Rapid and uniform cooling and mixing device for wind tunnel PIV tracer particles

Abstract

The invention relates to a wind tunnel PIV tracer particle rapid and uniform cooling and mixing device, and the device comprises a mixing channel section which is internally provided with a mixing channel, and the mixing channel is cylindrical; the first airflow inlets are formed in the end face of the inlet end of the mixing channel section and are annularly distributed along the end face of the inlet end of the mixing channel section; the center of the ring where the first airflow inlet is located coincides with the axis of the end face of the inlet end of the mixing channel; the second airflow inlet is formed in the end face of the inlet end of the mixing channel section and is formed in the axis of the end face of the inlet end of the mixing channel; the third airflow inlet is formed in the inlet end of the mixing channel section, and the third airflow inlet is formed in the tangential direction of the radial section of the mixing channel; the airflow outlet is formed in the outlet end of the mixing channel section; the first, second and third airflow inlets are in communication with the mixing channel. The device has the advantages of being simple in structure and low in cost, rapid mixing heat transfer of wind tunnel PIV tracer water particles can be achieved, and large-proportion collision in the mixing process is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of particle image velocimetry, and in particular to a wind tunnel PIV tracer particle rapid and uniform cooling and mixing device. Background Art

[0002] A wind tunnel is a pipe-shaped experimental device that uses the principle of relative motion to artificially generate and control airflow to simulate the flow of gas around an aircraft or object, and can measure the effect of airflow on an object and observe physical phenomena. It is the most commonly used and effective equipment for aerodynamic ground experiments. Since wind tunnels are the country's main strategic resources, the United States regards aerodynamic technology, including wind tunnel technology, as a key technology second only to nuclear technology, and imposes restrictions and blockades on other countries. According to the Mach number of the airflow in the test section, wind tunnels can be divided into low-speed wind tunnels, subsonic wind tunnels, transonic wind tunnels, supersonic wind tunnels and hypersonic wind tunnels. In order to increase the Mach number of the airflow inside the wind tunnel, an effective approach is to increase the Reynolds number by lowering the total temperature, thereby increasing the Mach number. At the same time, low-temperature transonic wind tunnels are important test platforms for the development of high-end equipment. In order to reduce the pollution of internal test equipment during the wind tunnel test process, clean water is tried as the tracer particle material for PIV tracing. Since my country's low-temperature transonic wind tunnel technology is in its infancy, there is currently no precedent for the successful engineering application of such technology in China.

[0003] Solid particles or oil mist are commonly used as PIV tracer particles during wind tunnel testing. Long-term use will cause irreversible contamination inside the wind tunnel. Replacing the contaminated material parts is not only expensive, but also places high demands on the state recovery after replacement. Water, as a clean material, will not cause contamination or damage to the wind tunnel. Therefore, using water particles as tracer particles is considered to be the best solution to replace traditional solid particles or oil mist.

[0004] Low-temperature wind tunnels have relatively high requirements for the temperature and particle size of tracer particles entering the test section, and the low-temperature nitrogen flow and the normal-temperature nitrogen flow carrying water particles will inevitably have an impact during the mixing process, which may cause the water particles to aggregate and break. Traditional tracer ice particle production devices, such as an IV tracer ice particle production system provided by Chinese utility model patent CN218901755U, include a water particle generator and an ice particle generation component; wherein the water particle generator includes a tank body and an air inlet pipe, the tank body includes a cavity for storing water, a water particle outlet connected to the upper part of the cavity, the air inlet pipe extends into the cavity, and the portion of the air inlet pipe located in the cavity is provided with at least one air outlet; the ice particle generation component includes a mixing chamber and a cold flow inlet pipe for introducing a cooling fluid, the water particle outlet and the cold flow inlet pipe are respectively connected to the mixing chamber, and the water particle aggregation and breakage are prone to occur, resulting in the destruction of water particles, which affects the test effect of the wind tunnel. Summary of the invention

[0005] In order to solve the technical problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a wind tunnel PIV tracer particle rapid and uniform cooling mixing device to achieve rapid mixing and heat transfer of wind tunnel PIV tracer water particles and avoid large-scale collisions during the mixing process.

[0006] In order to achieve the above-mentioned purpose of the invention, the present invention provides a wind tunnel PIV tracer particle rapid and uniform cooling mixing device, comprising:

[0007] A mixing channel section, wherein a mixing channel is provided inside the mixing channel, and the mixing channel is cylindrical;

[0008] A plurality of first airflow inlets are arranged on the inlet end face of the mixing channel section and are distributed in an annular shape along the inlet end face of the mixing channel; the center of the annular shape where the first airflow inlets are located coincides with the axial center of the inlet end face of the mixing channel;

[0009] A second air flow inlet is arranged on the inlet end face of the mixing channel section and on the axis of the inlet end face of the mixing channel;

[0010] A third air flow inlet is arranged at the inlet end of the mixing channel section, and the third air flow inlet is arranged along the tangent direction of the radial cross section of the mixing channel;

[0011] An air flow outlet is arranged at the outlet end of the mixing channel section;

[0012] The first air flow inlet, the second air flow inlet and the third air flow inlet are connected to the mixing channel, the first air flow inlet is a room temperature nitrogen flow inlet containing water particles, and the second air flow inlet and the third air flow inlet are low temperature nitrogen inlets.

[0013] According to a technical solution of the present invention, it also includes a channel end plate, which is arranged on the end face of the inlet end of the mixing channel section, and the channel end plate is fixedly connected to the mixing channel section through an end plate flange and bolts; the first air flow inlet and the second air flow inlet are arranged on the channel end plate.

[0014] According to a technical solution of the present invention, a cone is provided on the end face of one end of the channel end plate connected to the mixing channel section, and the cone is distributed along the circumference of the mixing channel; a first swirl channel is formed on the side of the cone close to the axis of the mixing channel, and a second swirl channel is formed on the side of the cone close to the inner wall of the mixing channel, the first air flow inlet and the second air flow inlet are connected to the first swirl channel, and the third air flow inlet is connected to the second swirl channel.

[0015] According to a technical solution of the present invention, the axial cross-section of the cone is triangular, and the tip of the triangle is arranged on a side of the cone close to the axis of the mixing channel.

[0016] According to a technical solution of the present invention, a plurality of swirl blades are provided on the inner wall of the mixing channel, and the swirl blades are arranged in the second swirl channel.

[0017] According to a technical solution of the present invention, the angle between the radial cross section of the swirl blade and the radius of the mixing channel is 30-60°.

[0018] According to a technical solution of the present invention, there are two third air flow inlets, and the two third air flow inlets are symmetrically arranged on the radial cross section of the mixing channel.

[0019] According to a technical solution of the present invention, the air flow outlet comprises:

[0020] The reduced diameter section is in a truncated cone shape, and its inner diameter gradually decreases in a direction away from the mixing channel;

[0021] An outlet section is arranged at an end of the diameter-reducing section away from the mixing channel;

[0022] The reduced diameter section and the outlet end of the mixing channel are connected by a smooth transition, as well as between the reduced diameter section and the outlet section.

[0023] According to a technical solution of the present invention, it also includes:

[0024] Temperature sensors are respectively arranged at the inlet end and the outlet end of the mixing channel;

[0025] Pressure sensors are respectively arranged at the inlet end and the outlet end of the mixing channel;

[0026] A pressure relief valve is communicated with the mixing passage.

[0027] According to a technical solution of the present invention, the method of use comprises the following steps:

[0028] The method of use includes the following steps:

[0029] Step S1, closing the pressure relief valve;

[0030] Step S2, connecting a room temperature nitrogen source containing water particles to the first air flow inlet, connecting a low temperature nitrogen source to the second air flow inlet and the third air flow inlet, and connecting the air flow outlet to the wind tunnel;

[0031] Step S3, according to the overall back pressure requirement in the wind tunnel, match the pressure of the room temperature water particle nitrogen source and the low temperature nitrogen source, input micron-sized water particles to the first air flow inlet respectively, input low temperature nitrogen to the second air flow inlet and the third air flow inlet, the room temperature water particle nitrogen flow and the low temperature nitrogen flow intersect for heat exchange, and the ice particle flow obtained by cooling is transmitted to the wind tunnel through a pipeline for use as PIV tracer particles.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] The wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided by the present invention makes full use of flow and heat transfer theory to achieve rapid heat exchange through the large temperature difference between the cold and hot air flows. At the same time, the device has a simple structure and low cost, which can reduce the damage caused by aggregation and breakage of particles during the cooling process. It is a relatively ideal new method in the field of low-temperature wind tunnel PIV testing and can be applied in engineering, which solves the technical problem of using ice particles as tracer particles.

[0034] The present invention sets a first airflow inlet and a second airflow inlet on the end face of the mixing channel section, wherein the first airflow inlet is distributed in an annular manner and the second airflow inlet is set along the axis of the mixing channel. By setting the positions of the first airflow inlet, the second airflow inlet and the third airflow inlet, the two-phase flow is fully mixed to increase the heat transfer effect. At the same time, the third airflow inlet is set tangentially along the radial cross section of the mixing channel to form a central interlayer, which can ensure the stability during the internal movement, reduce the occurrence of turbulence and backflow, and avoid direct contact between water particles and the tube wall during the movement. The present invention sets swirl blades on the inner wall of the mixing channel to increase the swirl effect of the axial flow, thereby reducing the generation of particle collision problems caused by natural sedimentation.

[0035] In the present invention, temperature and pressure conditions are detected in real time by setting a temperature sensor and a pressure sensor. Once the pressure exceeds the designed threshold, the pressure can be quickly released through the pressure relief valve to ensure the safe operation of the device.

[0036] In the present invention, the air flow outlet adopts a variable diameter outlet structure, including a reduced diameter section and an outlet section, which conforms to the law of fluid mechanics and can minimize the turbulence and collision caused by the reduction of the pipe diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0038] Figure 1 Schematically showing the structure of a wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided in one embodiment of the present invention;

[0039] Figure 2 A schematic diagram of an axial cross-section of a wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided in another embodiment of the present invention is shown;

[0040] Figure 3 A schematic diagram showing the structure of a channel end plate provided in another embodiment of the present invention;

[0041] Figure 4 A schematic diagram of a radial cross-section of a wind tunnel PIV tracer particle rapid uniform cooling mixing device provided in another embodiment of the present invention is shown;

[0042] Figure 5 A schematic diagram showing the distribution of swirl blades provided in an embodiment of the present invention is shown;

[0043] Figure 6 Schematically showing the particle flow direction inside the wind tunnel PIV tracer particle rapid uniform cooling mixing device provided in an embodiment of the present invention;

[0044] Figure 7 Schematically showing the velocity cloud diagram inside the wind tunnel PIV tracer particle rapid uniform cooling mixing device provided in an embodiment of the present invention;

[0045] Figure 8 Schematically showing the internal temperature cloud diagram of the wind tunnel PIV tracer particle rapid uniform cooling mixing device provided in an embodiment of the present invention;

[0046] Fig. 9 A schematic diagram of the outlet particle temperature distribution of a wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided in an embodiment of the present invention is schematically shown.

[0047] The corresponding relationship between the component names and the reference numerals is as follows:

[0048] 1. Mixing channel section; 2. First air flow inlet; 3. Second air flow inlet; 4. Third air flow inlet; 5. Air flow outlet; 6. Channel end plate;

[0049] 11. Mixing channel; 12. Swirl blade; 13. First sensor installation position; 14. Second sensor installation position;

[0050] 51. reduced diameter section; 52. outlet section;

[0051] 61. Cone. DETAILED DESCRIPTION

[0052] The description of the embodiments of this specification should be combined with the corresponding drawings, which should be considered as part of the complete specification. In the drawings, the shape or thickness of the embodiments may be enlarged and indicated for simplification or convenience. Furthermore, the parts of each structure in the drawings will be described separately. It is worth noting that the elements not shown in the drawings or not described in words are in a form known to ordinary technicians in the relevant technical field.

[0053] The description of the embodiments herein and any reference to directions and orientations are only for the convenience of description and are not to be construed as any limitation on the scope of protection of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination, and the present invention is not particularly limited to the preferred embodiments. The scope of the present invention is defined by the claims.

[0054] It should be noted that, in the present invention, the direction along the axis of the mixing channel 11 is the axial direction, and the direction perpendicular to the axial direction is the radial direction.

[0055] like Figure 1 As shown, in one embodiment of the present invention, a wind tunnel PIV tracer particle rapid and uniform cooling mixing device of the present invention comprises:

[0056] The mixing channel section 1 has a mixing channel 11 disposed therein, and the mixing channel 11 is cylindrical;

[0057] A plurality of first airflow inlets 2 are arranged on the inlet end face of the mixing channel section 1 and are distributed in a ring shape along the inlet end face of the mixing channel 11; the center of the ring where the first airflow inlet 2 is located coincides with the axis of the inlet end face of the mixing channel 11;

[0058] The second air flow inlet 3 is arranged on the inlet end face of the mixing channel section 1 and on the axis of the inlet end face of the mixing channel 11;

[0059] The third air flow inlet 4 is arranged at the inlet end of the mixing channel section 1, and the third air flow inlet 4 is arranged tangentially along the radial cross section of the mixing channel 11;

[0060] An air flow outlet 5 is arranged at the outlet end of the mixing channel section 1;

[0061] The first air inlet 2, the second air inlet 3 and the third air inlet 4 are connected to the mixing channel 11, the first air inlet 2 is a room temperature nitrogen inlet containing water particles, and the second air inlet 3 and the third air inlet 4 are low temperature nitrogen inlets.

[0062] In another embodiment of the present invention, Figures 2 to 4As shown, it also includes a channel end plate 6, which is arranged on the inlet end face of the mixing channel section 1, and the channel end plate 6 is fixedly connected to the mixing channel section 1 through an end plate flange and bolts; the first air flow inlet 2 and the second air flow inlet 3 are arranged on the channel end plate 6.

[0063] The channel end plate 6 is detachably connected to the mixing channel section 1, which improves the convenience of maintenance of the wind tunnel PIV tracer particle rapid and uniform cooling mixing device.

[0064] In the embodiment of the present invention, Figure 4 As shown, a cone cylinder 61 is provided on the end face of one end of the channel end plate 6 connected to the mixing channel section 1, and the cone cylinder 61 is distributed along the circumference of the mixing channel 11; a first swirl channel is formed on the side of the cone cylinder 61 close to the axis of the mixing channel 11, and a second swirl channel is formed on the side of the cone cylinder 61 close to the inner wall of the mixing channel 11, the first air flow inlet 2 and the second air flow inlet 3 are connected to the first swirl channel, and the third air flow inlet 4 is connected to the second swirl channel.

[0065] The axial cross section of the cone 61 is triangular, and the tip of the triangle is arranged on a side of the cone 61 close to the axis of the mixing channel 11 .

[0066] By setting the shape of the cone 61, the divergence effect of the airflow entering the mixing channel through the first airflow inlet and the second airflow inlet can be reduced, thereby further improving the mixing cooling effect of the two-phase airflow.

[0067] In some embodiments of the present invention, a plurality of swirl blades 12 are provided on the inner wall of the mixing channel 11, and the swirl blades 12 are arranged in the second swirl channel. The angle α between the radial cross section of the swirl blade 12 and the radius of the mixing channel 11 is 30-60°, preferably 45°. The addition of the swirl blades can enhance the swirl effect of the axial flow and reduce the particle collision problem caused by natural sedimentation.

[0068] The wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided by the present invention is designed to fully combine heat transfer, fluid, and flow theories, and adopts an inlet distributed design to achieve an inner, middle, and outer three-layer flow pattern. The swirl blades are distributed around the inner wall at a certain deflection angle, and can rotate and accelerate the airflow entering from the axial inlet to reduce the sinking and collision of water particles in the interlayer during movement. Even when the flow rate is very high, the internal flow field can ensure a high stability, and regardless of the flow rate, mixed heat transfer can also occur well. The low-temperature nitrogen entering from the inlet on the central axis of the device and the two inlets on the axial direction can not only quickly achieve an internal low-temperature environment, but also the central interlayer formed by the two airflows can achieve stable heat transfer with the maximum effect.

[0069] In some embodiments of the present invention, there are two third air flow inlets 4 , and the two third air flow inlets 4 are symmetrically arranged on the radial cross section of the mixing channel 11 .

[0070] In some embodiments of the present invention, the air flow outlet 5 comprises:

[0071] The reduced diameter section 51 is in a truncated cone shape, and its inner diameter gradually decreases in a direction away from the mixing channel 11;

[0072] The outlet section 52 is arranged at an end of the diameter-reducing section 51 away from the mixing channel 11;

[0073] The diameter-reducing section 51 and the outlet end of the mixing channel 11 , as well as the diameter-reducing section 51 and the outlet section 52 are smoothly connected.

[0074] In some embodiments of the present invention, the apparatus further comprises:

[0075] Temperature sensors are respectively arranged at the inlet and outlet ends of the mixing channel 11;

[0076] Pressure sensors are respectively arranged at the inlet end and the outlet end of the mixing channel 11;

[0077] The pressure relief valve is communicated with the mixing passage 11 .

[0078] like Figure 2 As shown, a first sensor installation position 13 and a second sensor installation position 14 are provided on the mixing channel section 1. The first sensor installation position 13 and the second sensor installation position 14 are respectively provided at the inlet end and the outlet end of the mixing channel 11 for installing a temperature sensor and a pressure sensor. The pressure relief valve is connected to the mixing channel 11, and can quickly relieve the pressure of the mixing channel 11 when the pressure in the mixing channel 11 is too high according to the detection result of the pressure sensor.

[0079] The method for using the wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided by the present invention comprises the following steps:

[0080] Step S1, closing the pressure relief valve;

[0081] Step S2, connecting the room temperature nitrogen source containing water particles to the first air flow inlet 2, connecting the low temperature nitrogen source to the second air flow inlet 3 and the third air flow inlet 4, and connecting the air flow outlet 5 to the wind tunnel;

[0082] Step S3, according to the overall back pressure requirement in the wind tunnel, match the pressure of the room temperature water particle nitrogen source and the low temperature nitrogen source, input micron-sized water particles to the first air flow inlet 2, input low temperature nitrogen to the second air flow inlet 3 and the third air flow inlet 4 respectively, the room temperature water particle nitrogen flow and the low temperature nitrogen flow intersect for heat exchange, and the ice particle flow obtained by cooling is transmitted to the wind tunnel through a pipeline for use as PIV tracer particles.

[0083] like Figures 6 to 9 As shown, through simulation verification, the wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided by the present invention can achieve good mixing heat exchange effect under the premise of ensuring the stability of the internal flow field.

[0084] It should be noted that the above is a preferred embodiment of the present invention. It should be pointed out that although the preferred embodiment of the present invention has been described, once the basic creative concept of the present invention is known, a number of improvements and modifications can be made by a person skilled in the art without departing from the principles of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention. Therefore, the attached claims are intended to be interpreted as including the preferred embodiment and all changes and modifications that fall within the scope of the embodiments of the present invention.

Claims

1. A wind tunnel PIV tracer particle rapid and uniform cooling and mixing device, characterized in that: include: A mixing channel section (1), wherein a mixing channel (11) is provided inside the mixing channel, and the mixing channel (11) is cylindrical; A plurality of first air flow inlets (2) are arranged on the inlet end face of the mixing channel section (1) and are distributed in a ring shape along the inlet end face of the mixing channel (11); the center of the ring where the first air flow inlets (2) are located coincides with the axis of the inlet end face of the mixing channel (11); A second air flow inlet (3) is arranged on the inlet end face of the mixing channel section (1) and on the axis of the inlet end face of the mixing channel (11); A third air flow inlet (4) is arranged at the inlet end of the mixing channel section (1), and the third air flow inlet (4) is arranged tangentially along the radial cross section of the mixing channel (11); An air flow outlet (5) is arranged at the outlet end of the mixing channel section (1); The first air flow inlet (2), the second air flow inlet (3) and the third air flow inlet (4) are connected to the mixing channel (11); the first air flow inlet (2) is a room temperature nitrogen flow inlet containing water particles, and the second air flow inlet (3) and the third air flow inlet (4) are low temperature nitrogen flow inlets.

2. The device according to claim 1, characterized in that It also includes a channel end plate (6) arranged on the inlet end face of the mixing channel section (1), and the channel end plate (6) is fixedly connected to the mixing channel section (1) via an end plate flange and bolts; the first air flow inlet (2) and the second air flow inlet (3) are arranged on the channel end plate (6).

3. The device according to claim 2, characterized in that A cone (61) is provided on the end surface of one end of the channel end plate (6) connected to the mixing channel section (1), and the cone (61) is distributed along the circumference of the mixing channel (11); a first swirl channel is formed on the side of the cone (61) close to the axis of the mixing channel (11), and a second swirl channel is formed on the side of the cone (61) close to the inner wall of the mixing channel (11); the first air flow inlet (2) and the second air flow inlet (3) are connected to the first swirl channel, and the third air flow inlet (4) is connected to the second swirl channel.

4. The device according to claim 3, characterized in that The axial cross section of the cone (61) is triangular, and the tip of the triangle is arranged on a side of the cone (61) close to the axis of the mixing channel (11).

5. The device according to claim 3, characterized in that A plurality of swirl blades (12) are provided on the inner wall of the mixing channel (11), and the swirl blades (12) are arranged in the second swirl channel.

6. The device according to claim 5, characterized in that The angle between the radial cross section of the swirl blade (12) and the radius of the mixing channel (11) is 30-60°.

7. The device according to claim 1, characterized in that There are two third air flow inlets (4), and the two third air flow inlets (4) are symmetrically arranged on the radial cross section of the mixing channel (11).

8. The device according to claim 1, characterized in that The air flow outlet (5) comprises: The reduced diameter section (51) is in a truncated cone shape, and its inner diameter gradually decreases in a direction away from the mixing channel (11); An outlet section (52) is arranged at an end of the diameter-reducing section (51) away from the mixing channel (11); There is a smooth transition connection between the reduced diameter section (51) and the outlet end of the mixing channel (11), and between the reduced diameter section (51) and the outlet section (52).

9. The device according to any one of claims 1 to 8, characterized in that Also includes: Temperature sensors are respectively arranged at the inlet end and the outlet end of the mixing channel (11); Pressure sensors are respectively arranged at the inlet end and the outlet end of the mixing channel (11); A pressure relief valve is communicated with the mixing channel (11).

10. The device according to claim 9, characterized in that The method of use includes the following steps: Step S1, closing the pressure relief valve; Step S2, connecting a room temperature nitrogen source containing water particles to the first airflow inlet (2), connecting a low temperature nitrogen source to the second airflow inlet (3) and the third airflow inlet (4), and connecting the airflow outlet (5) to the wind tunnel; Step S3, according to the overall back pressure requirement in the wind tunnel, the pressures of the room temperature water particle nitrogen source and the low temperature nitrogen source are matched, micron-sized water particles are input into the first air flow inlet (2), and low temperature nitrogen is input into the second air flow inlet (3) and the third air flow inlet (4), the room temperature water particle nitrogen flow and the low temperature nitrogen flow intersect to perform heat exchange, and the ice particle flow obtained by cooling is transmitted to the wind tunnel through a pipeline for use as PIV tracer particles.

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