CN114838912A - Particle scattering device, system and particle scattering method - Google Patents
Particle scattering device, system and particle scattering method Download PDFInfo
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- CN114838912A CN114838912A CN202210637595.6A CN202210637595A CN114838912A CN 114838912 A CN114838912 A CN 114838912A CN 202210637595 A CN202210637595 A CN 202210637595A CN 114838912 A CN114838912 A CN 114838912A
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Abstract
The invention discloses a particle scattering device, a particle scattering system and a particle scattering method. Wherein, the particle scattering device comprises a box body and a particle scattering unit. The particle inlet is arranged at the bottom of the box body and is configured to introduce tracing particle flow into the box body, the particle first outlet is arranged at the top of the box body and is configured to allow the tracing particle flow in the box body to flow out and then enter the particle scattering unit; the particle scattering unit is communicated with the box body through a first particle outlet and is configured to decelerate the tracer particle flow, a second particle outlet is arranged in the particle scattering unit and is configured to enable the tracer particles in the particle scattering unit to flow out and then flow to the test flat plate, and the direction of the second particle outlet is parallel to the test surface of the test flat plate.
Description
Technical Field
The invention relates to the technical field of fluid measurement, in particular to a particle scattering device, a particle scattering system and a particle scattering method.
Background
The boundary layer is a thin flow layer with non-negligible viscous force close to the object surface in the flowing fluid, and is also called as a flow boundary layer and a boundary layer. The flow in the near-wall area is related to the problems of resistance coefficient of an object, pneumatic friction, surface pneumatic heating, heat exchange and the like, and the measurement and the research of the flow condition in the boundary layer are very important.
With the development of laser and image processing technology, a PIV flow display experiment is carried out on a boundary layer flow field, flow field information of a near-wall area can be intuitively obtained in a non-contact mode, and in the PIV experiment, because sufficient momentum and material exchange are lacked between the flow in the boundary layer and an incoming flow main flow, a conventional main flow area tracer particle scattering method is adopted: that is, the problem that the tracer particles are difficult to uniformly enter the near-wall region due to the fact that the tracer particles are directly scattered in the upstream incoming flow region occurs, and therefore boundary layer PIV test cannot be performed.
Disclosure of Invention
The present invention provides a particle scattering device, system and method for at least partially solving the above technical problems.
An aspect of embodiments of the present invention provides a particle scattering device including a case and a particle scattering unit.
The particle inlet is arranged at the bottom of the box body and is configured to introduce tracing particle flow into the box body, the particle first outlet is arranged at the top of the box body and is configured to allow the tracing particle flow in the box body to flow out and then enter the particle scattering unit;
the particle scattering unit is communicated with the box body through a first particle outlet and is configured to decelerate the tracer particle flow, a second particle outlet is arranged in the particle scattering unit and is configured to enable the tracer particles in the particle scattering unit to flow out and then flow to the test flat plate, and the direction of the second particle outlet is parallel to the test surface of the test flat plate.
According to an embodiment of the invention, wherein:
the particle scattering unit includes a first scattering member, a second scattering member, and a third scattering member;
in the scattering unit, a first space is formed by a first scattering component, a second space is formed by a second scattering component, and a third space is formed by a third scattering component, wherein the first space is communicated with the box body through a first particle outlet, the first space is communicated with the second space, the second space is communicated with the third space, and the third space is communicated with the outside through a second particle outlet.
According to an embodiment of the invention, wherein:
the first dispersing component is enclosed by a surrounding wall structure to form a first space, and a first-stage particle through hole is formed in the surrounding wall of the first dispersing component;
the second dispersing component is enclosed outside the first dispersing component through a surrounding wall structure, a second space is enclosed between the outer wall of the first dispersing component and the inner wall of the second dispersing component, the second space is communicated with the first space through a primary particle through hole, and a secondary particle through hole is arranged in the surrounding wall of the second dispersing component;
and a third dispersing member, wherein a third space is formed between the surrounding wall structure and the outer walls of the second dispersing member and the first dispersing member, the third space is communicated with the second space through a secondary particle through port, and a particle second outlet is arranged in the third dispersing member.
According to an embodiment of the invention, wherein:
the second space comprises two second subspaces, and the second dispersion member comprises two groups of surrounding wall structures which respectively surround two sides of the first dispersion member to form two second subspaces;
the third space includes two third subspaces, and the inner wall of the third dispersion member and the outer wall of the first dispersion member are connected by a partition plate so that the third space is partitioned by the partition plate to form the two third subspaces.
According to an embodiment of the invention, wherein:
the third spreading member has a plate-like structure;
the top of the second dispersing component is a plane structure, and the secondary particle passing port is arranged on the wall surface of the top of the second dispersing component;
a second particle outlet is formed between the third dispersing member and the top of the second dispersing member, and the ratio of the height of the second particle outlet to the width of the secondary particle through opening is in the range: 2 to 5.
According to an embodiment of the invention, wherein:
the box is provided with a rectifying plate, and the rectifying plate is provided with a plurality of rectifying holes.
A second aspect of the present invention provides a particle seeding system comprising:
a particle seeding apparatus comprising:
the particle distribution device comprises a box body, a particle inlet and a particle first outlet, wherein the bottom of the box body is provided with the particle inlet, the particle inlet is configured to introduce tracing particle flow into the box body, the top of the box body is provided with the particle first outlet, and the particle first outlet is configured to allow the tracing particle flow in the box body to flow out and then enter a particle distribution unit;
the particle scattering unit is communicated with the box body through a first particle outlet and is configured to decelerate the tracer particle flow, a second particle outlet is formed in the particle scattering unit and is configured to allow tracer particles in the particle scattering unit to flow out and then flow to the test flat plate, and the direction of the second particle outlet is parallel to the test surface of the test flat plate;
a liquid particle generator comprising:
the liquid storage tank is configured to store oily liquid of a preset type, and the top of the liquid storage tank is provided with an air inlet;
the air inlet purging probe is of a hollow tubular structure and is vertically arranged in the liquid storage tank, an opening at the upper end of the air inlet purging probe is communicated with the air inlet, and a plurality of probe small holes are formed in the lower end of the air inlet purging probe;
the gas outlet is arranged at the top of the liquid storage tank and is communicated with a particle inlet arranged in the box body;
a drive air supply, comprising:
an air compressor;
the inlet of the gas transmission pipeline is communicated with the outlet of the air compressor, and the outlet of the gas transmission pipeline is communicated with the gas inlet arranged at the top of the liquid storage tank.
According to an embodiment of the invention, wherein:
and a circle of secondary air blowing holes are formed in the pipe wall of the middle upper part of the air inlet blowing probe.
According to an embodiment of the invention, wherein:
the tank body of the liquid storage tank is marked with a highest liquid level line and a lowest liquid level line;
the position of the small hole of the probe is lower than the lowest liquid level line, and the position of the secondary gas purging hole is higher than the highest liquid level line;
the bottom of the liquid storage tank is provided with a liquid discharge port.
A third aspect of the present invention provides a method for performing particle scattering by using the particle scattering system, including:
conveying preset gas with preset pressure to a liquid storage tank of the liquid particle generator by using an air compressor so that the preset gas with the preset pressure can form tracer particle flow with a first preset speed at an air outlet at the top of the liquid storage tank after the oily liquid in the liquid storage tank is blown and the bubbles are broken by an air inlet blowing probe arranged in the liquid storage tank;
introducing the tracer particle flow with the first preset speed into a box body of the particle scattering device through a particle inlet arranged in the particle scattering device so that the tracer particle flow enters a particle scattering unit after flowing out through a particle first outlet arranged at the top of the box body;
decelerating the tracer particle flow through the particle scattering unit, so that the tracer particle flow flows out along a second particle outlet arranged on the particle scattering unit at a second preset speed and then flows to the test flat plate, wherein the direction of the second particle outlet is parallel to the test surface of the test flat plate;
wherein the first predetermined speed is 10-30 m/s, and the second predetermined speed is 0-2.0 m/s.
According to the embodiment of the disclosure, the tracing particle flow is decelerated by arranging the particle scattering unit, so that the tracing particle flow has a lower flow speed before entering the boundary layer, the condition that the tracing particle flow can smoothly enter the boundary layer without interfering the flow in the boundary layer is met, the effective proceeding of a test is ensured, and the test measurement precision is improved. By configuring the two third subspaces and the two particle second outlets for the particle scattering unit, the requirement of simultaneously carrying out two flat boundary layer tests can be met, and the test convenience and the test efficiency are improved.
According to the embodiment of the disclosure, the particle scattering device provided by the embodiment of the invention is used for scattering particles, so that a clear velocity field structure diagram can be obtained, the problem that the PIV tracer particles cannot enter a boundary layer or a super-cavity in the existing PIV tracer particle scattering method is solved, the tracer particles can be uniformly scattered into a large-size wall surface boundary layer, disturbance to a main flow and the boundary layer can be minimized, and a good technical support is provided for researching the internal eddy current mechanism of the boundary layer, such as boundary layer transition, boundary layer separation and the like.
Drawings
Fig. 1 is a schematic structural view of a particle scattering device according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a tracer particle seeding system according to an embodiment of the invention;
FIG. 3 is a schematic diagram of a system for driving an air supply in accordance with an embodiment of the present invention;
FIG. 4 is a schematic structural view of a liquid particle generator according to an embodiment of the present invention;
fig. 5 is a schematic view of the flow of tracer particles in a particle seeding apparatus according to an embodiment of the invention.
Description of reference numerals:
1. a driving gas source;
11. an air compressor;
12. a ball valve;
13. a pressure reducing valve;
14. a needle valve;
2. a liquid particle generator;
21. an air inlet;
22. an intake purge probe;
221. a probe well;
222. secondary air is blown to the hole;
23. a liquid storage tank;
231. a liquid level meter;
232. installing a flange;
233. a tapping hole;
234. a tapping hole plug;
24. a top cover of the liquid storage tank;
25. an air outlet;
31. a particle inlet;
32. a box body;
33. a rectifying plate;
34. a particle scattering unit;
340. a first outlet for particles;
341. a first spreading member;
3411. a first-order particle passage port;
3412. a secondary particle passage port;
342. a second dispersion member;
343. a third dispersion member;
344. a second outlet for particles;
345. a partition plate.
Detailed Description
In order that the objects, technical solutions and advantages of the present invention will become more apparent, the present invention will be further described in detail with reference to the accompanying drawings in conjunction with the following specific embodiments.
Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that the description is illustrative only and is not intended to limit the scope of the present disclosure. In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the disclosure. It may be evident, however, that one or more embodiments may be practiced without these specific details. Moreover, in the following description, descriptions of well-known structures and techniques are omitted so as to not unnecessarily obscure the concepts of the present disclosure.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. The terms "comprises," "comprising," and the like, as used herein, specify the presence of stated features, steps, operations, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.
All terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art unless otherwise defined. It is noted that the terms used herein should be interpreted as having a meaning that is consistent with the context of this specification and should not be interpreted in an idealized or overly formal sense.
Where a convention analogous to "at least one of A, B and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B and C" would include but not be limited to systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.). Where a convention analogous to "A, B or at least one of C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B or C" would include but not be limited to systems that have a alone, B alone, C alone, a and B together, a and C together, B and C together, and/or A, B, C together, etc.).
The boundary layer is a thin flow layer with non-negligible viscous force close to the object surface in the flowing fluid, and is also called as a flow boundary layer and a boundary layer. If fluid with small viscosity (such as water, air and the like) is in contact with an object at a large Reynolds number and moves relatively, a thin fluid layer close to the object surface reduces the speed due to viscous shear stress; the fluid tightly attached to the object surface is adhered to the object surface, and the relative speed of the fluid and the object surface is equal to zero; the object is extended towards the fluid interior, and the velocity of each layer is gradually increased until the free flow rate is equal. This thin layer of fluid deceleration up the object plane is called the boundary layer. The speed is rapidly increased to the local free flow speed from the object surface to the outside, and the speed gradient in the direction vertical to the surface in the boundary layer is large because the boundary layer is thin, and even if the viscosity of the fluid is not large, such as air, water and the like, the viscosity force is still relatively large. When the Reynolds number is less than a certain value, the laminar boundary layer is formed, the airflow in the boundary layer flows smoothly, and when the main flow speed is increased, the laminar boundary layer is transited to the turbulent boundary layer and reaches the state of the turbulent boundary layer. In nature and engineering, the flow on the surface of moving objects (such as airplanes, cascades, etc.) is mostly a turbulent boundary layer, and the internal structure of the turbulent boundary layer is much more complicated than that of a laminar boundary layer because the turbulent flow has vortex flow and random pulsation, and the flow changes with space and time. In addition, a flow separation phenomenon also exists within the boundary layer: as the fluid flows through the curve, its velocity and pressure change, and as the flow rate decreases, the pressure must increase. Due to the loss of momentum of the fluid micelles within the boundary layer, the momentum is reduced again when the downstream pressure increases (i.e., there is a back pressure gradient) until the fluid micelles can no longer advance on the object plane. Due to the separation of the boundary layer, fluid backflow is generated at the separation position, collision friction between fluids and between the fluids and the boundary is increased, and flow energy loss is formed, which needs to be avoided as much as possible by engineering designers. In a word, the flow in the near-wall area is related to the problems of the resistance coefficient of an object, pneumatic friction, surface pneumatic heating, heat exchange and the like, and the measurement and the research of the flow condition in the boundary layer are very important.
With the development of laser and image processing technology, PIV flow display experiments are carried out on boundary layer flow fields, flow field information of a near-wall area can be intuitively obtained in a non-contact mode, the convenience of the experiments is greatly improved, the images are shot and then processed, detailed information of a flow field such as a velocity vector, vorticity, a turbulence structure, root-mean-square velocity and the like can be obtained, and the accuracy is high. In the PIV test, due to the lack of sufficient momentum and mass exchange between the flow inside the boundary layer and the incoming mainstream, a conventional mainstream region tracer particle scattering method is adopted: that is, the problem that the tracer particles are difficult to uniformly enter the near-wall region due to the fact that the tracer particles are directly scattered in the upstream incoming flow region occurs, and therefore boundary layer PIV test cannot be performed.
For example, in the related art, the outlet axis of the particle scattering slit of the thin-wall cover plate of the tracer particle scattering device is arranged at an angle of 15 ° with the surface of the cover plate, but the tracer particle gas flow coming out of the scattering port may disturb the flow in the boundary layer to some extent, resulting in a decrease in the measurement accuracy.
For another example, the tracer particle flow is set to flow out from only one smaller injection hole at the upper part of the cavity in the related art, but the coverage area and the area of the particle flow are limited by the method, and the method is not suitable for large-size boundary layer flow display tests such as a flat boundary layer.
In view of the above, embodiments of the present invention are directed to solving the above technical problems, so as to not only uniformly scatter trace particles into a large-sized wall boundary layer, but also minimize disturbance to a main flow and the boundary layer, and is particularly suitable for a flat plate flow test.
An aspect of the embodiments of the present invention provides a particle scattering device, fig. 1 is a schematic structural diagram of a particle scattering device according to an embodiment of the present invention, and the particle scattering device according to an embodiment of the present invention is described below with reference to fig. 1.
As shown in fig. 1, the particle scattering device includes a case 32 and a particle scattering unit 34.
Wherein, the bottom of box 32 is equipped with particle import 31, and particle import 31 is configured as letting in the tracer particle flow of certain speed to box 32, and in the use, particle import 31 communicates with liquid particle generator, and liquid particle generator is used for producing the tracer particle flow. The top of the box 32 is provided with a first particle outlet 340, and the first particle outlet 340 is configured to allow the tracer particle flow in the box 32 to flow out and enter the particle scattering unit 34.
The particle scattering unit 34 is communicated with the box 32 through a first particle outlet 340 and configured to decelerate the tracer particle flow, wherein a second particle outlet 344 is provided in the particle scattering unit 34, the second particle outlet 344 is configured to allow the tracer particles in the particle scattering unit 34 to flow out and then flow to the test plate, and the direction of the second particle outlet 344 is parallel to the test surface of the test plate.
According to the embodiment of the present invention, the test plate may be horizontally placed near the second particle outlet 344 of the particle scattering unit 34, in which case the second particle outlet 344 is also horizontally oriented, and the particle flow is allowed to flow out and enter the wall surface boundary layer of the test plate in the horizontal direction because the particle flow direction is parallel to the test surface of the test plate and the particle flow flows against the surface of the test plate. Compared with the traditional method of scattering particles from a main flow region, the method of the embodiment of the disclosure can enable the tracer particles to enter the near-wall region more easily because the interference of the flow of the main flow region does not exist. Compared with a method that the axis of the particle scattering slit outlet and the surface of the cover plate form a certain included angle in the related technology, the method provided by the embodiment of the disclosure has no interference on the flow in the boundary layer, and the reliability of the test measurement result is higher.
According to the embodiment of the invention, the liquid particle generator is used for generating a tracer particle flow with a certain speed, and if the tracer particle flow is directly broadcast, the particle flow flowing out of the outlet of the liquid particle generator has a high initial speed, so that the flow in the boundary layer of the test flat plate can be strongly interfered, and the test result is seriously influenced. Therefore, the embodiment of the present disclosure decelerates the tracer particle flow by setting the particle scattering unit 34 to meet the test requirements. The particle dispersing unit 34 may be provided with one or more stages of speed reducing spaces (or channels), and after the tracer particle flow enters the particle dispersing unit 34 from the first particle outlet 340 at the top of the box 32, the flow rate gradually decreases after passing through each stage of speed reducing space until the final flow rate required by the test is reached, and then the tracer particle flow flows out from the second particle outlet 344.
According to the embodiment of the disclosure, the tracing particle flow is decelerated by arranging the particle scattering unit 34, so that the tracing particle flow has a lower flow speed before entering the boundary layer, and the condition that the tracing particle flow can smoothly enter the boundary layer without interfering the flow in the boundary layer is met, the effective proceeding of a test is ensured, and the test measurement precision is improved.
According to the embodiment of the disclosure, the particle scattering device provided by the embodiment of the invention is used for scattering particles, so that a clear velocity field structure diagram can be obtained, the problem that the PIV tracer particles cannot enter a boundary layer or a super-cavity in the existing PIV tracer particle scattering method is solved, the tracer particles can be uniformly scattered into a large-size wall surface boundary layer, disturbance to a main flow and the boundary layer can be minimized, and a good technical support is provided for researching the internal eddy current mechanism of the boundary layer, such as boundary layer transition, boundary layer separation and the like.
Further, according to the embodiment of the present invention, particle scattering unit 34 includes first scattering member 341, second scattering member 342, and third scattering member 343.
In the dispersing unit, a first space is formed by the first dispersing member 341, a second space is formed by the second dispersing member 342, and a third space is formed by the third dispersing member 343, wherein the first space communicates with the tank 32 through the particle first outlet 340, the first space communicates with the second space, the second space communicates with the third space, and the third space communicates with the outside through the particle second outlet 344.
Specifically, as shown in fig. 1, the first dispersion member 341 is surrounded by a wall structure to form a first space, and the wall of the first dispersion member 341 has a first-stage particle passage 3411; a second dispersing member 342 surrounded outside the first dispersing member 341 by a surrounding wall structure, a second space formed by surrounding between the outer wall of the first dispersing member 341 and the inner wall of the second dispersing member 342, the second space and the first space being communicated by a primary particle passage port 3411, a secondary particle passage port 3412 being provided in the surrounding wall of the second dispersing member 342; the third dispersing member 343 forms a third space between the outer walls of the second dispersing member 342 and the first dispersing member 341 by the wall structure, the third space and the second space are communicated with each other through the secondary particle passage port 3412, and the third dispersing member 343 is provided with a particle second outlet 344.
According to the embodiment of the present invention, in the dispersing unit, three stages of speed reducing spaces (or channels) are formed by the three dispersing members, and the tracer particle flow enters the first space from the particle first outlet 340 at the top of the box body 32, enters the second space through the first particle passing port 3411 after being subjected to first stage speed reduction in the first space, enters the third space through the second particle passing port 3412 after being subjected to second stage speed reduction in the second space, and exits from the particle second outlet 344 after reaching the final flow rate required in the test after being subjected to third stage speed reduction in the third space.
Further, according to an embodiment of the present invention, the third spreading member 343 may be adopted as a flat plate-like structure. The top of the second dispersion member 342 has a planar structure, and the secondary particle passage ports 3412 are provided on the top wall surface of the second dispersion member 342. For example, as shown in fig. 1, the first dispersing member 341 may be a first space surrounded by a plurality of flat plates to form a cubic or rectangular parallelepiped structure, and the first dispersing member 341 may have a first-stage particle passage port 3411 in a side wall thereof. Second dispersion member 342 can be enclosed outside first dispersion member 341 using an inverted L-shaped plate, and a slit is formed between the inverted L-shaped plate and the sidewall of first dispersion member 341 as secondary particle passage opening 3412. The third dispersion member 343 is a thin flat plate supported and fixed in parallel on the top of the first dispersion member 341 by a vertical partition plate 345. A second outlet 344 for particles is formed between the thin flat plate and the upper surface of second dispersion member 342.
According to an embodiment of the present invention, the ratio of the height of the second particle outlet 344 to the width of the secondary particle passage port 3412 ranges from: 2 to 5. Thus, the outlet flow velocity of the tracer particles can be ensured to be within the design range.
Further, according to an embodiment of the present invention, the second space includes two second sub-spaces, and the second dispersion member 342 includes two sets of wall structures, which are respectively enclosed on both sides of the first dispersion member 341 by the two sets of wall structures to form the two second sub-spaces. The third space includes two third subspaces, and the inner wall of the third dispersion member 343 and the outer wall of the first dispersion member 341 are connected by a partition plate 345 (vertical plate) so as to partition the third space by the partition plate 345 to form two third subspaces.
As shown in fig. 1, the second dispersing member 342 is enclosed on the left and right sides of the first dispersing member 341 by two inverted L-shaped plates, and two second subspaces are formed on the two sides of the second dispersing member 342. The third spreading member 343 and the upper surface of the first spreading member 341 are connected by a partition plate (vertical plate) to partition the third space into two left and right third sub-spaces, and the height of the third spreading member 343 from the top of the second spreading member 342 is set to 5 to 30mm depending on the size of the flat boundary layer flow test scale.
According to the embodiment of the present invention, two particle second outlets 344 are formed by the above structure, and the two particle second outlets 344 are respectively located at two sides of the box 32, so that two sets of comparison tests can be performed simultaneously, and if the particle flows flowing out of the two particle second outlets 344 have the same flow state, it is ensured that the initial states (speed, flow direction) of the particle flows entering the boundary layer are the same in the two sets of comparison tests, and the test accuracy is ensured.
According to the embodiment of the present invention, further, as shown in fig. 1, a rectifying plate 33 is provided in the case 32, and a plurality of rectifying holes are provided in the rectifying plate 33. The fairing 33 is installed in the middle of the box 32, and divides the box 32 into an upper cavity and a lower cavity, wherein the lower cavity plays a role in stabilizing pressure, and the upper cavity plays a role in storing liquid tracer particles. In order to ensure that the particles have sufficient particle density when finally flowing into the flat plate, the particle flow entering through the particle inlet 31 needs to have high initial velocity, therefore, the particle inlet 31 is arranged on the side wall of the box body 32 at the lower part of the rectifying plate 33, the particle flow entering through the particle inlet 31 rectifies the particle flow through the rectifying plate 33, on one hand, the velocity is reduced, on the other hand, the flow velocity and distribution of the particle flow are more uniform, and the requirement of a subsequent test is ensured.
A second aspect of the present invention provides a particle scattering system including the above-mentioned particle scattering device, fig. 2 is a schematic structural diagram of a tracer particle scattering system according to an embodiment of the present invention, and the tracer particle scattering system according to an embodiment of the present invention is described below with reference to fig. 2.
As shown in fig. 2, the tracer particle scattering system comprises the particle scattering device as described above, and further comprises a liquid particle generator 2 and a driving gas source 1.
Fig. 3 is a schematic structural diagram of a system of a driving air source 1 according to an embodiment of the present invention, and as shown in fig. 3, the driving air source 1 includes an air compressor 11 and an air pipe.
Wherein, the inlet of the gas transmission pipeline is communicated with the outlet of the air compressor 11, and the outlet of the gas transmission pipeline is communicated with the gas inlet 21 of the liquid particle generator 2. The gas transmission pipeline is provided with a ball valve 12, a pressure reducing valve 13 and a needle valve 14, the pressure reducing valve 13 can control the gas pressure in a gas storage tank of the air compressor 11 to be 0.1-0.3 MPa, and the needle valve 14 is used for adjusting the air flow entering the liquid particle generator 2.
Fig. 4 is a schematic structural view of the liquid particle generator 2 according to the embodiment of the present invention.
As shown in fig. 4, the liquid particle generator 2 includes a liquid storage tank 23, an air intake purge probe 22, a top cover of the liquid storage tank 23, and an air outlet 25, wherein the liquid storage tank 23 is configured to store a predetermined kind of oily liquid, and an air inlet 21 is arranged at the top of the liquid storage tank 23; the air inlet purging probe 22 is of a hollow tubular structure and is vertically arranged in the liquid storage tank 23, an opening at the upper end of the air inlet purging probe 22 is communicated with the air inlet 21, a plurality of probe small holes 221 are formed in the lower end of the air inlet purging probe 22, the hole diameter is 0.5-1 mm, and bubbles are generated; the air outlet 25 is disposed at the top of the reservoir 23, and the air outlet 25 is communicated with a particle inlet 31 disposed in a box 32.
According to the embodiment of the invention, a circle of secondary air blowing holes 222 with the aperture of 1-2 mm are formed in the middle-upper pipe wall of the air inlet blowing probe 22, and the secondary air is used for secondarily crushing oily bubbles to enable the particle size to be uniform.
According to an embodiment of the present invention, the tank body of the fluid reservoir 23 is marked with a highest fluid level and a lowest fluid level; the position of the probe small hole 221 is lower than the lowest liquid level line, and the position of the secondary gas purging hole 222 is higher than the highest liquid level line; the liquid storage tank 23 is further provided with a liquid level meter 231 for measuring and calibrating the liquid level.
According to the embodiment of the invention, the liquid storage tank 23 is also provided with the mounting flange 232, the liquid discharge port 233 and the liquid discharge port 233 plug, and the liquid storage tank 23 is hermetically connected with the top cover of the liquid storage tank 23 through the mounting flange 232; an air inlet purging probe 22 is fixed on the top cover of the liquid storage tank 23, one end of the air inlet purging probe 22 is connected with the air inlet 21, the other end of the air inlet purging probe 22 is inserted below the liquid level at the bottom of the liquid storage tank 23, and the air outlet 25 is arranged on the top cover of the liquid storage tank 23.
According to the embodiment of the invention, the lower end of the air inlet purging probe 22 is provided with the probe small hole 221, air flow with certain pressure enters from the air inlet 21 of the liquid particle generator 2 and is sprayed out through the probe small hole 221 at the bottom of the air inlet purging probe 22, oil bubbles are generated after the oil liquid is blown, and move upwards, and a part of the bubbles are broken at the liquid level; further, the airflow blown out through the secondary air purge hole 222 interferes with the non-broken oily bubbles, and the oily bubbles are broken under the shearing force action of the secondary air purge hole 222 purge airflow, so that a uniform particle flow can be formed, and the generation of the particle flow is promoted.
A third aspect of the present invention provides a method for performing particle scattering by using the particle scattering system, comprising the following operations:
operation S1: conveying preset gas with preset pressure to a liquid storage tank 23 of the liquid particle generator 2 by using an air compressor 11, so that the preset gas with the preset pressure can blow up oily liquid in the liquid storage tank 23 and form a first preset-speed tracer particle flow at an air outlet 25 after bubbles break through an air inlet purging probe 22 arranged in the liquid storage tank 23;
operation S2: introducing the tracer particle flow with the first preset speed into a box body 32 of the particle scattering device through a particle inlet 31 arranged in the particle scattering device, so that the tracer particle flow enters a particle scattering unit 34 after flowing out through a particle first outlet 340 arranged at the top of the box body 32;
operation S3: the tracer particle flow is decelerated by the particle scattering unit 34, so that the tracer particle flow flows out along a second particle outlet 344 provided in the particle scattering unit 34 at a second preset speed and then flows to the test flat plate, wherein the direction of the second particle outlet 344 is parallel to the test surface of the test flat plate.
Fig. 5 is a schematic view of the flow of tracer particles in a particle seeding apparatus according to an embodiment of the invention.
As shown in fig. 5, in the flat plate test, the top wall surface of the second scattering member 342 is used at the same height as the test flat plate.
The air flow with certain pressure generated by the air compressor 11 enters from the air inlet 21 of the liquid particle generator 2, is sprayed out through the blowing holes at the bottom and the side wall of the air inlet blowing probe 22 to generate oily bubbles to move upwards, one part of the bubbles are broken at the liquid level interface, the other part of the bubbles are broken under the action of the shearing force of the blowing air flow of the secondary air blowing hole 222 to form uniform particle flow, and then the uniform particle flow flows out from the air outlet 25 on the top cover of the liquid storage tank 23 and enters the particle scattering device.
The tracer particle flow enters a first space formed by the first dispersing member 341 from the first particle outlet 340 at the top of the box body 32, after first-stage deceleration, enters a second space formed by the second dispersing member 342 through the first particle passage port 3411, after second-stage deceleration, enters a third space formed by the third dispersing member 343 through the second particle passage port 3412, after third-stage deceleration, is blocked by a thin flat plate in the third space, reaches a final flow velocity required by the test, then slowly flows in the horizontal direction from the second particle outlet 344, and enters the flat plate boundary layer.
According to the embodiment of the present disclosure, in order to ensure a sufficient particle density (concentration) when the particles finally flow into the flat plate, the particle flow entering through the particle inlet 31 needs to have a high initial velocity, and therefore, the first preset velocity of the tracer particle flow at the outlet 25 of the liquid storage tank 23 is 10 to 30 m/s.
According to the embodiment of the disclosure, in order to enable the particle flow finally entering the boundary layer to smoothly enter the boundary layer without interfering the flow in the boundary layer, it is required to ensure that the tracer particle flow has a low flow velocity before entering the boundary layer, and therefore, after the tracer particle flow is decelerated by the scattering unit, the tracer particle flow flowing out of the particle second outlet 344 of the scattering unit flows at the second preset velocity of 0-2.0 m/s, so that the effective performance of a test can be ensured, and the test measurement precision is improved.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are only exemplary embodiments of the present invention and are not intended to limit the present invention, and any modifications, equivalents, improvements and the like made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A particle seeding apparatus comprising:
the particle scattering unit comprises a box body, wherein a particle inlet is formed in the bottom of the box body, the particle inlet is configured to introduce tracing particle flow into the box body, a first particle outlet is formed in the top of the box body, and the first particle outlet is configured to allow the tracing particle flow in the box body to flow out and then enter the particle scattering unit;
and the particle scattering unit is communicated with the box body through the first particle outlet and is configured to decelerate the tracer particle flow, a second particle outlet is arranged in the particle scattering unit and is configured to allow tracer particles in the particle scattering unit to flow out and then flow to a test flat plate, and the direction of the second particle outlet is parallel to the test surface of the test flat plate.
2. The apparatus of claim 1, wherein:
the particle spreading unit includes a first spreading member, a second spreading member, and a third spreading member;
wherein, in the scattering unit, a first space is formed by the first scattering member, a second space is formed by the second scattering member, and a third space is formed by the third scattering member, wherein the first space communicates with the tank through the particle first outlet, the first space communicates with the second space, the second space communicates with the third space, and the third space communicates with the outside through the particle second outlet.
3. The apparatus of claim 2, wherein:
the first dispersing component is surrounded by a surrounding wall structure to form the first space, and a first-stage particle through hole is formed in the surrounding wall of the first dispersing component;
the second dispersing component is enclosed outside the first dispersing component through a surrounding wall structure, the second space is enclosed between the outer wall of the first dispersing component and the inner wall of the second dispersing component, the second space is communicated with the first space through the primary particle through port, and a secondary particle through port is arranged in the surrounding wall of the second dispersing component;
the third dispersing member forms the third space between the surrounding wall structure and the outer walls of the second dispersing member and the first dispersing member, the third space and the second space are communicated through the secondary particle through port, and the third dispersing member is provided with a second particle outlet.
4. The apparatus of claim 3, wherein:
the second space comprises two second subspaces, and the second dispersion member comprises two groups of enclosure wall structures which respectively enclose two sides of the first dispersion member to form two second subspaces;
the third space includes two third subspaces, and the inner wall of the third dispersion member and the outer wall of the first dispersion member are connected by a partition plate so that the two third subspaces are formed by dividing the third space by the partition plate.
5. The apparatus of claim 3, wherein:
the third dispersion member has a plate-like structure;
the top of the second dispersing component is a plane structure, and the secondary particle passing port is arranged on the wall surface of the top of the second dispersing component;
the second particle outlet is formed between the third dispersing member and the top of the second dispersing member, and the ratio of the height of the second particle outlet to the width of the secondary particle through opening is in the range: 2 to 5.
6. The apparatus of claim 1, wherein:
be equipped with the cowling panel in the box, be equipped with a plurality of rectification holes in the cowling panel.
7. A particle seeding system comprising:
a particle seeding apparatus comprising:
the particle scattering unit comprises a box body, wherein a particle inlet is formed in the bottom of the box body, the particle inlet is configured to introduce tracing particle flow into the box body, a first particle outlet is formed in the top of the box body, and the first particle outlet is configured to allow the tracing particle flow in the box body to flow out and then enter the particle scattering unit;
the particle scattering unit is communicated with the box body through the first particle outlet and is configured to decelerate the tracer particle flow, a second particle outlet is arranged in the particle scattering unit and is configured to allow tracer particles in the particle scattering unit to flow out and then flow to a test flat plate, and the direction of the second particle outlet is parallel to the test surface of the test flat plate;
a liquid particle generator comprising:
the liquid storage tank is configured to store a predetermined type of oily liquid, and an air inlet is formed in the top of the liquid storage tank;
the air inlet purging probe is of a hollow tubular structure and is vertically arranged inside the liquid storage tank, an opening at the upper end of the air inlet purging probe is communicated with the air inlet, and a plurality of probe small holes are formed in the lower end of the air inlet purging probe;
the gas outlet is arranged at the top of the liquid storage tank and is communicated with the particle inlet arranged in the box body;
a drive air supply, comprising:
an air compressor;
the inlet of the gas transmission pipeline is communicated with the outlet of the air compressor, and the outlet of the gas transmission pipeline is communicated with the gas inlet arranged at the top of the liquid storage tank.
8. The system of claim 7, wherein:
and a circle of secondary air blowing holes are formed in the pipe wall of the middle upper part of the air inlet blowing probe.
9. The system of claim 8, wherein:
the tank body of the liquid storage tank is marked with a highest liquid level line and a lowest liquid level line;
the position of the probe pore is lower than the lowest liquid level line, and the position of the secondary gas purging pore is higher than the highest liquid level line;
and a liquid discharge port is formed at the bottom of the liquid storage tank.
10. A method of particle seeding using the particle seeding system according to any of claims 7 to 9, comprising:
conveying preset gas with preset pressure to a liquid storage tank of a liquid particle generator by using an air compressor, so that after the preset gas with the preset pressure passes through an air inlet purging probe arranged in the liquid storage tank, oily liquid in the liquid storage tank is blown and bubbles are broken, and then forming tracer particle flow with a first preset speed at an air outlet at the top of the liquid storage tank;
introducing the tracer particle flow with the first preset speed into a box body of the particle scattering device through a particle inlet arranged in the particle scattering device, so that the tracer particle flow enters a particle scattering unit after flowing out through a particle first outlet arranged at the top of the box body;
decelerating the tracer particle flow through the particle scattering unit, so that the tracer particle flow flows out along a second particle outlet arranged on the particle scattering unit at a second preset speed and then flows to a test flat plate, wherein the direction of the second particle outlet is parallel to the test surface of the test flat plate;
wherein the first preset speed is 10-30 m/s, and the second preset speed is 0-2.0 m/s.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220214245A1 (en) * | 2019-08-29 | 2022-07-07 | Zhejiang University | Tracer Particle Spreading Device for a Boundary Layer Flow Visualization Experiment Based on a Flat Plate |
| CN115824560A (en) * | 2023-02-21 | 2023-03-21 | 中国空气动力研究与发展中心空天技术研究所 | Planar cascade wind tunnel PIV experiment slit tracer particle distribution device and distribution method |
| CN117804733A (en) * | 2024-03-01 | 2024-04-02 | 中国空气动力研究与发展中心低速空气动力研究所 | Wall turbulence boundary layer test device for generating space-time evolution |
-
2022
- 2022-06-07 CN CN202210637595.6A patent/CN114838912A/en active Pending
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20220214245A1 (en) * | 2019-08-29 | 2022-07-07 | Zhejiang University | Tracer Particle Spreading Device for a Boundary Layer Flow Visualization Experiment Based on a Flat Plate |
| US11953405B2 (en) * | 2019-08-29 | 2024-04-09 | Zhejiang University | Tracer particle spreading device for a boundary layer flow visualization experiment based on a flat plate |
| CN115824560A (en) * | 2023-02-21 | 2023-03-21 | 中国空气动力研究与发展中心空天技术研究所 | Planar cascade wind tunnel PIV experiment slit tracer particle distribution device and distribution method |
| CN115824560B (en) * | 2023-02-21 | 2023-04-14 | 中国空气动力研究与发展中心空天技术研究所 | Planar cascade wind tunnel PIV experiment slit tracer particle distribution device and distribution method |
| CN117804733A (en) * | 2024-03-01 | 2024-04-02 | 中国空气动力研究与发展中心低速空气动力研究所 | Wall turbulence boundary layer test device for generating space-time evolution |
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