CN115127817A - Experimental engine for measuring transient burning speed and collecting condensed phase product under overload - Google Patents
Experimental engine for measuring transient burning speed and collecting condensed phase product under overload Download PDFInfo
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- CN115127817A CN115127817A CN202210652332.2A CN202210652332A CN115127817A CN 115127817 A CN115127817 A CN 115127817A CN 202210652332 A CN202210652332 A CN 202210652332A CN 115127817 A CN115127817 A CN 115127817A
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- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
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Abstract
The invention discloses an experimental engine capable of measuring transient burning speed and collecting condensed-phase products under overload, and belongs to the field of solid rocket engine overload experiments. The invention simulates the overload environment of the engine by rotating the cantilever of the overload table; and collecting condensed-phase products staying on the combustion surface of the solid propellant by a collecting device B. And collecting the condensed-phase product through a collecting device A by utilizing the inertia difference of the gas and the condensed-phase product. The high-precision and high-efficiency measurement of the transient burning rate is realized by establishing a solid propellant transient burning rate measurement model and utilizing the solid propellant transient burning rate measurement model. The collecting device A collects condensed-phase products flowing away along with the fuel gas in a partition mode, and then the two-phase flow law in the combustion chamber and the appearance, granularity and component conditions of the condensed-phase products are analyzed under the action of overload force. An overload experiment that the overload direction and the combustion surface retreating direction form any angle theta is carried out by adopting a structural layout that an air injection device is vertical to a combustion chamber shell; engine experiments under different overloads are carried out by changing the rotating speed of the cantilever of the overload table.
Description
Technical Field
The invention relates to an experimental engine for measuring transient burning speed and collecting condensed phase products under overload, belonging to the field of solid rocket engine overload experiments.
Background
During the working process of the solid rocket engine, overload situations, such as takeoff acceleration and high maneuvering, particularly a power system of an advanced missile are inevitable. In order to increase the energy, most propellants are added with cheap and easily available aluminum powder, and the addition of the aluminum powder improves the acceleration sensitivity of the propellant. When acceleration or acceleration component in the same direction as the combustion surface retreating direction exists, a part of condensed phase product generated by combustion stays on the combustion surface under the combined action of acceleration force and aerodynamic force, a thermal short circuit is formed between flame and the combustion surface, the transient combustion speed of the propellant is changed, and further the pressure rise of the combustion chamber, the combustion time shortening, the internal ballistic performance and the thrust changing are induced. And even pose a threat to the safety of the missile in flight. When there is an acceleration or acceleration component opposite to the direction of combustion face retreating, the condensed phase products from combustion will leave the combustion face under the influence of overload and aerodynamic forces. Affecting the specific impulse of the solid rocket engine, the ablation of the thermal insulation layer and the nozzle, the stability of combustion, slag deposition and energy release.
Therefore, ignition experiments of the overload solid rocket engine need to be developed, and guidance is provided for design of the solid rocket engine.
The overload experiment engine is fixed on the cantilever of the over-loading platform through the passive test bed, and the variable speed motor and the actuating mechanism are utilized to drive the cantilever to rotate so as to simulate the overload environment in the flying process of the missile. Through the ground simulation overload experiment, the overload environment in the missile flight process is simulated, and the experiment cost is greatly saved. Collecting condensed phase products staying on the combustion surface and condensed phase products flowing away along with the fuel gas by simulating the acceleration or acceleration component in the same direction as the combustion surface moving back on the ground, measuring the transient burning rate of the propellant, and analyzing the relation between the condensed phase products staying on the combustion surface and the transient burning rate of the propellant and the relation between the particle size of the condensed phase products flowing away along with the fuel gas and the theoretical critical diameter; and (3) collecting condensed phase products flowing away along with the fuel gas by simulating the acceleration or acceleration component opposite to the combustion surface retreating direction on the ground, and obtaining the appearance, components and particle size of the condensed phase products. The method has important theoretical significance and engineering application value for improving the processing technology of the solid propellant and improving the performance of a solid engine.
To do good, the worker should first benefit his device. However, the existing overload experimental engine, for example, the document "research progress on combustion chamber particle characteristics and insulation layer ablation under overload" discloses a set of experimental apparatus for collecting particles under aggregation, which collects and analyzes particles under overload for the first time by converging the particles. However, the volume is large and heavy, the collected condensed-phase product is not subjected to the real overload force, the collected condensed-phase product is in a simulation stage, and only condensed-phase particles in the combustion chamber (namely the condensed-phase particles flowing away with the combustion gas) can be collected, and the experiment on the overload table is limited by the collected liquid in the collecting tank. Condensed phase products that stay on the propellant combustion surface due to real overloading cannot be collected. And it does not have the function of measuring the transient burning rate of the propellant.
Disclosure of Invention
In order to carry out more real evaluation on the performance of the solid rocket engine under the overload. The invention mainly aims to provide an experimental engine which can measure transient burning rate and collect condensed phase products under overload, the experimental engine which can measure the transient burning rate and collect the condensed phase products is placed on a cantilever of an overload platform, the overload environment of the engine is simulated by rotating the cantilever of the overload platform, and the following experimental functions can be realized: when the condensed-phase product generated by the combustion of the solid propellant charge is subjected to an overload force in the same direction as the retreating direction of the combustion surface, which is larger than the aerodynamic force of the condensed-phase product, the condensed-phase product staying on the combustion surface of the solid propellant is collected by a collecting device B. And (II) the collecting device A is opposite to the combustion surface of the solid propellant and is arranged along the axial direction of the engine, and the air injection device is vertical to the combustion chamber shell. The propellant combustion surface generates gas and condensed-phase products along the axial direction, the gas is discharged through the gas spraying device by utilizing the inertia difference of the gas and the condensed-phase products, and the condensed-phase products can enter the collecting device A due to the inertia, namely the condensed-phase products are collected through the collecting device A. And (III) establishing a solid propellant transient burning rate measuring and calculating model by analyzing the pressure intensity of the combustion chamber, the performance of the propellant and the parameters of the engine, and realizing high-precision and high-efficiency measurement of the transient burning rate by using the solid propellant transient burning rate measuring and calculating model so as to be convenient for analyzing the transient characteristic of the propellant. And (IV) the collecting device A is divided into 4 areas, and condensed phase products flowing away along with the fuel gas can be collected in a partition mode, so that the two-phase flow law in the combustion chamber and the appearance, granularity and component conditions of the condensed phase products under the action of overload force are analyzed. Adopting a structural layout that an air injection device is vertical to a combustion chamber shell, and the end covers on the two sides of the engine are the same, so that an overload experiment that the overload direction and the combustion surface retreating direction form any angle theta (theta is more than or equal to 0 and less than or equal to pi) can be carried out; by changing the angular speed of the cantilever of the overload table, engine experiments under overload of different sizes can be carried out. Namely, the invention can measure the transient burning speed of the propellant and collect condensed phase products under overload of different sizes and at any angle theta (theta is more than or equal to 0 and less than or equal to pi) formed by the overload direction and the burning surface retreating direction. The invention is helpful to improve the processing technology of the solid propellant and improve the performance of the solid engine.
The purpose of the invention is realized by the following technical scheme.
The invention discloses an experimental engine capable of measuring transient burning rate and collecting condensed phase products under overload, which comprises an experimental engine capable of measuring transient burning rate and collecting condensed phase products, a fixed tool and an overload platform. The experimental engine which can measure the transient burning rate and collect condensed-phase products is fixed on the cantilever of the over-loading platform through the fixing tool, and the engine overload environment is simulated by rotating the over-loading platform cantilever.
The experimental engine capable of measuring the transient combustion speed and collecting the condensed-phase product comprises an end cover, a combustion chamber shell, an outer cushion block, a plug, a bottom cover of a collecting device B, an O-shaped sealing ring, a tetrafluoro gasket, an inner cushion block, a box of the collecting device B, a solid propellant, a heat-insulating sleeve, an ignition cartridge, a cover of the collecting device A, a box of the collecting device A, an igniter base, an igniter sealing element, a pressure sensor base, a pressure relief valve base, a blasting plug, a pressure relief valve end enclosure, a nozzle base, a nozzle end enclosure, a nozzle liner, a nozzle throat sleeve and a nozzle.
The solid propellant is provided with a coating layer and is poured into the box of the collecting device B in advance. The experimental engine is arranged on the overload table cantilever, and the overload environment in the missile flying process is simulated by rotating the overload table cantilever. That is, when the condensed-phase product generated by the combustion of the solid propellant charge is subjected to an overload force in the same direction as the moving direction of the combustion surface, which is larger than the aerodynamic force applied to the condensed-phase product, the condensed-phase product stays on the combustion surface and is directly collected by the collecting device B.
The combustion chamber shell is a hollow cylinder; the collecting device B and the collecting device A are respectively positioned at the left end and the right end in the shell and are oppositely arranged; the air injection device is vertical to the combustion chamber shell; the gas generated by the combustion surface of the propellant and the condensed-phase product flowing away along with the gas move along the axial direction of the engine, when the gas reaches the inlet of the gas injection device, the gas is discharged through the gas injection device due to the inertia difference of the gas and the condensed-phase product, and the condensed-phase product continues to move along the axial direction and enters the collecting device.
Preferably, the initial distance between the combustion surface of the propellant and the collection device A is only 100mm, and the distance between the central axis of the gas spraying device and the collection device A is only 30mm, so that condensed-phase products can enter the collection device A.
The sensor base is used for mounting a high-frequency (the collection frequency is more than 150kHz) pressure sensor and measuring the pressure in the combustor; the method comprises the steps of establishing a solid propellant transient burning rate measuring and calculating model by analyzing the pressure intensity of a combustion chamber, the performance of a propellant and engine parameters, and realizing high-precision and high-efficiency measurement of the transient burning rate by utilizing the solid propellant transient burning rate measuring and calculating model so as to be convenient for analyzing the transient characteristic of the propellant.
The collection device a comprises four areas: the collecting area 1 is a liner, the collecting area 2 is along the gravity acceleration direction, the collecting area 3 is along the Coriolis acceleration direction, and the collecting area 4 is also arranged; and further analyzing the influence of gravity and Coriolis acceleration on the two-phase flow rule in the combustion chamber and the appearance, granularity and components of condensed-phase products under the action of overload force.
Different from the traditional engine jet device which is arranged along the axial structure of the engine shell, the experimental engine adopts the structure that the jet device is vertical to the combustion chamber shell. Even if the angle theta formed by the overload direction and the fuel surface retreating direction is not less than 90 degrees, the fixing device and the overload platform can not be damaged by high-temperature fuel gas sprayed by the air spraying device. Namely, the overload experiment can be carried out, wherein the overload direction and the combustion surface retreating direction form any angle theta (theta is more than or equal to 0 and less than or equal to pi). Meanwhile, end covers on two sides of the engine are the same, and the positions of the engine on the overload table can be conveniently exchanged. The overload environments with different sizes are simulated by changing the angular speed omega of the cantilever of the overload table, namely the invention can measure the transient burning speed of the propellant and collect condensed phase products under the overload conditions that the overload direction and the burning surface retreating direction form any angle theta (theta is more than or equal to 0 and less than or equal to pi) and the overload with different sizes.
The engine can be symmetrically arranged along the cantilevers on the two sides, the experiment under two working conditions is carried out at one time, and the experiment cost is obviously saved.
The inner diameter of the solid collecting device A is larger than that of the middle part of the combustion chamber shell, so that the collection of condensed-phase products is facilitated; the outer diameter of the solid collecting device A is smaller than the inner diameter of the right side part of the combustion chamber shell, and the collecting device A is taken out conveniently.
Preferably, when the angle θ between the overload direction and the combustion surface retreating direction is 0 °, the collection method for the collection device B is as follows.
The experimental engine is clamped on the cantilever of the over-loading platform and rotates anticlockwise along with the cantilever, and the rotating angular speed is a constant value omega e At a velocity v e The vector distance from the condensed-phase product to the center of the mobile overload table is r, and the relative speed between the condensed-phase product and the experimental engine is v g . The condensed phase product is stood by itself 1gThe acceleration in a straight downward direction is subjected to centrifugal overload, and the vector form of the acceleration is as follows:
the vector form of the applied coriolis acceleration is: a is c ＝2·ω e ×v g The acceleration vector due to the movement of the condensed phase product relative to the experimental engine is in the form:
the acceleration vector due to aerodynamic forces is in the form:
wherein F D The product is subjected to aerodynamic forces due to pressure differences caused by differences in flow velocity over the surface of the condensed-phase product. m is the mass of the condensed-phase product. When a is e +a r ≥a D The condensed phase products will move back with the combustion surface. And is thus collected by the collecting means B. When a is e +a r ＜a D During the time, congeal looks result and can leave the face of burning along with the gas, because gas jet system is perpendicular with the casing, and congeal looks result and gaseous inertia difference, the gas can be followed gas jet system and discharged, congeals the looks result and can be collected by collection device A in the collection device A.
Preferably, the method for acquiring the transient burning rate under overload comprises the following steps:
the method comprises the following steps: determining the amount of change in the gas storage in the free volume of the combustion chamber
The mass generation rate of the combustion surface of the propellant is controlled by taking the free volume of the whole combustion chamber as a control body according to the principle of mass conservation
The method is divided into two parts: a portion being discharged through the nozzle, i.e. the nozzle mass flow rate
The other part is the variation of the gas storage capacity in the free volume of the combustion chamber
Namely, it is
The expression of (c) is:
step two: to pair
The expression of (c) is modified.
The gas storage amount in the free volume of the combustion chamber is the gas density in the free volume of the combustion chamber multiplied by the free volume of the combustion chamber, and the variation is the derivative to time, namely:
mass generation rate of combustion surface
Is the mass of solid propellant burned per unit time. Namely, it is
The mass flow rate of the nozzle is as follows:
the combination of the formulas (2), (3) and (4) can change the formula (1) into the formula:
in the formula: ρ is a unit of a gradient c Is the density of the fuel gas; v c Is the free volume of the combustion chamber; t is time; rho p Is the density of the propellant; a. the b Is the area of the combustion surface; r is at The instantaneous burning rate is adopted; c D Is the flow rate coefficient; a. the t Is the sectional area of the throat part of the spray pipe; Γ is a function of the specific heat ratio k; r is the gas constant of the fuel gas; t is a unit of c Is the temperature of the gas in the combustion chamber;
step three: determining the transient burning rate r at Expression (c):
to calculate
Equation of state
Derivative of time, RT, taking into account the constant temperature and composition of the gas c Is a constant. Obtaining:
the increase in free volume in the combustion chamber is equal to the volume vacated by the reduction in charge volume resulting from combustion of the propellant, i.e.
The expression of the function Γ of the specific heat ratio k is:
substituting (6), (7) and (8) into the formula (5) can obtain the transient combustion speed r at The expression of (a) is:
in the formula: r is at Is the transient burning rate of the solid propellant; v 0 Is the initial volume of the combustion chamber; r is the gas constant of the fuel gas; t is c Is the temperature of the gas in the combustion chamber; p c The transient pressure of the combustion chamber is acquired by a high-frequency (the acquisition frequency is more than 150kHz) pressure sensor installed on the experimental engine; a. the t Is the sectional area of the throat part of the spray pipe; r is the gas constant of the fuel gas; t is c Is the temperature of the gas in the combustion chamber; k is the specific heat ratio; a. the b Is the area of the combustion surface; rho p Is the propellant density;
and the collecting device B comprises a collecting device B bottom cover, a tetrafluoro gasket, an inner cushion block and a collecting device B box. The box of the collecting device B is of a hollow cylindrical structure with the top end not sealed; the PTFE gasket plays a role in sealing and prevents high-temperature fuel gas from entering the collecting device B from the bottom; meanwhile, the charge is provided with a coating layer to prevent high-temperature gas from eroding the collecting device B in the combustion process; the inner cushion block and the outer cushion block play a role in buffering and jointly protect the base of the collecting device B.
The sensor base is used for mounting a high-frequency (acquisition frequency is larger than 150kHz) pressure sensor, measuring transient pressure intensity in the combustor and further obtaining transient burning speed.
Preferably, the air injection device is fixedly welded on the side wall of the cavity of the combustion chamber.
An ignition explosive bag is placed in the cavity.
The diameter of the throat part of the spray pipe is 2mm, the positioning effect is achieved, the actual diameter can be drilled according to test requirements, and overload tests under different pressures are carried out.
The invention adopts the design of the outer end cover, and provides arrangement positions and spaces for the double-collecting device.
The heat insulation sleeve and the nozzle liner protect the exposed part in the experimental engine and prevent the corrosion of high-temperature and high-pressure gas. And the whole structure that can disassemble that adopts can use repeatedly.
Has the advantages that:
1. the experimental engine has the functions of measuring the transient burning rate and collecting the condensed phase product under overload, adopts double collecting devices, can collect the condensed phase product staying on the burning surface because the overload force vertical to the burning surface is larger than the aerodynamic force, simultaneously measures the transient burning rate, analyzes the influence of the condensed phase product staying on the burning surface on the transient burning rate of the solid propellant, and provides important guidance for researching the transient characteristic of the burning of the aluminum-containing composite propellant under overload. The collecting device A can collect condensed phase products flowing away with the fuel gas when aerodynamic resistance is larger than overload force vertical to the combustion surface, and can analyze the relationship between the aerodynamic force, the overload force vertical to the combustion surface and the particle size of the condensed phase products.
2. The invention discloses an experimental engine capable of measuring transient burning rate and collecting condensed phase products under overload, wherein a collecting device A is divided into 4 areas, a collecting area 1 is an inner container, a collecting area 2 is along the direction of gravitational acceleration, a collecting area 3 is along the direction of Coriolis acceleration, and a collecting area 4 is arranged, so that the influence of gravity and Coriolis acceleration on the two-phase flow law in a combustion chamber and the appearance, granularity and components of the condensed phase products under the action of overload can be analyzed.
3. The experimental engine for measuring the transient combustion speed and collecting condensed phase products under overload adopts two identical outer end covers, not only provides positions for double collecting devices, but also can freely change the direction on the cantilever of an overload table; and the overload experiment of any angle theta (theta is more than or equal to 0 and less than or equal to pi) can be carried out by adopting the structural layout that the air injection device and the engine shaft body are vertically arranged. Through changing the angular velocity of transshipping platform cantilever beam, can carry out the overload experiment of arbitrary size.
4. The experimental engine capable of measuring the transient burning rate and collecting the condensed phase product under overload disclosed by the invention is beneficial to improving the processing technology of the solid propellant and improving the performance of the solid engine on the basis of realizing the beneficial effects 1, 2 and 3.
Drawings
FIG. 1 is a schematic diagram of the present overload test engine; FIG. a is a front view in cross section; FIG. (b) is a sectional view taken along the left side of the nozzle axis of the overload test engine;
FIG. 2 is a schematic view showing the arrangement of the overload direction and the combustion surface retreating direction at an angle theta (0 DEG to 90 DEG);
FIG. 3 is a schematic view showing the arrangement of the overload direction and the combustion surface retreating direction at an angle theta (90 DEG to 180 DEG) in the embodiment;
fig. 4 is an acceleration analysis chart of condensed-phase products generated by combustion when θ is 0 °.
FIG. 5 is an electron micrograph of the condensed phase product collected on collection device B at 30g overload.
Fig. 6 shows the transient burning rate obtained when the angle θ is 0 ° and the overload is 50 g.
Wherein: 1-experimental engine, 2-fixing device, 3-transition platform, 1.1-end cover, 1.2-combustion chamber shell, 1.3-outer cushion block, 1.4-plug, 1.5-collecting device B bottom cover, 1.6-O type sealing ring, 1.7-tetrafluoro gasket, 1.8-inner cushion block, 1.9-collecting device B box, 1.10-solid propellant, 1.11-heat insulating sleeve, 1.12-ignition explosive bag, 1.13-collecting device A cover, 1.14-collecting device A box, 1.15-igniter base, 1.16-igniter sealing element, 1.17-pressure sensor base, 1.18-pressure relief valve base, 1.19-explosion plug, 1.20-pressure relief valve, 1.21-nozzle base, 1.22-nozzle end cover, 1.23-nozzle lining, 1.24-nozzle throat sleeve, 1.18-nozzle sleeve, 1-25 spray pipes.
Detailed Description
To better illustrate the objects and advantages of the present invention, the present invention is further described below with reference to the drawings and specific examples.
As shown in fig. 1, the experimental engine capable of measuring transient combustion rate and collecting condensed-phase products under overload disclosed in this embodiment includes an end cover 1.1, a combustion chamber housing 1.2, an outer cushion block 1.3, a plug 1.4, a collecting device B bottom cover 1.5, an O-ring 1.6, a tetrafluoro gasket 1.7, an inner cushion block 1.8, a collecting device B box 1.9, a solid propellant 1.10, a thermal insulation sleeve 1.11, an ignition charge 1.12, a collecting device a cover 1.13, a collecting device a box 1.14, a pressure relief valve base 1.15, an igniter sealing member 1.16, a pressure sensor base 1.17, a pressure relief valve base 1.18, a bursting plug 1.19, a pressure relief valve sealing head 1.20, a nozzle base 1.21, a nozzle sealing head 1.22, a nozzle liner 1.23, a nozzle throat sleeve 1.24, and a nozzle 1.25.
The assembly sequence is as follows: the spray pipe base 1.21, the pressure relief valve base 1.18 and the pressure sensor base 1.17 are connected with the shell 1.2 through welding. The heat insulation sleeve 1.11 is arranged in the middle of the shell 1.2 and is positioned through the spray pipe bushing 1.23, and the bottom of the spray pipe bushing 1.23 is flush with the inner diameter of the heat insulation sleeve 1.11; note that the holes in the insulating sleeve 1.11 correspond one-to-one to the hole locations and sizes in the housing 1.2. An ignition charge 1.12 is placed inside the insulating sheath 1.11.
The collecting device A is placed on the right side of the combustion chamber shell 1.2, the right side end cover 1.1 is connected with the shell 1.2 through threads, and sealing is carried out through an O-shaped ring 1.6. The ignition wire is connected to the ignition charge 1.12 through the right end cap 1.1 and the collecting device a and is sealed by means of an igniter seal 1.16. The igniter base 1.15 is screwed to the right end cap 1.1.
Placing the boss face of the blasting plug 1.19 upwards on the base 1.18 of the pressure relief valve; the pressure relief valve end socket 1.20 is connected with the pressure relief valve base 1.18 through threaded connection, and plays a role in limiting and sealing through the blasting plug 1.19;
the propellant charge 1.10 is poured into the box 1.9 of the collecting device B in advance, and a bottom cover 1.5 of the collecting device B, a tetrafluoro gasket 1.7 and an inner cushion block 1.8 are fixed on the box 1.9 of the collecting device B through inner hexagon screws; put into combustion chamber casing left side with collection device B charge face in facing, put into outer cushion 1.3 afterwards, left side end cover 1.1 is connected with the combustion chamber casing through the screw thread, seals through O type circle 1.6. The plug 1.4 is connected with the left end cover 1.1 through threads.
The nozzle end enclosure 1.22 is connected with the nozzle base 1.21 through threads, the nozzle 1.25 and the nozzle throat sleeve 1.24 are fixed in the nozzle base 1.21, and end face sealing is carried out through a red copper gasket. And drilling the required throat diameter according to the test requirement.
The working method of the experimental engine which is disclosed by the embodiment and is used for measuring the transient burning rate and collecting the condensed-phase product under overload comprises the following steps:
the experimental engine 1 is assembled according to the assembly sequence;
the assembled overload test engine 1 is fixed on a cantilever of the overload table 3 through a fixing device 2 according to the installation angle required by the test, namely the combustion surface retreating direction and the overload direction form a certain angle theta as shown in figure 2 (theta is more than or equal to 0 degree and less than or equal to 90 degrees) or figure 3 (theta is more than or equal to 90 degrees and less than or equal to 180 degrees). Measuring the distance L from the center of a spray pipe 1.25 of an overload experimental engine 1 to the central axis of an overload table 3, calculating the distance L from a combustion surface of a charge 1.10 to the central axis of the overload table 3 according to the installation position of the charge 1.10, installing a calibrated high-frequency pressure sensor on a pressure sensor base 1.17, simultaneously connecting the pressure sensor with a data acquisition system, and connecting an ignition system with the overload experimental engine.
And calculating the rotating speed of the overload test bed 3 according to the acceleration required by the test.
And (3) starting the overload test bed 3 to rotate, starting the data acquisition system after the rotation is stable, then igniting the overload test engine 1, and measuring and acquiring transient pressure in the combustion chamber under overload.
And closing the data acquisition system and the over-loading platform 3, removing the overload experiment engine 1 after stopping rotation, disassembling the overload experiment engine 1, and collecting condensed phase products in the collection device A and the collection device B.
And cleaning the disassembled overload experiment engine 1, reassembling and carrying out the next experiment.
For the collected transient pressure in the combustion chamber, obtaining the transient burning rate by the following steps:
step one, forward difference is carried out on the acquired transient pressure intensity (pressure intensity-time) data, namely:
in the formula: p c And delta t is the time difference between two adjacent acquisition of the high-frequency pressure sensor for acquiring the transient pressure.
Step two, determining parameters of the experimental engine 1 and initial volume V of a combustion chamber 0 Nozzle throat section area A t ；
Step three, determining parameters of 1.10 of solid propellant charge, gas constant R of gas and temperature T of gas in a combustion chamber in an experiment c (with insulating sleeve and nozzle liner, no heat loss in the combustion chamber is to be expected, i.e. the adiabatic combustion temperature of the propellantCan be used as the temperature T of the fuel gas c ) Specific heat ratio k, combustion surface area A b Density of propellant ρ p 。
And step four, substituting the results obtained in the first three steps into a transient burning rate calculation model formula (9) to obtain the transient burning rate of the solid propellant under overload. Fig. 6 shows a transient burning rate-time curve obtained when the overload direction and the combustion surface retreating direction form an angle θ of 0 ° and the overload size is 50 g.
The collected condensed-phase product was subjected to electron microscope scanning, and the microstructure (see fig. 5), composition, particle size, and other parameters were analyzed.
The embodiment can collect condensed-phase products flowing away along with fuel gas and condensed-phase products remaining on the combustion surface, which are generated by combustion of the solid propellant agent, under the conditions that the overload directions and the combustion surface retreating directions are at any angles, and can obtain the experimental engine combustion chamber pressure and the transient combustion speed of the propellant, thereby having important significance for evaluating the propellant formula and predicting the performance of the solid rocket engine.
The above description is further intended to illustrate the objects, aspects and advantages of the present invention, and it should be understood that the above description is only an exemplary embodiment of the present invention, and is not intended to limit the scope of the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (10)
1. Have the experimental engine of measuring transient burning rate and collecting congealing the looks product under transshipping concurrently, its characterized in that: the device comprises an experimental engine (1) for measuring the transient burning rate and collecting condensed phase products, a fixed tool (2) and an overload table (3); an experimental engine (1) which has the functions of measuring the transient burning rate and collecting condensed-phase products is fixed on a cantilever of a loading platform (3) through a fixing tool (2), and the overload environment of the engine is simulated by rotating an overload platform cantilever;
the experimental engine (1) capable of measuring the transient burning rate and collecting the condensed-phase product, which is called the experimental engine (1) for short, comprises an end cover (1.1), a combustion chamber shell (1.2), an outer cushion block (1.3), a plug (1.4), a collecting device B bottom cover (1.5), an O-shaped sealing ring (1.6), a gasket (1.7), an inner cushion block (1.8), a collecting device B box (1.9), a solid propellant (1.10), a heat insulation sleeve (1.11), an ignition cartridge (1.12), a collecting device A cover (1.13), a collecting device A box (1.14), an igniter base (1.15), an igniter sealing element (1.16), a pressure sensor base (1.17), a pressure relief valve base (1.18), a blasting plug (1.19), a pressure relief valve end enclosure (1.20), a spray pipe base (1.21), a spray pipe end enclosure (1.22), a spray pipe lining (1.23), a spray pipe throat sleeve (1.24) and a spray pipe (1.25);
the solid propellant (1.10) is provided with a coating layer and is poured into a box (1.9) of a collecting device B in advance; the experimental engine (1) is arranged on a cantilever of the carrying platform (3), and an overload environment in the missile flying process is simulated by rotating the cantilever of the carrying platform (3); namely, when the condensed-phase product generated by the combustion of the solid propellant charge (1.10) is subjected to the overload force which is the same as the retreating direction of the combustion surface and is larger than the aerodynamic force applied to the condensed-phase product, the condensed-phase product can stay on the combustion surface and is directly collected by the collecting device B;
the combustion chamber shell (1.2) is a hollow cylinder; the collecting device B and the collecting device A are respectively positioned at the left end and the right end in the shell (1.2) and are oppositely arranged; the air injection device is vertical to the combustion chamber shell (1.2); gas generated by the combustion surface of the propellant (1.10) and condensed phase products flowing away with the gas move along the axial direction of the engine (1), when the gas reaches the inlet of the gas spraying device, the gas slides away through the gas spraying device due to the inertia difference of the gas and the condensed phase products, and the condensed phase products continue to move along the axial direction and enter the collecting device A;
the collecting device B comprises a collecting device B bottom cover (1.5), a gasket (1.7), an inner gasket (1.8) and a collecting device B box (1.9); a box (1.9) of the collecting device B is of a hollow cylindrical structure with an unsealed top end; the gasket (1.7) plays a role in sealing and prevents high-temperature fuel gas from entering the collecting device B from the bottom; meanwhile, the charge (1.10) is provided with a coating layer to prevent high-temperature gas from corroding the collecting device B in the combustion process; the inner cushion block (1.8) and the outer cushion block (1.3) play a role in buffering and jointly protect the bottom cover (1.5) of the collecting device B.
2. The experimental engine for measuring transient burning rate and collecting condensed-phase products under overload as set forth in claim 1, wherein: the sensor base (1.17) is used for mounting a high-frequency pressure sensor and measuring the pressure in the combustor; the method comprises the steps of establishing a solid propellant transient burning rate measuring and calculating model by analyzing the pressure intensity of a combustion chamber, the performance of a propellant and engine parameters, and realizing high-precision and high-efficiency measurement of the transient burning rate by utilizing the solid propellant transient burning rate measuring and calculating model so as to be convenient for analyzing the transient characteristic of the propellant.
3. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 2, wherein: the collecting device a comprises four zones: the collecting area 1 is a liner, the collecting area 2 is along the direction of gravitational acceleration, the collecting area 3 is along the direction of Coriolis acceleration, and the collecting area 4 is also arranged; and further analyzing the influence of gravity and Coriolis acceleration on the two-phase flow rule in the combustion chamber and the appearance, granularity and components of condensed-phase products under the action of overload force.
4. The experimental engine for measuring transient burning rate and collecting condensed-phase products under overload as set forth in claim 3, wherein: the structure layout that the air injection device is vertical to the combustion chamber shell (1.2) is adopted; even if the angle theta formed by the overload direction and the combustion surface retreating direction is more than or equal to 90 degrees, the fixing device (2) and the overload table (3) cannot be damaged by high-temperature fuel gas sprayed by the air spraying device; namely, the overload experiment that the overload direction and the combustion surface retreating direction form any angle theta (theta is more than or equal to 0 and less than or equal to pi) can be carried out; meanwhile, end covers (1.1) on two sides of the engine are the same, so that the positions of the end covers on the passing platform (3) can be conveniently exchanged; the overload environments with different sizes are simulated by changing the angular speed omega of the cantilever of the over-loading platform (3), namely the invention can measure the transient burning speed of the propellant and collect condensed phase products under the condition that the overload direction and the burning surface retreating direction form any angle theta (theta is more than or equal to 0 and less than or equal to pi) and the overload with different sizes.
5. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 4, wherein: the engine is symmetrically placed along the cantilevers on the two sides, the experiment under two working conditions is carried out at a time, and the experiment cost is remarkably saved.
6. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 5, wherein: the inner diameter of the solid collecting device A is larger than that of the middle part of the combustion chamber shell (1.2), so that condensed phase products can be collected; the outer diameter of the solid collecting device A is smaller than the inner diameter of the right side part of the combustion chamber shell (1.2), and the solid collecting device A is convenient to take out.
7. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 6, wherein: the initial distance between the combustion surface of the propellant (1.10) and the collecting device A is only 100mm, and the distance between the central axis of the air injection device and the collecting device A is only 30mm, so that condensed-phase products can enter the collecting device A.
8. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 6, wherein: when the angle θ between the overload direction and the combustion surface retreating direction is 0 °, the collection method for the collection device B is as follows,
the experimental engine (1) is clamped on a cantilever of the over-loading platform (3) and rotates anticlockwise along with the cantilever, and the rotating angular speed is a constant value omega e At a velocity v e The vector distance from the condensed phase product to the center of the passing platform (3) is r, and the relative speed between the condensed phase product and the experimental engine (1) is v g (ii) a The condensed-phase product is subjected to the acceleration of 1g of the condensed-phase product vertically downwards by the condensed-phase product, and the acceleration subjected to centrifugal overload has the vector form:
the vector form of the Coriolis acceleration is: a is c ＝2·ω e ×v g The acceleration vector due to the movement of the condensed phase product relative to the experimental engine (1) is in the form:
due to aerodynamic forceThe resultant acceleration vector is in the form:
wherein F D The aerodynamic force is applied to the condensed-phase product, and the aerodynamic force is generated by pressure difference caused by flow speed difference on the surface of the condensed-phase product; m is the mass of the condensed-phase product; when a is e +a r ≥a D When the gas is burnt, the condensed phase product moves back along with the burning surface; thereby being collected by the collecting means B; when a is e +a r ＜a D During the time, congeal looks product can leave the face of burning along with the gas, because gas jet system is perpendicular with casing (1.2), and congeal looks product and gaseous inertia difference, the gas can be followed gas jet system and slided away, congeals the looks product and can be collected by collection device A in the collection device A.
9. The experimental engine for measuring transient burning rate and collecting condensed phase products under overload condition as claimed in claim 6, wherein: the method for acquiring the transient burning rate under overload comprises the following steps,
the method comprises the following steps: determining the amount of change in the gas storage in the free volume of the combustion chamber
The mass generation rate of the combustion surface of the propellant is controlled by taking the free volume of the whole combustion chamber as a control body according to the principle of mass conservation
The method is divided into two parts: a portion being discharged through the nozzle, i.e. nozzle mass flow rate
The other part is the variation of the gas storage capacity in the free volume of the combustion chamber
Namely, it is
The expression of (a) is:
step two: to pair
The expression of (2) is deformed;
the gas storage amount in the free volume of the combustion chamber is the gas density in the free volume of the combustion chamber multiplied by the free volume of the combustion chamber, and the variation is the derivative to time, namely:
mass generation rate of combustion surface
Mass of solid propellant burned per unit time; namely that
The mass flow rate of the nozzle is as follows:
the combination formulas (2), (3) and (4) change the formula (1) into the following formula:
in the formula: rho c Is the density of the fuel gas; v c Is the free volume of the combustion chamber; t is time; rho p Is the propellant density; a. the b Is the area of the combustion surface; r is at The instantaneous burning rate is adopted; c D Is the flow rate coefficient; a. the t Is the sectional area of the throat part of the spray pipe; Γ is a function of the specific heat ratio k; r is the gas constant of the fuel gas; t is a unit of c Is the temperature of the gas in the combustion chamber;
step three: determining the transient burning rate r at Expression (c):
to calculate
Equation of state
Derivative of time, RT, taking into account the constant temperature and composition of the gas c Is a constant; obtaining:
the increase in free volume in the combustion chamber is equal to the volume vacated by the reduction in charge volume resulting from combustion of the propellant, i.e.
The expression of the function Γ of the specific heat ratio k is:
substituting (6), (7) and (8) into the formula (5) to obtain the transient burning rate r at The expression of (a) is:
in the formula: r is at Is a transient burning rate of solid propellant；V 0 Is the initial volume of the combustion chamber; r is the gas constant of the fuel gas; t is c Is the temperature of the gas in the combustion chamber; p is c The transient pressure intensity of the combustion chamber is acquired by a high-frequency pressure sensor arranged on an experimental engine; a. the t Is the sectional area of the throat part of the spray pipe; r is the gas constant of the fuel gas; t is c Is the temperature of the gas in the combustion chamber; k is the specific heat ratio; a. the b Is the area of the combustion surface; ρ is a unit of a gradient p Is the density of the propellant.
10. The experimental engine of claim 6 with both transient combustion rate measurement and condensed-phase product collection under overload, wherein: the sensor base (1.17) is used for mounting a high-frequency pressure sensor and measuring transient pressure intensity in the combustor so as to obtain transient burning speed;
the air injection device is fixedly welded on the side wall of the cavity of the combustion chamber (1.2);
an ignition explosive bag (1.12) is arranged in the cavity;
the diameter of the throat part of the spray pipe (1.25) is 2mm, the positioning effect is realized, the actual diameter is drilled according to the test requirement, and the overload tests under different pressures are carried out;
the design of an outer end cover (1.1) is adopted to provide arrangement positions and spaces for the double-collecting device;
the heat insulation sleeve (1.11) and the spray pipe bushing (1.23) protect the exposed part in the experimental engine (1) and prevent the corrosion of high-temperature and high-pressure gas; and the whole structure of being convenient for disassemble that adopts can use repeatedly.
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