Tracer particle spreading device in large wind tunnel PIV technology

Abstract

The utility model relates to a tracer particle spreading device in a large wind tunnel PIV (particle image velocimetry) technology, which is characterized in that the spreading device is longitudinally suspended in a wind tunnel and comprises a magnetic rod which is of a vertically arranged slender cylinder structure; the coil is of a spring type structure, and the axial clearance of the coil is sleeved and matched with the outer side of the magnetic bar; the heat transfer sheet is of a tubular structure and is axially attached to the outer side of the coil in a matched mode; the heat-resistant sponge is of a tubular structure, is axially attached to the outer side of the heat transfer sheet in a matched mode and is used for adsorbing the liquid tracer particles; the two fixing and supporting covers are axially connected to the ends of the heat-resisting sponge in a sleeving mode respectively, the ends of the magnetic rods are rotationally connected with the inner end faces of the corresponding fixing and supporting covers respectively, and the bottom ends of the magnetic rods extend out of the outer sides of the corresponding fixing and supporting covers; the pneumatic fan is axially and fixedly connected to the bottom end of the magnetic bar in a sleeving manner; the spreading device can form a single tracer particle surface, so that pollution of tracer particles to a wind tunnel and other internal precision equipment is reduced, and interference of non-laser surface tracer particles in a space is effectively avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of PIV tracer particle spreading, in particular to a tracer particle spreading device in a large wind tunnel PIV technology. Background Art

[0002] Particle Image Velocimetry (PIV) is an advanced flow measurement technology. Its principle is to spread tracer particles in the flow field, and then illuminate the particles in the flow field through a pulsed laser sheet light source incident on the measured flow field area. The particles will scatter light under the irradiation of the laser. Through two or more consecutive exposures, the image of the particles is recorded on the CMOS chip. Subsequently, the image processing method of the cross-correlation method is used to process the image recorded by the CMOS point by point to obtain the velocity distribution information of the flow field.

[0003] In existing wind tunnel experiments, the spreading of tracer particles in super-large wind tunnels usually uses multiple heated smoke generators to spread tracer particles throughout the wind tunnel test section. Although it can cover a large area, there is a problem of uneven distribution of tracer particles, and the thickness of the laser surface irradiation is limited, resulting in the actual observed flow field distribution being limited to the laser irradiation surface. In addition, since the entire wind tunnel is filled with tracer particles, tracer particles in different areas will interfere with each other, further affecting the uniformity of spreading. Tracer particles are a type of aerosol and will adhere to the walls of the wind tunnel and other precision instruments, causing pollution. Moreover, when the laser irradiates a surface, it will be affected by the particles in the front and back space. At this time, the projection generated on the CMOS will have a false image of ghost particles, resulting in accuracy errors in the flow field test. Utility Model Content

[0004] In view of the shortcomings of the prior art, the utility model provides a device for spreading tracer particles in a large wind tunnel PIV technology. The specific technical solution is as follows:

[0005] The utility model provides a spreading device for tracer particles in a large wind tunnel PIV technology. The spreading device is detachably suspended in the wind tunnel longitudinally. The spreading device comprises

[0006] A magnetic bar, which is a vertically arranged elongated cylindrical structure;

[0007] The coil is a spring-type structure, and its axial gap is sleeved and fitted on the outside of the magnetic rod;

[0008] A heat transfer sheet, which is a tubular structure and is axially attached to the outside of the coil;

[0009] A heat-resistant sponge, which is a tubular structure and is axially attached to the outside of the heat transfer sheet. The heat-resistant sponge is used to absorb liquid tracer particles;

[0010] Two fixed support covers, which are respectively axially sleeved on the ends of the heat-resistant sponge, the ends of the magnetic rods are respectively rotatably connected to the corresponding inner end surfaces of the fixed support covers, and the bottom ends of the magnetic rods extend to the outer sides of the corresponding fixed support covers;

[0011] The pneumatic fan is axially fixedly sleeved on the bottom end of the magnetic rod.

[0012] As a preferred technical solution of the utility model, the heat-resistant sponge is a dense hole structure made of any one of polyimide and polyarylether.

[0013] As a preferred technical solution of the utility model, a plurality of liquid storage holes for absorbing and storing liquid tracer particles are formed in the dense hole structure of the heat-resistant sponge.

[0014] As a preferred technical solution of the utility model, the liquid tracer particles are glycerol.

[0015] As a preferred technical solution of the utility model, a particle concentration display is radially embedded on the outer peripheral surface of the top of the heat-resistant sponge.

[0016] As a preferred technical solution of the utility model, the particle concentration display is a hydraulic sensor.

[0017] The beneficial effects of the utility model are:

[0018] The spreading device of the utility model is a slender rod-shaped structure as a whole relative to the experimental wind tunnel. Under the blowing of wind from a single direction in the wind tunnel, the tracer particles in the spreading device form a single tracer particle surface, thereby avoiding the waste caused by spreading tracer particles in a large range in the wind tunnel, saving the experimental cost, and reducing the pollution of the wind tunnel and other precision equipment inside by tracer particles. At the same time, it can also effectively avoid the interference of tracer particles on non-laser surfaces in the space; the wind force converted by the pneumatic fan is axially transmitted to the magnetic rod, so that the magnetic rod can continuously rotate under the drive of the wind force to cut the coil to generate an induced current, and the heat generated at the same time heats the liquid tracer particles through the heat transfer sheet, and evaporates them into smoke-like particles and spreads them out, making use of the internal wind tunnel. The wind speed in the wind tunnel is fast, and there is no need to set up an external power source, which reduces energy consumption and improves the reliability of the device. The faster the wind speed in the wind tunnel, the more heat the coil generates, the faster the tracer particles evaporate, and the higher the tracer particle concentration. The release concentration of the tracer particles can be controlled by wind speed to meet the requirements for tracer particle concentration during the experiment. There is no need for manual control and the operation is simple. The heat transfer sheet transfers the heat generated by the coil to the heat-resistant sponge, heats the liquid tracer particles in the heat-resistant sponge and atomizes them into smoke-like particles and spreads them out. The wind in a single direction through the wind tunnel forms a single tracer particle surface, and no tracer particles are generated in the entire wind tunnel space, which avoids the tracer particles outside the laser surface affecting the experimental measurement accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The overall structure schematic diagram of the spreading device of the utility model is shown;

[0020] Figure 2 A schematic cross-sectional structure diagram of the spreading device of the utility model is shown;

[0021] Figure 3 The oblique cross-sectional structure diagram of the spreading device of the utility model is shown (I);

[0022] Figure 4 The oblique cross-sectional structural schematic diagram (II) of the spreading device in the utility model is shown.

[0023] As shown in the figure: 1. Magnetic rod; 2. Coil; 3. Heat transfer sheet; 4. Heat-resistant sponge; 5. Support cover; 6. Pneumatic fan; 7. Particle concentration display. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solution and advantages of the utility model more clear, the utility model is further described in detail in combination with the embodiments below. It should be understood that the specific embodiments described here are only used to explain the utility model, and are not used to limit the utility model.

[0025] Embodiment 1

[0026] In order to solve the technical problems in the background technology, a device for spreading tracer particles in a large wind tunnel PIV technology is provided as follows:

[0027] Combination Figure 1 to Figure 4 As shown, a device for spreading tracer particles in a large wind tunnel PIV technology is provided. The device is suspended longitudinally in a detachable manner in the wind tunnel. The device comprises

[0028] The magnetic bar 1 is a vertically arranged elongated cylindrical structure;

[0029] The coil 2 is a spring-type structure, and its axial gap is sleeved and fitted on the outside of the magnetic rod 1;

[0030] The heat transfer sheet 3 is a tubular structure and is axially attached to the outer side of the coil 2;

[0031] The heat-resistant sponge 4 is a tubular structure, and is axially attached to the outer side of the heat transfer sheet 3. The heat-resistant sponge 4 is used to absorb liquid tracer particles.

[0032] Two fixed support covers 5, which are respectively axially sleeved on the ends of the heat-resistant sponge 4, the ends of the magnetic rod 1 are respectively rotatably connected to the corresponding inner end surfaces of the fixed support covers 5, and the bottom end of the magnetic rod 1 extends to the outside of the corresponding fixed support covers 5;

[0033] The pneumatic fan 6 is axially fixedly sleeved on the bottom end of the magnetic rod 1 .

[0034] By adopting the above technical solution, the spreading device as a whole is a slender rod-shaped structure relative to the experimental wind tunnel. Under the blowing of wind in a single direction of the wind tunnel, the tracer particles in the spreading device form a single tracer particle surface, avoiding the waste caused by spreading tracer particles in a large range in the wind tunnel, saving experimental costs, and reducing the pollution of the wind tunnel and other precision equipment inside by tracer particles. At the same time, it can also effectively avoid the interference of tracer particles on non-laser surfaces in the space; the wind force converted by the pneumatic fan 6 is axially transmitted to the magnetic rod 1, so that the magnetic rod 1 can continue to rotate and cut the coil 2 under the drive of the wind force to generate an induced current. At the same time, the heat generated heats the liquid tracer particles through the heat transfer sheet 3, and evaporates them into smoke-like particles and spreads them out. The wind force inside the wind tunnel is utilized, and there is no need to set up an external power source, which reduces energy consumption and improves the reliability of the device. In addition, the faster the wind speed in the wind tunnel, the more heat is generated by the coil 2, the faster the tracer particles evaporate, and the higher the tracer particle concentration is, so that the release concentration of the tracer particles can be controlled by the wind speed to meet the requirements of the tracer particles during the experiment. The heat transfer sheet 3 transfers the heat generated by the coil 2 to the heat-resistant sponge 4, heats the liquid tracer particles in the heat-resistant sponge 4 and atomizes and spreads them out in the form of smoke-like particles. The wind in a single direction through the wind tunnel forms a single tracer particle surface, and no tracer particles are generated in the entire wind tunnel space, thereby avoiding the tracer particles outside the laser surface from affecting the accuracy of experimental measurement. The heat transfer sheet 3 can effectively disperse the heat generated by the coil 2, thereby avoiding equipment damage caused by local overheating. The fixed support covers 5 at both ends play a limiting support role for each component of the spreading device, ensuring the normal operation of the spreading device, so that the spreading device can spread tracer particles on a single surface in the wind tunnel, thereby achieving high-precision measurement of the fluid flow velocity field. The spreading device can be detachably suspended in the wind tunnel, which is convenient for the installation and maintenance of the spreading device and the adjustment of the position of the spreading device, so that the single tracer particle surface it spreads is in the same plane with the laser surface, thereby reducing the influence of other tracer particles on the experimental measurement.

[0035] Embodiment 2

[0036] Combination Figure 1 to Figure 4 As shown, based on the above embodiment, this embodiment further provides the following contents:

[0037] Combination Figure 1 to Figure 4 As shown, in this embodiment, the heat-resistant sponge 4 is a dense hole structure made of any one of polyimide and polyarylether.

[0038] By adopting the above technical solution, the heat-resistant sponge 4 made of polyimide or polyarylether can maintain the stability of its structural shape in a high temperature environment, avoiding its deformation when the liquid tracer particles are heated, thereby improving the reliability and stability of the device and ensuring the normal use of the tracer particle spreading device.

[0039] Combination Figure 1 to Figure 4 As shown, a plurality of liquid storage holes for absorbing and storing liquid tracer particles are formed in the dense hole structure of the heat-resistant sponge 4 .

[0040] By adopting the above-mentioned technical scheme, the dense pore structure of the heat-resistant sponge 4 provides a large surface area, so that the liquid tracer particles can be quickly and fully adsorbed into the liquid storage holes, avoiding the leakage of the liquid tracer particles at room temperature. At the same time, when heated, the liquid tracer particles can be evenly dispersed through the dense pore structure of the heat-resistant sponge 4 to achieve uniform spreading of the tracer particles; the liquid tracer particles evaporate into an aerosol after being heated, and the diameter of the tracer particle aerosol can be controlled by replacing the heat-resistant sponge 4 with different pore sizes to meet the needs of different wind tunnel experiments, thereby improving the versatility of the spreading device.

[0041] Combination Figure 1 to Figure 4 As shown, the liquid tracer particles are propylene glycol.

[0042] By adopting the above technical scheme, propylene glycol has a low melting point, and can fully utilize the heat generated when the coil 2 generates an induced current to evaporate, and evenly disperse it through the heat-resistant sponge 4, ensuring the normal and uniform spreading of the tracer particles; propylene glycol has good optical transparency, and can provide a clear image together with the fluid medium, and will not interfere with laser irradiation and fluorescence detection; propylene glycol is a non-toxic substance, which is relatively safe to the human body and the environment, ensuring its safety in experimental environments; propylene glycol can be well dispersed in water and is not easy to aggregate or precipitate, ensuring the uniform distribution of tracer particles in the entire flow field, thereby ensuring the acquisition of high-quality PIV images and the accuracy of velocity field data.

[0043] Combination Figure 1 to Figure 4 As shown, a particle concentration display 7 is radially embedded on the outer peripheral surface of the top of the heat-resistant sponge 4.

[0044] By adopting the above technical solution, the particle concentration display 7 can reflect the amount of liquid tracer particles in the spreading device, so as to replenish the liquid tracer particles in time, realize the continuous spreading of tracer particles during the wind tunnel experiment, and ensure the smooth progress of the wind tunnel experiment.

[0045] Combination Figure 1 to Figure 4 As shown, the particle concentration display 7 is a hydraulic sensor.

[0046] By adopting the above technical solution, the hydraulic sensor detects the height of the liquid tracer particles in the heat-resistant sponge 4, and displays different colors on the display screen to reflect the height range of the liquid tracer particles. This can quickly assist in judging whether the storage amount of the tracer particles meets the experimental needs, and can make corresponding supplements to ensure the smooth progress of the wind tunnel experiment.

[0047] The working principle and use process of this utility model:

[0048] First, the spreading device is manually screwed and fixed at a suitable position in the wind tunnel longitudinally. At this time, the spreading device and the laser surface in the wind tunnel experiment are at the same horizontal plane. At the beginning of the experiment, the unidirectional wind in the wind tunnel drives the pneumatic fan 6 to rotate, and then the magnetic bar 1 rotates to cut the coil 2. The induced current is generated in the coil 2 and heat is released at the same time. The heat is transferred to the heat-resistant sponge 4 through the heat transfer sheet 3, and the low-melting-point liquid tracer particles in the liquid storage holes of the heat-resistant sponge 4 are continuously heated, so that the liquid tracer particles evaporate into smoke-like particles, and are evenly and continuously dispersed along the pores of the heat-resistant sponge 4, and then are entrained by the unidirectional wind in the wind tunnel to form a single tracer particle surface in the same plane as the laser surface, and image acquisition can be carried out.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A device for spreading tracer particles in large wind tunnel PIV technology, characterized by: The spreading device is detachably suspended in the wind tunnel longitudinally. The spreading device includes A magnetic bar (1) which is a vertically arranged elongated cylindrical structure; The coil (2) is a spring-type structure, and its axial gap is sleeved and fitted on the outside of the magnetic rod (1); A heat transfer sheet (3) which is a tubular structure and is axially attached to the outside of the coil (2); A heat-resistant sponge (4) having a tubular structure and axially attached to the outside of the heat transfer sheet (3), wherein the heat-resistant sponge (4) is used to absorb liquid tracer particles; Two fixed support covers (5) are respectively axially sleeved on the ends of the heat-resistant sponge (4), the ends of the magnetic rod (1) are respectively rotatably connected to the inner end surfaces of the corresponding fixed support covers (5), and the bottom ends of the magnetic rod (1) extend to the outside of the corresponding fixed support covers (5); A pneumatic fan (6) is axially fixedly sleeved on the bottom end of the magnetic rod (1).

2. The device for spreading tracer particles in a large wind tunnel PIV technique according to claim 1, characterized in that: The heat-resistant sponge (4) is a densely porous structure made of any one of polyimide and polyarylether.

3. The device for spreading tracer particles in a large wind tunnel PIV technique according to claim 2, characterized in that: A plurality of liquid storage holes for absorbing and storing liquid tracer particles are formed in the dense hole structure of the heat-resistant sponge (4).

4. The device for spreading tracer particles in a large wind tunnel PIV technique according to claim 3, characterized in that: The liquid tracer particles are glycerol.

5. The device for spreading tracer particles in a large wind tunnel PIV technique according to claim 4, characterized in that: A particle concentration display (7) is radially embedded on the outer peripheral surface of the top of the heat-resistant sponge (4).

6. The device for spreading tracer particles in a large wind tunnel PIV technique according to claim 5, characterized in that: The particle concentration display (7) is a hydraulic sensor.

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