Low-pressure type nozzle jet flow method of compressed gas foam fire fighting equipment

Abstract

The invention discloses a low-pressure nozzle jet method of compressed gas foam fire fighting equipment. The low-pressure jet nozzle comprises a nozzle body, a nozzle inlet and a nozzle outlet, the nozzle body is provided with a fluid channel formed in the nozzle body, the nozzle inlet is communicated with the fluid channel, and the nozzle outlet is communicated with the fluid channel. According to the jet method, when fluid is jetted through the low-pressure jet nozzle, the pressure at the inlet of the nozzle is smaller than or equal to 0.4 Mpa, so that the working pressure of compressed gas foam equipment provided with the low-pressure jet nozzle is reduced, energy is saved, consumption is reduced, the load of mobile fire fighting equipment is reduced to a certain extent, maneuverability is relatively improved, and the mobile fire fighting equipment is suitable for being used in a fire fighting system. And the cost is relatively reduced.

Description

Technical Field

[0001] The present application relates to the technical field of fire fighting products, and in particular to a low-pressure nozzle jetting method for compressed gas foam fire fighting equipment. Background Art

[0002] Jet technology is a technology that ejects fluid from a nozzle under pressure. Jet technology is widely used in fire safety, industrial production, health care and other fields. In actual production applications, the jet principle of gas-liquid mixed phase homogeneous flow or gas-solid mixed phase homogeneous flow can be used to make corresponding jet nozzles. For example, in compressed gas foam spraying equipment such as compressed gas foam guns and compressed gas foam cannons, the compressed gas foam is mixed and stirred by a compressed gas foam generator to a near homogeneous state before entering the nozzle. Whether it is a compressed air foam system or a low-pressure liquefied gas foam system, it is basically a gas-liquid homogeneous flow before entering the jet nozzle, and such flow is similar to the flow of gas. When a fluid in a homogeneous state is ejected from a nozzle under pressure, the velocity reaches a specific value.

[0003] In jet technology, the pressure at each part of the nozzle will affect the final jet effect, such as jet velocity, jet flow, jet angle, etc. In current compressed gas foam spraying equipment, the pressure at the nozzle inlet is usually higher than 0.4MPa. For example, the pressure at the nozzle inlet of conventional compressed gas foam fire fighting guns and fire monitors is about 0.7MPa, or higher than 0.7MPa. Such compressed gas foam spraying equipment has high working energy consumption, large volume and weight, and high cost. Summary of the invention

[0004] One advantage of the present application is that it provides a low-pressure nozzle jet method for compressed gas foam fire-fighting equipment, wherein the pressure at the inlet of the low-pressure nozzle is relatively low, so that the working pressure of the compressed gas foam equipment equipped with the low-pressure nozzle is reduced, which is more energy-saving and consumption-reducing, and the load of mobile fire-fighting equipment can be reduced to a certain extent, the maneuverability is relatively improved, and the cost is relatively reduced.

[0005] One advantage of the present application is that it provides a low-pressure nozzle jet method for compressed gas foam fire-fighting equipment, wherein the pressure at the inlet of the low-pressure nozzle is relatively low to allow the compressed gas foam to produce a certain pressure loss during transportation, thereby reducing the requirements for components and pipelines in the compressed gas foam equipment.

[0006] Another advantage of the present application is that it provides a low-pressure nozzle jet method for compressed gas foam fire fighting equipment, wherein the parameters of various parts of the low-pressure nozzle are set so that the low-pressure nozzle can ensure a larger injection speed and a longer range while maintaining a lower inlet pressure.

[0007] Another advantage of the present application is that it provides a low-pressure nozzle jet method for compressed gas foam fire fighting equipment, wherein the sound velocity of the gas-liquid homogeneous flow or the gas-solid homogeneous flow is controlled by controlling the cross-sectional gas content of the nozzle inlet of the low-pressure nozzle.

[0008] According to one aspect of the present application, a low-pressure nozzle jetting method for compressed gas foam fire fighting equipment is provided, which comprises the steps of: making the pressure at the nozzle inlet less than or equal to 0.4 MPa when the low-pressure nozzle jets fluid.

[0009] In one embodiment of the present application, the pressure at the nozzle inlet is less than or equal to 0.3 MPa.

[0010] In one embodiment of the present application, the pressure at the nozzle inlet is less than or equal to 0.2 MPa, and less than or equal to 0.4 MPa.

[0011] In one embodiment of the present application, the pressure at the nozzle inlet is greater than or equal to 0.2 MPa and less than or equal to 0.3 MPa.

[0012] In one embodiment of the present application, the pressure at the nozzle inlet is greater than or equal to 0.3 MPa and less than or equal to 0.4 MPa.

[0013] In one embodiment of the present application, the nozzle body of the low-pressure nozzle includes a tapered section, and the tapered section gradually shrinks in a direction from the nozzle inlet to the nozzle outlet.

[0014] In one embodiment of the present application, the nozzle inlet and the tapered section are configured so that the velocity of the fluid reaches the speed of sound after the fluid reaches the tapered section.

[0015] In one embodiment of the present application, the nozzle body of the low-pressure nozzle also includes a gradually expanding section and a throat, the gradually expanding section gradually increases in the direction from the nozzle inlet to the nozzle outlet, the throat extends between the gradually expanding section and the gradually converging section, and the gradually expanding section extends between the throat and the nozzle outlet.

[0016] In one embodiment of the present application, the nozzle inlet, the convergent section, the throat and the divergent section are configured so that the velocity of the fluid reaches supersonic speed after reaching the divergent section.

[0017] In one embodiment of the present application, the liquid is water, the liquid flow rate is 480 L / min, the atmospheric pressure gas-liquid ratio is 15, the nozzle inlet gas content is 0.75 to 0.8333, and the nozzle outlet area is 1039.87 to 1683.83 mm 2 The flow rate at the outlet is 45.79~48.61m / s.

[0018] According to one aspect of the present application, there is provided a low-pressure nozzle, comprising:

[0019] a nozzle body having a fluid passage formed therein;

[0020] a nozzle inlet, the nozzle inlet being connected to the fluid passage; and

[0021] a nozzle outlet, the nozzle outlet being connected to the fluid channel;

[0022] Wherein, when the fluid is sprayed through the low-pressure nozzle, the pressure at the nozzle inlet is less than or equal to 0.4 MPa.

[0023] When the low-pressure nozzle is used for spraying a mixed phase of air and water, the liquid flow rate is 480 L / min, the atmospheric pressure gas-liquid ratio is 15, the nozzle inlet gas content is 0.75 to 0.8333, and the nozzle outlet area is 1039.87 to 1683.83 mm 2 . BRIEF DESCRIPTION OF THE DRAWINGS

[0024] These and / or other aspects and advantages of the present application will become clearer and easier to understand from the following detailed description of the embodiments of the present application in conjunction with the accompanying drawings, in which:

[0025] Figure 1 A schematic diagram illustrating an implementation of a low-pressure nozzle for compressed gas foam fire fighting equipment according to an embodiment of the present application is shown.

[0026] Figure 2 A schematic diagram illustrating another implementation of a low-pressure nozzle for compressed gas foam fire fighting equipment according to an embodiment of the present application is shown. DETAILED DESCRIPTION

[0027] The terms and words used in the following specification and claims are not limited to the literal meanings, but are merely used by the inventor to enable a clear and consistent understanding of the present application. Therefore, it will be apparent to those skilled in the art that the following description of various embodiments of the present application is provided for illustration purposes only and not for the purpose of limiting the present application as defined by the appended claims and their equivalents.

[0028] It is to be understood that the term "one" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element may be one, while in another embodiment, the number of the element may be multiple, and the term "one" should not be understood as a limitation on the quantity.

[0029] Although ordinals such as "first," "second," and the like will be used to describe various components, those components are not limited herein. The term is used only to distinguish one component from another. For example, a first component may be referred to as a second component, and likewise, a second component may be referred to as a first component without departing from the teachings of the present application. The term "and / or" as used herein includes any and all combinations of one or more associated listed items.

[0030] The terms used herein are only used for the purpose of describing various embodiments and are not intended to be limiting. As used herein, singular forms are intended to also include plural forms, unless the context clearly indicates an exception. In addition, it will be understood that the terms "including" and / or "having" when used in this specification specify the presence of the described features, numbers, steps, operations, components, elements or combinations thereof, without excluding the presence or addition of one or more other features, numbers, steps, operations, components, elements or groups thereof.

[0031] Referring to the drawings of this application specification Figure 1 and Figure 2 As shown, a low-pressure nozzle for compressed gas foam fire fighting equipment according to an embodiment of the present invention is illustrated. The compressed gas foam fire fighting equipment includes a compressed air foam generating device, a jet nozzle, a control device, a valve and a pipeline, etc., which can apply compressed air foam to the protection area when a fire occurs. Among them, the compressed air foam generating device is a device that can generate compressed air foam, including a premixed compressed air foam generating device and a non-premixed compressed air foam generating device. The premixed compressed air foam generating device mainly includes a foam premix liquid storage tank, a foam premix liquid power unit, an air supply device, a gas-liquid mixing device, a control unit (when applicable), pipelines, etc.; the non-premixed compressed air foam generating device mainly includes a water supply device, an air supply device, a foam liquid storage tank, a foam proportion mixing device, a gas-liquid mixing device, a control unit (when applicable), pipelines, etc.

[0032] The low-pressure nozzle for compressed gas foam fire fighting equipment comprises a nozzle body 10, a nozzle inlet 20, and a nozzle outlet 30. The nozzle body 10 has a fluid channel 101 formed therein, the nozzle inlet 20 is connected to the fluid channel 101, and the nozzle outlet 30 is connected to the fluid channel 101. In the compressed gas foam fire fighting equipment equipped with the low-pressure nozzle, the compressed gas foam is mixed and stirred by the compressed gas foam generator before entering the low-pressure nozzle to be close to a homogeneous state, forming a gas-liquid homogeneous flow, and the fluid in a homogeneous state is discharged from the low-pressure nozzle under pressure.

[0033] It should be understood that the low-pressure nozzle can also be used in a gas-solid mixing system, that is, a mixture in a homogeneous state forms a gas-solid homogeneous flow.

[0034] The type and specific form of the low-pressure nozzle are not limited by the present application. In some embodiments of the present application, the low-pressure nozzle is a Rafale nozzle. In some embodiments of the present application, the low-pressure nozzle is a converging nozzle. In some embodiments of the present application, the low-pressure nozzle is a converging and diverging nozzle.

[0035] like Figure 1 As shown, in one embodiment of the present application, the low-pressure nozzle is a tapered nozzle. The nozzle body 10 of the low-pressure nozzle includes a tapered section 12 and a connecting section 11. The connecting section 11 extends between the tapered section 12 and the nozzle inlet 20. The tapered section 12 gradually narrows in the direction from the nozzle inlet 20 to the nozzle outlet 30. One end of the tapered section 12 extends to the nozzle outlet 30, and the other end of the tapered section 12 extends to the connecting section 11. The nozzle outlet 30 forms the throat 13 of the low-pressure nozzle.

[0036] In this embodiment, the nozzle inlet 20 and the tapered section 12 are configured such that the velocity of the fluid reaches the speed of sound after the fluid reaches the tapered section 12 .

[0037] like Figure 2 As shown, in another embodiment of the present application, the low-pressure nozzle is a gradually converging and expanding nozzle. The nozzle body 10 of the low-pressure nozzle includes a gradually converging section 12, a connecting section 11, a gradually expanding section 14 and a throat 13. The connecting section 11 extends between the gradually converging section 12 and the nozzle inlet 20. The throat 13 extends between the gradually expanding section 14 and the gradually converging section 12. The gradually expanding section 14 extends between the throat 13 and the nozzle outlet 30. The gradually converging section 12 gradually narrows in the direction from the nozzle inlet 20 to the nozzle outlet 30. One end of the gradually converging section 12 extends to the throat 13, and the other end of the gradually converging section 12 extends to the connecting section 11. The gradually expanding section 14 gradually increases in the direction from the nozzle inlet 20 to the nozzle outlet 30. One end of the gradually expanding section 14 extends to the nozzle outlet 30, and the other end extends to the throat 13.

[0038] As mentioned above, in current compressed gas foam spraying equipment, the pressure at the inlet of the nozzle is usually higher than 0.4MPa. Such compressed gas foam spraying equipment has high working energy consumption, large volume and weight, and high cost. In the present application, the pressure at the inlet of the low-pressure nozzle is low, so that the working pressure of the compressed gas foam equipment equipped with the low-pressure nozzle is reduced, which is more energy-saving and consumption-reducing. The load of mobile fire-fighting equipment can be reduced to a certain extent, the maneuverability is relatively improved, the cost is relatively reduced, and the compressed gas foam is allowed to produce a certain pressure loss during transportation, thereby reducing the requirements for components and pipelines in the compressed gas foam equipment.

[0039] Accordingly, in an embodiment of the present application, the low-pressure nozzle has a specific structural configuration so that the pressure at the nozzle inlet 20 is less than or equal to 0.4MPa when the fluid is ejected through the low-pressure nozzle. For example, in some embodiments of the present application, the pressure at the nozzle inlet 20 is less than or equal to 0.3MPa when the fluid is ejected through the low-pressure nozzle. In some embodiments of the present application, the pressure at the nozzle inlet 20 is greater than or equal to 0.2MPa, and less than or equal to 0.4MPa when the fluid is ejected through the low-pressure nozzle. In some embodiments of the present application, the pressure at the nozzle inlet 20 is greater than or equal to 0.2MPa, and less than or equal to 0.3MPa when the fluid is ejected through the low-pressure nozzle. In some embodiments of the present application, the pressure at the nozzle inlet 20 is greater than or equal to 0.3MPa, and less than or equal to 0.4MPa when the fluid is ejected through the low-pressure nozzle.

[0040] It is worth mentioning that in the embodiment of the present application, the parameters of the low-pressure nozzle, such as the cross-sectional area, can be set by a specific calculation method, so that the low-pressure nozzle can ensure a higher injection speed and a longer range while maintaining a lower inlet pressure.

[0041] Specifically, the flow rate of the gas-liquid homogeneous flow or the gas-solid homogeneous flow is usually a function of the cross-sectional gas content, and the flow rate of the gas-liquid homogeneous flow or the gas-solid homogeneous flow can be controlled by controlling the cross-sectional gas content of the nozzle inlet 20 of the low-pressure nozzle.

[0042] Next, the calculation method of the mixture flow rate is introduced.

[0043] For an infinitesimal volume of a mixture, the dispersed phase and the continuous phase are represented by subscripts A and B, respectively. Assume that the initial volume is 1 and the initial density of the dispersed phase is ρ A , the initial density of the continuous phase is ρ B , the initial pressure of the continuous phase is p B , the particle radius of the dispersed phase is R, and the surface tension is S. The initial pressure of the dispersed phase is p A , p A =pB +2S / R.

[0044] Further, the analysis pressure is given by p A becomes p A +δp A The case where δp A is infinitesimal, and any dynamic characteristics caused by the fluid motion are temporarily ignored. Assume that a new equilibrium state is formed, during which the mass is δ m The mixture is transferred from the continuous phase to the dispersed phase. Accordingly, the mass of the new dispersed phase is ρ A e A +δm, the mass of the continuous phase is ρ B α B -δm.α A is the volume content of the new dispersed phase, α B is the volume content of the new continuous phase, α A =1-α B . Therefore, the volume of the newly formed dispersed phase is: The volume of the newly formed continuous phase is Among them, the thermodynamic constraint Q A and Q B The variable δ of the total volume is obtained by adding the above two equations, i.e., the volume equation of the newly formed dispersed phase and the volume equation of the newly formed continuous phase, and subtracting 1. V , therefore, the equation for flow velocity is:

[0045] Assuming that the dispersed particles are neither regenerated nor destroyed, the new dispersed particle radius R+δR is calculated based on the new dispersed phase volume, using the relationship The ratio δp can be obtained A / δp B for:

[0046]

[0047] 1 / c is expressed by the following formula A 2 and 1 / c B 2 :

[0048]

[0049] The ratio δp A / δp B Substituting the equation for the flow rate into the equation for the flow rate, we obtain:

[0050]

[0051] In the absence of any mass exchange between the various components, the equation can be simplified to:

[0052]

[0053] In most practical cases, since S<<ρ A c A 2 R, so the surface tension effect can be ignored, then,

[0054]

[0055] When one component is a gas (denoted by subscript G) and its compressibility is much higher than that of other components (such as liquids or solids, denoted by subscript L), the surface tension effect (P = P G =P L ). Assume that the gas is an ideal gas and obeys the multi-party relation p G k ∝p, the equation can be written as:

[0056]

[0057] In many applications, p / ρ L c L 2 <<1, so it can be further simplified to

[0058]

[0059] c is the flow rate, α is the gas content, k is the gas adiabatic coefficient, p is the pressure, ρ is the density, ρ L is the density of the liquid or solid phase, ρ G is the density of the gas phase.

[0060] Next, a method for calculating the diameter of the nozzle outlet 30 of the low-pressure nozzle will be described.

[0061] In theory, as long as the equation for the flow rate is integrated (it needs to be expressed in terms of c 2 = dp / dρ) to obtain the positive pressure relationship of the mixture. However, in practice, in addition to c 2 The algebraic form is very complicated except for some simpler forms of . Here we consider the special case of a two-component mixture, that is, the case where mass exchange and surface tension are not considered in the above derivation. Assume that the volumetric air content is not very small and the density of the liquid or solid is ρ L is a constant, and p G k ∝p, we can use In addition, as in gas dynamics, the reservoir formation conditions p = p0, α = α0, ρG =ρ G0 To determine the integration constant. By integrating the above formula, we can get the equation for the density of the mixture: ρ = ρ0 (1-α) (1-α0)

[0062] The positive pressure relationship is:

[0063]

[0064] Where ρ0 = ρ L (1-α0)+ρ G0 α0, accordingly,

[0065]

[0066] The positive pressure relationship can be combined with the steady-state one-variable continuity equation

[0067]

[0068] and the inviscid momentum equation

[0069]

[0070] Combined for computing homogenous multiphase flows in pipes and nozzles.

[0071] s is the coordinate measured along the streamline or pipeline centerline, u is the flow velocity, and A is the flow cross-sectional area.

[0072] Applying the barotropic pressure relationship and the equation describing the density of the mixture to eliminate p and ρ from the momentum equation yields:

[0073]

[0074] Integrating the above equation and applying the reservoir formation condition u0=0, we can obtain:

[0075] When k≠0,

[0076]

[0077] When k = 1,

[0078]

[0079] As in gas dynamics, the throat 13 condition plays an important role in the overall flow and mass flow rate. This conclusion can be obtained by changing the equation It can be seen from the analysis that in the throat 13 where dA / ds=0, either dp / ds=0 or u=c. The former is true when the flow is purely subsonic and unobstructed; the latter is true when the flow is blocked. The subscript * represents the blocked condition of the throat 13, and u=c is set. The right sides of ① and ② (or ③) are equal. When k≠1, it can be based on

[0080]

[0081] Calculate the air content of the throat 13 as α ＊ It is worth mentioning that when the low-pressure nozzle is a tapered nozzle, the nozzle outlet 30 forms the throat 13 of the low-pressure nozzle. Accordingly, the gas content of the throat 13 calculated by the above formula is the gas content of the nozzle outlet 30 of the low-pressure nozzle.

[0082] For an isothermal gas (k = 1), the volumetric gas fraction α ＊ Then use the following formula to calculate

[0083]

[0084] Finally, the mass flow rate m c =ρ ＊ A ＊ c ＊ Substitution You can get:

[0085]

[0086] According to the above formula, the cross-sectional area of ​​the throat 13 can be obtained. As mentioned above, when the low-pressure nozzle is a tapered nozzle, the nozzle outlet 30 forms the throat 13 of the low-pressure nozzle. Accordingly, the cross-sectional area of ​​the throat 13 calculated by the above formula is the cross-sectional area of ​​the nozzle outlet 30 of the low-pressure nozzle.

[0087] In the calculation, the reservoir formation conditions are first determined, that is, the pressure p0 at the nozzle inlet 20, the gas content α0 at the nozzle inlet 20 (usually controlled by controlling the gas distribution rate), and the density ρ0 at the nozzle inlet 20. The critical gas content of the throat 13 (that is, the nozzle outlet 30 of the low-pressure nozzle implemented as a tapered nozzle) can be obtained by the gas content at the nozzle inlet 20. The sound velocity of the nozzle outlet 30 under specific conditions, that is, the outlet flow rate, is obtained. The cross-sectional area of ​​the nozzle outlet 30 is obtained.

[0088] The following example further illustrates the method for calculating the parameters of the low-pressure nozzle.

[0089] Example 1

[0090] In Example 1, first, the reservoir formation conditions are determined. Specifically, if the pressure at the nozzle inlet 20 is expected to be 2 bar, i.e., 0.2 MPa, it is known that before entering the nozzle inlet 20, the density of the liquid in the gas-liquid mixture is 1000 kg / m 3 , the density of the gas is 1.23kg / m 3 , the gas-liquid ratio at normal pressure is 15. The gas content of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0091] Gas content at the nozzle inlet = atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) / [atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) + 1];

[0092] It is calculated that the gas content of the fluid in a homogeneous state at the nozzle inlet 20 is about 0.8333.

[0093] The density of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0094] Density at the nozzle inlet = gas content at the nozzle inlet × gas density + (1-gas content at the nozzle inlet) × liquid density;

[0095] It can be calculated that the density of the fluid in a homogeneous state at the nozzle inlet 20 is about 167.69 kg / m 3 .

[0096] Solve the following equation by bisection method;

[0097]

[0098] The calculated gas content of the nozzle outlet 30 is 0.8956.

[0099] The flow rate at the nozzle outlet 30 is calculated by the following formula, knowing that the thermal insulation coefficient is 1.4. Note: The outlet flow rate of water at a water pressure of 12 bar is 49 m / s.

[0100]

[0101] The flow velocity of the nozzle outlet 30 is calculated to be 45.79 m / s.

[0102] According to the mass flow rate The cross-sectional area A of the nozzle outlet 30 is found to be 1683.83 mm 2 , diameter 46.30mm, mass flow rate m c is 8.15kg / s, and the mixture density ρ0 is 169.74Kg / m 3 .

[0103] Example 2

[0104] In Example 1, first, the reservoir formation conditions are determined. Specifically, if the pressure at the nozzle inlet 20 is expected to be 2.5 bar, i.e., 0.25 MPa, it is known that before entering the nozzle inlet 20, the density of the liquid in the gas-liquid mixture is 1000 kg / m 3 , the density of the gas is 1.23kg / m 3 , the gas-liquid ratio at normal pressure is 15. The gas content of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0105] Gas content at the nozzle inlet = atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) / [atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) + 1];

[0106] It is calculated that the gas content of the fluid in a homogeneous state at the nozzle inlet 20 is about 0.8108.

[0107] The density of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0108] Density at the nozzle inlet = gas content at the nozzle inlet × gas density + (1-gas content at the nozzle inlet) × liquid density;

[0109] It can be calculated that the density of the fluid in a homogeneous state at the nozzle inlet 20 is about 190.19 kg / m 3 .

[0110] Solve the following equation by bisection method;

[0111]

[0112] The calculated gas content of the nozzle outlet 30 is 0.8809.

[0113] The flow rate at the nozzle outlet 30 is calculated by the following formula, knowing that the thermal insulation coefficient is 1.4.

[0114]

[0115] The flow velocity of the nozzle outlet 30 is calculated to be 46.51 m / s.

[0116] According to the mass flow rate The cross-sectional area A of the nozzle outlet 30 is found to be 1454.03 mm 2 , diameter 43.03mm, mass flow rate m c is 8.15kg / s, and the mixture density ρ0 is 192.68Kg / m 3 .

[0117] Example 3

[0118] In Example 1, first, the reservoir formation conditions are determined. Specifically, if the pressure at the nozzle inlet 20 is expected to be 3 bar, i.e., 0.3 MPa, it is known that before entering the nozzle inlet 20, the density of the liquid in the gas-liquid mixture is 1000 kg / m 3 , the density of the gas is 1.23kg / m 3 , the gas-liquid ratio at normal pressure is 15. The gas content of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0119] Gas content at the nozzle inlet = atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) / [atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) + 1];

[0120] It is calculated that the gas content of the fluid in a homogeneous state at the nozzle inlet 20 is about 0.7895.

[0121] The density of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0122] Density at the nozzle inlet = gas content at the nozzle inlet × gas density + (1-gas content at the nozzle inlet) × liquid density;

[0123] It can be calculated that the density of the fluid in a homogeneous state at the nozzle inlet 20 is about 211.50 kg / m 3 .

[0124] Solve the following equation by bisection method;

[0125]

[0126] The calculated gas content of the nozzle outlet 30 is 0.8669.

[0127] The flow rate at the nozzle outlet 30 is calculated by the following formula, knowing that the thermal insulation coefficient is 1.4.

[0128]

[0129] The flow velocity of the nozzle outlet 30 is calculated to be 47.23 m / s.

[0130] According to the mass flow rate The cross-sectional area A of the nozzle outlet 30 is 1281.57 mm 2 , diameter 40.39mm, mass flow rate m c is 8.15kg / s, and the density of the mixture ρ0 is 214.41Kg / m 3 .

[0131] Example 4

[0132] In Example 1, first, the reservoir formation conditions are determined. Specifically, if the pressure at the nozzle inlet 20 is expected to be 3.5 bar, i.e., 0.35 MPa, it is known that before entering the nozzle inlet 20, the density of the liquid in the gas-liquid mixture is 1000 kg / m 3 , the density of the gas is 1.23kg / m 3 , the gas-liquid ratio at normal pressure is 15. The gas content of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0133] Gas content at the nozzle inlet = atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) / [atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) + 1];

[0134] It is calculated that the gas content of the fluid in a homogeneous state at the nozzle inlet 20 is about 0.7692.

[0135] The density of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0136] Density at the nozzle inlet = gas content at the nozzle inlet × gas density + (1-gas content at the nozzle inlet) × liquid density;

[0137] It can be calculated that the density of the fluid in a homogeneous state at the nozzle inlet 20 is about 231.72 kg / m 3 .

[0138] Solve the following equation by bisection method;

[0139]

[0140] The calculated gas content of the nozzle outlet 30 is 0.8535.

[0141] The flow rate at the nozzle outlet 30 is calculated by the following formula, knowing that the thermal insulation coefficient is 1.4.

[0142]

[0143] The flow velocity of the nozzle outlet 30 is calculated to be 47.92 m / s.

[0144] According to the mass flow rate The cross-sectional area A of the nozzle outlet 30 is found to be 1147.34 mm 2 , diameter 38.22mm, mass flow rate m c is 8.15kg / s, and the density of the mixture ρ0 is 235.03Kg / m3 .

[0145] Example 5

[0146] In Example 1, first, the reservoir formation conditions are determined. Specifically, if the pressure at the nozzle inlet 20 is expected to be 3.5 bar, i.e., 0.4 MPa, it is known that before entering the nozzle inlet 20, the density of the liquid in the gas-liquid mixture is 1000 kg / m 3 , the density of the gas is 1.23kg / m 3 , the gas-liquid ratio at normal pressure is 15. The gas content of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0147] Gas content at the nozzle inlet = atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) / [atmospheric pressure gas-liquid ratio / (expected nozzle inlet pressure + 1) + 1];

[0148] It is calculated that the gas content of the fluid in a homogeneous state at the nozzle inlet 20 is about 0.7500.

[0149] The density of the fluid in a homogeneous state at the nozzle inlet 20 is calculated by the following formula:

[0150] Density at the nozzle inlet = gas content at the nozzle inlet × gas density + (1-gas content at the nozzle inlet) × liquid density;

[0151] It can be calculated that the density of the fluid in a homogeneous state at the nozzle inlet 20 is about 250.92 kg / m 3 .

[0152] Solve the following equation by bisection method;

[0153]

[0154] The calculated gas content of the nozzle outlet 30 is 0.8406.

[0155] The flow rate at the nozzle outlet 30 is calculated by the following formula, knowing that the thermal insulation coefficient is 1.4.

[0156]

[0157] The flow velocity of the nozzle outlet 30 is calculated to be 48.61 m / s.

[0158] According to the mass flow rate The cross-sectional area A of the nozzle outlet 30 is found to be 1039.87 mm 2 , diameter 36.39mm, mass flow rate m cis 8.15kg / s, and the mixture density ρ0 is 254.61Kg / m 3 .

[0159] The basic principles of the present application are described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, effects, etc. mentioned in the present application are only examples and not limitations, and it cannot be considered that these advantages, strengths, effects, etc. are required by each embodiment of the present application. In addition, the specific details disclosed above are only for the purpose of illustration and ease of understanding, rather than limitation. The above details do not limit the present application to being implemented by adopting the above specific details. The functions and structural principles of the present application have been demonstrated and explained in the embodiments. Without departing from the principles, the embodiments of the present invention may be deformed or modified in any way.

Claims

1. A low-pressure nozzle jet method for compressed gas foam fire fighting equipment, characterized in that: The method comprises the following steps: when the low-pressure nozzle sprays fluid, the pressure at the nozzle inlet is less than or equal to 0.4Mpa.

2. The low-pressure nozzle jet method of the compressed gas foam fire fighting equipment according to claim 1, wherein: The pressure at the nozzle inlet is less than or equal to 0.3 MPa.

3. The low-pressure nozzle jet method of the compressed gas foam fire fighting equipment according to claim 1, wherein: The pressure at the nozzle inlet is less than or equal to 0.2 MPa and less than or equal to 0.4 MPa.

4. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to claim 2, wherein: The pressure at the nozzle inlet is greater than or equal to 0.2 MPa and less than or equal to 0.3 MPa.

5. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to claim 1, wherein: The pressure at the nozzle inlet is greater than or equal to 0.3 MPa and less than or equal to 0.4 MPa.

6. The low-pressure nozzle jet method of the compressed gas foam fire fighting equipment according to any one of claims 1 to 5, wherein: The nozzle body of the low-pressure nozzle includes a tapered section, which gradually shrinks in a direction from the nozzle inlet to the nozzle outlet.

7. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to claim 6, wherein: The nozzle inlet and the tapered section are configured so that the velocity of the fluid reaches the speed of sound after reaching the tapered section.

8. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to claim 6, wherein: The nozzle body of the low-pressure nozzle also includes a gradually expanding section and a throat, wherein the gradually expanding section gradually increases in the direction from the nozzle inlet to the nozzle outlet, the throat extends between the gradually expanding section and the gradually converging section, and the gradually expanding section extends between the throat and the nozzle outlet.

9. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to claim 8, wherein: The nozzle inlet, the convergent section, the throat and the divergent section are configured so that the velocity of the fluid reaches supersonic speed after reaching the divergent section.

10. The low-pressure nozzle jet method of compressed gas foam fire fighting equipment according to any one of claims 1 to 5, wherein the liquid is water, the liquid flow rate is 480 L / min, the atmospheric pressure gas-liquid ratio is 15, the nozzle inlet gas content is 0.75 to 0.8333, and the nozzle outlet area is 1039.87 to 1683.83 mm 2 The flow rate at the outlet is 45.79~48.61m / s.

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