Liquid engine inner wall liquid film forming and visual diagnosis system

Abstract

The invention belongs to the technical field of liquid engines, and discloses a liquid engine inner wall liquid film forming and visual diagnosis system which comprises a multifunctional spray pipe support and a calibration device, a liquid film forming device is arranged at the top of the multifunctional spray pipe support, and a visual spray pipe is arranged at the bottom of the liquid film forming device. According to the technical scheme, the liquid film forming device, the visual spray pipe and the multifunctional spray pipe support are arranged, when the liquid film forming device, the visual spray pipe and the multifunctional spray pipe support are used in a whole and matched mode, liquid film generation can be achieved, optical diagnosis can be conducted on the generated liquid film, and therefore a set of complete experimental research method is formed; an effective analysis means can be provided for a breaking mechanism of the liquid film in a high-temperature and high-speed airflow environment, the research blank is filled up, so that the understanding of breaking of the liquid film and generation of liquid drops is improved, and the initial flowing parameters of the liquid film can be accurately controlled and instability and experimental errors can be reduced through a method for forming the liquid film by impacting the wall surface through jet flow.

Description

Technical Field

[0001] The invention relates to the technical field of liquid engines, in particular to a liquid film formation and visualization diagnosis system for the inner wall of a liquid engine. Background Art

[0002] During the operation of the liquid engine, its non-steady-state characteristics make the combustion 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. A portion of the droplets cannot be completely evaporated and are ejected from the engine under the action of aerodynamic forces, forming liquid pollutants in the plume. The 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 toward 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 deeply understand which factors play a major role in the characteristics of the initial droplets. 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, many visual experimental studies have been conducted on the entrainment of the liquid film surface by gas-liquid two-phase annular flow. Several basic forms of gas shearing effects on the liquid film have been observed, and the droplet formation process has been discussed in detail.

[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. The propellant can be injected from the head of the thrust chamber or from the wall of the body of the thrust chamber. It is usually injected tangentially along the wall through holes and slots, or by a cooling jet hitting the wall to form a liquid film. The propellant can also penetrate through the porous medium wall to form a liquid film. For some small engines, no special coolant injection channel is set, but liquid film cooling is achieved by droplet sedimentation. This patent analyzes the above-mentioned multiple filling methods during the design process, and selects one of the types to simulate its filling form to design a liquid film forming device. For wall injection liquid film filling, due to the difference in the liquid film forming device and the visual nozzle material, it needs to be divided into two workpieces for processing. If the wall injection method is adopted, there will be wall discontinuity at the connection between the liquid film forming device and the visualization nozzle. The sudden change of the wall will cause the flow disturbance when the liquid film flows through this place, increasing the instability of the liquid film flow. The instability of the liquid film flow is the main influencing factor of its breakup to form droplets. Therefore, this method may cause the droplet generation state to deviate from the actual situation. For the formation of liquid film by droplet sedimentation, this method will cause a large number of tiny droplets in the flow field in the nozzle. These tiny droplets will collide with the liquid film, aggravate the liquid phase entrainment phenomenon on the surface of the liquid film, increase the influencing factors of the liquid film flow, and is not conducive to independent research on the influence of other factors on the liquid film. In addition, this method has low efficiency in generating liquid film and it is difficult to accurately control the initial flow parameters of the liquid film.

[0006] 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. The system is divided into two parts: a liquid film forming device and a visible transparent nozzle, so as to fill the gaps in existing research and provide an in-depth understanding of the liquid film breakup process and its droplet generation mechanism. Summary of the invention

[0007] The purpose of the present invention is to provide a liquid film formation and visualization diagnosis system for the inner wall of a liquid engine, comprising a multifunctional nozzle bracket and a calibration device, wherein a liquid film forming device is arranged on the top of the multifunctional nozzle bracket, and a visualization nozzle is arranged on the bottom of the liquid film forming device.

[0008] Preferably, the multifunctional nozzle bracket includes a supporting assembly platform, and a mounting bearing platform is provided on one side of the top of the supporting assembly platform.

[0009] Preferably, the liquid film forming device comprises a connecting platform, and the connecting platform is fixedly mounted on the top of the mounting platform.

[0010] Preferably, an annular seam channel outer cavity is provided on the top of the connecting platform, and an annular seam channel inner cavity is provided on the top of the annular seam channel outer cavity.

[0011] Preferably, a gas filling port is provided at the top of the inner cavity of the annular seam channel, and liquid filling ports are fixedly connected to both sides of the outer cavity of the annular seam channel.

[0012] Preferably, a liquid collecting chamber is provided inside the liquid filling port, and the liquid collecting chamber adopts a cylindrical design. Preferably, the visualization nozzle includes a connecting flange ring block, the connecting flange ring block is arranged at the bottom of the connecting platform, a sealing rubber ring is arranged on the top of the connecting flange ring block, and the bottom of the connecting flange ring block is fixedly connected to a Laval nozzle.

[0013] Preferably, the Laval nozzle is made of plexiglass.

[0014] Preferably, optical slits are provided on both sides of the bottom of the supporting assembly platform.

[0015] Preferably, the calibration device comprises a nozzle external calibration surface and a nozzle internal calibration surface, and the nozzle external calibration surface and the nozzle internal calibration surface are respectively arranged on the outside and inside of the Laval nozzle.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The above technical scheme arranges a liquid film forming device, a visualization nozzle and a multifunctional nozzle holder. When the liquid film forming device, the visualization nozzle and the multifunctional nozzle holder are used in combination as a whole, liquid film generation can be achieved, and optical diagnosis of the generated liquid film can be performed, thereby forming a complete set of experimental research methods. It can provide an effective analytical means for the breakup mechanism of liquid film in a high-temperature, high-speed airflow environment, fill the research gap, and thus improve the understanding of liquid film breakage and droplet generation.

[0018] The method of forming a liquid film by jet impacting a wall surface can accurately control the initial flow parameters of the liquid film and reduce instability and experimental errors.

[0019] The present invention provides a Laval nozzle, and since the Laval nozzle uses organic glass as a visualization material, it not only ensures sufficient transparency but also satisfies the processing performance and precision requirements well. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 It is a cross-sectional structural schematic diagram of the present invention;

[0022] Figure 3 It is a structural schematic diagram of the liquid film forming device of the present invention;

[0023] Figure 4It is a cross-sectional structural schematic diagram of the liquid film forming device of the present invention;

[0024] Figure 5 It is a structural schematic diagram of the visualization nozzle of the present invention;

[0025] Figure 6 It is a structural schematic diagram of the multifunctional nozzle support of the present invention;

[0026] Figure 7 It is a schematic diagram of the structure of the calibration device of the present invention.

[0027] In the figure: 1. liquid film forming device; 101. inner cavity of annular seam channel; 102. outer cavity of annular seam channel; 103. liquid filling port; 104. gas filling port; 105. connecting platform; 2. visualization nozzle; 201. Laval nozzle; 202. connecting flange ring block; 203. sealing rubber ring; 3. multifunctional nozzle bracket; 301. mounting platform; 302. supporting assembly platform; 303. optical slit; 401. external calibration surface of nozzle; 402. internal calibration surface of nozzle. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] like Figures 1 to 7 As shown, the present invention provides a liquid film formation and visualization diagnosis system for the inner wall of a liquid engine, including a multifunctional nozzle bracket 3 and a calibration device, wherein a liquid film forming device 1 is arranged on the top of the multifunctional nozzle bracket 3, and a visualization nozzle 2 is arranged on the bottom of the liquid film forming device 1.

[0030] Through the design of the multifunctional nozzle bracket 3, the visualization nozzle 2 and the liquid film forming device 1 can be installed and fixed as a whole on the corresponding laboratory frame, and alcohol and nitrogen can be added to the liquid film forming device 1 at the same time, and then enter the inner wall of the visualization nozzle 2 to form a complete liquid film. At this time, the optical diagnostic technology combining laser and high-speed camera can be used to observe and analyze the formation, flow and breakup process of the liquid film in detail.

[0031] like Figure 6 As shown, the multifunctional nozzle bracket 3 includes a supporting assembly platform 302 , and a mounting bearing platform 301 is arranged on one side of the top of the supporting assembly platform 302 .

[0032] By adopting the above solution, by providing the supporting assembly platform 302, when the entire device is being installed, the supporting assembly platform 302 can be connected to the laboratory frame as a whole, thereby ensuring the stability of the position of the entire device.

[0033] like Figure 1 and Figure 3 As shown, the liquid film forming device 1 includes a connecting platform 105 , and the connecting platform 105 is fixedly installed on the top of the mounting and carrying platform 301 .

[0034] With the above solution, when the entire liquid film forming device 1 needs to be installed on the top of the multifunctional nozzle bracket 3, the connecting platform 105 can be fixedly connected to the top of the mounting platform 301 by bolts. Figure 3 As shown, an annular seam channel outer cavity 102 is disposed on the top of the connecting platform 105 , and an annular seam channel inner cavity 101 is disposed on the top of the annular seam channel outer cavity 102 .

[0035] like Figure 3 As shown, a gas filling port 104 is provided at the top of the inner cavity 101 of the annular seam channel, and liquid filling ports 103 are fixedly connected to both sides of the outer cavity 102 of the annular seam channel.

[0036] The above scheme is adopted: by providing an annular gap channel inner cavity 101 and annular gap channel outer cavity 102, when alcohol and nitrogen enter the narrow channel formed in the annular gap channel inner cavity 101 and the annular gap channel outer cavity 102 through the liquid filling port 103 and the gas filling port 104 on both sides respectively, and flow into the visualization nozzle 2, an oblique impact jet is formed, and a liquid film is formed. At this time, in order to ensure the uniformity and stability of the liquid film, the annular gaps of the liquid filling port 103 and the gas filling port 104 need to be small enough so that the liquid can completely fill the annular gap at the minimum design flow rate. At the same time, under the condition of the maximum design flow rate, the annular gap should not be too small to avoid excessive liquid flow rate, resulting in excessive instability when the jet hits the wall. The width of the annular gap also determines the thickness of the initial liquid film.

[0037] like Figure 3 and Figure 4 As shown, a liquid collecting chamber is provided inside the liquid filling port 103, and the liquid collecting chamber adopts a cylindrical design.

[0038] The above solution is adopted: by providing a liquid filling port 103 and a liquid collecting cavity, the equivalent area in the liquid filling port 103 on both sides should not be less than the area of ​​the annular gap, so as to ensure that the annular gap can be quickly filled, and the pipeline design should avoid a diameter that is too small to reduce the influence of the capillary effect. The narrow size of the capillary tube will increase the viscous resistance of the fluid, resulting in a higher pressure drop, thereby reducing the flow rate;

[0039] The design of the liquid collecting chamber can serve as a buffer zone to absorb instantaneous changes in flow rate and reduce fluctuations in liquid flow rate in the flow system, thereby ensuring the stability of liquid film formation. At the same time, the size of the liquid collecting chamber should match the flow demand of the system. The capacity of the liquid collecting chamber is determined based on the maximum flow rate and expected flow fluctuations. In addition, since the liquid collecting chamber is designed to be cylindrical, compared with the rectangular liquid collecting chamber, the cylindrical structure performs better in stress distribution, can better withstand internal pressure, and facilitates smooth flow of liquid, reducing dead corners and stagnation areas. Compared with the spherical liquid collecting chamber, the cylindrical liquid collecting chamber has a lower manufacturing complexity.

[0040] like Figure 1 and Figure 5 As shown, the visualization nozzle 2 includes a connecting flange ring block 202, which is arranged at the bottom of the connecting platform 105, a sealing rubber ring 203 is arranged on the top of the connecting flange ring block 202, and the bottom of the connecting flange ring block 202 is fixedly connected to the Laval nozzle 201.

[0041] The above scheme is adopted: by providing a connecting flange ring block 202, the connecting flange ring block 202 can be matched with the mounting holes of the connecting platform 105 by bolts, and the connecting flange ring block 202 can be fastened and installed on the bottom of the connecting platform 105. Through the design of the sealing rubber ring 203, a reliable sealing effect can be provided between the Laval nozzle 201 and the inner cavity 101 of the annular seam channel and the outer cavity 102 of the annular seam channel, thereby avoiding leakage of liquid and gas during the experiment.

[0042] like Figure 5 As shown, the Laval nozzle 201 is made of organic glass.

[0043] The above solution is adopted: due to the characteristics of organic glass, the Laval nozzle 201 can have sufficient transparency while meeting the accuracy requirements of the throat and other key parts, thereby realizing accurate observation and research on the liquid film generation and its breakup process.

[0044] like Figure 6 As shown, optical slits 303 are provided on both sides of the bottom of the supporting assembly platform 302 .

[0045] The above scheme is adopted: by providing an optical slit 303, the optical slit 303 is a slit with a side groove width of 1 to 2 mm, and its main function is to control the thickness of the sheet light. Because the sheet light has a certain thickness, when it is irradiated to the wall of the conical nozzle, the incident direction is not completely perpendicular to the wall, and part of the laser will be reflected by the wall and emitted to the camera, resulting in interference light in the image. The optical slit 303 can control the light sheet to coincide with the center position of the Laval nozzle 201 to ensure the integrity of the image.

[0046] like Figure 7As shown, the calibration device includes a nozzle external calibration surface 401 and a nozzle internal calibration surface 402 , and the nozzle external calibration surface 401 and the nozzle internal calibration surface 402 are respectively arranged on the outside and inside of the Laval nozzle 201 .

[0047] The above scheme is adopted: through the design of the nozzle external calibration surface 401 and the nozzle internal calibration surface 402, it can be ensured that the camera can focus clearly and obtain high-quality experimental images before the experiment. The calibration area covers the outside and inside of the Laval nozzle 201. It is particularly important to note that the image inside the Laval nozzle 201 will be distorted due to passing through the conical surface. Image correction is required after shooting to ensure a clear image without distortion.

[0048] The working principle and use process of the present invention:

[0049] First, the connecting platform 105 can be installed and connected to the mounting platform 301 by bolts, and then the supporting assembly platform 302 can be connected to the laboratory frame. Finally, the connecting flange ring block 202 can be connected and installed corresponding to the mounting holes on the connecting platform 105 by bolts, and then the positions of the nozzle external calibration surface 401 and the nozzle internal calibration surface 402 can be calibrated respectively to ensure that the subsequent use of the camera can focus clearly to obtain high-quality experimental images. At this time, in order to eliminate interference light in the image, the laser plane can be completely overlapped with the center position of the Laval nozzle 201 through the optical slit 303.

[0050] When entering the experiment, the gas filling port 104 of the liquid film forming device 1 is connected to the gas supply bellows through a ball joint, and then connected to the nitrogen source outside the cabin through the vacuum cabin flange, and then the gas path parameters can be controlled by the pressure reducing valve and the flow controller.

[0051] Afterwards, the alcohol to be added can be added into the liquid filling ports 103 on both sides of the annular seam channel inner cavity 101, and the liquid collecting cavity in the liquid filling port 103 can be completely filled. At this time, the liquid filling port 103 can play a buffering role for the alcohol. At the same time, nitrogen can be introduced into the annular seam channel inner cavity 101 through the gas filling port 104, and then the alcohol in the liquid filling ports 103 on both sides and the nitrogen in the gas filling port 104 are discharged through the annular seam channel inner cavity 101 and the annular seam channel outer cavity 102 at the same time.

[0052] Subsequently, the discharged alcohol and nitrogen mixture will flow out through the Laval nozzle 201 to form an oblique impact jet. After the jet hits the wall, a liquid film is formed on the inner wall of the Laval nozzle 201. At this time, the Laval nozzle 201 has a certain transparency, and a camera can be used to accurately capture the process of liquid film formation and subsequent breakup, thereby obtaining high-quality and clear images.

Claims

1. Liquid film formation and visualization diagnosis system for the inner wall of liquid engine, characterized in that: It comprises a multifunctional nozzle support (3) and a calibration device, wherein a liquid film forming device (1) is arranged on the top of the multifunctional nozzle support (3), and a visual nozzle (2) is arranged on the bottom of the liquid film forming device (1).

2. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 1, characterized in that: The multifunctional nozzle support (3) comprises a supporting assembly platform (302), and a mounting bearing platform (301) is arranged on one side of the top of the supporting assembly platform (302).

3. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 1, characterized in that: The liquid film forming device (1) comprises a connecting platform (105), and the connecting platform (105) is fixedly mounted on the top of the mounting support platform (301).

4. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 3, characterized in that: An annular seam channel outer cavity (102) is provided on the top of the connection platform (105), and an annular seam channel inner cavity (101) is provided on the top of the annular seam channel outer cavity (102).

5. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 4, characterized in that: A gas filling port (104) is provided at the top of the inner cavity (101) of the annular seam channel, and liquid filling ports (103) are fixedly connected at both sides of the outer cavity (102) of the annular seam channel.

6. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 5, characterized in that: The liquid filling port (103) is provided with a liquid collecting chamber inside, and the liquid collecting chamber is cylindrical in design.

7. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 2, characterized in that: The visualization nozzle (2) comprises a connecting flange ring block (202), wherein the connecting flange ring block (202) is arranged at the bottom of the connecting platform (105), a sealing rubber ring (203) is arranged at the top of the connecting flange ring block (202), and the bottom of the connecting flange ring block (202) is fixedly connected to the Laval nozzle (201).

8. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 7, characterized in that: The Laval nozzle (201) is made of organic glass.

9. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 2, characterized in that: Optical slits (303) are arranged on both sides of the bottom of the supporting assembly platform (302).

10. The liquid film formation and visualization diagnosis system for the inner wall of a liquid engine according to claim 1, characterized in that: The calibration device comprises a nozzle external calibration surface (401) and a nozzle internal calibration surface (402), wherein the nozzle external calibration surface (401) and the nozzle internal calibration surface (402) are respectively arranged outside and inside the Laval nozzle (201).

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