Wind tunnel PIV tracer particle rapid and uniform cooling mixing device

Abstract

The present invention relates to a wind tunnel PIV tracer particle rapid and uniform cooling mixing device, comprising: a mixing channel section, wherein a mixing channel is provided inside the mixing channel, and the mixing channel is cylindrical; a plurality of first airflow inlets, arranged on the inlet end face of the mixing channel section, and distributed in an annular pattern along the inlet end face of the mixing channel; the center of the annular pattern where the first airflow inlet is located coincides with the axis of the inlet end face of the mixing channel; a second airflow inlet, arranged on the inlet end face of the mixing channel section, and arranged on the axis of the inlet end face of the mixing channel; a third airflow inlet, arranged on the inlet end of the mixing channel section, and arranged tangentially along the radial cross-section of the mixing channel; an airflow outlet, arranged on the outlet end of the mixing channel section; the first, second, and third airflow inlets are connected to the mixing channel. The present invention has the advantages of simple structure and low cost, and can achieve rapid mixing and heat transfer of wind tunnel PIV tracer water particles and avoid large-scale collisions during the mixing process.

Description

Technical Field

[0001] The present invention relates to the technical field of particle image velocimetry, 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. It can measure the effects of airflow on objects and observe physical phenomena. It is the most commonly used and effective equipment for ground-based aerodynamic experiments. Based on 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. To increase the Mach number of the airflow within the wind tunnel, an effective approach is to lower the total temperature to increase the Reynolds number, and thus the Mach number. At the same time, low-temperature transonic wind tunnels are important testing platforms for the development of high-end equipment. To reduce contamination of the internal test equipment during wind tunnel testing, experiments are underway to use clean water as the tracer particle material for PIV tracing. Because low-temperature transonic wind tunnel technology in my country is still in its infancy, there is currently no precedent for the successful engineering application of this technology in China.

[0003] During wind tunnel testing, solid particles or oil mist are commonly used as PIV tracer particles. However, long-term use can cause irreversible contamination inside the wind tunnel. Replacing contaminated components is not only expensive but also places high demands on post-replacement restoration. Water, as a clean material, does not contaminate or damage the wind tunnel. Therefore, using water particles as tracer particles is considered the best alternative to 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. Furthermore, the mixing process between the low-temperature nitrogen flow and the room-temperature nitrogen flow carrying water particles inevitably creates an impact, potentially causing the water particles to coalesce and break up. Conventional tracer ice particle production devices, such as the IV tracer ice particle production system described in Chinese utility model patent CN218901755U, include a water particle generator and an ice particle generation assembly. The water particle generator comprises a tank body, an air inlet pipe, a water storage chamber, and a water particle outlet connected to the upper portion of the chamber. The air inlet pipe extends into the chamber, and the portion of the air inlet pipe located within the chamber is provided with at least one air outlet. The ice particle generation assembly includes a mixing chamber and a cold flow inlet pipe for introducing cooling fluid. The water particle outlet and the cold flow inlet pipe are each connected to the mixing chamber. This can easily lead to the coalescence and breakage of water particles, resulting in damage to the water particles and thus affecting the wind tunnel test results. 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 and 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] To achieve the above-mentioned purpose, the present invention provides a wind tunnel PIV tracer particle rapid and uniform cooling and 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 air flow inlets are provided on the inlet end face of the mixing channel section and are distributed in an annular pattern along the inlet end face of the mixing channel; the center of the annular pattern where the first air flow inlets are located coincides with the axial center of the inlet end face of the mixing channel;

[0009] A second air flow inlet is provided 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, provided at the inlet end of the mixing channel section, wherein the third air flow inlet is provided along a tangential direction of a radial cross section of the mixing channel;

[0011] an air flow outlet, 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 inlet end face 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 vortex channel is formed on the side of the cone close to the axis of the mixing channel, and a second vortex 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 vortex channel, and the third air flow inlet is connected to the second vortex 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 includes:

[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, arranged at an end of the diameter-reducing section away from the mixing channel;

[0022] The diameter-reducing section and the outlet end of the mixing channel are smoothly connected, as are the diameter-reducing section and the outlet section.

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

[0024] temperature sensors, respectively disposed on the inlet and outlet ends of the mixing channel;

[0025] pressure sensors, respectively disposed on the inlet and outlet ends of the mixing channel;

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

[0027] According to a technical solution of the present invention, the method of use includes 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 inlet, connecting a low-temperature nitrogen source to the second air inlet and the third air inlet, and connecting the air outlet to the wind tunnel;

[0031] Step S3: According to the overall back pressure requirement in the wind tunnel, the pressures of the room-temperature nitrogen source containing water particles and the low-temperature nitrogen source are matched, and micron-sized water particles are respectively input into the first air flow inlet, and low-temperature nitrogen is input into the second and third air flow inlets. The room-temperature nitrogen flow containing water particles and the low-temperature nitrogen flow intersect to exchange heat, and the cooled ice particle flow 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 and mixing device provided by the present invention fully utilizes flow and heat transfer theories 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 air flow inlet and a second air flow inlet on the end face of the mixing channel section, wherein the first air flow inlet is distributed in an annular manner and the second air flow inlet is set along the axis of the mixing channel. By setting the positions of the first air flow inlet, the second air flow inlet and the third air flow inlet, the two-phase flow is fully mixed to increase the heat transfer effect. At the same time, the third air flow inlet is set tangentially along the radial cross-section of the mixing channel to form a central interlayer, which can ensure stability during internal movement, reduce turbulence and backflow, and avoid direct contact between water particles and the tube wall during movement. The present invention increases the swirl effect of the axial flow by setting swirl blades on the inner wall of the mixing channel, thereby reducing the problem of particle collision 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 diameter reduction section and an outlet section, which complies with the law of fluid mechanics and can minimize turbulence and collision caused by the reduction of the pipe diameter. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

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

[0039] Figure 2 Schematically showing an axial cross-sectional view of a wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided in another embodiment of the present invention;

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

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

[0042] Figure 5 Schematically showing the distribution diagram of the swirl blades provided in an embodiment of the present invention;

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

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

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

[0046] Figure 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 shown.

[0047] The corresponding relationship between component names and 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. Exit section;

[0051] 61. Cone. DETAILED DESCRIPTION

[0052] The description of the embodiments in this specification should be combined with the corresponding drawings, which should be considered a complete part of this specification. In the drawings, the shapes and thicknesses of the embodiments may be exaggerated and indicated for simplicity or convenience. Furthermore, the various structural components in the drawings will be described separately. It is worth noting that components not shown in the drawings or not described in words are known to those of ordinary skill in the art.

[0053] The description of the embodiments herein and any references to directions and orientations are for ease of description only and are not to be construed as limiting the scope of the present invention. The following description of the preferred embodiments may involve combinations of features, which may exist independently or in combination. The present invention is not specifically 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 therein, and the mixing channel 11 is cylindrical;

[0057] A plurality of first air flow inlets 2 are provided 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;

[0058] The second air flow inlet 3 is provided 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 provided at the inlet end of the mixing channel section 1 , and the third air flow inlet 4 is provided along the tangent direction of the radial cross section of the mixing channel 11 ;

[0060] An air flow outlet 5 is provided 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. 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 maintenance convenience 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 61 is provided on the end face of the channel end plate 6 connected to the mixing channel section 1, and the cones 61 are 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.

[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 mixing channel 11 and disposed within the second swirl channel. The angle α between the radial cross-section of swirl blades 12 and the radius of mixing channel 11 is 30-60°, preferably 45°. The addition of swirl blades can enhance the swirl effect of the axial flow, reducing particle collisions caused by natural settling.

[0068] The wind tunnel PIV tracer particle rapid and uniform cooling mixing device provided by the present invention is designed to fully integrate heat transfer, fluid, and flow theories. It adopts a distributed inlet 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 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 the direction away from the mixing channel 11;

[0072] The outlet section 52 is provided at the 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 and outlet ends of the mixing channel 11;

[0077] The pressure relief valve is connected to the mixing channel 11.

[0078] like Figure 2 As shown, mixing channel section 1 is provided with a first sensor mounting position 13 and a second sensor mounting position 14. These positions are located at the inlet and outlet of mixing channel 11, respectively, for mounting a temperature sensor and a pressure sensor. A pressure relief valve is connected to mixing channel 11 and, based on the pressure sensor's detection results, quickly relieves pressure in mixing channel 11 when excessive pressure is detected.

[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 inlet 2, connecting the low temperature nitrogen source to the second air inlet 3 and the third air inlet 4, and connecting the air outlet 5 to the wind tunnel;

[0082] Step S3: According to the overall back pressure requirement in the wind tunnel, the pressures of the room-temperature nitrogen source containing water particles and the low-temperature nitrogen source are matched. Micron-sized water particles are input into the first air inlet 2, and low-temperature nitrogen is input into the second and third air inlets 3 and 4, respectively. The room-temperature nitrogen flow containing water particles and the low-temperature nitrogen flow intersect for heat exchange. The cooled ice particle flow 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 and heat exchange effect while 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 noted that although the preferred embodiment of the present invention has been described, it is clear that those skilled in the art, once they understand the basic inventive concept of the present invention, can make various improvements and modifications without departing from the principles of the present invention. Such improvements and modifications should also be considered as within the scope of protection of the present invention. Therefore, the appended 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 an annular pattern along the inlet end face of the mixing channel (11); the center of the annular pattern where the first air flow inlets (2) are located coincides with the axial center 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 provided at the inlet end of the mixing channel section (1), and the third air flow inlet (4) is provided along a tangential direction of a radial cross section of the mixing channel (11); An air flow outlet (5) is provided 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 in communication with the mixing channel (11); the first air flow inlet (2) is a normal temperature nitrogen flow inlet containing water particles; the second air flow inlet (3) and the third air flow inlet (4) are low temperature nitrogen flow inlets; It also includes a channel end plate (6) arranged on the inlet end face of the mixing channel section (1), the channel end plate (6) being 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); A conical cylinder (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 conical cylinder (61) is distributed along the circumference of the mixing channel (11); a first swirl channel is formed on the side of the conical cylinder (61) close to the axis of the mixing channel (11), and a second swirl channel is formed on the side of the conical 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 in communication with the first swirl channel, and the third air flow inlet (4) is in communication with the second swirl channel; 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.

2. The device according to claim 1, 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).

3. The device according to claim 1, characterized in that The included angle between the radial cross section of the swirl blade (12) and the radius of the mixing channel (11) is 30-60°.

4. 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).

5. 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) disposed at an end of the diameter-reducing section (51) away from the mixing channel (11); There is a smooth transition connection between the diameter-reducing section (51) and the outlet end of the mixing channel (11), and between the diameter-reducing section (51) and the outlet section (52).

6. The device according to any one of claims 1 to 5, 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 connected to the mixing channel (11).

7. The device according to claim 6, 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 air flow inlet (2), connecting a 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; Step S3, according to the overall back pressure requirement in the wind tunnel, the pressure of the room temperature water particle nitrogen source and the low temperature nitrogen source are matched, micron-sized water particles are input to the first air flow inlet (2), and low temperature nitrogen is input to 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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