RU2789574C1 - Gas generator for a fire extinguishing device that forms a self -operating stream - Google Patents

Abstract

FIELD: fire extinguishing equipment.

SUBSTANCE: invention relates to fire extinguishing equipment, namely to gas-generating devices of fire-extinguishing means. A gas generator for a fire extinguishing device that forms a self-foaming jet, equipped with a charge of solid fuel and an igniter, ensuring the outflow of combustion products of solid fuel through the nozzles into the hermetic container of the device, and through the cooler, into the nozzle device, communicated with the internal cavity of the hermetic chamber located inside the hermetic container, at the same time, it consists of two sequentially arranged chambers, the rear bottom of the chamber with a charge of solid fuel is equipped with a conical nozzle with overexpansion, directed along the axis into the chamber with an endothermically decomposing coolant, fixed on both sides by support grids, with the front grid being a gas flow divider, and the rear bottom. The chamber with the cooler is equipped with pylons that fasten at a distance from the bottom a plate with a central hole bent towards the cooled gas flow, connected to the nozzle device and forming an annular hole together with the bottom. The body of the chamber with an endothermically decomposing cooler is made of a heat-absorbing material. Tableted capsules are used as an endothermically decomposing coolant. A monoblock multi-channel charge is used as an endothermically decomposing cooler.

EFFECT: invention provides an increase in the efficiency of the gas generator of the displacement system due to the use of an endothermically decaying cooler, which is an additional source of the working body with specified characteristics, and ensuring the uniformity of supplanting the combustion of solid fuel of the aqueous solution and the granulated hydraulic regulation due to structural solutions.

4 cl, 2 dwg, 1 tbl

Description

SUBSTANCE: invention relates to fire-fighting equipment, namely to gas-generating devices of fire extinguishing means and can be used in a device that forms a self-foaming jet, which uses a system for displacing high-temperature gas generation products from a sealed container of an aqueous solution with a foaming agent, and displacing cooled gas generation products from another sealed chambers of granular hydroreactive composition into the trunk of the fire extinguishing device. A jet of an aqueous solution of a foaming agent with a hydroreactive composition introduced into it flows out of the barrel in a non-foamed state, and foaming of the jet is provided at a given distance behind the barrel cut.

Known design of the gas generator, in which the cooler is made in the form of a labyrinth of coaxial cylinders of heat-absorbing material (author's certificate No. 860773, IPC A62S 13/22, 1981). gas generator.

Known design of a gas generator for producing inert gas (author's certificate for utility model No. 3464, IPC F02C 7/25, 1997), containing a housing, inside of which are placed: a solid propellant charge, an igniter and a filter cooler, which is made of vibration-compacting sand with various fractions and has a supporting perforated grate. This design cannot ensure the stability of the output parameters of temperature, gas flow, during operation, slagging of the pores of the dispersed material of the coolant occurs, which leads to an unplanned change in pressure in the combustion chamber of the gas generator.

A gas generator is known (patent RU 2292234 C, IPC B01J 19/14, publ. 01/27/2007), consisting of a housing inside which a solid propellant charge, an igniter and a filter cooler are placed, made of a gas-permeable coarse powder, characterized in that the filter cooler contains gas-permeable disks placed perpendicular to its axis, made of a material with a thermal conductivity exceeding the thermal conductivity of the coolant disk powder. This design also cannot ensure the stability of the gas output parameters due to the slagging of the filter-cooler.

In the gas generators described above, the cooler is not an additional source of the working fluid. Various schemes of gas generators are described in detail in the book "Gas generators of rocket systems" (M.: "Mashinostroenie". 1981. - 152 p.), which make it possible to obtain low-temperature gas during the combustion of solid rocket fuel. However, the book does not contain a description of the design scheme of the gas generator, which ensures the simultaneous production of gas with different temperatures as a working fluid for powering consumer devices.

Patent RU 2756039 C1 (MPK А62С 5/02, А62С 32/02, publ. 09/24/2021) proposes a method for the formation of a self-foaming jet of a given multiplicity and a device for its implementation, which is taken as a prototype, a gas generator with a charge of solid fuel, providing outflow through nozzle holes of solid fuel combustion products into a sealed container with an aqueous solution of a foaming agent, inside which a sealed chamber with a granular hydro-reacting composition is installed. The gas generator is equipped with a receiver with a filter-cooler communicated with the internal cavity of the sealed chamber through a nozzle device for supplying combustion products throughout the entire volume of the chamber with a hydro-reacting composition.

The higher the specific performance of gases (RT, R - gas constant, T - gas temperature) supplied to a sealed container with an aqueous solution, the less solid propellant is required to displace a given volume of liquid.

The temperature of the combustion products of solid fuel for the displacement of an aqueous solution is selected based on the resistance of the structure to overheating, and when displacing a granular hydroreactive composition, the ability of gas generation products to create a suspension from granules without their coagulation and sublimation.

The design of the gas generator uses a cooler, which is not an additional source of the working fluid, which requires an increased amount of solid fuel. In this device, it is difficult to ensure a complete uniform displacement of the granular hydroreactive composition from the sealed chamber without coagulation and sublimation. The disadvantages of the design of the gas generator is that during the operation of the gas generator is slagging products of combustion of solid fuel filter-cooler. This leads to an unplanned increase in pressure in the combustion chamber of the gas generator and does not provide the desired displacement diagram for both the aqueous solution and the granular hydro-reacting composition.

The aim of the invention is to increase the efficiency of the gas generator through the use of a cooler, which is an additional source of the working fluid with specified characteristics, and the uniformity of the displacement of the combustion products of the aqueous solution and granular hydroreactive composition by changing the design.

This goal is achieved by the fact that the gas generator of the fire extinguishing device, which forms a self-foaming jet, which ensures the outflow of solid fuel combustion products through nozzles directed at an angle to the axis of the gas generator into the chamber with an aqueous solution of the foaming agent, and through the cooler into the nozzle device, consists of two sequentially located chambers. The rear bottom of the chamber with a charge of solid fuel is equipped with a conical nozzle with overexpansion, directed along the axis into the chamber with endothermically decomposing coolant, fixed on both sides by support grids, the front grid being a gas flow divider, and the rear bottom of the chamber with a coolant, equipped with pylons mounted on at some distance from the bottom, a plate bent along the flow of the cooled gas flow with a central hole, connected to the nozzle device, and forming, together with the bottom, an annular hole.

In FIG. 1 is a diagram of a fire extinguishing device that forms a self-foaming jet.

In FIG. 2 shows the following diagrams:

- thermogravimetric diagram of the change in the completeness of gasification of the coolant (ammonium oxalate) η on temperature;

- diagram of change in the rate of heat supply ∂Q/∂T acting on the coolant (ammonium oxalate) versus temperature;

от температуры.- diagram of the change in the value of the endothermic effect of the decomposition reaction of the coolant (ammonium oxalate)

from temperature.

In FIG. 1 gas generator (1) contains a chamber with a charge of solid propellant (2) with an igniter (3) on the front bottom of the chamber. The chamber with a charge of solid fuel is located in a sealed container with an aqueous solution of a foaming agent (4). The rear bottom of the chamber is equipped with nozzles (5) directed at an angle to the axis of the chamber into a sealed container with an aqueous solution of a foaming agent (4), and one conical nozzle (6) with overexpansion is directed along the axis into the second chamber with a coolant (7).

The rear bottom of the chamber with a charge of solid fuel is simultaneously the front bottom of the second cylindrical chamber (7) with a cooler, made of a heat-intensive material.

The cooler (8), which is pelletized elements or a monoblock multi-channel charge, is fixed on both sides by support grids (9), the front grid is a gas flow divider. Ammonium oxalate monohydrate (NH ₄ ) ₂ C ₂ O ₄ ⋅H ₂ O in a binder - rubber is used as a coolant.

The rear bottom of the chamber with a cooler is equipped with several pylons, which fasten a plate bent towards the cooled gas flow at some distance from the bottom, forming an annular hole (11) and having one central hole (12).

The plate is connected to the tube of the injector device (13) made of heat-intensive material, equipped with a number of jet nozzles and located coaxially inside the sealed chamber (14) with hydroreacting composition, which is placed inside the sealed container with an aqueous solution of the foaming agent (4).

A nozzle (15) is used to feed the granules of the hydroreactive composition into the barrel (16). Nozzles (17) are used to supply the barrel (16) with an aqueous solution with a foaming agent from a sealed container (4).

The solid fuel combustion products flow from the gas generator chamber into the cooler chamber at supersonic speeds. To increase the efficiency of the cooler, they are retarded by using an overexpansion nozzle, which provides separation of the flow from the nozzle walls and a direct jump inside the nozzle.

где

,

d_T - диаметр в месте отрыва потока от стенок сопла, d_кр - критическое сечение сопла, d_a - диаметр среза сопла, ξ_а - геометрическая степень расширения сопла, ξ_т - степень расширения, соответствующая отрыву потока от стенок сопла:To ensure separation of the flow from the walls of the nozzle, it is necessary that the expansion of the nozzle

Where

,

d _T - diameter at the point of flow separation from the nozzle walls, d _cr - nozzle critical section, d _a - nozzle exit diameter, ξ _a - geometric expansion ratio of the nozzle, ξ _t - expansion ratio corresponding to flow separation from the nozzle walls:

где

Where

P ₀ - pressure in the chamber with a charge of solid fuel, kg/cm ² ;

_РН - pressure in the chamber with a cooler, kg/cm ² ;

k is the adiabatic index;

π _cr - gas-dynamic function of relative pressure.

(A.A. Shishkov "Gas dynamics of powder engines" p. 77, ed. "Engineering", Moscow, 1968.)

For combustion products of solid propellant at k=1.16, Р ₀ =25, Р _Н =10, π _cr =0.57: ξ _Т =1.23.

Thus, to ensure a guaranteed separation of the flow from the nozzle walls and the transition to the subsonic flow regime in the chamber with a cooler, it is necessary that

The endothermic reaction of the decomposition of the coolant occurs under the influence of heat from the combustion products of solid fuel. The coolant decomposes into the following components: H ₂ O, N ₂ , CO, CO ₂ , CH ₄ .

The mass of the coolant (8), taking into account its complete decomposition in accordance with the heat balance, is estimated as follows:

где

Where

m _cool - coolant mass, kg;

m _TT - mass of solid fuel of the gas generator, kg;

η - completeness of combustion of solid fuel of the gas generator;

Q _n.TT - lower calorific value of solid fuel gas generator,

- удельная величина эндотермического эффекта - количество тепла поглощенного охладителем при прохождении через него продуктов сгорания твердого топлива,

- specific value of the endothermic effect - the amount of heat absorbed by the cooler when the combustion products of solid fuel pass through it,

C _cool - heat capacity of coolant granules,

T ₀ - ambient temperature, K;

- температура окончания разложения охладителя, К.

- temperature of the end of decomposition of the coolant, K.

и

выбираются исходя из термогравиметрической диаграммы и диаграммы изменения величины эндотермического эффекта реакции разложения охладителя при полноте разложения η=1(Фиг. 2).Values

And

are selected based on the thermogravimetric diagram and the diagram of the change in the value of the endothermic effect of the decomposition reaction of the coolant at the completeness of decomposition η=1 (Fig. 2).

When estimating the mass of the coolant, the following assumption was made that at the end of its decomposition, the temperature of the mixture of products of combustion of solid fuel and decomposition of the coolant will become equal to

The values of the characteristics of physicochemical transformations, density and heat capacity of ammonium oxalate are presented in table 1.

- температура начала разложения охладителя, ρ_m - плотность таблетированных капсул охладителя. Взаимодействие смеси продуктов сгорания твердого топлива и продуктов разложения охладителя с гидрореагирующим составом, представляющим собой смесь порошкообразных кислот и солей, образующих при гидролизе щелочную среду, происходит только физически без химических реакций в диапазоне рабочих температур 333-348 К. Пример гидрореагирующего состава: смесь лимонной кислоты (45%), гидрокарбоната натрия (50%) и глицерина (5%).Table

- the temperature of the beginning of the decomposition of the coolant, ρ _m - the density of tableted coolant capsules. The interaction of a mixture of solid fuel combustion products and coolant decomposition products with a hydro-reactive composition, which is a mixture of powdered acids and salts that form an alkaline medium during hydrolysis, occurs only physically without chemical reactions in the operating temperature range of 333-348 K. An example of a hydro-reactive composition: a mixture of citric acid (45%), sodium bicarbonate (50%) and glycerin (5%).

To exclude coagulation and sublimation of the granular hydroreactive composition by a mixture of solid fuel combustion products and coolant decomposition products, the chamber housing with the coolant and the tube of the injector device must be made of a high heat capacity material.

до верхней границы диапазона рабочих температур гидрореагирующего состава (Т_{гидрореаг.сост}), масса конструкции форсуночного устройства оценивается следующим образом:Based on the heat balance during cooling of the mixture of products of combustion of solid fuel and decomposition of the coolant from the temperature of the end of the decomposition of the coolant

up to the upper limit of the operating temperature range of the hydroreacting composition (T _{hydroreag.composition} ), the mass of the injector device structure is estimated as follows:

где

Where

C _konstr - heat capacity of the material of the injector device,

C _{p prod.sgor.TT} - heat capacity of combustion products of solid fuel,

C _{p ohl} - heat capacity of the decomposition products of the coolant,

T _{hydroreactive composition} - the upper limit of the operating temperature range of the hydroreactive composition, K;

T _O - ambient temperature, K.

The gas generator of the claimed design works as follows. When an electrical signal is applied, an igniter (3) is activated, which ignites a charge of solid propellant (2). Part of the combustion products of the solid fuel charge passes through the nozzles (5) into a sealed container (4) with an aqueous solution of a foaming agent with the optimum temperature to displace the solution, and the other part enters the chamber with a coolant (7), where the coolant decomposes.

The cooled solid fuel combustion products, together with the gaseous decomposition products of the coolant, flow through the annular (11) and central (12) holes into the nozzle device (13), and then into the chamber with the hydroreacting composition (14).

The operation of such a gas generator provides in the fire extinguishing device that forms a self-foaming jet, the displacement of an aqueous solution with a foaming agent and a granular hydro-reactive composition into the barrel. The granules of the hydroreacting composition pass into a suspended state, turning into a pseudo-liquid, which flows through the nozzle (15) into the barrel (16), simultaneously through the nozzles (17), an aqueous solution with a foaming agent from a sealed container enters the barrel (16), where a self-foaming jet is formed .

The described design of the gas generator provides a programmable change in pressure in the chamber with a charge of solid fuel, which is determined by the design of the charge of solid fuel and does not depend on changes in parameters in the second chamber with a cooler. And due to the uniform distribution of gas jets in a sealed chamber with a granular hydroreactive composition, uniform displacement of granules is ensured without their coagulation and sublimation.

Claims (4)

1. A gas generator for a fire extinguishing device that forms a self-foaming jet, equipped with a charge of solid fuel and an igniter, which ensures the outflow of solid fuel combustion products through nozzles, into the sealed container of the device, and through the cooler, into the nozzle device, communicated with the internal cavity of the sealed chamber located inside the sealed tank, characterized in that it consists of two sequentially arranged chambers, the rear bottom of the chamber with a charge of solid fuel is equipped with a conical nozzle with overexpansion, directed along the axis into the chamber with an endothermically decomposing coolant, fixed on both sides by support grids, and the front grid is a gas flow divider , and the rear bottom of the chamber with a cooler is equipped with pylons that fasten at a distance from the bottom a plate with a central hole bent towards the cooled gas flow, connected to the nozzle device and forming an annular hole together with the bottom. 2. The gas generator according to claim 1, characterized in that the chamber body with an endothermically decomposing coolant is made of a heat-intensive material. 3. The gas generator according to claim 1 or 2, wherein tablet capsules are used as the endothermically decomposing coolant. 4. Gas generator, according to claim 1 or 2, in which a monoblock multi-channel charge is used as an endothermically decomposing coolant.

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