EP1908526A1 - Nozzle for a diphasic mixture - Google Patents

Abstract

The device has an ejection nozzle (EJ) with a geometry comprising a minimal section or neck at a location (X) of an axis-vector (AX). The geometry permits to induce an expansion obtained inside the nozzle permitting a liquid-gas mixture (MLG1) from a distribution chamber to be converted into another mixture (MLG2), according to a flow configuration. The latter mixture has an ejection range and liquid particle size, which are controlled according to a liquid (L1) and gas (G1) mass flow and an absolute pressure at an injection inlet (IN1, IN2).

Description

The present invention relates to a device for ejecting an at least two-phase mixture according to the preamble of claim 1, as well as various advantageous uses of this device according to claims 16 to 20.

Basically, a known way to fight effectively against a fire is the water lance, allowing to "drown" a fire, especially under a large range of ejection but at the cost of a large flow of water.

Another ejection device uses a two-phase mixture, for example by means of, inter alia, water and pressurized gas, and adapts itself in the field of extinguishing fire in order to create a mist of water or fire-fighting foam, such as a conventional fire extinguisher. The amount of water required is therefore reduced. Other agents may also be included in the pressurized water-gas phase, such as an emulsifying agent or another agent of a non-obligatorily emulsifying nature such as carbon dioxide. The addition of agent remains however binding for example because of the limited storage of a fire extinguisher. The scope of conventional fire extinguishers is also limited because they are designed for small-scale fire suppression.

Other systems, for example adapted to a long-range lance, use a high-pressure gas such as nitrogen, allowing atomization of the water, however previously treated (demineralization). Thus, the specific properties of the injected liquid remain binding. As a result, seawater or other water with impurities does not properly form a diphasic mixture. which, even in addition to high gas pressure, does not reach a long range.

It has been attempted to overcome this disadvantage by using a device for generating a two-phase flow, as described in the patent French FR 2 548 052 . A device of this type comprises a wall delimiting a chamber where this two-phase pressure flow is produced, perforated by at least one opening through which a gas under a so-called "supply pressure" pressure, equipped with a first upstream end connected to a liquid supply source substantially at the same pressure, and a second downstream end connected to a fluid accelerating nozzle where it relaxes, and from which it escapes in the form of jet at high speed. Such a device makes it possible to create a two-phase jet of water and non-oxidizing gas at the site of the fire intervention, from the existing water resource, and from a source of non-oxidizing gas. Experience shows that the implementation of such devices is satisfactory as long as the supply pressure is sufficiently low. They then make it possible to extinguish a fire with an efficiency comparable to that of a foam extinguisher, thus with a restricted range of the two-phase mixing jet. However, if the supply pressure is increased to obtain jets at such speeds that they can reach fires at great distances, the operation of the devices becomes defective.

From there, a new device has been developed, such as that described in the patent application. FR 2 766 108 , in order to generate a two-phase flow whose operating quality is substantially constant regardless of the pressure (liquid and gas) at the input of the device. This device for ejecting a two-phase mixture comprises two separate inputs for a liquid injection inlet and the injection inlet gas, an emulsion chamber for producing a liquid-gas mixture and an ejection nozzle of the first liquid-gas mixture in a main direction defined by a vector axis. In particular, the gas is injected perpendicularly into the water inlet pipe and through perforated elements promoting the emulsion of the liquid-gas mixture. In addition, partition elements such as lamellae are arranged parallel to the flow of the water pipe so as to form separate channels of flow. These slats can be spaced angularly on a section of the water pipe surrounded by the perforated elements for the entry of gas into the channels. Admittedly, this device makes it possible to generate a constant two-phase jet for various pressures, but may be subject to disturbances due to untimely obstructions at the level of the lamellae or perforated elements, for example when introducing impurities (sand, pebble, dirt, etc.) via the water pipe or via the gas line. This can also result in a point or prolonged degeneration of the diphasic mixture which makes the extinction of a fire less manageable. In addition, the elements internally arranged at the levels of the pipes require the manufacture and maintenance of the complex device.

An object of the present invention is to provide a simple device for ejecting a mixture at least two-phase that allows at least a precise control of its ejection range in two-phase assured.

In particular, this device should adapt to various liquid and gas injection pressures, or even in the low pressure range while reaching long spans of the two-phase jet.

The device should be able to overcome internal elements with shutter potential and complex and remain insensitive to input impurity factors, in that the two-phase mixture at the device outlet is provided over the entire length of the jet and permanently .

The invention thus proposes a solution based on a device for ejecting an at least two-phase mixture, comprising at least one injection inlet for a liquid and a gas, an emulsion chamber for producing a first liquid-gas mixture. , an ejection nozzle of the first liquid-gas mixture in a main direction defined by a vector axis.
Since the ejection nozzle has a geometry with at least a minimum cross-sectional area along its length, at a location of the vector axis, not only is an expansion effect within the nozzle created as known in any Venturi type flow, but it is important to note that the geometry of the nozzle is adapted such that a relaxation within the ejection nozzle is induced allowing the first liquid-gas mixture from the chamber of emulsion to be converted, in the direction of the flow configuration, into a second liquid-gas mixture at the outlet of the nozzle, the ejection range of the second mixture and the particle size of the liquid in the form of droplets can be controlled according to the mass flow rates of the liquid and gas and the absolute pressure at the injection inlet.

It should be noted that the invention makes it possible to optionally use a common inlet for the liquid and the gas, which decreases the complexity favorably vis-à-vis device with two separate inputs whose relative position is to be taken into account in particularly for the emulsion.

In addition, the invention does not require the use of sharing or perforation elements in one of the injection inlets to allow quality emulsion and two-phase mixing, because the geometry of the nozzle coupled to the generating conditions at the inlet of the device (mass flow rates of the liquid and the gas and the absolute pressure at the injection inlet) ensure optimum emulsion and in addition allow the two-phase mixture at the nozzle inlet to be transformed, in the direction of the flow configuration, in a second two-phase mixture at the outlet of nozzles whose particle size and range are clearly related to the generating conditions, thus controlled. Thus, the device is very simplified and moreover avoids any shutter effect by the absence of elements arranged in the complete flow. Of course, such elements (perforated cone, grid, stirrer, etc.) may be arranged upstream or downstream of the nozzle if the emulsion or the configuration of the jet must be modified.

The geometry of the nozzle is adapted so that the ejected mixture, called the second mixture to distinguish it from the first mixture at the nozzle inlet, forms a fog jet mainly along the vector axis of the nozzle and whose particle size, the range and volume deployment out of the vector axis (also commonly referred to as jet divergence) are controllable and assured up to the desired fire attack surface.

Because of the section geometry of the nozzle of the order of one or more millimeters of opening, the impurities or even grains of sand for example do not cause significant disturbances at the two-phase ejected mixture. It is even possible to add to the water-gas mixture an abrasive product such as consisting of fine solid particles.

Subsequently, an example of geometry adapted for a nozzle (or a multi-nozzle device), in particular at its inlet, its narrowing and its output will be illustrated. Mainly, the nozzle inlet consists of a first high gradient convergent access zone followed by a second low gradient convergent zone, a transition to the minimum cross section also referred to as the nozzle neck, and possibly a third divergent area ending in the nozzle outlet section. It is thanks to such a configuration or to similar configurations that the expansion within the nozzle makes it possible to control the particle size of the fog jet and its range, as a function of generating conditions that are simply definable at the inlet of the device.

In fact, advanced simulations of nozzle geometry have been made to arrive at the above example, but also at other variations allowing a control adapted to a desired exercise, for example to ensure a range of range variable while tending to maintain a controlled particle size of the fog jet.

A strong advantage of the invention is that the device can be used for a low absolute pressure (generally of the order of 5 to 10 bar) at the inlet to the emulsion chamber or the nozzle. For this pressure range, a fog jet flow at the outlet of the nozzle is, however, perfectly ensured in a range from 50 to 150 m / s and a particle size of droplets of 50 to 150 microns. The device therefore does not require a high input pressure or at least a considerable increase, in order to guarantee a larger jet range, such as for a long range light. Thus, during a considerable variation in range of the jet, untimely and abrupt variations in its particle size (and therefore its diphasic state) are discarded.

• une granulométrie contrôlée du mélange diphasique par un fractionnement du liquide en gouttelettes
• une accélération et une vectorisation des gouttelettes de liquide par la détente du gaz également pré-émulsionné en entrée de tuyère.

In short, the geometry (with at least two variable diameter sections along the input and output vector axis) of the nozzle according to the invention is adapted to allow a rate of expansion at the outlet of the nozzle which ensures:

• a controlled particle size of the diphasic mixture by splitting the liquid into droplets
• an acceleration and a vectorization of the liquid droplets by the expansion of the gas also pre-emulsified at the nozzle inlet.

In other words, the geometry of the nozzle allows a liquid-gas emulsion at its inlet to provide particle size uniformity as well as controlled range (and vice versa). It could then be understood that to vary the range thus obtained without modifying the particle size of the jet and the generating conditions, it would be necessary to modify the geometry of the nozzle, which would be practically impossible. In fact, nozzle geometry has also been calculated and adapted to allow range variation of the jet for a stable particle size factor by simply varying one or more of the generating conditions at the inlet or in the device. For the sake of ease, the input pressure (liquid-gas injection) of the device is for example adjustable by a single valve.

The invention also has a second advantageous aspect coupling several nozzles as described above and arranged on a rotary support, allowing in addition to a gyratory action by the detents of the nozzles and their particular provisions on the rotor and between them, of sweep targeted surfaces in a complete and extensive way or to project jets of fog over a large volume without trying to reach precisely a flame zone for example. In the same way as for the control of the range and particle size of the jet, the rotational speed can also be favorably controlled for a desired exercise, depending on the generating conditions of the multi-nozzle device, similar to that of a single nozzle.

Thus, the ejection device according to the invention satisfies the requirements of the control of large particle size in practice. Indeed, the size of the droplets must be adapted according to the type of fire, for example by means of finer drops to attack hydrocarbon foci or to cool very hot environments, or by means of larger drops for wet fires forming embers.

• Utilisation pour l'extinction d'un incendie, la prévention d'incendie par humidification à faible consommation de liquide ou le refroidissement de matériau avec comme liquide de l'eau pouvant contenir un agent extincteur, un agent mouillant.
• Utilisation pour un traitement surfacique d'un matériau, telle que :
  • + pour le nettoyage d'un matériau, 1e liquide étant de l'eau ou/et pouvant contenir un agent de nettoyage ;
  • + pour une application de peinture sur le matériau où le liquide contient principalement un agent colorant ;
  • + pour un traitement abrasif du matériau où le deuxième mélange contient une solution chimique liquide ou partiellement de faible granulométrie solide.
• Utilisation comme dispositif d'éjection d'un combustible (liquide ou gazeux).
• Utilisation comme dispositif pour la propulsion d'un élément comprenant la tuyère comme moyen de propulsion.
• etc.

Advantageously, various uses of the nozzle or of a multi-nozzle device (rotary or otherwise) are possible as an example and in a non-exhaustive manner:

• Use for the extinguishing of a fire, fire prevention by humidification with low liquid consumption or cooling of material with water as liquid which may contain an extinguishing agent, a wetting agent.
• Use for surface treatment of a material, such as:
  • for cleaning a material, the liquid being water and / or capable of containing a cleaning agent;
  • + for a painting application on the material where the liquid mainly contains a coloring agent;
  • + for an abrasive treatment of the material where the second mixture contains a liquid chemical solution or partially of small solid particle size.
• Use as a device for ejecting a fuel (liquid or gaseous).
• Use as a device for propelling an element comprising the nozzle as a means of propulsion.
• etc.

A set of subclaims also has advantages of the invention.

Figure 1

description générale d'une tuyère pour un mélange diphasique,

Figure 2

coupe d'un dispositif multi-tuyères rotatif,

Figure 3

vue de dessous du dispositif multi-tuyères rotatif,

Figure 4

vue de côté (droite) du dispositif multituyères rotatif.

Examples of implementation and application are provided using the figures described:

Figure 1

general description of a nozzle for a diphasic mixture,

Figure 2

cutting a rotary multi-nozzle device,

Figure 3

bottom view of the rotary multi-nozzle device,

Figure 4

side view (right) of the multi-rotator device.

• une détente à forts gradients de pression et associée à un intense transfert aussi bien de quantité de mouvement (trainée interfaciale) que d'énergie (chaleur et travail interfaciaux), l'efficacité de ces transferts est liée à l'augmentation de l'aire interfaciale (surface d'échange liquide-gaz) résultant de l'atomisation.
• un fractionnement et une accélération contrôlés de la phase liquide.

FIG. 1 generally describes an example of an EJ nozzle for a two-phase mixture MLG1 produced via an emulsion chamber EMC with optional elements or forms designed to promote the mixing of a liquid L1 with a gas G1, both injected at low pressure. (less than 20 bar, in practice between 5 and 10 bar). A more accurate profile of suitable nozzle will be described later in the document. The liquid L1 and the gas G1 entering the emulsion chamber EMC or directly into the nozzle EJ can be brought by two separate channels IN1, IN2 converging to the input IN. These channels advantageously do not need to have a particular arrangement as in most two-phase nozzle devices of the state of the art. Thus, in the emulsion chamber EMC or more generally downstream of the inlet of the nozzle EJ, the first two-phase mixture MLG1 is formed in a manner still not ideally controlled, in that the particle size of the mixture MLG1 or liquid L1 and the flow of gas G1 are still coarse and highly variable. Thanks to the adapted geometry of the nozzle EJ of length L with a nozzle neck disposed at a location X (which may be local as well as extended), a transformation of the first mixture MLG1 into a second two-phase mixture MLG2 takes place, while along the optimized nozzle through the trigger. The mixture then has a particle size with controlled character, that is to say that the liquid L1 supplied in the first MLG1 mixture is in the MLG2 mixture in the form of GOUT droplets having small diameters (50 to 150 μm) resulting from the atomization produced within the nozzle .. Thus the particle size of the liquid L1 and thus the outgoing fog jet is perfectly controlled on a range PO. In addition, the gas G1, as a component at the base of the first MLG1 low pressure mixture, is relaxed with a strong gradient, so that it causes an acceleration and a vectorization of GOUT droplets according to a major axis AX driver (main axis of symmetry of the nozzle In this jet may have a variable but controlled divergence, the gas G1 in the second MLG2 mixture therefore has a carrier effect GOUT droplets on the range PO.P range is of course related to the particular geometry of the nozzle used and to the generating conditions During the expansion with a suitable geometry nozzle, the gas G1 from the first mixture MLG1 provides a work which thus ensures on the one hand an additional propulsion of the liquid L1, at the base roughly coarse, and secondly its atomization in fine uniform droplets.The outgoing jet is in the form of rapidly moving fog (50 to 150 m / s).
This concept takes advantage of a nozzle geometry of simple shape, and including "large" orifices (up to a few mm) to implement, within the two-phase flow, a complex pressure-expansion physics associating:

• a relaxation with strong pressure gradients and associated with an intense transfer of both momentum (interfacial drag) and energy (heat and interfacial work), the efficiency of these transfers is related to the increase of the area interfacial (liquid-gas exchange surface) resulting from atomization.
• controlled fractionation and acceleration of the liquid phase.

où ṁ₁ est le débit massique (en kg/sec) du liquide L1, ṁ_g est le débit massique (en kg/sec) du gaz G1 et Pin est la pression absolue du mélange MLG1 (en bar) en entrée de tuyère.The particle size and range characteristics of the second ejected MLG2 liquid-gas mixture are controllable by said generator conditions such as the total inlet pressure of the EMC emulsion chamber or of the EJ nozzle (s) and the mass flow rates of the liquid. L1 and gas G1. These generating conditions relating to a nozzle flow are adapted for operating points of the nozzle with targeted particle size and range.
For a given nozzle geometry, the feed conditions (pressure of the first mixture MLG1 inlet nozzle EJ, incoming flow of the liquid L1, incoming flow of the gas G1) are not arbitrary. It is possible to demonstrate that there exists for a nozzle geometry a unique relation f such that: $$\mathrm{f}\left({\dot{\mathrm{m}}}_1{\dot{\mathrm{m}}}_{\mathrm{boy\; Wut}}\mathrm{Pine}\right)=0$$

where ṁ ₁ is the mass flow (in kg / sec) of the liquid L1, ṁ _g is the mass flow (in kg / sec) of the gas G1 and Pin is the absolute pressure of the mixture MLG1 (in bar) at the nozzle inlet.

1. 1. En écoulement diphasique, la grandeur utilisée est le titre massique en gaz TM (rapport du débit massique gaz et du débit massique total « liquide + gaz »), plutôt que le débit massique gaz. $$\mathrm{TM}\mathrm{=}\frac{\dot{{\mathrm{m}}_{\mathrm{g}}}}{\dot{{\mathrm{m}}_{\mathrm{g}}}\mathrm{+}\dot{{\mathrm{m}}_{\mathrm{l}}}}$$
   
2. 2. Il est alors possible de définir des points de fonctionnement de la tuyère qui sont donc caractérisés par un ensemble de triplet {ṁ₁, TM, Pin} qui constitue les conditions génératrices de l'écoulement en entrée de tuyère. D'un point de vue pratique cette relation a pour conséquence de rendre impossible un choix quelconque de débits (liquide et gaz) et de pression. I1 faut donc « relaxer » une des variables (par exemple le débit gaz). Ainsi lorsque qu'un réglage est effectué, il est possible de choisir un débit liquide ṁ₁ et une pression d'alimentation Pin, mais le débit gaz ṁ_g est alors imposé.

Note :

1. 1. In two-phase flow, the quantity used is the mass content in TM gas (ratio of the gas mass flow rate and the total mass flow "liquid + gas"), rather than the mass flow gas. $$\mathrm{TM}\mathrm{=}\frac{\dot{{\mathrm{m}}_{\mathrm{boy\; Wut}}}}{\dot{{\mathrm{m}}_{\mathrm{boy\; Wut}}}\mathrm{+}\dot{{\mathrm{m}}_{\mathrm{l}}}}$$
   
2. 2. It is then possible to define operating points of the nozzle which are therefore characterized by a set of triplet {ṁ ₁ , TM, Pin} which constitute the conditions generating the nozzle inlet flow. From a practical point of view this relation has the consequence of making impossible any choice of flows (liquid and gas) and pressure. It is therefore necessary to "relax" one of the variables (for example the gas flow rate). Thus, when an adjustment is made, it is possible to choose a liquid flow ṁ ₁ and a supply pressure Pin, but the gas flow ṁ _g is then imposed.

1. 1. Une dynamique de jet de l'ordre de 50 à 150 m/sec en sortie de tuyère
2. 2. Une granulométrie (taille des gouttelettes) de l'ordre de 50 à 150 µm
3. 3. Une enveloppe de jet (c'est à dire la frontière entre le jet et l'extérieur du jet)

According to this scheme, output values as relevant quantities are to be considered. The two-phase jet that develops at the outlet of the EJ nozzle is characterized by:

1. 1. A jet velocity of about 50 to 150 m / sec at the outlet of the nozzle
2. 2. A particle size (droplet size) of the order of 50 to 150 μm
3. 3. A jet envelope (ie the border between the jet and the outside of the jet)

• La portée PO, distance maximum au delà de laquelle la dynamique du jet n'est plus suffisante pour être efficace sur un feu.
• La densité d'aire interfaciale, c'est-à-dire la surface totale développée par l'ensemble des gouttes contenues dans un volume unitaire.
• Le volume protégé (couverture volumique du jet)

Of these three characteristics of prime importance, it is possible to deduce the relevant quantities, for example in the fight against fires such as:

• The range PO, maximum distance beyond which the dynamics of the jet is no longer sufficient to be effective on a fire.
• The interfacial area density, that is to say the total area developed by all the drops contained in a unit volume.
• The protected volume (volume coverage of the jet)

Of course, the jet outlet conditions (jet velocity, particle size and envelope) are entirely a function of the conditions generating the flow, directly also related to the geometry of the nozzle. It is thus possible to map, for a nozzle geometry, operating points according to the generating and output conditions for each desired ejection application.

• Disposer les tuyères en différents lieux du volume et suivant différentes directions (disposition en réseau dit en peigne ou en « swirl ») ;
• Regrouper plusieurs tuyères sur un même corps fixe (dispositif multi-têtes) ;
• Disposer plusieurs tuyères sur un corps rotatif (corps multi-tuyères rotatif).

In the general framework of the fight against fires, and more particularly by means of fog of water, there are two distinct approaches: the point protection (the jet is directly directed on the site identified with risk, for example a reservoir, a motor, etc.) and the volume protection where the jet is oriented so as to protect the entire volume without trying to reach precisely the flame zone.
The two-phase mist jet nozzles according to the invention produce, in addition to a certain divergence tolerance, a jet of great dynamic and relatively directional. Thus for volume protection applications, where one seeks to protect a volume as a whole without privileging a particular direction, it is necessary to use a set of several nozzles capable of covering all directions in the entire volume. For this, several solutions exist (non-exhaustive list):

• Arrange the nozzles in different places of the volume and in different directions (network arrangement called comb or "swirl");
• Group several nozzles on the same fixed body (multi-head device);
• Arrange several nozzles on a rotating body (rotary multi-nozzle body).

In addition to very interesting results, the network arrangements and the multi-head device, have the disadvantage of leaving unprotected areas of the volume, while the solution of a rotating body on which several nozzles are fixed can scan all a set of direction and optimally cover the volume to be protected.

In FIG. 2, such a device for ejecting a two-phase fluid MLG1 injected into a multi-nozzle rotary system is shown in cross-section. The system comprises a stator STAT rotating guide a rotor ROT, on which are arranged nozzles EJ, EJ1, EJ2.- according to Figure 1. It should be noted that the gas G1 and liquid L1 are directly injected to the inputs nozzles via the single input IN of the stator STAT leading to a free inner space of the rotor ROT which simply serves as an EMD distribution chamber for the MLG1 mixture. It should be noted that an effective emulsion chamber, for example with perforated or partition elements, is no longer indispensable insofar as the mixture is admitted directly into the distribution chamber. If the control of the quality of the admitted mixture requires it, it is possible to place an emulsion chamber EMC, similar to that of Figure 1, upstream of the EMD distribution chamber. Thus, no perforated or sharing element or risk shutter is present in the EMD distribution chamber. The EMD distribution chamber materialized between the rotor ROT and the STAT stator is thus common to all the nozzles EJ, EJ1, EJ2 ... that it feeds into water / gas mixture or any other liquid / gas mixture (which could also contain more than two phases).

The nozzles EJ1, EJ2... And their axes AX1, AX2... Arranged in an offset or asymmetrical manner relative to the axis of rotation RX of the rotor ROT allow the rotational propulsion by the same reaction forces of the outgoing jets of the nozzles. The axis AX of a nozzle EJ can be superimposed on the axis of rotation RX of the rotor ROT, but does not contribute to the rotation of the rotor. This nozzle EJ can also be fixed on the stator STAT to simplify the construction of the complete device and avoid a rotation of the nozzle on itself.
Thus, several exhaust nozzles EJ1, EJ2,... Provided with their axes-vector AX1, AX2,... Separate jets are disposed on the walls of the EMD distribution chamber, in particular so as to obtain a surface or a fog cover volume extended to at least one defined range. Some vector axes AX1, AX2, ... ejector nozzles EJ1, EJ2, - can be arranged on the rotor ROT asymmetrically about a plane comprising the axis of rotation RX, and are in particular oriented from staggered at an angle between 0 ° and 90 ° in a plane perpendicular to the axis of rotation RX. To simply favor the jet distribution, this angle is different between at least two adjacent nozzles.

By the geometry of the nozzles, the expansions at the outlet of the ejector nozzles EJ1, EJ2, ... or / and the directions distinct from the vector axes AX1, AX2,... Are thus adapted so that a rotating effect of the rotor ROT with controlled rotation speed is produced. In particular, the vector axes AX1, AX2,... May also be free from any intersection with the axis of rotation RX in order to generate on the rotor ROT by the reaction forces in a nozzle a torque component laterally to the nozzle inducing an angular displacement of the rotor ROT about its axis RX.

It is of course possible to have on the rotor ROT ej1, EJ2, ... ejection nozzles having different geometries influencing the particle size and / or the range of the second liquid-gas mixture MLG2. Thus, the fog obtained can have various properties useful for various exercises (close and far extinction, several controlled diameters of drops).

In this device and as for the nozzle of FIG. 1, the pressure of the liquid L1 or / and the gas G1 at the injection inlet is adaptable according to the ratio of the inlet flow rates for the liquid L1 and the gas G1 . Similarly, the device is designed with geometrically studied nozzles, so that particle size characteristics and scope of the second ejected MLG2 liquid-gas mixture are controllable by generating conditions such as the total inlet pressure of the EMD distribution chamber or / of the nozzle (s) EJ, EJ1, EJ2, ... and mass flow rates of the liquid L1 and gas G1. It follows that as for a nozzle, the rotary device responds to generating conditions relating to a nozzle flow and which are adapted for operating points of the device for one (or more) granulometry (s) and / or one (or several) targeted reach (s). According to this configuration, liquid flow rates L1 of the order of less than 2 kg / s are made possible.

Finally, Figure 2 corresponding to an embodiment suitable for the rotary multi-nozzle device has one of the ideal geometries of the nozzle according to the invention. This geometry has been detailed for the nozzle EJ2 seen in section at the level of its axis-vector AX2 (axis of symmetry of the nozzle). Principally, the nozzle EJ2 consists of three portions of length La, Lb, LC along its vector axis AX2. The nozzle inlet consists of a first zone, of length La, converging with a strong gradient followed by a second zone, of length Lb, converging at a low gradient, of a passage at the minimum section also called neck of the nozzle, and optionally to a third zone, of length Lc, diverging ending in the nozzle outlet section of dimension D2 (usually greater than 1 mm for extinguishing or cooling applications over a few tens of meters). The first zone with high gradient favors a rapid atomization of the flow, the increase of the exchange surface resulting from this atomization allows intense transfers of momentum and energy, between liquid and gas, in the together the nozzle which thus jointly ensures atomization and acceleration of the liquid during relaxation. It is thanks to such a geometry and such dimensions that the two-phase mixture can be ejected after expansion into a fog nozzle with particle size, range and volume controlled as the invention describes it.

Figures 3 and 4 show a bottom view and a side view (right) of rotary multi-nozzle device according to Figure 2. In particular, it should be noted that the arrangement of the nozzles EJ1, EJ2, ..., EJ6 relative to the axis of rotation RX of the rotor ROT (or with respect to a plane comprising the axis of rotation RX) is asymmetrical considering two nozzles whose vector axes are included in a single plane also comprising the axis of rotation. RX rotation of the rotor (for example the EJ4 and EJ6 nozzles with their vector axes AX4 and AX6). The neighboring nozzles are also angularly offset relative to the axis of rotation RX of the rotor ROT. This arrangement promotes the controlled rotational effect of the rotor ROT, but also offers an extended jet scan on volumes to be humidified.

It is important to point out that this system provides an ecological advantage because it operates at low water flow rates with respect to current devices for ejecting a two-phase water-gas mixture (weakly compressed gas). It therefore allows a low consumption of water coupled to a precisely controlled distribution of water. This device could therefore also be advantageously used, outside a building, for the prevention of fire in natural environments. The water could come from any source (especially a water table). A humidification or even watering function is also possible over large spaces while minimizing water consumption without the need for high pressure at the inlet of the device. Other media such as flammable industrial surfaces may also be protected against suspicious heating or fire.

The present invention is potentially adaptable to other types of applications such as propellant feed / atomization for rocket engines, or for fuel injection optimization for combustion heat engines.

It is also possible according to the invention to improve the device for ejecting a fuel (liquid or gaseous) to form a large flame (example of industrial application: burners in glass furnaces, example of military application : flamethrower).

Use of the device for the propulsion of a vehicle comprising the nozzle as a means of propulsion is also possible, such as for the propulsion of a marine or air vehicle (submarine, jet-ski, airplane, etc.).

Thus, it is easy to understand that the present invention goes well beyond an exhaustive list of possibilities of field of application or use of the nozzle or more generally of the ejection device.

Claims (20)

Device for ejecting an at least two-phase mixture, comprising at least one injection inlet (IN1, IN2) for a liquid (L1) and a gas (G1), a distribution chamber (EMD) for producing a first mixture liquid-gas (MLG1), an ejector nozzle (EJ) of the first liquid-gas mixture (MLG1) in a main direction defined by a vector axis (AX),
characterized in that
the ejection nozzle (EJ) has a geometry with at least a minimum cross-sectional area, called a collar, at a location (X) of the vector axis (AX),
and for which geometry an expansion within the ejection nozzle (EJ) is induced allowing the first liquid-gas mixture (MLG1) from the distribution chamber to be converted, in the flow configuration sense, into a second mixture of liquid-gas (MLG2) at the outlet of the nozzle, the ejection range of the second mixture (MLG2) and the particle size of the liquid (L2) in the form of droplets (GOUT) can be controlled according to the mass flow rates of the liquid (L1) and gas (G1) and the absolute pressure at the injection inlet. Device according to claim 1, for which the ejected second mixture (MLG2) is a diphasic mist jet mainly along the vector axis (AX) and whose particle size, range and voluminal deployment out of the vector axis (AX ) are controllable. Device according to claim 2, in which the pressure at the injection inlet of the emulsion chamber (EMC) is low, for example less than 20 bar, and a The speed of the fog jet is high, for example above 50 m / s. Device according to one of the preceding claims, wherein the gas injection inlet (G1) and the liquid (L1) is common at an inlet section (IN) of the nozzle. Device according to one of the preceding claims, for which a plurality of ejection nozzles (EJ1, EJ2,...) Provided with distinct vector axes (AX1, AX2,...) Are arranged on the walls of the emulsion chamber. (EMC), in particular so as to obtain a surface or a volume of fog cover extended to at least a defined range. Device according to one of claims 4 or 5, for which the distribution chamber (EMD) is between a stator (STAT) and a rotor (ROT) with an axis of rotation (RX) and on said rotor (ROT) is arranged at least one ejection nozzle (EJ, EJ1, EJ2, ...). Device according to claim 6, wherein at least one ejection nozzle is disposed on the stator (STAT) Device according to claims 5 and 6, for which certain vector axes (AX1, AX2, ...) of ejection nozzles (EJ1, EJ2, ...) are arranged asymmetrically on the rotor (ROT) with respect to a plane comprising the axis of rotation (RX), and in particular are oriented staggered at an angle between 0 ° and 90 ° in a plane perpendicular to the axis of rotation (RX). Device according to one of Claims 5 to 8, for which the vector axes of the ejection nozzles (EJ1, EJ2, are free to intersect with the axis of rotation (RX) and their arrangement is adapted for a rotational effect of the rotor (ROT) controlled rotational speed is produced. Device according to one of claims 5 to 8, for which the ejection nozzles (EJ1, EJ2, ...) have different geometries affecting the particle size distribution and / or the range of the second liquid-gas mixture (MLG2). Device according to one of the preceding claims, for which the particle size and span characteristics of the ejected second liquid-gas mixture (MLG2) are controllable by generating conditions such as the total inlet pressure of the distribution chamber (EMD) or of nozzle (s) (EJ, EJ1, EJ2, ...) and mass flow rates of the liquid (L1) and the gas (G1). Device according to claim 11, for which the generating conditions relating to a nozzle flow are adapted for operating points with a targeted particle size and range. Device according to one of the preceding claims, for which an emulsion chamber (EMC) and / or the distribution chamber (EMD) comprise sharing means and / or emulsion means and / or rotational drive means. . Device according to one of the preceding claims, in which the liquid (L1) is water and the gas (G1) is compressed air. Device according to one of the preceding claims, for which several liquids and / or several gases and / or fine solid particles are injected into the emulsion chamber (EMC). Use of the device according to one of the preceding claims for the extinguishing of a fire, the prevention of fire by humidification with low consumption of liquid or the cooling of material with liquid (L1) which may contain an extinguishing agent, a humidifying agent or a coolant. Use of the device according to one of the preceding claims 1 to 15 for a surface treatment of a material, such as: for cleaning a material, the liquid (L1) being water and / or containing a cleaning agent; - for a paint application on the material where the liquid (L1) contains mainly a coloring agent; - For an abrasive treatment of the material where the second mixture (MLG2) contains a liquid chemical solution or partially of small solid particle size. Use of the device according to one of the preceding claims 1 to 15 for propellant feed / atomization of a rocket engine or for fuel injection of an optimized combustion engine. Use of the device according to one of the preceding claims 1 to 15 for the ejection of a fuel, such as for forming a large flame. Use of the device according to one of the preceding claims 1 to 15 for which the nozzle is a means of propulsion of a vehicle.

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