Ventilation bubble internal and external flow field synchronous measurement experiment system

Abstract

The invention provides a ventilation bubble internal and external flow field synchronous measurement experiment system, and belongs to the technical field of flow field measurement experiments. The problem that the scattering effect is poor due to the fact that solid tracer particles are agglomerated in air and cannot be scattered is solved. The device comprises a circulating water tank which is connected with a fluid circulating assembly, the fluid circulating assembly is used for driving fluid in the circulating water tank to move directionally, and liquid-phase fluorescent particles with a certain concentration are arranged in the fluid carried by the circulating water tank; an opening is formed in the end surface of the structural body in a penetrating manner; the outlet end of the gas chamber is communicated with the opening of the structural body, the inlet end of the gas chamber is communicated with the particle treatment device, and the particle treatment device is used for releasing gas-phase fluorescent particles with preset concentration and preset speed into the gas chamber; the laser system is used for irradiating upper and lower areas of a fluid interface; a high-speed image pickup system; and a particle dispersing device for mixing gas-phase fluorescent particles with gas flow in advance is arranged in the particle processing device. The device is mainly used for bubble internal and external flow field measurement.

Description

Technical Field

[0001] The invention belongs to the technical field of flow field measurement experiments, and in particular relates to a synchronous measurement experimental system for flow fields inside and outside a ventilation bubble. Background Art

[0002] Ventilated two-phase flows are common in marine engineering applications, such as hydraulic machinery, large ships, and underwater vehicles. By modifying the flow field environment on the structure's surface, they achieve objectives such as drag reduction, enhanced motion stability, and load reduction. Understanding the evolution of the flow field within the ventilation bubble and the coupling between the internal and external flow fields is crucial for artificially manipulating the bubble's internal flow field, controlling the ventilation effect, and improving drag reduction, stability enhancement, and load reduction efficiency. Capturing and measuring the structure and characteristics of the two-phase flow field inside and outside the ventilation bubble is essential for exploring the evolution of the ventilation bubble and revealing the coupling mechanism between the internal and external flow fields. Traditional particle image velocimetry (PIV) can be used to measure the liquid flow field outside the bubble. However, solid tracer particles often aggregate in air due to intermolecular forces, making them difficult to disperse evenly. Continuously, evenly, and controllably distributing tracer particles into the bubble interior while effectively eliminating strong reflections from the bubble interface and capturing the gas flow field inside the bubble is key to achieving simultaneous measurement of the gas-liquid two-phase flow field inside and outside the ventilation bubble.

[0003] Patent Publication No. CN1654962A discloses a method and device for digital particle image velocimetry of two-phase flow. This device separates tracer particles in the liquid phase from moving bubbles, enabling the measurement of the velocity of the two-phase flow. However, this device can only measure the external flow field of multiphase flow and cannot measure the flow field inside the bubbles. Patent Publication No. CN107703325A discloses a tracer particle seeding device and operating method for PIV measurement of two-phase flow fields. This device can effectively seed tracer particles into the gas and liquid simultaneously, but its structure determines its main application in flows with stratified gas-liquid interfaces, and the particle concentration in the gas phase cannot be continuously seeded and adjusted. Patent Publication No. CN104729827A discloses a device for observing the evolution of ventilation cavitation flow fields. This device pre-deploys tracer particles in the ventilation annulus of the vehicle shoulder to measure the flow field inside the ventilation bubbles. However, this device also cannot achieve continuous seeding of particles within the ventilation bubbles or manual adjustment of the concentration. Moreover, the device eliminates the influence of reflected light by spraying fluorescent paint on the surface of the navigation body, which is costly and not convenient. It will also change the surface roughness of the model and affect the test results.

[0004] Therefore, in order to achieve the synchronous measurement of the flow field inside and outside the ventilation bubble and promote the development of multiphase flow field testing technology, it is necessary to develop a low-cost, convenient and efficient test method for synchronous measurement of the flow field inside and outside the ventilation bubble, which can perform continuous seeding and concentration adjustment of gas phase tracer particles. Summary of the Invention

[0005] In view of this, the present invention aims to propose an experimental system for synchronously measuring the flow field inside and outside a ventilation bubble, so as to solve the problem that solid tracer particles agglomerate in the air and cannot disperse, resulting in poor spreading effect.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: an experimental system for synchronously measuring the internal and external flow fields of a ventilation bubble, comprising:

[0007] A circulating water tank connected to a fluid circulation assembly, wherein the fluid circulation assembly is used to drive the directional movement of the fluid in the circulating water tank, and a certain concentration of liquid-phase fluorescent particles is set in the fluid carried by the circulating water tank;

[0008] The structure is arranged in the circulating water tank and immersed a certain distance below the liquid surface of the fluid, and an opening is provided through the end surface;

[0009] an air chamber, wherein the outlet end is in communication with the opening of the structure, and the inlet end is in communication with a particle processing device, wherein the particle processing device is used to release gas-phase fluorescent particles of a predetermined concentration and a predetermined speed into the air chamber;

[0010] A laser system for irradiating the upper and lower areas of the fluid interface;

[0011] High-speed camera system, used to capture the upper and lower areas of the fluid interface and eliminate reflections from the wall and bubble surface;

[0012] Wherein, the particle processing device is provided with a particle dispersing device for pre-mixing the gas phase fluorescent particles with the air flow.

[0013] Furthermore, the particle processing device also includes a ventilation component, which includes an air compressor. The air compressor is connected to the inlet end of the particle dispersion device through a pipeline, and a pressure reducing valve, a throttle valve, a solenoid valve and a gas flow meter are provided on the pipeline.

[0014] Furthermore, the particle dispersion device includes an outer shell and a gas shearing portion, the outer shell is provided with an air inlet and an air outlet, the gas shearing portion is arranged between the air inlet and the air outlet and divides the outer shell into a gas buffer chamber and a mixing chamber, a certain concentration of gas-phase fluorescent particles is arranged in the mixing chamber, and the gas buffer chamber is used to diffuse the gas entering the air inlet and then shear it through the gas shearing portion and enter the mixing chamber to couple with the gas-phase fluorescent particles.

[0015] Furthermore, the shell is cylindrical.

[0016] Furthermore, the particle dispersion device also includes a gas bypass, one end of which is connected to a flow control part provided at the air inlet, and the other end is connected to the air outlet of the shell. The flow control part is used to control the connection and disconnection between the air inlet and the gas bypass and the flow rate and speed of the gas entering the gas bypass.

[0017] Furthermore, the gas shearing portion is in a plate shape, and evenly distributed through holes are provided on the plate surface.

[0018] Furthermore, the laser system includes a laser generator, a light guide arm and an optical lens connected in sequence, and the optical lens is used to project a sheet-like light curtain on the target area.

[0019] Furthermore, the high-speed camera system includes a high-speed camera, a filter and a computer. The high-speed camera is connected to the computer, and the filter is set on the camera head of the high-speed camera.

[0020] Furthermore, a Pitot tube is provided downstream of the circulating water tank.

[0021] Furthermore, the structure is a plate-shaped transparent acrylic plate.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] 1. This system is equipped with a particle dispersion device to mix solid particles in advance before spreading, which can avoid solid particle agglomeration and ensure the uniformity of the spread particles.

[0024] 2. This system sets the gas shearing part into a plate shape with evenly distributed through holes on the plate surface, so that the particles can be fully sheared and dispersed and fully mixed with the gas after the gas flows through, so that the particles are evenly suspended in the gas for a long time, and continuous and uniform tracer particle sowing can be achieved inside the ventilation bubble; thanks to the effective dispersion and full mixing of particles by the particle dispersion device, solid particle agglomeration is avoided, and the particle consumption in non-experimental processes is effectively reduced; by spreading a proper amount of tracer particles on the upper surface of the gas shearing part, continuous particle sowing for a long time can be achieved; it is convenient and efficient, not only economical, but also convenient for continuous testing or debugging for a long time.

[0025] 3. By providing a gas bypass and flow control unit, this system can adjust the amount of gas entering the housing through both the main and bypass routes, thereby adjusting the particle concentration within the bubbles. This regulation method presupposes that the particles and gas are fully mixed within the housing through turbulent gas flow, and that continuous shearing prevents particle aggregation. When the concentration is uniform, the output gas concentration can be adjusted by adjusting the main and bypass flow rates. The two work together to ensure a controllable and adjustable concentration.

[0026] 4. This system adopts a fluorescent particle gas-liquid two-phase dual-tracing scheme, combined with a filter and a high-speed camera system, which can effectively eliminate the strong reflection interference from the gas-liquid interface and the wall of the structure, and realize the synchronous capture of the dynamic evolution of the flow field inside and outside the bubble.

[0027] 5. This system can be used to achieve the synchronous capture of the internal and external flow field structures of the ventilation bubble two-phase flow. It is suitable for the synchronous capture of the ventilation two-phase flow of simple structures such as flat wall surfaces and marine engineering structures such as ships, underwater vehicles, and hydraulic machinery. It has broad application prospects and high practical engineering significance. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings, which constitute part of the present invention, are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0029] Figure 1 This is a schematic structural diagram of an experimental system for synchronously measuring the internal and external flow fields of a ventilation bubble according to the present invention;

[0030] Figure 2 is a front view of the particle dispersion device of the present invention;

[0031] Figure 3 2 is a cross-sectional view of the particle dispersion device according to the present invention.

[0032] Circulating water tank 1; fluid circulation component 2; structure 3; air chamber 4; air compressor 5; pressure reducing valve 6; throttle valve 7; solenoid valve 8; gas flow meter 9; particle dispersion device 10; housing 10-1; gas bypass 10-2; gas shearing part 10-3; three-way valve 10-4; three-way pipeline 10-5; hose 11; laser generator 12; light guide arm 13; optical lens 14; sheet light curtain 15; high-speed camera 16; filter 17; computer 18; liquid-phase fluorescent particles 19; gas-phase fluorescent particles 20; Pitot tube 21. DETAILED DESCRIPTION

[0033] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features therein can be combined with each other in the absence of conflict, and the embodiments described are only part of the embodiments of the present invention, not all of the embodiments.

[0034] It should be noted that the descriptions of the present invention regarding directions such as "left", "right", "left side", "right side", "upper", "lower", "top", and "bottom" are all defined based on the relationship between the orientations or positions shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the structure described must be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on the present invention. In the description of the present invention, the meaning of "plurality" is more than two, unless otherwise clearly and specifically defined.

[0035] In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed connections, detachable connections, or integral connections; they may refer to direct connections, indirect connections through an intermediary, or internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0036] Referring to the accompanying drawings, this embodiment is described, which is a ventilation bubble internal and external flow field synchronous measurement experimental system, characterized by comprising:

[0037] A circulating water tank 1 is connected to a fluid circulation component 2, wherein the fluid circulation component 2 is used to drive the directional movement of the fluid in the circulating water tank 1. A certain concentration of liquid-phase fluorescent particles 19 is set in the fluid carried by the circulating water tank 1;

[0038] Specifically, the fluid is water, and the concentration of liquid-phase fluorescent particles 19 can be appropriately set based on actual conditions. To achieve directional flow of water within the circulating water tank 1, a fluid circulation assembly 2 is built into the lower layer of the circulating water tank 1. The fluid circulation assembly 2 is specifically configured as a circulating water pump to provide constant flow. Liquid-phase fluorescent particles 19 are pre-seeded in the circulating water to measure the liquid flow field. A Pitot tube 21 is installed downstream of the circulating water tank 1 to measure flow rate, forming a closed loop of feedback regulation to ensure controllable water flow rate.

[0039] Structure 3 is placed within circulating water tank 1 and submerged a certain distance below the fluid surface. It has an opening extending through its end surface. Structure 3 is specifically a plate-shaped transparent acrylic sheet, located in the middle of the entire length of circulating water tank 1. Specifically, it is arranged parallel to the water surface and a certain distance below the surface. The opening is circular and extends through the sheet, allowing gas to flow out and form ventilation bubbles. Structure 3 can also be made of other materials and shapes, depending on the desired experiment.

[0040] The gas chamber 4 has an outlet end connected to the opening of the structure 3 and an inlet end connected to a particle processing device, which is used to release gas-phase fluorescent particles 20 of predetermined concentration and predetermined speed into the gas chamber 4; the gas-phase fluorescent particles 20 are used to capture the gas flow form in the cavitation.

[0041] A laser system for irradiating the upper and lower areas of the fluid interface;

[0042] High-speed camera system, used to capture the upper and lower areas of the fluid interface and eliminate reflections from the wall and bubble surface;

[0043] The particle processing device is provided with a particle dispersing device 10 for pre-mixing the gas phase fluorescent particles 20 with the air flow.

[0044] In this embodiment, the particle processing device also includes a ventilation component, which includes an air compressor 5. The air compressor 5 is connected to the inlet end of the particle dispersion device 10 through a pipeline. The pipeline is provided with a pressure reducing valve 6, a throttle valve 7, a solenoid valve 8 and a gas flow meter 9. The pipeline is specifically a hose 11. The gas is stored by the air compressor 5. The pressure reducing valve 6 ensures a stable output pressure, and the throttle valve 7 adjusts the gas flow in the pipeline. The solenoid valve 8 quickly controls the on-off of the gas circuit, and the gas flow meter 9 monitors the gas flow rate in real time. Due to the high precision of the solenoid valve 8 and the gas flow meter 9, the accuracy and repeatability of the test are guaranteed.

[0045] In this embodiment, the particle dispersion device 10 includes a shell 10-1 and a gas shearing portion 10-3. The shell 10-1 is provided with an air inlet and an air outlet. The gas shearing portion 10-3 is arranged between the air inlet and the air outlet and divides the shell 10-1 into a gas buffer chamber and a mixing chamber. A certain concentration of gas-phase fluorescent particles 20 is arranged in the mixing chamber. The gas buffer chamber is used to diffuse the gas entering the air inlet and then shear it through the gas shearing portion 10-3 and then enter the mixing chamber to couple with the gas-phase fluorescent particles 20.

[0046] In this embodiment, the housing 10 - 1 is cylindrical.

[0047] In this embodiment, the particle dispersion device 10 further includes a gas bypass 10-2, one end of which is connected to a flow control unit located at the air inlet and the other end to the air outlet of the housing 10-1. The flow control unit is used to control the connection between the air inlet and the gas bypass 10-2, as well as the flow rate and velocity of the gas entering the gas bypass 10-2. The flow control unit is specifically a three-way valve 10-4. A three-way pipe 10-5 is provided to connect the air inlet and outlet of the particle dispersion device 10. The gas-phase fluorescent particles 20 pre-arranged therein are dispersed by the turbulent shearing action of the gas and then move synchronously with the gas to form a particle-containing mixed gas. The gas inflow channel is controlled by the three-way valve 10-4, and the main and bypass gases are mixed at the outlet channel three-way pipe 10-5. The flow rates of the main and bypass channels are controlled by the air inlet valve to adjust the particle concentration in the gas. On the one hand, by setting up the three-way valve 10-4 and the gas bypass 10-2, the concentration of the gas-phase fluorescent particles 20 in the output gas can be controlled. At the same time, thanks to the shearing effect of the gas shearing part 10-3 and the gas suspension effect in the outer shell 10-1, the gas-phase fluorescent particles 20 in the gas in the mixing chamber are mixed evenly and have a uniform concentration. At this time, by controlling the gas flow rate of the gas bypass 10-2 and the main flow path, the concentration of the gas-phase fluorescent particles 20 in the output gas can be fully controlled, so as to ensure that the sustainable observability, stability and economy of the dynamic evolution of the flow field inside and outside the bubble are highly unified.

[0048] In this embodiment, the gas shearing section 10-3 is specifically configured in a plate-like shape with evenly distributed through-holes. The gas-phase fluorescent particles 20 are placed in the gas shearing section 10-3 of the particle dispersion device 10. Due to the turbulent shearing of the incoming gas, they are fully dispersed and mixed with the gas. They are then uniformly introduced into the aforementioned gas chamber 4 along with the incoming gas. The ventilation system allows for rapid on / off switching of the stored gas, ensuring high test accuracy and efficiency.

[0049] In this embodiment, the laser system includes a laser generator 12, a light guide arm 13, and an optical lens 14 connected in sequence. The optical lens 14 is used to project a sheet light curtain 15 on the target area. The sheet light curtain 15 illuminates the test section flow field to provide a background light source.

[0050] In this embodiment, the high-speed camera system includes a high-speed camera 16, a filter 17, and a computer 18. The high-speed camera 16 is connected to the computer 18, and the filter 17 is set on the camera head of the high-speed camera 16. The filter 17 is used to eliminate strong reflections from the wall and bubble surface.

[0051] During use, after the system is assembled, a sheet-like light curtain 15 is projected onto a predetermined area through an optical lens 14. Liquid-phase fluorescent particles 19 of a predetermined concentration are placed in the circulating water tank 1. The water flow rate within the circulating water tank 1 is adjusted to the target speed through the cooperation of a water pump and a Pitot tube 21. High-speed camera 16 is used to observe whether the predetermined operating conditions are met. A predetermined number of gas-phase fluorescent particles 20 are placed on the gas shearing section 10-3. Gas is introduced into the housing 10-1 at a predetermined speed through the ventilation assembly. This allows the gas-phase fluorescent particles 20 to be fully dispersed and mixed with the incoming gas under the turbulent shearing action of the incoming gas, and then evenly introduced into the aforementioned gas chamber 4 along with the incoming gas. The ventilation system enables rapid on-off control of the stored gas, ensuring high test accuracy and efficiency. The pre-placed gas-phase fluorescent particles 20 are dispersed by the turbulent shearing action of the gas and then move synchronously with the gas, forming a particle-containing mixed gas. The gas inflow channel is controlled by a three-way valve 10-4, and the main and bypass gases are mixed at the outflow channel three-way pipe 10-5. The main and bypass flow rates are controlled by the air inlet valve to adjust the particle concentration in the gas. In this case, only a small amount of gas-phase fluorescent particles 20 is needed to ensure sufficient uniform and controllable input into the bubbles, avoiding excessive waste of particles.

[0052] The gas phase fluorescent particles 20 enter the cavitation bubble from the gas chamber 4 along with the air flow, and the evolution pattern is photographed by the high-speed camera 16 .

[0053] In the above description, the sensors, controllers and control programs that may be involved are all existing technologies and will not be described in detail.

[0054] The embodiments of the present invention disclosed above are intended only to illustrate the present invention. The embodiments do not describe all details in detail, nor do they limit the present invention to the specific embodiments described. Numerous modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention.

Claims

1. A ventilation bubble internal and external flow field synchronous measurement experimental system, characterized in that: include: A circulating water tank (1) is connected to a fluid circulation component (2), wherein the fluid circulation component (2) is used to drive the directional movement of the fluid in the circulating water tank (1), and a certain concentration of liquid-phase fluorescent particles (19) is set in the fluid carried by the circulating water tank (1); The structure (3) is arranged in the circulating water tank (1) and immersed a certain distance below the liquid surface of the fluid, and an opening is provided through the end surface; An air chamber (4), the outlet end of which is in communication with the opening of the structure (3), and the inlet end of which is in communication with a particle processing device, wherein the particle processing device is used to release gas-phase fluorescent particles (20) of a predetermined concentration and a predetermined speed into the air chamber (4); A laser system for irradiating the upper and lower areas of the fluid interface; High-speed camera system, used to capture the upper and lower areas of the fluid interface and eliminate reflections from the wall and bubble surface; The particle processing device is provided with a particle dispersion device (10) for pre-mixing gas-phase fluorescent particles (20) with an air flow.

2. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 1, characterized in that: The particle processing device further comprises a ventilation component, wherein the ventilation component comprises an air compressor (5), and the air compressor (5) is connected to the inlet end of the particle dispersion device (10) through a pipeline, and a pressure reducing valve (6), a throttle valve (7), a solenoid valve (8) and a gas flow meter (9) are provided on the pipeline.

3. A ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 1 or 2, characterized in that: The particle dispersion device (10) comprises a shell (10-1) and a gas shearing portion (10-3); the shell (10-1) is provided with an air inlet and an air outlet; the gas shearing portion (10-3) is arranged between the air inlet and the air outlet and divides the shell (10-1) into a gas buffer chamber and a mixing chamber; a certain concentration of gas-phase fluorescent particles (20) are arranged in the mixing chamber; the gas buffer chamber is used to diffuse the gas entering the air inlet, shear the gas through the gas shearing portion (10-3), and then enter the mixing chamber to couple with the gas-phase fluorescent particles (20).

4. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 3, characterized in that: The shell (10-1) is cylindrical.

5. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 4, characterized in that: The particle dispersion device (10) further comprises a gas bypass (10-2), one end of which is connected to a flow control unit provided at the air inlet, and the other end of which is connected to the air outlet of the housing (10-1). The flow control unit is used to control the connection and disconnection between the air inlet and the gas bypass (10-2), as well as the flow rate and speed of the gas introduced into the gas bypass (10-2).

6. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 3, characterized in that: The gas shearing portion (10-3) is in the shape of a plate, and evenly distributed through holes are provided on the plate surface.

7. A ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 1, 2, 5, 6 or 7, characterized in that: The laser system comprises a laser generator (12), a light guide arm (13) and an optical lens (14) connected in sequence. The optical lens (14) is used to project a sheet-shaped light curtain (15) on a target area.

8. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 7, characterized in that: The high-speed camera system comprises a high-speed camera (16), a filter (17) and a computer (18). The high-speed camera (16) is connected to the computer (18), and the filter (17) is arranged on the camera head of the high-speed camera (16).

9. A ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 1, 2, 5, 6, 7 or 8, characterized in that: A Pitot tube (21) is provided downstream of the circulating water tank (1).

10. The ventilation bubble internal and external flow field synchronous measurement experimental system according to claim 1, characterized in that: The structure (3) is a plate-shaped transparent acrylic plate.

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