Visual simulation device for liquid film on inner wall of liquid engine

Abstract

The invention relates to a liquid engine inner wall liquid film visual simulation device, and belongs to the technical field of liquid film simulation devices.The liquid engine inner wall liquid film visual simulation device comprises a spray pipe and two air guide strips, and the spray pipe comprises two panels and two side strips which are sequentially spliced and connected in a square shape; one side faces of the two air guide strips are fixed to the inner side plate face of one panel, the other side faces of the two air guide strips make contact with the inner side plate face of the other panel, the side faces, away from each other, of the two air guide strips make contact with the inner side faces of the two side strips, and a gap between the two air guide strips is a Laval type airflow channel. The side face, away from the other air guide strip, of one air guide strip is provided with an air guide groove penetrating through the bottom end. According to the invention, the Laval type airflow channel is defined in the pipe hole by using the two air guide strips, and then the liquid slit channel is defined by using the air guide groove in one air guide strip and the inner side surface of the opposite side strip, so that when liquid enters, a liquid film with a smaller thickness is formed firstly, and then the liquid film is further spread under the shearing action of airflow, and the liquid film is formed in the pipe hole. And the liquid film characteristics of the liquid engine during working are highly simulated.

Description

Technical Field

[0001] The invention relates to the technical field of liquid film simulation devices, in particular to a liquid engine inner wall liquid film visualization simulation device. Background Art

[0002] During the operation of a liquid engine, its non-steady-state characteristics cause the combustion to be in a chemically non-equilibrium state during the startup and shutdown process, resulting in incomplete combustion of the propellant and the production of some intermediate products. Some droplets cannot be completely evaporated and are ejected from the engine under the action of aerodynamic forces, forming liquid phase pollutants in the plume. Incompletely burned droplets accumulate on the inner wall of the engine to form a liquid film, which breaks up at the nozzle outlet and forms droplets. The lateral movement of these droplets to the nozzle is the only droplet that may move in the opposite direction of the engine jet.

[0003] The breakup mechanism of the liquid film directly affects the distribution, particle size, velocity direction and size of the initial droplets. These parameters constitute the initial conditions for studying the behavior of droplets in the plume field. Through the dynamic study of the liquid film breakup process, we can gain a deeper understanding of which factors play a major role in the initial droplet characteristics. At present, experimental research on liquid phase pollution mainly focuses on the distribution and deposition pollution effects of liquid phase pollution in the space environment, while there is less research on the process of liquid film breakup to form droplets at the nozzle outlet, and there is a lack of in-depth mechanistic research on the mechanism of liquid film breakup to produce droplets.

[0004] In similar research fields, a lot of visual experimental studies have been conducted on the entrainment of the liquid film surface by the annular flow of gas-liquid two-phases, and several basic forms of gas shearing effects on the liquid film have been observed, and the droplet formation process has been discussed in detail. Therefore, the purpose of the present invention is to design a system that can form a stable liquid film on the inner wall of the nozzle and realize visual optical diagnosis, which is divided into two parts: a liquid film forming device and a visible transparent nozzle, so as to fill the gap in existing research and provide an in-depth understanding of the liquid film breakup process and its droplet generation mechanism.

[0005] In actual liquid rocket engines, propellant can be injected into the inner wall of the thrust chamber in a variety of ways to form a liquid film. Propellant can be injected from the head of the thrust chamber or from the wall of the thrust chamber shell, usually by injecting tangentially along the wall through holes or slots, or by forming a liquid film by impacting the wall with a cooling jet. However, these injection methods are not suitable for the study of the liquid film breakup mechanism.

[0006] When the liquid film passes through the throat, a large number of tiny droplets will be generated due to the intense interaction between the airflow and the liquid film in the narrow space of the throat. These droplets may hit the liquid film flowing along the wall during the movement in the expansion section of the nozzle, thereby interfering with the flow state of the liquid film and affecting the breakup behavior of the liquid film at the nozzle outlet. In addition, due to the large number of liquid films and droplets in the throat, the gas-liquid interaction is strong and exhibits coupling characteristics, which will have a significant impact on the gas flow field at the throat position, causing the flow field to deviate from the design value.

[0007] This flow field deviation makes it impossible to accurately correspond the flow field parameters measured in the experiment to the parameters calculated by numerical simulation. Due to the inconsistency between the experimental and simulated flow fields, the parameters that are difficult to measure in the experiment cannot be directly used in the simulation calculation results, which in turn affects the comparative analysis between the experiment and the simulation, limiting the in-depth study of the liquid film breakup mechanism.

[0008] Therefore, how to design a visual simulation device that has a simple structure, is easy to assemble, and can more realistically simulate the inner wall film of a liquid engine is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0009] The invention provides a liquid engine inner wall liquid film visualization simulation device, which solves the technical problem that there is no liquid engine inner wall liquid film simulation device at present.

[0010] The technical solution of the present invention to solve the above technical problems is as follows: a liquid film visualization simulation device for the inner wall of a liquid engine, comprising: a nozzle and an air guide strip,

[0011] The nozzle comprises two panels and two side strips, the two panels and the two side strips are sequentially spliced ​​and connected in a "mouth" shape, and the gap between them is a tube hole, and the top of the tube hole is a gas inlet;

[0012] The two air guide strips are arranged opposite to each other and placed in the tube hole at an interval. One side of the two air guide strips is respectively fixed on the inner plate surface of one of the panels and the other side thereof is respectively in contact with the inner plate surface of the other panel. The sides of the two air guide strips away from each other are respectively in contact with the inner side surfaces of the two side strips. The gap between the two air guide strips is a Laval-type airflow channel. The side of one air guide strip away from the other air guide strip is provided with an air guide groove running through the bottom end. The air guide groove and the inner side surface of the opposite side strip define a liquid slit channel. The side strip corresponding to the liquid slit channel is provided with a liquid inlet connected to the liquid slit channel.

[0013] The beneficial effects of the present invention are:

[0014] 1. First, two gas guide strips are used to define a Laval-type airflow channel in the tube hole, and then the gas guide groove on one gas guide strip and the inner side of the opposite side strip are used to define a liquid slit channel. When the liquid enters the liquid slit channel through the liquid inlet, a liquid film with a smaller thickness is first formed, and then further spreads under the shearing action of the airflow, and the thickness is further reduced, which is close to the actual thickness of the wall liquid film when the actual attitude and orbit control engine is working, thereby highly simulating the liquid film characteristics in the operation of the liquid rocket engine. Through the optimized design, the thickness and morphology of the liquid film generated under laboratory conditions are closer to the liquid film characteristics in actual applications, which makes the experimental results more realistic reference value and can provide more reliable experimental data support for the design and optimization of liquid rocket engines.

[0015] 2. By optimizing the width, angle and liquid film formation conditions of the liquid slit channel, the liquid film can be stably generated under different experimental conditions, and the thickness and uniformity of the liquid film can be precisely controlled. This not only improves the stability and repeatability of the liquid film experiment, but also provides a more reliable experimental basis for subsequent research on the liquid film breakup and droplet generation process.

[0016] 3. The method of splicing and assembling liquid slit channels has significantly improved the processing accuracy and feasibility of extremely narrow channels, breaking through the technical barrier that traditional methods are difficult to process extremely small-sized channels, and can realize the manufacture of extremely narrow liquid channels without increasing the difficulty of processing.

[0017] Based on the above technical solution, the present invention can also be improved as follows.

[0018] Furthermore, the tube hole includes a first tube hole section at the top and a second tube hole section at the bottom, and the aperture of the second tube hole section increases from top to bottom; the two air guide strips are both located in the first tube hole section and divide the interior of the fixed hole section into an upper fixed hole section and a lower expansion hole section, and the liquid inlet is arranged opposite to the expansion hole section.

[0019] A further beneficial effect of the above method is that the liquid film enters the inner wall of the nozzle in the expansion hole section. In this way, the liquid film will not flow through the narrow area (throat) between the air guide strips and will not affect the flow field in the nozzle; at the same time, a large number of accompanying droplets will not be generated, and small droplets will not collide with the liquid film, resulting in the interference phenomenon of liquid phase entrainment.

[0020] Furthermore, a plurality of pressure measuring holes arranged at intervals are provided on the portion of the side strip corresponding to the second pipe hole section.

[0021] The above-mentioned further beneficial effect is as follows: a pressure measuring hole is set at the position of the side strip corresponding to the strain gauge section, and is connected to the tower-type pressure interface of the micro-differential pressure transmitter through a section of flexible hose as the pressure input end. The tower-type pressure interface at the other end of the micro-differential pressure transmitter is connected to the vacuum environment as the comparison end. By recording the pressure difference between the two ends, the pressure distribution on the wall of the nozzle expansion section can be accurately measured. This pressure measurement scheme realizes high-precision capture and real-time monitoring of the wall pressure by utilizing the high sensitivity of the micro-differential pressure transmitter and the stability of the vacuum environment. The acquired pressure data can be used to analyze the size and distribution of the surface shear force of the liquid film under the action of the central airflow, thereby evaluating the influence of the airflow on the spreading and flow stability of the liquid film. By combining the image observation of the liquid film flow and the quantitative measurement of the wall pressure, comprehensive experimental support and data basis are provided for the study of the coupling effect between the liquid film and the airflow.

[0022] Furthermore, the two panels, the two side strips and the two air guide strips are all made of transparent materials.

[0023] A further beneficial effect of the above is that the two panels, two side strips and two air guide strips are designed as transparent structures, which can realize dynamic visualization of the liquid film flow process and provide quantitative research technology for the liquid film formation process.

[0024] Furthermore, the two panels, the two side strips and the two air guide strips are all made of acrylic material.

[0025] Furthermore, it also includes a connecting flange, a connecting sleeve is fixed on the outer peripheral side of the connecting flange corresponding to the tube hole, the connecting sleeve is fixed on the two panels and the two side strips, and the inner hole of the connecting flange is connected to the liquid slit channel.

[0026] A further beneficial effect of the above method is that the Laval-type airflow channel is more easily connected to the external air source by using the connecting flange sleeve fixed to the two panels and the two side strips.

[0027] Furthermore, it also includes a sealing ring, and an annular groove is provided on the outer peripheral side of the connecting flange corresponding to the vent hole; the sealing ring is embedded in the annular groove.

[0028] A further beneficial effect of the above method is that the sealing performance between the Laval-type air flow channel and the external air source can be improved by embedding the sealing ring in the annular groove on the outer peripheral side of the air vent of the connecting flange.

[0029] Furthermore, a liquid inlet pipe communicating with the liquid inlet is integrally connected to the side strip corresponding to the liquid slit channel.

[0030] Furthermore, the longitudinal section of the air guide groove is a rectangular structure.

[0031] The further beneficial effects of adopting the above are: in order to optimize the conditions for liquid film formation, the angle between the liquid slit channel and the relative side strip is designed to be as small as possible, so that when the liquid enters the inner plate surface through the liquid slit channel, it is easier to change the direction of movement and flow along the expansion direction of the variable diameter section, reducing the fluctuation and instability of the liquid film flow; in order to further reduce the thickness of the liquid film, the width of the liquid slit channel can be further reduced, and the liquid spreads under the action of the airflow after flowing through the slit to form a thinner liquid film; however, the thickness of the liquid film formed after the airflow spreads may vary at different positions. In order to ensure the uniformity of the liquid film thickness, the present design adopts a rectangular channel cross-section. After the liquid flows into the liquid inlet and fills the liquid slit channel, a liquid film of uniform thickness can be formed. The width of the rectangular channel is designed to be smaller than the width of the tube hole, in order to avoid the liquid film from expanding along the circumferential direction to the front view surface of the tube hole, thereby avoiding adverse effects on the camera observation of the liquid film thickness. This design ensures the accuracy of optical observation and improves the reliability of experimental data. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the three-dimensional structure of a liquid film visualization simulation device for the inner wall of a liquid engine according to the present invention;

[0033] Figure 2 A schematic diagram of the internal structure of a device for visualizing the simulation of the inner wall liquid film of a liquid engine according to the present invention;

[0034] Figure 3 It is a schematic diagram of the three-dimensional structure of a flange in a liquid film visualization simulation device for the inner wall of a liquid engine according to the present invention;

[0035] Figure 4 It is a schematic diagram of the assembly structure of the panel and the air guide strip in a liquid engine inner wall liquid film visualization simulation device of the present invention;

[0036] Figure 5 This is a schematic diagram of the structure of a panel in a device for visualizing the simulation of the inner wall liquid film of a liquid engine according to the present invention;

[0037] Figure 6 It is a schematic diagram of the connection structure between the side strip and the liquid inlet pipe in a liquid engine inner wall liquid film visualization simulation device of the present invention;

[0038] Figure 7 The present invention is a schematic diagram of the structure of the side strips in a device for visualizing the simulation of the liquid film on the inner wall of a liquid engine.

[0039] In the accompanying drawings, the components represented by the reference numerals are listed as follows:

[0040] 1. Nozzle, 11. Panel, 12. Side strip, 121. Pressure measuring hole, 2. Air guide strip, 21. Air guide groove, 3. Connecting flange, 4. Connecting sleeve, 5. Sealing ring, 6. Liquid inlet pipe. DETAILED DESCRIPTION

[0041] The principles and features of the present invention are described below in conjunction with the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0042] like Figure 1 and Figure 2 As shown, a liquid film visualization simulation device for the inner wall of a liquid engine comprises: a nozzle 1 and an air guide strip 2,

[0043] The nozzle 1 includes two panels 11 and two side strips 12. The two panels 11 and the two side strips 12 are spliced ​​and connected in sequence in the shape of a "mouth" and the gap between them is a tube hole, and the top of the tube hole is a gas inlet; the two air guide strips 2 are arranged opposite to each other and are placed in the tube hole at an interval, one side of the two air guide strips 2 is respectively fixed on the inner plate surface of one panel 11 and the other side thereof is respectively in contact with the inner plate surface of the other panel 11, the sides of the two air guide strips 2 away from each other are respectively in contact with the inner side surfaces of the two side strips 12, and the gap between the two air guide strips 2 is a Laval type airflow channel, and the side of one air guide strip 2 away from the other air guide strip 2 is provided with an air guide groove 21 running through the bottom end, and the air guide groove 21 and the inner side surface of the opposite side strip 12 define a liquid slit channel, and the side strip 12 corresponding to the liquid slit channel is provided with a liquid inlet connected to the liquid slit channel.

[0044] like Figure 2 As shown, in some specific embodiments, the tube hole includes a first tube hole section at the top and a second tube hole section at the bottom, and the aperture of the second tube hole section increases from top to bottom; the two air guide strips 2 are both located in the first tube hole section and divide the interior of the fixed hole section into an upper fixed hole section and a lower expansion hole section, and the liquid inlet is arranged opposite to the expansion hole section.

[0045] like Figure 1 and Figure 2 As shown, in some specific embodiments, a plurality of pressure measuring holes 121 arranged at intervals are provided at the portion of the side strip 12 corresponding to the second pipe hole section.

[0046] Specifically, the two panels 11 , the two side strips 12 and the two air guide strips 2 are all made of transparent materials.

[0047] Specifically, the two panels 11 , the two side strips 12 and the two air guide strips 2 are all made of acrylic material.

[0048] like Figure 1 , Figure 2 and Figure 3 As shown, in some specific embodiments, a connecting flange 3 is further included, and a connecting sleeve 4 is fixed to the outer peripheral side of the connecting flange 3 corresponding to the pipe hole. The connecting sleeve 4 is fixed outside the two panels 11 and the two side strips 12, and the inner hole of the connecting flange 3 is connected to the liquid slit channel.

[0049] like Figure 1 , Figure 2 and Figure 3 As shown, in some specific embodiments, a sealing ring 5 may also be included, and an annular groove is provided on the outer peripheral side of the connecting flange 3 corresponding to the vent hole; the sealing ring 5 is embedded in the annular groove.

[0050] like Figure 1 , Figure 2 As shown, in some specific embodiments, a liquid inlet pipe 6 communicating with the liquid inlet is integrally connected to the side strip 12 corresponding to the liquid slit channel.

[0051] like Figure 4 As shown, in some specific embodiments, the longitudinal section of the air guide groove 21 can be a rectangular structure.

[0052] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for visualizing and simulating the liquid film on the inner wall of a liquid engine, characterized in that: include: A nozzle (1), the nozzle (1) comprising two panels (11) and two side strips (12), the two panels (11) and the two side strips (12) being spliced ​​and connected in sequence in a "mouth" shape, with the gap therebetween being a tube hole, and the top of the tube hole being a gas inlet; Air guide strips (2), the air guide strips (2) are arranged opposite to each other and are spaced apart in the tube hole, one side of the two air guide strips (2) is respectively fixed on the inner plate surface of one panel (11) and the other side thereof is respectively in contact with the inner plate surface of the other panel (11), the sides of the two air guide strips (2) away from each other are respectively in contact with the inner side surfaces of the two side strips (12), the gap between the two air guide strips (2) is a Laval type air flow channel, the side of one air guide strip (2) away from the other air guide strip (2) is provided with an air guide groove (21) passing through the bottom end, the air guide groove (21) and the inner side surface of the opposite side strip (12) define a liquid slit channel, and the side strip (12) corresponding to the liquid slit channel is provided with a liquid inlet connected to the liquid slit channel.

2. A liquid engine inner wall liquid film visualization simulation device according to claim 1, characterized in that: The tube hole comprises an upper first tube hole section and a lower second tube hole section, the aperture of the second tube hole section increases from top to bottom; the two air guide strips (2) are both located in the first tube hole section and divide the interior of the fixed tube hole section into an upper fixed hole section and a lower expansion hole section, and the liquid inlet is arranged opposite to the expansion hole section.

3. A device for visualizing and simulating the inner wall liquid film of a liquid engine according to claim 2, characterized in that: A plurality of pressure measuring holes (121) arranged at intervals are provided on the portion of the side strip (12) corresponding to the second pipe hole section.

4. The device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 1, characterized in that: The two panels (11), the two side strips (12) and the two air guide strips (2) are all made of transparent materials.

5. The device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 1, characterized in that: The two panels (11), the two side strips (12) and the two air guide strips (2) are all made of acrylic material.

6. The device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 1, characterized in that: It also includes a connecting flange (3), a connecting sleeve (4) is fixed on the outer peripheral side of the connecting flange (3) corresponding to the pipe hole, the connecting sleeve (4) is fixed on the outside of the two panels (11) and the two side strips (12), and the inner hole of the connecting flange (3) is connected to the liquid slit channel.

7. A device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 6, characterized in that: It also includes a sealing ring (5); an annular groove is provided on the outer peripheral side of the connecting flange (3) corresponding to the vent hole; and the sealing ring (5) is embedded in the annular groove.

8. The device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 1, characterized in that: A liquid inlet pipe (6) communicating with the liquid inlet is integrally connected to the side strip (12) corresponding to the liquid slit channel.

9. The device for visualizing and simulating the liquid film on the inner wall of a liquid engine according to claim 1, characterized in that: The longitudinal section of the air guide groove (21) is a rectangular structure.

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