connecting rod or motorized system.

[0034] The main channel (1) is intended for the supply of the gas phase, for example compressed air, a neutral gas such as nitrogen. For a particular application, the compressed gas is air, used both for the production of the fog and incidentally for the supply of a respiratory mask intended for a human operator.

[0035] The supply plate (100) has a second threaded connection (151) for connecting a supply pipe with the liquid phase, for example pressurized water. It opens into the control body (200) via a conduit placed in a plane not visible in Figures 1 and 2, in a second ball valve (251) provided with a body (252) actuated by a rod (253), manually or motorized.

[0036] The outlet of this second ball valve (251) opens into a radial conduit (270) opening into an annular chamber (260) coaxial with the main channel (1). Optionally, this radial conduit (270) also opens into the outer wall of the control body (200) by a threaded connection (271) allowing the connection of a pipe for supplying a secondary fluid. When not in use, this threaded connection (271) is hermetically sealed by a screw cap (272).

[0037] The intermediate body (300) ensures the transmission of the two fluids from the control body (200) to the mixing chamber (400). It comprises the main channel (1), arranged along the longitudinal axis of the intermediate body (300) and the mixing chamber (400), and one or more secondary conduits (301, 302), typically a bundle of secondary conduits extending from said annular chamber (260) to the inlet of the mixing chamber (400). These secondary conduits (301, 302) are oriented along axes (311, 312) forming with respect to the longitudinal axis (10) an angle of approximately 10°, typically between 8 and 15°. The main air channel (1) and the secondary liquid conduit(s) (301, 302) open into the same transverse plane (306), perpendicular to the axis of the main air channel (1), into a hollow volume located in the converging part (410) of the mixing chamber.

[0038] The axes (311, 312) define with the generator (413) of the cone of the converging part (410) an angle of approximately 30°.

[0039] Other configurations may be provided, for example a conical chamber extending from said annular chamber (260) to an annular outlet in the inlet of the mixing chamber (400). This conical chamber may be partitioned longitudinally to ensure the rigidity of the peripheral walls.

[0040] The mixing chamber (400) forms a so-called Laval nozzle. It is formed by a rectilinear conduit with variable section, consisting of a converging part (410) extended by a diverging part (420) with a constriction (430) between these two parts (410, 420). The tubular volume passing longitudinally through the chamber is completely free and devoid of any obstacle or organ likely to restrict the flow of the mixed fluid.

[0041] The converging part (410) is configured so that an annular zone (411) is in the extension of the axes (311, 312) of the secondary conduits respectively (301 to 305), without any obstacle or wall between the outlet of said secondary conduits (301 to 305) and the wall of this converging annular zone (411). The truncated volume defined by the converging part (410) is free of any obstacle to form a hollow volume into which the main air supply channel (1) and the secondary liquid conduits (301 to 305) open at the upstream base defined by the transverse plane (306), which are oriented at a non-zero angle relative to the axis of the main air supply channel (1) so that the water jet emerging from these secondary liquid conduits (301 to 305) are oriented directly towards the surface of the converging part (410) of the mixing chamber, upstream of the narrowest part.

[0042] This configuration is essential for the liquid jet to break on the surface of the converging portion (410) and atomize the liquid flow into a drop projected into the central vein in the jet of the gas phase and create turbulence in the converging portion (410) before being entrained by the central vein through the neck (430) into the diverging portion (420) of the nozzle, for example a so-called Laval configuration. This diverging portion (420), also of flared truncated cone shape, is completely hollow and devoid of any obstacle or part likely to totally or partially block the vein passing through the convergent-divergent mixing chamber.

[0043] This convergent-divergent mixing chamber opens directly into a tightly connected deformable nozzle, without the passage of air from outside the nozzle. Detailed description of a deformable nozzle

[0044] Figures 5 to 10 relate to a deformable nozzle device for a two-phase jet comprising a mixture of at least one liquid phase and a gas, with a system of movable jaws. The deformation of the end of the nozzle makes it possible to have jets of different shapes, particle sizes and projection distances.

[0045] This deformable nozzle device constitutes a complement to the nozzle previously described. However, it could also be adapted to other solutions for pressurized two-phase mixture generators, in particular to solutions already marketed or known from the prior art.

[0046] Figure 4 represents an overall view of an exemplary embodiment of such a nozzle. It comprises a deformable sleeve (500) of which figures 5 and 6 represent views in the open and pinched position respectively. This deformable sleeve (500) is placed between two fixed jaws (510, 520) and two movable jaws (530, 540) actuated by control pistons (531, 541). The fixed jaws (510, 520) and movable jaws (530, 540) are integral with a rigid base (550) adaptable to the nozzle previously described or to a nozzle for diffusing a two-phase jet under pressure having a vein of a diameter close to that of the inlet of the sleeve (500).The deformation of the sleeve (500) is achieved by the angular displacement of the two movable jaws (530, 540) whose rear end is articulated to allow pivoting relative to a transverse axis respectively (531, 541) passing through the base (550) and the rear end of the fixed jaws respectively (510, 520).

[0047] The sleeve (500) forms at its outlet a variable configuration between a circular shape and a flattened shape where it has a slot (501) of low height delimited by the edges of the sleeve forming two transverse lips. The front end of the sleeve (501) matches the internal shape of the movable jaws (530, 540).

[0048] The front parts of the fixed jaws (510, 520) have series of grooves (512, 522) oriented in parallel transverse planes. These grooves (512, 522) are interposed between complementary grooves (532, 542) oriented in parallel transverse planes, provided at the front part of the movable jaws (530, 540), to provide guidance during the angular movement of the movable jaws (530, 540) to modify the configuration of the sleeve (500).

[0049] The jet composed of the gas and liquid mixture has different fluidic characteristics depending on whether the sleeve is pinched (movable jaws (530, 540) closed) or in the open position (movable jaws (530, 540) separated).

[0050] the grain size is finer and the jet opening cone angle is more open when the outlet is pinched.

[0051] The geometric configuration in the open or pinched position is not limited to a circular or pinched shape, but can take other forms.

[0052] The sleeve (500) shown in Figure 5 is made of a piece of flexible material, for example neoprene, natural rubber or a flexible polymer or even a rubber-coated textile. It has a neck (502) extended by a deformable tubular part opening onto an outlet (501). On the other side, the neck (502) rests on a base (503) ensuring the sealed junction with the front surface of the nozzle or a connector.

[0053] The front part (501) of the sleeve (500) has two diametrically opposed protrusions (504, 505). They allow anchoring of the front part (501) in complementary cavities (535, 545) provided on the front inner surface of the two movable jaws (530, 540).

[0054] The rear part of the movable jaws (530, 540) have inclined ramps (536, 546) against which the ends of the connecting rods (531, 541) to control the tilting of the movable jaws (530, 540).

[0055] Figures 8 to 10 show the nozzle being assembled. The rigid base (550) has a rear surface complementary to that of the nozzle to allow a sealed assembly, for example using a quick connector.

[0056] The base (550) has two diametrically opposed notches (551, 552) to allow the passage of the connecting rods (531; 541).

[0057] The assembly between the rigid base (550) and the movable jaws (530, 540) is carried out by transverse axes (537, 547). Multifunctional control handle

[0058] Figure 11 represents a view of an assembly for diffusing a two-phase jet using a system comprising a nozzle producing a two-phase jet, in particular a nozzle in accordance with the invention described above associated with a variable geometry nozzle, in particular a variable geometry nozzle in accordance with the invention described above.

[0059] The diffusion assembly comprises a main body (700) in which the nozzle for producing the two-phase jet is enclosed, for example a nozzle according to the invention. This body (700) has at its rear part a base (701) intended for the connection of a connector (601) of the supply pipe (600). At the front, the body (700) is extended by a secondary body (702) enclosing the jet shaping nozzle, for example the deformable nozzle previously described. This secondary body (702) has a front plate (708) cut by an outlet orifice (710).

[0060] The body (700) is provided with a fixed handle (703) for directing and holding the body (700) in the direction of the fire to be extinguished. It has a side button (709) for controlling an electrical function, for example the starting the pressurized air production turbine or opening a pressurized oxygen supply valve.

[0061] The body (700) has a connector (704) allowing the connection of a hose supplying oxygen or breathable air to a protective mask worn by the operator in order to allow him to continue his action in a polluted or smoky environment.

[0062] The body (700) and / or the secondary body (702) further comprises rails (706, 707) for attaching accessories, for example a flashlight or a camera.

[0063] Finally, the body (700) comprises a tilting handle (705) actuating a transmission member controlling the configuration of the outlet jet. In the case of a deformable nozzle according to the invention described above, the transmission member is constituted by the two connecting rods (531, 541) actuated by cams driven by the tilting handle (705). Pivots (715) ensure the articulated connection between the tilting handle (705) and the body (700).

[0064] This multifunction handle allows the operator to move towards the fire and to act on the different parameters of the two-phase jet in a very intuitive way. The operation of this handle is illustrated by Figure 12 showing a cross-sectional view

[0065] The mechanism comprises a cam (720) articulated in rotation relative to an eccentric transverse pivot (721). The external face (722) of the cam (720) pushes the piston (730) against which the connecting rods (531, 541) bear to control the tightening of the front end of said movable jaws (530, 540), or the loosening by releasing the handle.

[0066] The pivoting of the cam (720) thus serves to position the nozzle shape via the jaws (620, 540) of the deformable nozzle, and this with synchronization of the opening(s) of the gas and / or liquid channels.

[0067] The valves are controlled via the cam track (740) (for example, the left side controls the gas and the other side controls the water. Everything is operated by the handle (705), so no adjustment is necessary, all the opening / closing / flow and jet shape sequences are "programmed" by the different positions of the handle (705).

Claims

Demands 1. A device for generating a two-phase fluid jet comprising a nozzle having a main conduit (1) supplied by a pressurized gaseous fluid and opening into a mixing chamber (400), and at least one secondary conduit (301 to 305) supplied by at least one pressurized liquid fluid opening into said mixing chamber (400) in a direction forming a non-zero angle with the axis of said main conduit, characterized in that • said mixing chamber (400) has a convergent-divergent cylindrical wall having a constriction (430) defining a disc opening in the plane perpendicular to the axis of said main conduit, said disc opening • the convergent part (410) of said wall having a frustoconical zone in the extension of the axis of said at least one secondary conduit (301 to 305), to form a fragmentation chamber of the liquid phase.

2. A two-phase fluid jet generation device according to claim 1 characterized in that said axis (311, 312) of said at least one secondary conduit (301 to 305) forms with the axis (10) of said main conduit (1) an angle between 2° and 20°.

3. A two-phase fluid jet generation device according to claim 1 characterized in that the axes (311, 312) of the secondary conduits (301 to 305) define with the generatrix (411) of the cone of the convergent part (410) an angle between 0° and 60° and preferably of 45° ±10°.

4. A two-phase fluid jet generation device according to claim 1 characterized in that the diameter of said opening of the constriction (430) is between 0.8 and 1.2 times the diameter of said main conduit.

5. A two-phase fluid jet generation device according to claim 1 characterized in that it comprises a plurality of secondary conduits (301, 305) converging towards said mixing chamber (400), distributed around the periphery of said main conduit.

6. Device for generating a two-phase fluid jet according to claim 1 characterized in that the ejection channel (420) of said nozzle, located in the diverging part, has a truncated ogival shape.

7. Device for generating a two-phase fluid jet according to claim 1 characterized in that the ejection channel (420) of said nozzle is extended by a deformable ejection nozzle.

8. A two-phase fluid jet generation device according to the preceding claim, characterized in that said deformable ejection nozzle is constituted by a deformable sleeve (500) disposed between two movable jaws (530, 540) articulated between a position where they ensure the pinching of the front part (510) of said deformable sleeve (500) and a spread-away position where the sleeve has a nominal cross-section.

9. A two-phase fluid jet generation device according to the preceding claim, characterized in that said movable jaws (530, 540) have a ramp (536, 546) against which connecting rods (531, 541) respectively bear to control the tightening of the front end of said movable jaws (530, 540). Device for generating a two-phase fluid jet according to claim 1 characterized in that it is integrated into a body (700) having a fixed rear handle (703) and a pivoting front handle (705) controlling the variation of the jet parameters. A two-phase fluid jet generation device according to the preceding claim, characterized in that said body (700) has a fitting (709) for connecting a supply hose to an air mask.

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