SYSTEM FOR DRIPPING A LIQUID

Description

[0001] The present invention relates, in general, to the release of a liquid contained in a tank and more particularly to a system for releasing a liquid contained in a tank.

[0002] The release of a liquid from a tank is particularly advantageous in various applications such as the dispersal on the ground by aerial means of a retardant in the field of firefighting, of products for agricultural, meteorological or environmental purposes, but also in the field of industry.

[0003] The two most commonly used liquid delivery methods in firefighting are gravity delivery and pressurized delivery.

[0004] The gravity release method is based on the controlled opening of a tank hatch from which the liquid gradually escapes under the effect of gravity. US5326053A discloses a release system according to the prior art.

[0005] The flow rate of the liquid leaving the tank is variable, since it is a function of the height of the liquid in the tank. Although the liquid outlet rate can be adjusted, to some extent, by controlling the percentage of opening of the hatch, such a process results in an inhomogeneous footprint on the area to be covered.

[0006] Pressurized dropping involves using an on-board compressed air source, accumulator or compressed air generator, to compress the liquid in the tank to allow a more regular release of the liquid.

[0007] However, it leads to too violent a release and, consequently, too great a dispersion of the liquid on the ground.

[0008] In addition, pressure jettisoning poses safety concerns related to the high operating pressure of the system which requires a significant amount of compressed air on board the aircraft.

[0009] Furthermore, the configuration of known liquid release systems leads to the appearance of drain vortices as the height of the liquid in the tank decreases, disturbing the flow of liquid leaving the tank, the speed and flow rate of which decrease, and transforming the initially single-phase liquid to be released into a two-phase mixture of gas and liquid.

[0010] The invention therefore aims to remedy these drawbacks and to propose a liquid release system with improved hydraulic performance, leading to a single-phase flow and a constant liquid outlet flow rate for an efficient and homogeneous footprint.

[0011] A liquid release system is therefore proposed, comprising a liquid storage tank with a liquid outlet area provided with an outlet nozzle and a release hatch.

[0012] In addition, the release system includes means for varying the air pressure in the storage tank depending on the height of liquid in the tank.

[0013] The storage tank comprises a cylindrical storage area with a round base and a conical liquid outlet area.

[0014] Advantageously, the means for varying the air pressure in the tank may comprise a pressurized air diffuser capable of distributing the air supply over the surface of the liquid.

[0015] According to one embodiment, the air diffuser comprises a disc arranged in the storage tank downstream and at a distance from an air inlet and perpendicular to said air inlet.

[0016] According to another embodiment, the air diffuser may comprise at least one tube arranged perpendicular to an air inlet supplying the diffuser with air.

[0017] According to another embodiment, the air diffuser may comprise at least two tubes arranged perpendicular to an air inlet supplying the diffuser with air, the tubes being arranged so that the longitudinal axes of the tubes form a non-zero angle between them.

[0018] According to one embodiment, the pressurized air diffuser has a spiral shape.

[0019] According to one embodiment, the outlet nozzle may be bent.

[0020] Advantageously, the release system may comprise a pressure regulator acting on the air pressure in the tank and capable of regulating the pressure of the liquid leaving the tank around a set value.

[0021] Preferably, the set value is given by the pressure of the liquid taken at the liquid outlet zone or at the terminal part of the outlet nozzle, more precisely before the last bend of the outlet nozzle 4 when a bend is present.

[0022] The storage tank comprises a cylindrical storage area with a round base and a conical liquid outlet area, the conical liquid outlet area forming an angle with a general axis of the storage tank of between 30° and 50°.

[0023] Advantageously, the release system may include a gas detector at the outlet of the storage tank.

[0024] Preferably, the release system comprises a control module acting on the pressure regulator and on the release hatch.

[0025] According to a particular embodiment, the release hatch comprises a converging nozzle whose liquid outlet section is variable.

[0026] The invention also relates to a firefighting aircraft, comprising a release system as described above and in which the liquid is a retardant.

[0027] Other aims, advantages and characteristics will emerge from the description which follows, given purely for illustrative purposes and with reference to the attached drawings in which: [ Fig 1 ] represents a liquid release system according to the invention, comprising a release hatch in the closed position. [ Fig 2 ] represents the liquid release system illustrated in the figure 1 , including a release hatch in the open position. [ Fig 3 ] represents a liquid release system according to the invention, comprising an angled outlet nozzle. [ Fig 4 ] illustrates a first embodiment of a pressurized air diffuser of a release system according to the invention. [ Fig 5 ] illustrates a second embodiment of a pressurized air diffuser of a release system according to the invention. [ Fig 6 ] illustrates a third embodiment of a pressurized air diffuser of a release system according to the invention. [ Fig 7 ] illustrates a fourth embodiment of a pressurized air diffuser of a release system according to the invention. [ Fig 8 ] illustrates a variant of the second embodiment of the pressurized air diffuser illustrated in the figure 5 . [ Fig. 9 ] is a sectional view along a vertical plane of a particular embodiment of the release hatch in the closed position. [ Fig 10 ] represents the release hatch of the figure 9 , in open position at minimum diameter D1. [ Fig 11 ] represents the release hatch of the figure 9 , in open position at maximum diameter D3. [ Fig 12 ] is a sectional view along a horizontal plane of the release hatch of the embodiment illustrated in figure 9 , in closed position when opening at minimum diameter D1. [ Fig 13 ] represents the release hatch illustrated in the figure 11 , in open position at maximum diameter D3. [ Fig 14 ] illustrates a self-supporting chassis device.

[0028] We will first refer to the figure 1 illustrating a liquid delivery system according to the invention, designated by the general reference numeral 1.

[0029] Depending on the application, the liquid is a solution containing water. It can be a retardant used in firefighting, a product for agricultural, meteorological or environmental purposes, or a product used in industry.

[0030] In the remainder of the description, the invention applies to the field of firefighting. The liquid is thus a retardant or water.

[0031] The release system 1 comprises a storage tank 2 capable of containing the liquid for its release from the release system 1.

[0032] The storage tank 2 comprises a liquid outlet area 3. The liquid outlet area is provided with an outlet nozzle 4 and a release hatch 5.

[0033] In the example illustrated, the storage tank 2 is surmounted by a cover 6 and advantageously comprises an air inlet 7 which can be arranged, as shown, in the center of the cover 6. The air inlet 7 is preferably supplied with compressed air.

[0034] The release hatch 5 can be associated with a latch 8 for locking the release hatch 5 in the closed position.

[0035] Furthermore, the section of the release hatch 5 is preferably determined according to the proportions of the tank 2.

[0036] The release hatch 5 will preferably be an instant-opening hatch.

[0037] THE figures 1 And 2 illustrate, respectively, the release hatch 5 in the closed position and in the open position.

[0038] Furthermore, the release system 1 comprises means for varying the air pressure in the storage tank 2 as a function of the height of liquid in the tank 2.

[0039] In this regard, the release system 1 comprises a pressure regulator 10 acting on the air pressure in the tank 2 and capable of regulating the pressure of the liquid leaving the tank 2 around a set value.

[0040] It should be noted in passing that initially, that is to say prior to release, the liquid fills the reservoir 2, the liquid outlet zone 3 and the outlet nozzle 4, which makes it possible to avoid the formation of a two-phase mixture of gas and liquid.

[0041] The pressure regulator 10 acts on a solenoid valve 9 preferably arranged at the level of an air supply duct of the air inlet 7, upstream of the air inlet 7. The pressure of the liquid at the outlet of the reservoir 2 can thus be adjusted by varying the air pressure in the reservoir 2, itself regulated by controlling the opening of the solenoid valve 9.

[0042] In a particular embodiment, the pressure regulator 10 acts on a solenoid valve 9 arranged at an air supply duct of the air inlet 7, upstream of the air inlet 7. Here, the pressure of the liquid is taken by means of a pressure sensor preferably arranged at the convergent part of the liquid outlet zone or at the horizontal part of the outlet nozzle 4 before the last bend, if a bend is present, or at the terminal part 4a of the outlet nozzle, if no bend is present. Here, the pressure sensor gives a pressure which will subsequently be called P0. This control as a function of the pressure P0 will make it possible to minimize cases of two-phase air and liquid flow. Indeed, it was found that controlling the pressure regulator as a function of P0 makes it possible to obtain a better air front between the air and the liquid, which is cleaner, avoiding a two-phase flow.

[0043] Still in this embodiment, the pressure regulator 10 is controlled to maintain the pressure P0 constant.

[0044] In a particular embodiment, the pressure P0 will make it possible to obtain additional data, namely the flow rate of the liquid.

[0045] This data can be processed by the operator in charge of the release to optimize the release of liquid depending in particular on the surface to be covered, for example in the case of a fire.

[0046] In another particular embodiment, the pressure regulator 10 generates one or more pressure ramps. Pressure management is ensured by a predefined program.

[0047] The pressure ramp(s) can be adjusted based on aircraft-related data such as load factor, trim, or external pressure.

[0048] Preferably, the release system 1 comprises a plurality of pressure sensors, not shown in the figures. The pressure sensors will advantageously be arranged on the upper part, on the central part and on the lower part of the storage tank 2 but also on the liquid outlet zone 3 and at the outlet nozzle 4, in particular at the terminal part 4a of the outlet nozzle 4. However, in the presence of one or more bends, the pressure sensors will advantageously be arranged upstream of the last bend.

[0049] The pressure sensors will thus make it possible to calculate the pressure in the different areas of tank 2.

[0050] The storage tank 2 comprises a cylindrical storage area 11 with a round base.

[0051] In addition, the liquid outlet area 3 is conical.

[0052] This configuration of the storage tank 2 makes it possible to minimize disturbances to the outgoing liquid flow and therefore makes it possible to avoid a two-phase air and liquid flow, in favor of a single-phase flow.

[0053] In order to further minimize disturbances, the conical liquid outlet zone 5 forms an angle with a general axis of the storage tank 2 of between 30° and 50°, preferably 30°C.

[0054] In the expression "between", the limits of the domain of values ​​are included in this domain.

[0055] When the release system 1 is, for example, mounted on an aircraft for airborne release of the liquid, it may be necessary, depending on the dimensions of the storage tank 2, to position the storage tank 2 at the center of gravity of the aircraft in order to reduce the impact of the release which could cause loss of control of the aircraft.

[0056] As illustrated in the figure 3 , the outlet nozzle 4 can thus be bent, which makes it possible to offset the release hatch 5 relative to the storage tank 2 and to position the release hatch 5 at a location determined according to the architectural constraints of the aircraft.

[0057] In an alternative embodiment, for example, still mounted on an aircraft, a self-supporting frame device 20, as illustrated in figure 14 , may be mounted in the aircraft to allow optimal distribution of the loads constituted in particular by the storage tank 2 and the various pipes, in particular the outlet nozzle 4.

[0058] A self-supporting chassis device will prevent imbalance problems when releasing the liquid

[0059] A self-supporting chassis device will allow the installation of a device for recovering liquids from possible leaks in the system.

[0060] Advantageously, the means for varying the air pressure in the tank further comprise a pressurized air diffuser capable of distributing the air supply over the surface of the liquid and thus preventing the formation of drain vortices when the liquid is released.

[0061] The pressurized air diffuser is preferably arranged in the upper part of the storage tank 2, upstream of the liquid and downstream of the air inlet 7.

[0062] There figure 4 represents the storage tank 2 comprising a first embodiment in which the pressurized air diffuser comprises a disc 12 arranged downstream, at a distance from the air inlet 7 in the tank 2. The disc 12 is arranged perpendicular to the air inlet 7 and therefore perpendicular to the air flow entering the storage tank 2 via the air inlet 7.

[0063] There figure 5 illustrates a second embodiment in which the pressurized air diffuser comprises a tube 13 arranged perpendicular to the air inlet 7 supplying the tube 13 with air.

[0064] There figure 6 illustrates a third embodiment in which the air diffuser comprises two tubes 14 and 15 arranged perpendicular to the air inlet 7 which supplies the diffuser with air. The tubes 14 and 15 are arranged so that their longitudinal axes form a non-zero angle between them, preferably 90°C.

[0065] It may be provided that the air diffuser includes a number of tubes greater than two.

[0066] The longitudinal axes of the two tubes 14 and 15 intersect at a connection point located in the center of the tubes 14 and 15, forming a cross. The air inlet 7 supplies the tubes 14 and 15 at the level of said connection point.

[0067] There figure 7 represents a fourth embodiment in which the pressurized air diffuser has a spiral shape. In the illustrated example, a duct 16 extends so as to form a spiral and is supplied with air by the air inlet 7 at the center of the spiral.

[0068] Preferably, and as illustrated on the figures 5, 6 And 7 , the pressurized air diffuser may comprise a plurality of holes preferably arranged homogeneously on the diffuser.

[0069] The plurality of holes is thus oriented so as to create strong and homogeneous agitation on the surface of the liquid, in particular in the central zone of the storage tank 2, in order to prevent the formation of drain vortices which could increase as the height of the liquid decreases.

[0070] There figure 8 represents a pressurized air diffuser comprising a tube 17 arranged perpendicular to the air inlet 7 as illustrated in figure 5 . Alternatively, the tube 17 comprises a plurality of holes whose size increases progressively as one moves away from the center of the tube and approaches the ends, so as to further disturb the surface of the liquid. The example is illustrated on a diffuser comprising a tube. Of course, this configuration can be applied to any type of shape of the air diffuser.

[0071] In a particular embodiment, the pressurization requirements between the liquid outlet zone 3 and the release hatch 5 can be reduced by increasing the altitude difference between the liquid outlet zone 3 and the release hatch 5.

[0072] More precisely, the difference in altitude between the lower end of the liquid outlet zone 3 and the level of the release hatch 5 will be noted H0. The higher H0, the less pressurization requirements, provided in particular by a pressurized air diffuser, will be necessary. This specific structure makes it possible to avoid a heavy structure that can constitute the pressurization means.

[0073] As shown on the figures 1 à 3 , the release system 1 comprises a control module 18 integrating the pressure regulator 10 and acting on the release hatch 5.

[0074] For example, the regulator 10 is a proportional-integral-derivative (PID) type regulator capable of regulating the pressure prevailing in the tank 2 around a set value, from the measured pressure value, by acting on the solenoid valve 9.

[0075] In the illustrated example, the control module 18 is connected to the pressure sensors.

[0076] The pressure is measured at the converging part of the liquid outlet zone 3 or at the horizontal part of the outlet nozzle 4 before the last bend, if a bend is present, or at the terminal part 4a of the outlet nozzle, if no bend is present. When the measured pressure deviates from the set value, the control module 18 can adjust the air flow entering the storage tank 2 via the pressure regulator 10 which it controls. The pressure regulator 10 will accordingly control the opening of the solenoid valve 9.

[0077] The liquid outlet flow rate is directly proportional to the liquid pressure at the outlet of the tank 2. By maintaining the liquid pressure at the outlet of the tank 2, either at the convergent part of the liquid outlet zone, or at the horizontal part of the outlet nozzle 4 before the last bend, if a bend is present, or at the terminal part 4a of the outlet nozzle, if no bend is present, around a set value it is possible to maintain the liquid outlet flow rate constant.

[0078] Thus, the air pressure in the storage tank 2 is adjusted, in the example illustrated by the control module 18, so as to compensate for the decrease in pressure at the bottom of the tank 2 caused by the decrease in the height of the liquid during the release. This regulation makes it possible to maintain a constant pressure at the outlet of the tank 2 and, consequently, to maintain a constant outlet flow rate and liquid outlet speed. By ensuring a constant release speed and flow rate, a constant release width and consequently a constant release footprint are ensured.

[0079] The resulting imprint made by the liquid on the area to be covered by the liquid will therefore be homogeneous and regular.

[0080] Such a release system 1 also makes it possible to compensate for variations in the load factor experienced by a moving aircraft in the case where the liquid release system 1 is installed on an aircraft.

[0081] When the pressure at the outlet of the tank 2 deviates significantly from the set value, the control module 18 can be configured to close the release hatch 5. This avoids the unnecessary release of the retardant, the cost of which is relatively high.

[0082] As recalled above, in an alternative embodiment, the set value is given by the pressure P0.

[0083] In a particular embodiment, the release hatch 5 comprises a converging nozzle and / or a honeycomb structure through which the liquid can pass.

[0084] In a particular embodiment illustrated in figures 9 à 14 , the release hatch includes a converging nozzle whose liquid outlet section is variable.

[0085] The liquid outlet section can have two diameters: a minimum outlet diameter D1 and a maximum outlet diameter D3.

[0086] In reference to the figures 9 à 14 , the release hatch here comprises a structure in the shape of a truncated cone at the top formed by a fixed wall 51. More precisely, the internal surface of this truncated cone at the top comprises several movable walls also called flaps 52a, 52b, 52c, 52d, 52e, 52f, 52g, 52h, 52i, 52j, 52k and 521, twelve movable walls in the illustrated example, rotatably mounted on the internal surface by their upper end. Only two opposite movable walls 52a, 52g are shown because this is a sectional representation.

[0087] The movable walls 52a to 521 of this cone truncated at the top are held at a distance from the internal surface of the wall 51 by means of position-holding springs 53a to 531 and thus define a minimum outlet diameter D1, the free end of the movable walls 52a to 521 forming a liquid outlet section of variable diameter.

[0088] The movable walls 52a, 52b are mounted to rotate by means of pivoting devices, here hinges 54a to 541.

[0089] Preferably, the movable walls 52a to 52g or flaps are isosceles trapezoids, the wider side of the two opposite parallel sides of the trapezoid corresponding to the end rotatably mounted on the fixed wall 51. The outlet of the release hatch 5 comprises two locking plates. A first locking plate 55 closes the opening formed by the free end of the fixed side walls 51a, 51b and prevents any liquid from escaping when it is in the closed position.

[0090] A second locking plate 56 is mounted upstream of the first locking plate 55, relative to the liquid outlet direction. The second locking plate 56 corresponds to a wall open in its center, the opening being of diameter D1.

[0091] Here, the periphery of the opening of the second locking plate 56 forms a stop 57 of the flaps 52a to 521 which, when the second locking plate 56 is in the closed position, prevents the flaps from forming a release section greater than the diameter D1.

[0092] The first and second locking plates 55 and 56 are each locked in the closed position by a latch 8 as described above and not shown in the figure 9 but represented on the figures 1 à 3 .

[0093] When the latch 8 associated with the first locking plate 55 and the latch 8 associated with the second locking plate 56 are actuated, the first and second locking plates 55 and 56 each pivot around a hinge and the liquid pours out according to a release section of diameter which can go up to the diameter D3, less than the diameter D2 of the outlet nozzle 4. The figure 11illustrates the release hatch 5 in the open position, when the two locking plates 55 and 56 are open. When the locking plates 55 and 56 are open, the springs 53a to 531 are calibrated so as not to oppose any resistance to the opening of the plates 52a to 52l when a flow of liquid exists, thus making it possible to form a release section with diameter D3.

[0094] The springs are calibrated to push the plates 52a to 521 back into the rest position when the outlet nozzle 4 is empty, forming an opening of section D1 which will allow the locking plate 56 to be repositioned in the closed position.

[0095] The greater the force exerted on the movable walls 52a to 521, and therefore on the spring, the greater the liquid outlet section. The less force exerted on the movable walls, the smaller the liquid outlet section.

[0096] When the second locking plate 56 is in the closed position and the first locking plate 55 is in the open position, the liquid pours through the opening of the second locking plate 56. Taking into account the holding stop 57, the diameter of the liquid outlet section does not exceed the diameter D1.

[0097] A gas detector 19 may be provided at the outlet of the storage tank 2 in order to detect a two-phase flow of the liquid resulting from the mixing of air with the liquid.

[0098] Furthermore, the storage tank may include a pressure relief valve.

[0099] As previously indicated, it may be provided that the liquid release system 1 is installed on a fire-fighting aircraft, in which the liquid will be a retardant.

[0100] It may also be provided that the liquid release system 1 is used for an application other than firefighting.

[0101] The 1 drop system could, for example, be used in industry, or in the dropping, by air or otherwise, of agricultural, meteorological or environmental products.

[0102] The liquid to be dropped could then be, for example, a pesticide, a solvent or even an oil slick treatment liquid.

[0103] In the liquid release system 1, the main source for the release is gravity. The release system, thus relying on simple means, also offers the possibility of maintaining a constant flow rate and speed of the liquid. The occurrence of disturbances in the liquid flow is avoided and the end of the release is carried out without loss of efficiency leading to an improved coverage rate by the liquid on the area to be covered.

Claims

1. A liquid dropping system, comprising a liquid storage reservoir (2) provided with a liquid outlet area (3) provided with an outlet nozzle (4) and a dropping hatch (5), the dropping system comprises means for varying the pressure of the air in the storage reservoir (2) depending on the level of liquid in the reservoir (2), characterised in that the storage reservoir (2) comprises a cylindrical storage area (11) with a round base and the liquid outlet area (3)which is conical, the conical liquid outlet area (3) forming an angle with a general axis of the storage reservoir (2) comprised between 30° and 50°.

2. The dropping system according to claim 1, wherein the means for varying the air pressure in the reservoir (2) comprise a pressurised air diffuser capable of distributing the air supply over the surface of the liquid.

3. The dropping system according to claim 2, wherein the pressurised air diffuser has a spiral shape.

4. The dropping system according to claim 2, wherein the air diffuser comprises at least one tube (13) disposed perpendicular to an air intake (7) supplying the diffuser with air.

5. The dropping system according to claim 2, wherein the air diffuser comprises at least two tubes (14, 15) disposed perpendicular to an air intake (7) supplying the diffuser with air, the tubes (14, 15) being disposed so that the longitudinal axes of the tubes (14, 15) form therebetween a non-zero angle.

6. The dropping system according to claim 2, wherein the air diffuser comprises a disc disposed in the storage reservoir (2) downstream and at a distance from an air intake (7) and perpendicular to said air intake (7).

7. The dropping system according to claim 1 to 6, wherein the outlet nozzle 4 is bent.

8. The dropping system according to any one of claims 2 to 7, characterised in that it comprises a pressure regulator acting on the air pressure in the reservoir (2) and able to regulate the pressure of the liquid leaving the reservoir (2) around a set value.

9. The dropping system according to claim 8, characterised in that the set value is given by the pressure (P0) of the liquid taken at the converging portion of the liquid outlet area, or else at the horizontal portion of the outlet nozzle (4) before the last bend, if a bend is present, or at the terminal portion (4a) of the outlet nozzle (4), if no bend is present.

10. The dropping system according to any one of claims 1 to 9, comprising a gas detector (19) at the outlet of the storage reservoir (2).

11. The dropping system according to any one of claims 8, 9 or 10, when the latter depends on claim 8, comprising a control module (18) acting on the pressure regulator (10) and on the dropping hatch (5).

12. The dropping system according to any one of claims 1 to 11, characterised in that the dropping hatch (5) comprises a converging nozzle the liquid outlet section of which is variable.

13. A firefighting aircraft, comprising a dropping system (1) according to any one of claims 1 to 12, and wherein the liquid is a retardant.