阅读说明：本技术 一种静电场调控的推进剂燃烧实验装置 (Propellant combustion experimental device regulated and controlled by electrostatic field ) 是由 敖文 赵明涛 黄星 熊婧伊 刘佩进 甘云华 霍超 高育科 于 2021-06-23 设计创作，主要内容包括：本发明公开了一种静电场调控的推进剂燃烧实验装置,包括：燃烧室和两个金属环形电极,两个金属环形电极设置于燃烧室内,在竖直方向上上下间隔设置,间距可调,且均呈水平状；一个为正电极,一个为负电极,其中正电极与设置于燃烧室外的直流高压电源的正极相连接；两个金属环形电极的环形空间内用于上下贯穿设置竖直向下的推进剂药条,且推进剂药条的上端安装于燃烧室的顶部；直流高压电源用于：向金属环形电极供电,在正电极和负电极间形成匀强电场,以使推进剂药条处在匀强电场中；使用该静电场调控的推进剂燃烧实验装置实现了推进剂在电场作用下工作状态模拟,能够定量获得电场强度与推进剂燃速的变化规律,以及电场对推进剂燃烧的影响机制。(The invention discloses a propellant combustion experimental device regulated and controlled by an electrostatic field, which comprises: the device comprises a combustion chamber and two metal annular electrodes, wherein the two metal annular electrodes are arranged in the combustion chamber, are arranged at intervals in the vertical direction, have adjustable intervals and are both horizontal; one is a positive electrode and the other is a negative electrode, wherein the positive electrode is connected with the positive electrode of a direct-current high-voltage power supply arranged outside the combustion chamber; the annular space of the two metal annular electrodes is used for vertically penetrating and arranging propellant strips downwards, and the upper ends of the propellant strips are arranged at the top of the combustion chamber; the direct current high voltage power supply is used for: supplying power to the metal annular electrode, and forming a uniform electric field between the positive electrode and the negative electrode so as to enable the propellant strips to be positioned in the uniform electric field; the propellant combustion experimental device regulated and controlled by the electrostatic field realizes the simulation of the working state of the propellant under the action of the electric field, and can quantitatively obtain the change rule of the electric field intensity and the combustion speed of the propellant and the influence mechanism of the electric field on the propellant combustion.)

1. The utility model provides a propellant burning experimental apparatus of electrostatic field regulation and control which characterized in that includes: the device comprises a combustion chamber (2) and two metal annular electrodes, wherein the two metal annular electrodes are arranged in the combustion chamber (2), are arranged at intervals from top to bottom in the vertical direction, have adjustable intervals and are both horizontal; one is a positive electrode (3) and the other is a negative electrode (11), wherein the positive electrode (3) is connected with the positive electrode of a direct-current high-voltage power supply (7) arranged outside the combustion chamber (2), and the negative electrode (11) is connected with the negative electrode and is grounded; the voltage of the direct-current high-voltage power supply (7) is adjustable;

propellant strips (4) vertically downward penetrate through the annular space of the two metal annular electrodes, the upper ends of the propellant strips (4) are arranged at the top of the combustion chamber (2), and the lower ends of the propellant strips are combustion surfaces;

the direct-current high-voltage power supply (7) is used for: supplying power to the metal annular electrode, and forming a uniform electric field between the positive electrode (3) and the negative electrode (11) so as to enable the propellant medicine strip (4) to be in the uniform electric field;

a thermocouple (6) and a pressure transmitter (5) are arranged in the combustion chamber (2), one ends of the thermocouple (6) and the pressure transmitter (5) are connected with wires, each wire is connected with a data acquisition unit (9) arranged outside the combustion chamber (2), and the data acquisition units (9) are also connected with a controller (13);

a high-speed thermal infrared imager (8) and a high-speed camera (10) are arranged outside the combustion chamber (2), and the working ends of the high-speed thermal infrared imager (8) and the high-speed camera (10) face the combustion chamber (2) side; a spectrometer (12) is arranged outside the combustion chamber (2); the high-speed thermal infrared imager (8), the high-speed camera (10) and the spectrometer (12) are connected with the data collector (9).

2. The propellant combustion experiment device regulated by the electrostatic field according to claim 1, wherein three vertical screw rods (15) are arranged in the combustion chamber (2), and the upper ends of the three screw rods (15) are detachably connected with the top of the combustion chamber (2) through threads;

the two metal annular electrodes are horizontally arranged and fixed on the three screw rods (15).

3. The propellant combustion experiment device regulated by the electrostatic field according to claim 2, wherein three through holes are formed in the outer edges of the two metal ring electrodes at intervals in a circle, the three through holes are used for being sleeved on the three lead screws (15), nuts (16) are sleeved on the lead screws (15) and positioned above and below the metal ring electrodes, and the upper nut (16) and the lower nut (16) are used for screwing and fixing the metal ring electrodes; and the upper nut (16) and the lower nut (16) can move on the screw rod (15) to change the distance between the two metal annular electrodes.

4. The propellant combustion experiment device regulated by the electrostatic field according to claim 2, wherein a horizontal support bracket (14) is sleeved on the three screw rods (15), and each support bracket (14) is used for stacking a metal ring electrode; the supporting brackets (14) are sheet insulators with openings in the middle, three through holes are formed in the edges at intervals, the through holes are used for being sleeved on the three screw rods (15), nuts (16) are sleeved on the screw rods (15) and positioned above and below the supporting brackets (14), and the upper nuts and the lower nuts (16) are used for screwing and fixing the supporting brackets (14); and the upper nut (16) and the lower nut (16) can move on the screw rod (15) to change the distance between the two metal annular electrodes.

5. An electrostatic field regulated propellant combustion experiment device as claimed in claim 3 or 4 wherein both said metal ring electrodes are in the form of a sheet.

6. The electrostatic field regulated propellant combustion experiment device as claimed in claim 5, wherein the combustion chamber (2) is made of organic glass.

7. The propellant combustion experiment device regulated by the electrostatic field according to claim 6, wherein the upper end of the combustion chamber (2) is connected with the high-pressure nitrogen tank (1) through an air inlet pipe, and the upper end of the combustion chamber (2) is further connected with an air outlet pipe.

8. The propellant combustion experiment device regulated by the electrostatic field according to claim 7, wherein the combustion chamber (2) is of a cavity structure and is composed of an upper shell and a lower shell which are buckled together and communicated, a rectangular flange (17) connected with the shells is arranged on the periphery of the outer edge of the connected end parts of the upper shell and the lower shell, and when the upper shell is transversely placed on the support table to be filled with the propellant, the rectangular flange (17) is used as a support piece.

9. An electrostatic field regulated propellant combustion experiment device as claimed in claim 8, wherein a combustion product collection device is placed at the bottom of the combustion chamber (2) and below the metal ring electrode.

10. The monitoring method of the electrostatic field regulated propellant combustion experiment device as claimed in any one of claims 1 to 9, wherein the monitoring method comprises the following steps:

horizontally placing the upper shell of the combustion chamber (2), taking a rectangular flange as a support piece, and installing a propellant charge bar (4) and an ignition wire at the top of the upper shell of the combustion chamber (2); after the mounting, the upper shell and the lower shell of the combustion chamber (2) are buckled;

debugging the frame value of the high-speed camera (10), debugging the high-speed thermal infrared imager (8) to set for automatic focusing, and debugging the frame value of the spectrometer (12); checking that the data acquisition of the data acquisition device (9) is normal;

exhausting air in the combustion chamber (2), and starting a high-pressure nitrogen tank (1) to pre-charge the combustion chamber (2) for checking the air tightness; turning on a direct-current high-voltage power supply (7) and adjusting voltage;

filling nitrogen into the combustion chamber (2) for pressurization, and closing an air inlet channel after the pressure is stable;

starting the high-speed camera (10), the high-speed thermal infrared imager (8) and the spectrometer (12);

igniting the propellant (4), and manually exhausting and decompressing the combustion chamber (2) after ignition; the propellant combustion products fall into a combustion product collection device;

dismantling the upper shell of the combustion chamber (2) and collecting products; and exporting data in the high-speed thermal infrared imager (8), the high-speed camera (10) and the spectrometer (12).

Technical Field

The invention belongs to the technical field of solid engines, and particularly relates to a propellant combustion experimental device regulated and controlled by an electrostatic field.

Background

The research on electrostatic field regulated combustion is one of the important research fields in the research on combustion, for example, clean combustion of coal is a typical electrostatic field regulated combustion technology which utilizes an external electric field to improve the combustion efficiency. The electrostatic field is applied in the combustion process, so that the electrostatic force among the particles is amplified, on one hand, the activity of the particles is improved, on the other hand, the agglomeration phenomenon among the particles is reduced, and the combustion efficiency is greatly improved.

In recent years, with the development of large-scale and heavy-duty solid rockets, many uncontrollable risks in development are increasingly serious, and the technical difficulty of development is increased. Compared with liquid rocket engines, the solid rocket engine has the main defects of small specific impulse, difficult control of combustion and the like, thereby being not beneficial to special flight.

The method for controlling the combustion of the solid rocket engine by using the electrostatic field to regulate and control the combustion of the propellant is a novel research direction.

Disclosure of Invention

The invention aims to provide a propellant combustion experimental device regulated and controlled by an electrostatic field, which realizes the simulation of the working state of a propellant under the action of the electric field, and can quantitatively obtain the change rule of the electric field intensity and the combustion speed of the propellant and the influence mechanism of the electric field on the propellant combustion.

The invention adopts the following technical scheme: an electrostatic field regulated propellant combustion experimental device comprises: the device comprises a combustion chamber and two metal annular electrodes, wherein the two metal annular electrodes are arranged in the combustion chamber, are arranged at intervals in the vertical direction, have adjustable intervals and are both horizontal; one is a positive electrode and the other is a negative electrode, wherein the positive electrode is connected with the positive electrode of a direct-current high-voltage power supply arranged outside the combustion chamber, and the negative electrode is connected with the negative electrode and is grounded; the voltage of the direct-current high-voltage power supply is adjustable;

the annular space of the two metal annular electrodes is used for vertically penetrating and arranging propellant strips downwards, the upper ends of the propellant strips are arranged at the top of the combustion chamber, and the lower ends of the propellant strips are combustion surfaces;

the direct current high voltage power supply is used for: supplying power to the metal annular electrode, and forming a uniform electric field between the positive electrode and the negative electrode so as to enable the propellant strips to be positioned in the uniform electric field;

a thermocouple and a pressure transmitter are arranged in the combustion chamber, one ends of the thermocouple and the pressure transmitter are connected with wires, each wire is connected with a data acquisition unit arranged outside the combustion chamber, and the data acquisition units are also connected with a controller;

a high-speed thermal infrared imager and a high-speed camera are arranged outside the combustion chamber, and the working ends of the high-speed thermal infrared imager and the high-speed camera face the side of the combustion chamber; a spectrometer is arranged outside the combustion chamber; the high-speed thermal infrared imager, the high-speed camera and the spectrometer are all connected with the data collector.

Furthermore, three vertical lead screws are arranged in the combustion chamber, and the upper ends of the three lead screws are detachably connected with the top of the combustion chamber through threads; the two metal annular electrodes are horizontally arranged and fixed on the three lead screws.

Furthermore, three through holes are formed in the outer edges of the two metal annular electrodes at intervals in the circumferential direction, the three through holes are used for being sleeved on the three lead screws, nuts are sleeved on the lead screws and positioned above and below the metal annular electrodes, and the upper nuts and the lower nuts are used for screwing and fixing the metal annular electrodes; and the upper nut and the lower nut can move on the screw rod so as to change the distance between the two metal annular electrodes.

Furthermore, a horizontal support bracket is sleeved on the three screw rods, and each support bracket is used for stacking a metal annular electrode; the supporting supports are sheet insulators with openings in the middle, three through holes are formed in the edges at intervals, the through holes are used for being sleeved on the three screw rods, nuts are sleeved on the screw rods and positioned above and below each supporting support, and the upper nuts and the lower nuts are used for screwing and fixing the supporting supports; and the upper nut and the lower nut can move on the screw rod so as to change the distance between the two metal annular electrodes.

Further, both the two metal ring electrodes are sheet-shaped bodies.

Furthermore, the combustion chamber adopts organic glass material.

Further, the upper end of the combustion chamber is connected with a high-pressure nitrogen tank through an air inlet pipe, and the upper end of the combustion chamber is also connected with an air outlet pipe.

Furthermore, the combustion chamber is of a cavity structure and is composed of an upper shell and a lower shell which are buckled together and communicated, a rectangular flange connected with the shells is arranged on the periphery of the outer edge of the end part connected with the upper shell and the lower shell, and when the upper shell is transversely placed on the supporting table and filled with propellant, the rectangular flange is used as a supporting piece.

Further, a combustion product collecting device is placed at the bottom inside the combustion chamber and below the metal ring electrode.

The invention also discloses a monitoring method of the propellant combustion experimental device regulated and controlled by the electrostatic field, which comprises the following steps:

horizontally placing an upper shell of the combustion chamber, taking a rectangular flange as a supporting piece, and installing a propellant powder strip and an ignition wire at the top of the upper shell of the combustion chamber; after the mounting, the upper shell and the lower shell of the combustion chamber are buckled;

debugging a frame value of a high-speed camera, debugging a high-speed thermal infrared imager to set automatic focusing, and debugging a spectrometer frame value; checking that the data acquisition of the data acquisition unit is normal;

discharging air in the combustion chamber, and opening a high-pressure nitrogen tank to pre-charge the combustion chamber to check the air tightness; turning on a direct-current high-voltage power supply and adjusting voltage;

filling nitrogen into the combustion chamber for pressurization, and closing the air inlet channel after the pressure is stable;

starting a high-speed camera, a high-speed thermal infrared imager and a spectrometer;

igniting the propellant, and manually exhausting and decompressing the combustion chamber after ignition; the propellant combustion products fall into a combustion product collection device;

removing the upper shell of the combustion chamber, and collecting products; and exporting data in the high-speed thermal infrared imager, the high-speed camera and the spectrometer.

The invention has the beneficial effects that: 1. the metal electrodes are arranged in the combustion chamber, one end of one electrode is electrified by adopting a direct-current high-voltage power supply, the other electrode is grounded, the effect of applying an electric field to the propellant is achieved, a uniform electric field is formed between the two electrodes, and the simulation of the working state of the propellant under the action of the electric field is realized. 2. The propellant is placed in an inverted mode, synchronous testing of propellant combustion surface shooting and product collection is achieved, and the combustion state of the electric field direction and the combustion natural convection direction in the same direction or the opposite direction can be tested respectively. 3. The distance between the two metal electrodes is changed by adjusting the position of the nut, so that the device is suitable for the medical strips with different lengths and also achieves the purpose of adjusting the electric field intensity.

Drawings

FIG. 1 is a schematic structural diagram of an experimental propellant combustion device regulated by an electrostatic field;

FIG. 2 is a schematic view of a combustion chamber configuration;

FIG. 3 is a schematic diagram of a structure of the applied electric field in the present embodiment;

FIG. 4 is another structural diagram of the applied electric field in the present embodiment;

FIG. 5 is a graph of the burning rate of the propellant sticks in this example under different electric fields;

FIG. 6 is a graph of the flame temperature of the propellant sticks in this example under different electric fields;

FIG. 7 is a graph of ignition delay times for the propellant sticks of this example under different electric fields;

FIG. 8 is an SEM photograph of a condensed-phase product in this example;

wherein: 1. the system comprises a high-pressure nitrogen tank, a combustion chamber, a positive electrode, a propellant powder strip, a pressure transmitter, a thermocouple, a direct-current high-voltage power supply, a high-speed thermal infrared imager, a data collector, a high-speed camera, a negative electrode, a spectrometer, a controller, a support holder, a lead screw and a controller, wherein the high-pressure nitrogen tank is 2, the combustion chamber is 3, the positive electrode is 4, the propellant powder strip is 4, the pressure transmitter is 5, the thermocouple is 6, the direct-current high-voltage power supply is 7, the high-speed thermal infrared imager is 8, the data collector is 9, the high-speed camera is 10, the negative electrode is 11, the spectrometer is 12, the controller is 13, the support holder is 14, and the lead screw is 15; 16. nut, 17 support piece.

Detailed Description

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

In solid rockets using hydrocarbon fuels which are similar to the propellant binder component, it has been found that combustion of hydrocarbon fuels results in a flame containing a plurality of electrically charged particles having a density of about 10⁹-10¹²Per cm³The electric field has an influence on the original combustion characteristics. Its impact is reflected in two aspects: firstly, in the pure runner aerodynamic flow, the influence of the flow nonuniformity of the runner and the turbulent flow of the charged electrode on the distribution of particles is small, and the total number of the particles is reduced; secondly, a large number of ions and ion clusters in the flame can be more violently combusted under the action of the electric field force.

The invention relates to a propellant combustion experimental device regulated by an electrostatic field, which is shown in figures 1 and 2 and comprises: the device comprises a combustion chamber 2 and two metal annular electrodes, wherein the two metal annular electrodes are arranged in the combustion chamber 2, are arranged at intervals in the vertical direction, have adjustable intervals and are both horizontal; one is a positive electrode 3, and the other is a negative electrode 11, wherein the positive electrode 3 is connected with the positive electrode of a direct current high voltage power supply 7 arranged outside the combustion chamber 2, and the negative electrode 11 is connected with the negative electrode and is grounded; the voltage of the direct-current high-voltage power supply 7 is adjustable; in the experimental process, the voltage is adjusted by the direct-current high-voltage power supply 7 so as to adjust the magnitude of an external electric field of the propellant drug strip 4.

The annular space of the two metal annular electrodes is used for vertically penetrating and arranging propellant drug strips 4 which are vertically downward, the upper ends of the propellant drug strips 4 are arranged at the top of the combustion chamber 2, and the lower ends of the propellant drug strips are combustion surfaces; the direct-current high-voltage power supply 7 is used for: and (3) supplying power to the metal annular electrode, and forming a uniform electric field between the positive electrode 3 and the negative electrode 11 so as to enable the propellant medicine strip 4 to be in the uniform electric field. In order to load the propellant charge 4, a cuboid groove with the length of 20mm, the width of 5mm and the depth of 5mm is turned at the middle position of the top of the combustion chamber 2, so that the propellant charge is fixed.

As shown in fig. 3 and 4, three vertical screw rods 15 are arranged in the combustion chamber 2, and the three screw rods 15 are detachably connected with the top of the combustion chamber 2 through threads.

Three through holes which are arranged at intervals are formed in the outer edges of the two metal annular electrodes, the three through holes are used for being sleeved on the three screw rods 15, threads 16 are arranged on the screw rods 15, nuts 16 are sleeved on the upper portions and the lower portions of the screw rods 15 and located on the metal annular electrodes, and the upper nuts 16 and the lower nuts 16 are used for screwing and fixing the metal annular electrodes. The distance between the two electrodes can be changed by adjusting the positions of different nuts 16 on the screw rod 14, so that the device is suitable for medicine strips with different lengths and can also achieve the aim of adjusting the electric field intensity. In one mode, as shown in fig. 3, a metal sheet may be directly used, and the middle portion of the metal sheet is hollowed to form a ring shape with an open middle, and the metal sheet is directly used as an electrode. Alternatively, as shown in fig. 4, a supporting bracket 14 may be selected, and an insulating material is selected, the supporting bracket is a sheet-shaped body, the middle of the supporting bracket 14 is hollowed, through holes are formed at intervals in the axial direction around the supporting bracket, the supporting bracket is fixed on the lead screw 15, and then a metal ring-shaped electrode, that is, a metal sheet-shaped body, is hollowed at the middle to form a ring shape, and is stacked on the supporting bracket 14.

For metals with a greater thickness, which act as electrodes, a tip effect is produced, and in order to avoid a tip effect in the combustion chamber 2, both metal ring electrodes are used as platelets.

The existing combustion chambers 2 are made of metal materials, but the metal combustion chambers have the following problems that firstly, the metal combustion chambers have interference effect on an electrostatic field; secondly, the metal combustion chamber is not beneficial to simultaneously shooting and measuring the high-speed thermal infrared imager, the high-speed camera and the spectrometer. In the experimental set-up of the invention, the combustion chamber 2 is made of PMMA, which overcomes the above-mentioned problems. The combustion chamber 2 is formed by processing an organic glass tube with the outer diameter of 300mm and the wall thickness of 20mm, and can bear the internal pressure theoretical value of 0.9MPa according to GB/T20801.

The temperature change and the pressure change in the combustion chamber 2 are measured using the thermocouple 6 and the pressure transmitter 5, respectively. The specification parameter of the pressure transmitter 5 is-0.1-1 MPa (0-5V). Thermocouple 6 was an S-type platinum rhodium thermocouple. The thermocouple 6 and the pressure transmitter 5 are connected with the top of the combustor 2 by threads. One ends of the thermocouple 6 and the pressure transmitter 5 are connected with wires, each wire is connected with a data acquisition unit 9 arranged outside the combustion chamber 2, and the data acquisition unit 9 is also connected with a controller 13. A high-speed thermal infrared imager 8 and a high-speed camera 10 are arranged on one side surface outside the combustion chamber 2, and the working ends of the high-speed thermal infrared imager 8 and the high-speed camera 10 face the combustion chamber 2; a spectrometer 12 is arranged on the opposite side surface outside the combustion chamber 2; the high-speed thermal infrared imager 8, the high-speed camera 10 and the spectrometer 12 are all connected with the data collector 9.

The high-speed camera 10 is also called a digital industrial camera, is a commonly used industrial shooting camera, is commonly used for replacing human eye measurement and judgment in the industrial field, works in a mode of converting a digital image shooting target into an image signal, and can achieve no frame loss of 100%. The spectrometer 12, also called a spectrometer, decomposes complex light into spectral lines by using a prism or a diffraction grating, and can detect light reflected or released by the surface of an object by using the spectrometer, and can detect what elements are contained in the object by capturing optical information. Since the time for the high-speed camera 10 and the spectrometer 12 to continuously record at a high level is extremely short, the experiment needs to photograph the whole combustion process of the propellant drug strip 4 in the electric field, so as to calculate the combustion speed of the propellant drug strip in the electric field, and the ignition delay time of the propellant needs to be calculated by using the peak time of the spectrum.

During the experiment, the pressure in combustion chamber 2 needs to be adjusted, and the upper end of combustion chamber 2 is connected with high-pressure nitrogen gas jar 1 through the intake pipe, and the upper end of combustion chamber 2 still is connected with the outlet duct.

Above-mentioned combustion chamber 2 is the cavity structures, by two upper and lower lock casing that just are linked together constitute, at the outward flange a week of the tip that is connected of casing under and above, be provided with the rectangle flange that is connected with the casing, when last casing was transversely placed in a supporting bench and is filled the propellant, the rectangle flange was as support piece, when having guaranteed to fill the explosive strip, combustion chamber 2's steadiness was difficult for rolling.

At the bottom inside the combustion chamber 2, and below the metal ring electrode, a combustion product collection device is placed. During collection, 80mL of deionized water is placed under the propellant drug strips 4 in an 80-by-80 mm crucible, and the deionized water is poured into a beaker to wait for one-step suction filtration treatment after collection is finished every time, and the crucible needs to be cleaned after collection is finished every time in order to avoid mutual interference of different groups of experimental products.

The monitoring method of the propellant combustion experimental device regulated and controlled by the electrostatic field comprises the following steps:

horizontally placing an upper shell of the combustion chamber 2, taking a rectangular flange as a supporting piece, and installing a propellant powder strip 4 and an ignition wire at the top of the upper shell of the combustion chamber 2; after installation, the upper casing and the lower casing of the combustion chamber 2 are fastened.

Debugging the frame value of the high-speed camera 10, debugging the high-speed thermal infrared imager 8 to set for automatic focusing, and debugging the frame value of the spectrometer 12; and checking that the data acquisition of the data acquisition unit 9 is normal.

Discharging air in the combustion chamber 2, and starting the high-pressure nitrogen tank 1 to pre-charge the combustion chamber 2 for checking the air tightness; the dc high voltage power supply 7 is turned on to regulate the voltage.

Filling nitrogen into the combustion chamber 2, pressurizing to an experimental value, and closing an air inlet channel after the pressure is stable;

the high-speed camera 10, the high-speed thermal infrared imager 8 and the spectrometer 12 are activated.

Propellant 4 was ignited, using a 0.3mm heating wire at 24V for this experiment. After ignition, the combustion chamber 2 is manually exhausted and decompressed; the propellant combustion products fall into the combustion product collection means.

Removing the upper shell of the combustion chamber 2 and collecting the products; data in the high-speed thermal infrared imager 8, the high-speed camera 10, and the spectrometer 12 are derived.

The propellant combustion experiment device regulated and controlled by the electrostatic field in the embodiment is used for monitoring the combustion process of the propellant drug strip 4 and processing data as follows:

qualitative and quantitative analytical studies were performed on AP/HTPB/Al propellants at different electric fields. The specific test environment is that in a combustion chamber 2 filled with nitrogen under atmospheric pressure, the distance between two electrodes is 7mm, and the combustion test is respectively carried out on an external voltage environment of-5 kV, -3.75kV, -2.5kV, -1.25kV, 0, 1.25kV, 2.5kV, 3.75kV and 5kV, and for the convenience of research, the direction of an electric field is determined to be positive from top to bottom, and is negative on the contrary. And three times of repeated experiments are carried out on each test environment so as to balance the interference of external unstable factors. The following results were obtained:

1. influence of an external electric field on the burning rate of the propellant:

before testing, the propellant charge 4 was coated to ensure that the propellant was end-fired. The method for calculating the burning rate mainly comprises the steps of calculating through pictures shot by the high-speed camera 10, specifically, recording positions of burning surfaces of propellant drug strips appearing and disappearing in the visual field of the high-speed camera 10 respectively, calculating and obtaining the burning time of the propellant in an electric field by combining the number of frames, and realizing that the measured height of the propellant in the high-speed camera is 7mm, so that the burning rates of the propellant under the action of different electric fields can be obtained. As shown in FIG. 5, there was no error bar at-5 kV, -3.75kV, -2.5kV, and 3.75kV data. The experimental result shows that when an electric field is applied in the positive direction, the burning rate generally shows a descending trend along with the increase of the field intensity; when the electric field is applied in the reverse direction, the burning rate generally increases as the field intensity increases.

2. Influence of an applied electric field on heat generation of the propellant:

the heat released by the propellant was measured with an S-type thermocouple, but considering that the propellant charge 4 needs to be between the two electrodes, direct measurement of the temperature of the propellant would present a greater challenge to the experimental system. Therefore, the system qualitatively reflects the heat generation state of the propellant drug strip 4 in different electric field environments by collecting the temperature signal of the gas around the propellant drug strip 4.

As shown in fig. 6. The ordinate represents the output voltage of the flame temperature measured by the propellant thermocouple, and the output voltage is utilized to reflect the flame temperature change trend because the temperature change is small and the temperature and the output voltage are in positive correlation. As can be seen from fig. 6, the propellant flame temperature is highest when no electric field is applied, and the propellant flame temperature is disturbed when the electric field is applied. However, from the perspective of heat transfer, the temperature of flame around the propellant is measured in the experiment, the slower the propellant burns, the longer the time for the thermocouple to collect the temperature in the combustion chamber 2, and the higher the collected temperature, so that the reverse electric field can be proved to promote the propellant to burn, and the forward electric field can play a certain role in inhibiting the propellant to burn.

3. Influence of applied electric field on ignition delay:

the ignition delay times for the propellant sticks under different electric field effects are shown in figure 7: the ignition delay time of the AP/HTPB/Al propellant is 1.84s in an environment filled with nitrogen at normal temperature and pressure. When a forward electric field and a reverse electric field are respectively applied to the propellant, the ignition delay time of the propellant is increased, the ignition delay time of the propellant is generally longer along with the larger applied voltage, and in the experiment, the electric field can be obviously found to have certain influence on the ignition delay time of the propellant. However, it was found by processing the data that the ignition delay time decreased to some extent at a specific electric field strength regardless of whether the forward electric field or the reverse electric field was applied.

4. Influence of applied electric field on condensed phase product formation:

the analysis of the condensed-phase product of the propellant mainly analyzes the particle size and the shape of the condensed-phase product under different field strengths, and the observation of the range in which the particle size mainly exists has important significance for the research of the combustion instability and the two-phase flow of the solid rocket engine. For this purpose, the main particle size range of the propellant is observed by a scanning electron microscope SEM and a laser particle size test method. The appearance and the size of the partial field intensity are shown in the following figure 8, the electric field conditions from left to right in the figure are sequentially-5 kV, -3.75kV, -2.5kV, -1.25kV, 0, 1.25kV, 2.5kV, 3.75kV and 5kV, and the figure shows that the external electric field can inhibit the agglomeration of aluminum powder, and the inhibiting effect of the reverse applied electric field is stronger than that of the forward electric field under the same field intensity; and the better the inhibition effect of the electric field on the aluminum powder agglomeration along with the increase of the field intensity in a certain range.