Double helix air flow mixer and its applications

Abstract

The disclosure provides a double helix airflow mixing device, comprising: an inner ring region comprising a plurality of inner ring blade arrays, each inner ring blade array comprising a plurality of inner ring guide vanes with airflow passages between them, the airflow passages on the same inner ring blade array extending in the same direction, the airflow passages between the plurality of inner ring blade arrays extending in different directions, for mixing the airflow into a first helical airflow; an outer ring region comprising a plurality of outer ring blade arrays and outer ring blocking vanes, each outer ring blade array comprising a plurality of outer ring guide vanes with airflow passages between them, the airflow passages on the same outer ring blade array extending in the same direction, the airflow passages between the plurality of outer ring blade arrays extending in different directions, for mixing the airflow into a second helical airflow opposite in helical direction to the first helical airflow; the outer ring blocking vanes being arranged at an angle to the outer ring guide vanes on opposite sides of each outer ring blade array.

Description

Technical Field

[0001] This disclosure relates to the field of mixers and airflow mixers, and more particularly to a double-helix airflow mixer and its applications. Background Technology

[0002] In experimental methods for cooling and heating of unitary air conditioners, the air enthalpy difference method is commonly used by manufacturing companies for rapid product testing due to its advantages of low investment and fast measurement. The laboratory built based on this method is called an enthalpy difference chamber. The air enthalpy difference method calculates the cooling and heating capacity on both sides by measuring the enthalpy difference between the refrigerant side and the air side separately. Generally, a relative error of no more than 5% between the two sides is considered a reliable experimental result.

[0003] However, due to differences in the design of air mixing and measuring equipment, the air capacity measurement may exceed the allowable error, resulting in erroneous test results. Therefore, accurately measuring the heat exchange capacity of air conditioning heat exchangers and air heat exchangers not only helps in the design and manufacturing of heat exchanger samples, but also avoids energy waste caused by repeated measurements due to measurement errors.

[0004] To avoid erroneous test results due to uneven air temperature, an air mixer is usually installed before the air sampling device. After mixing, the sampled air can represent the average state of the air after heat exchange.

[0005] Therefore, it is crucial to develop a mixer that can achieve good mixing performance under different air volumes and mixing temperature distributions, and has high mixing efficiency and low resistance. Summary of the Invention

[0006] In view of this, in order to at least partially solve at least one of the aforementioned technical problems, this disclosure provides a double-helix airflow mixer and its application.

[0007] According to one embodiment of this disclosure, a dual-helix airflow mixer is provided, comprising:

[0008] The inner ring region includes multiple inner ring blade arrays, wherein each inner ring blade array includes multiple inner ring guide vanes with airflow channels between them. The airflow channels on the same inner ring blade array extend in the same direction, while the airflow channels between the multiple inner ring blade arrays extend in different directions, for mixing the airflow passing through the multiple inner ring blade arrays into a first spiral airflow.

[0009] The outer ring region includes multiple outer ring blade arrays and outer ring deflector blades. Each outer ring blade array includes multiple outer ring deflector blades with airflow channels between them. The airflow channels on the same outer ring blade array extend in the same direction, while the airflow channels between the multiple outer ring blade arrays extend in different directions. This is used to mix the airflow passing through the multiple outer ring blade arrays into a second spiral airflow with a spiral direction opposite to that of the first spiral airflow.

[0010] The outer ring deflector blades are arranged at an angle to the outer ring guide blades on opposite sides of each outer ring blade array.

[0011] According to another aspect of this disclosure, an application of a double-helix airflow mixer as an airflow mixing device in enthalpy difference measurement is provided.

[0012] According to embodiments of this disclosure, the airflow is divided into two parts for mixing by the inner and outer ring regions of the mixer, and two opposing spiral airflows are formed by the inner and outer ring blade arrays, so that the airflow is fully mixed after passing through the mixer. When facing different temperature distribution patterns, the mixing efficiency can be maintained at more than 90%, with a maximum relative error of only 1.8%. It has a high mixing efficiency value and effectively reduces the mixing pressure drop, thus achieving a good mixing effect. Attached Figure Description

[0013] The above and other objects, features and advantages of this disclosure will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0014] Figure 1 This is a front view of the double-helix airflow mixer according to an embodiment of the present invention;

[0015] Figure 2 This is a test diagram of the double-helix airflow mixer according to an embodiment of the present invention;

[0016] Figure 3 This is a three-dimensional schematic diagram of the double-helix airflow mixer according to an embodiment of the present invention;

[0017] Figure 4 This is a schematic diagram showing the characteristic dimensions of the double-helix airflow mixer according to an embodiment of the present invention;

[0018] Figure 5 This is a comparison diagram of the mixing outlet temperature cloud map of the outer ring baffle blades in an embodiment of the present invention;

[0019] Figure 6 This is a schematic diagram of the blade structure according to an embodiment of the present invention;

[0020] Figure 7 This is a diagram showing the relationship between the blade structure and the airflow area in an embodiment of the present invention.

[0021] Figure 8 This is a schematic diagram of the optimized structure of the double-helix airflow mixer according to an embodiment of the present invention;

[0022] Figure 9 The diagram shows the test results of the structural optimization scheme in an embodiment of the present invention.

[0023] Figure 10 This is a schematic diagram of a test bench for a mixer according to an embodiment of the present invention;

[0024] Figure 11 This is a schematic diagram of the thermocouple arrangement on the mixer test bench according to an embodiment of the present invention;

[0025] Figure 12 This is a schematic diagram of the temperature mode of the mixer test bench according to an embodiment of the present invention;

[0026] Figure 13 This is a schematic diagram of the structure of multiple mixers according to an embodiment of the present invention;

[0027] Figure 14 The figures show test results of the structures of multiple mixers according to embodiments of the present invention.

[0028] In the attached diagram:

[0029] 1-Double helical airflow mixer;

[0030] 2-Inner circle area;

[0031] 3-Outer ring area;

[0032] 4-Outer ring baffle blades;

[0033] 5-Sectional baffles;

[0034] 6-Bend;

[0035] 7-Vertical section;

[0036] 9-Electric heater

[0037] 10-Air duct;

[0038] 11-Mixed flow pipe section;

[0039] 12-Thermocouple mesh;

[0040] 13 - Mixer under test;

[0041] 14-Main body of the air intake chamber;

[0042] 15-Static pressure hole;

[0043] 16 - Duct connection;

[0044] 17-Differential pressure transmitter. Detailed Implementation

[0045] The embodiments of the present disclosure will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of the disclosure. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of the present disclosure for ease of explanation. However, it will be apparent that one or more embodiments may be practiced without these specific details. Furthermore, descriptions of well-known structures and techniques are omitted in the following description to avoid unnecessarily obscuring the concepts of the present disclosure.

[0046] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The term "comprising" as used herein indicates the presence of features, steps, or operations, but does not exclude the presence or addition of one or more other features.

[0047] When using expressions such as "at least one of A, B, and C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, and C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). Similarly, when using expressions such as "at least one of A, B, or C," the expression should generally be interpreted in accordance with the meaning commonly understood by a person skilled in the art (e.g., "a system having at least one of A, B, or C" should include, but is not limited to, systems having A alone, having B alone, having C alone, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.).

[0048] It should also be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0049] In realizing this disclosed concept, it was discovered that there are currently many types of mixers, which can be divided into static mixers and dynamic mixers based on their mixing principles. A static mixer is a type of mixer that does not require external energy input during the mixing process. Through a special internal structure, the fluid is thoroughly mixed as it passes through the mixer and its pipes, achieving a uniform mixing effect. It is suitable for mixing low-viscosity fluids. The mixers used in enthalpy difference chambers are mainly static mixers. However, current standards only describe whether mixing is necessary and the mixing method, but do not specify the relevant requirements. Related research also does not address the details of the mixer. Therefore, it is necessary to design a high-efficiency mixer as a benchmark product to supplement relevant standards and research.

[0050] Current research and design of mixers faces challenges. High-efficiency mixers suffer from complex structures and long mixing distances, hindering manufacturing and often limiting mixing distance, thus compromising mixing effectiveness. Simpler mixers, on the other hand, typically only offer good mixing for specific temperature distribution patterns and cannot adapt to variations in temperature distribution caused by changes in airflow or heat exchange components. Therefore, optimization of existing mixer designs is necessary to achieve good mixing efficiency across different airflow temperature distributions over short mixing distances, while also ensuring ease of manufacturing.

[0051] Figure 1 This is a front view of the double-helix airflow mixer according to an embodiment of the present invention; Figure 2 This is a test diagram of the double-helix airflow mixer according to an embodiment of the present invention; Figure 3 This is a three-dimensional schematic diagram of the double-helix airflow mixer according to an embodiment of the present invention; Figure 4 This is a schematic diagram showing the characteristic dimensions of the double-helix airflow mixer according to an embodiment of the present invention.

[0052] Specifically, according to an embodiment of one aspect of this disclosure, such as Figures 1-4 As shown, a double-helix airflow mixer 1 is provided, comprising:

[0053] The inner ring region 2 includes multiple inner ring blade arrays, wherein each inner ring blade array includes multiple inner ring guide vanes with airflow channels between them. The airflow channels on the same inner ring blade array extend in the same direction, while the airflow channels between the multiple inner ring blade arrays extend in different directions, for mixing the airflow passing through the multiple inner ring blade arrays into a first spiral airflow.

[0054] The outer ring region 3 includes multiple outer ring blade arrays and outer ring deflector blades 4. Each outer ring blade array includes multiple outer ring deflector blades with airflow channels between them. The airflow channels on the same outer ring blade array extend in the same direction, while the airflow channels between the multiple outer ring blade arrays extend in different directions. This is used to mix the airflow passing through the multiple outer ring blade arrays into a second spiral airflow with a spiral direction opposite to that of the first spiral airflow.

[0055] Among them, the outer ring baffle blades 4 are arranged at an angle to the outer ring guide blades on opposite sides of each outer ring blade array.

[0056] According to embodiments of the present invention, the inner ring blade array refers to a group of blades arranged in an array, whose main function is to guide and control the flow of air; the inner ring guide vanes refer to individual blades constituting the inner ring blade array, which have airflow channels between them to guide the direction of airflow. The blades on each inner ring blade array extend in the same direction, which can be understood as the blades in the same inner ring blade array having the same tilt direction, or as the blades in the same inner ring blade array having the same tilt angle in the same direction.

[0057] Furthermore, the different extension directions of the airflow channels among the multiple inner blade arrays refer to the fact that the tilt direction or tilt angle of the blades in each inner blade array is different from that of the other inner blade arrays. Thus, the first spiral airflow refers to the spiral airflow formed after the airflow from the multiple inner blade arrays mixes. This airflow is formed because the different extension directions of the airflow channels in the different inner blade arrays cause the airflow to rotate and mix as it passes through these channels, ultimately forming a spiral airflow.

[0058] In some specific embodiments of the present invention, such as Figure 1 The middle arrow indicates the direction of the blades. The blades of each inner ring of the blade array can be arranged clockwise or counterclockwise.

[0059] According to an embodiment of the present invention, the outer ring blade array refers to a group of blades arranged in an array, whose main function is to guide and control the flow of air; the outer ring guide vanes refer to individual blades constituting the outer ring blade array, which have airflow channels between them to guide the direction of airflow. The blades on each outer ring blade array extend in the same direction, which can be understood as the blades in the same outer ring blade array having the same tilt direction, or as the blades in the same outer ring blade array having the same tilt angle in the same direction.

[0060] Furthermore, the different extension directions of the airflow channels among the multiple outer blade arrays refer to the fact that the tilt direction or tilt angle of the blades in each outer blade array is different from that of the other outer blade arrays. The second spiral airflow refers to the spiral airflow formed after the airflow from the multiple outer blade arrays mixes. This airflow is formed because the different extension directions of the airflow channels in the different outer blade arrays cause the airflow to rotate and mix as it passes through these channels, ultimately forming a spiral airflow.

[0061] The outer ring deflector blades 4 are arranged at an angle to the outer ring guide blades on opposite sides of each outer ring blade array.

[0062] According to an embodiment of the present invention, the outer ring baffle blades 4 are disposed on opposite sides of each outer ring blade array, and can work together with each outer ring blade array in the outer ring region to form a second spiral airflow. Since the span between the outer ring blade arrays is large, unlike the close proximity between the inner ring blade arrays, the mixing effect in the outer ring region can be enhanced by the outer ring baffle blades 4, thereby forming a second spiral airflow that can be uniformly mixed with the first spiral airflow.

[0063] Figure 5 This is a comparison diagram of the mixing outlet temperature cloud map of the outer ring baffle blades in an embodiment of the present invention.

[0064] according to Figure 5 It can be seen that after adding the outer ring baffle blade 4, the temperature of the airflow passing through the double helical airflow mixer can be more uniform. According to the temperature cloud map comparison, the temperature difference between hot and cold is smaller, achieving better mixing effect and higher mixing efficiency. At the same time, the mixing of the two helical airflows can be seen.

[0065] In some specific embodiments of the present invention, such as Figure 1 The middle arrow indicates the direction of airflow channel extension, or the orientation of the blades. The airflow channels of each outer ring blade array can be arranged clockwise or counterclockwise, while the airflow channels of each inner ring blade array can be arranged in the opposite direction to the inner ring blade array.

[0066] Furthermore, by setting the airflow channels of the outer and inner blade arrays in opposite directions, the inner and outer blade arrays can form two opposing spiral airflows, thereby enabling the airflow passing through the mixer to be mixed more thoroughly and evenly.

[0067] According to an embodiment of the present invention, the airflow is divided into two parts for mixing by the inner and outer ring regions of the mixer, and two opposing spiral airflows are formed by the inner and outer ring blade arrays, so that the airflow is fully mixed after passing through the mixer. When facing different temperature distribution patterns, the mixing efficiency can be maintained at more than 90%, and the maximum relative error is only 1.8%.

[0068] According to an embodiment of the present invention, the partition baffle 5 is used to separate the individual inner ring blade arrays.

[0069] In some embodiments of the present invention, partition baffles 5 are disposed between each inner ring blade array and on the outer periphery of the entire inner ring region 3.

[0070] According to an embodiment of the present invention, a partition baffle 5 is disposed between each inner ring blade array, separating the individual inner ring blade arrays and allowing independent control of the airflow in each array. This improves the accuracy and efficiency of airflow mixing. By separating the individual blade arrays, the partition baffle helps to form more complex airflow patterns between different arrays, which enhances the airflow mixing effect and makes the formation of the first spiral airflow more uniform and stable. Simultaneously, the partition baffle can optimize the airflow distribution within the blade array, reducing airflow turbulence and losses, and improving the efficiency and performance of the entire system.

[0071] Figure 6 This is a schematic diagram of the blade structure according to an embodiment of the present invention.

[0072] According to embodiments of the present invention, such as Figure 6 As shown, each blade in the multiple inner ring blade array and the multiple outer ring blade array has a vertical portion 6 and a bent portion 7, wherein the bent portion is located downstream of the vertical portion in the airflow inlet direction; and

[0073] The vertical section is configured to extend in the air intake direction;

[0074] The bend is set at a first tilt angle in the airflow intake direction.

[0075] According to an embodiment of the present invention, the vertical part 6 and the bent part 7 can increase the flow area of ​​the mixer, effectively reduce the mixing pressure drop, and at the same time, when the mixer structure changes, the blade spacing can be changed without changing the thickness of the mixer due to the design of the bent blades, while the thickness of the mixer remains unchanged and the structure of the outer ring baffle blades remains unchanged, so the function of the outer ring baffle blades 4 remains consistent before and after.

[0076] In some specific embodiments of the present invention, such as Figure 4 As shown in the schematic diagram, in the orthographic projection of each blade in the direction of its blade array, the widths of the projections of the bent portion 6 and the vertical portion 7 are the same, and the spacing between them and the two adjacent blades is the same.

[0077] According to an embodiment of the present invention, in the orthographic projection of each blade in the direction of its respective blade array, the widths of the projections of the bent portion 6 and the vertical portion 5 are respectively... Figure 4 In the diagram, D1 and D2 are adjacent to each other, and the distance between two adjacent blades is D3.

[0078] Figure 7 This is a diagram showing the relationship between the blade structure and the airflow area in an embodiment of the present invention.

[0079] According to an embodiment of the present invention, based on Figure 7 It can be seen that when the blade structure D1 and D2 are changed, and the spacing between two adjacent blades, D3, is also changed, the mixing efficiency remains unchanged when the blade spacing D3 is kept consistent with D1. However, due to the bending of the blades, the flow area of ​​the mixer is increased, which can effectively reduce the mixing pressure drop. Considering the influence of the mixing blade thickness, keeping D1 and D3 consistent, and using the spacing D3 between two adjacent blades of the mixer as a variable, we can derive D1 and D3 that maximize the flow area.

[0080] Preferably, according to Figure 7 It can be seen that the optimal flow area percentage is about 45.53% when D1(D3) = 0.036Dh (18mm), while it is 45.03% when D1(D3) = 0.05Dh (25mm). The difference between the two is only 1.1%. Considering lightweighting and ease of processing, the final design dimensions of D1 and D3 are 0.05Dh.

[0081] Figure 8 This is a schematic diagram of the optimized structure of the double-helix airflow mixer according to an embodiment of the present invention; Figure 9 The diagram shows the test results of the structural optimization scheme in an embodiment of the present invention.

[0082] exist Figure 8 In the optimization schemes, schemes A (including schemes A1 to A7), B (including schemes B1 to B7), X (including schemes X1 to X5), Y (including schemes Y1 to Y3), and Z (including schemes Z1 to Z3) are optimized.

[0083] In some specific embodiments of the present invention, the angle of the first tilt angle α includes 30° to 60°.

[0084] According to some specific embodiments of the present invention, all blades in the double helical airflow mixer 1 have the same structure.

[0085] According to embodiments of the present invention, such as Figure 8 As shown, by changing only the first tilt angle α, the mixer can maintain a high mixing efficiency. Figure 9 As shown.

[0086] according to Figure 9 It can be seen that changing the first tilt angle α of the inner and outer blades within the range of 30° to 60° can achieve a high mixing efficiency.

[0087] Preferably, once the first tilt angle α of the blade exceeds 45°, the mixing efficiency no longer changes significantly, and 45° is the optimal first tilt angle of the blade.

[0088] According to an embodiment of the present invention, the included angle β of the outer ring deflector blade 4 is set at 40°~45° in the airflow inlet direction.

[0089] According to an embodiment of the present invention, by changing only the included angle of the outer ring guide vanes, the mixer can maintain a high mixing efficiency. Figure 9 As shown.

[0090] according to Figure 9 It can be seen that the double-helix airflow mixer can achieve good mixing efficiency when the included angle β of the outer ring guide vane 4 is set within the range of 40°~45° in the airflow inlet direction.

[0091] Preferably, when the included angle β of the outer ring guide vane 4 exceeds 45°, the mixing efficiency no longer changes significantly, and 45° is the preferred included angle of the outer ring guide vane 4.

[0092] In some specific embodiments of the present invention, the mixer is square in the orthographic projection of the airflow inlet direction.

[0093] According to an embodiment of the present invention, the double-helix airflow mixer can be configured as a square or a rectangle, wherein the width Dh of the mixer refers to the side length of the square or the shorter side length of the rectangle.

[0094] According to an embodiment of the present invention, the length of each blade in the plurality of outer ring blade arrays is 0.2 to 0.3 times the width of the mixer.

[0095] According to an embodiment of the present invention, the length of each blade in the plurality of inner blade arrays is 0.1 to 0.3 times the width of the mixer.

[0096] According to an embodiment of the present invention, the length of each blade in the outer ring blade array is the outer ring characteristic dimension Dy, and the length of each blade in the inner ring blade array is the inner ring characteristic dimension Dn. If the inner ring structure Dn of the mixer is modified, Dy will change accordingly, as shown below. Figure 9 As shown.

[0097] Preferably, according to Figure 9It can be seen that when Dn = 0.3Dh (150mm), the mixer has a high mixing efficiency. 0.3Dh is the optimal structural parameter for the inner ring of the mixer.

[0098] According to an embodiment of the present invention, the thickness of the mixing fluid in the airflow inlet direction is 0.2 to 0.3 times the width of the mixer.

[0099] According to embodiments of the present invention, such as Figures 8-9 As shown, the thickness Dt of the mixer was structurally optimized. It was found that when Dt was reduced to be equal to D1, D2=0, and the mixing efficiency would decrease. Therefore, Dt was not changed and was kept at Dt=0.1Dh.

[0100] More preferably, the characteristic dimensions of the double-helix airflow mixer are Dt=0.1Dh, D1=D2=D3=0.05Dh, Dn=0.3Dh, Dy=0.2Dh, and α=β=45°.

[0101] As another aspect of the present invention, it also includes the application of the double-helix airflow mixer as an airflow mixing device in enthalpy difference measurement.

[0102] According to embodiments of the present invention, the double-helix airflow mixer of the present invention has a high mixing efficiency, reaching 90%, and a relative error of only about 1%. It maintains high mixing efficiency under different airflow and different mixing temperature distribution modes, while the mixing pressure drop is low. It can meet the requirement that the enthalpy difference chamber mixer has a good mixing effect under different airflow and different mixing temperature distribution conditions.

[0103] Figure 10 This is a schematic diagram of a test bench for a mixer according to an embodiment of the present invention; Figure 11 This is a schematic diagram of the thermocouple arrangement on the test bench for the mixer according to an embodiment of the present invention; Figure 12 This is a schematic diagram of the temperature mode of the mixer test bench according to an embodiment of the present invention.

[0104] According to an embodiment of the present invention, the mixing efficiency is measured by means of, for example Figures 10-12 The mixer structure shown was tested on a test bench, and measurements were taken using the following methods: Figure 9 The enthalpy difference was measured and calculated using the thermocouple arrangement shown, as described above. Figure 10 The temperature patterns shown are used to test mixing efficiency under various temperature modes. (The text repeats itself here, so the translation will only include the first instance.) Figure 8 The device shown is tested. The airflow is heated by the electric heater 9 and then enters the mixing pipe section 11 through the air duct 10. Thermocouple meshes 12 are installed at both ends of the mixing pipe section 11 to measure the inlet and outlet air temperatures of the mixing pipe section 11. The mixing device 13 to be tested is located downstream of the thermocouple meshes 12 at the air inlet of the mixing pipe section 11.

[0105] Figure 13 This is a schematic diagram of the structure of multiple mixers according to an embodiment of the present invention; Figure 14 The diagram shows the test results of the structures of multiple mixers in embodiments of the present invention.

[0106] exist Figure 13 In the present invention, structures 1 to 4 are comparative flow mixer structures, structures 5 to 8 are double-helix airflow mixers, wherein structure 5 is a comparative flow mixer without outer ring baffles, and structures 6 to 8 are double-helix airflow mixers of the present invention with outer ring baffles.

[0107] according to Figure 14 It can be seen that the double-helix airflow mixers set in this invention have high mixing efficiency and can effectively reduce the mixing pressure drop, thus having a good mixing effect.

[0108] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A double helical flow mixer, comprising: an inner ring region comprising a plurality of inner ring blade arrays, wherein each of the inner ring blade arrays comprises a plurality of inner ring guide vanes with air flow passages between them, the air flow passages on the same inner ring blade array have the same extension direction, the air flow passages between the plurality of inner ring blade arrays have different extension directions, and the plurality of inner ring blade arrays are configured to mix air flow passing through the plurality of inner ring blade arrays into a first helical flow; an outer ring region comprising a plurality of outer ring blade arrays and outer ring baffle vanes, wherein each of the outer ring blade arrays comprises a plurality of outer ring guide vanes with air flow passages between them, the air flow passages on the same outer ring blade array have the same extension direction, the air flow passages between the plurality of outer ring blade arrays have different extension directions, and the plurality of outer ring blade arrays are configured to mix air flow passing through the plurality of outer ring blade arrays into a second helical flow opposite to the first helical flow in the helical direction; wherein the outer ring baffle vanes are arranged at an angle to the outer ring guide vanes on opposite sides of each of the outer ring blade arrays; and the mixer is square in the orthographic projection in the air flow inlet direction; the length of each blade in the plurality of outer ring blade arrays is 0.2-0.3 times the width of the mixer.

2. The mixer of claim 1, wherein further comprising: partition baffles for partitioning each of the inner ring blade arrays. 3.The mixer of claim 1, wherein each blade in the plurality of inner ring blade arrays and the plurality of outer ring blade arrays has a vertical portion and a bent portion, wherein the bent portion is arranged downstream of the vertical portion in the air flow inlet direction; and the vertical portion is configured to extend in the inlet direction; the bent portion is arranged at a first inclination angle in the air flow inlet direction. 4.The mixer of claim 3, wherein the angle of the outer ring guide vanes comprises 40-45° in the air flow inlet direction; the first inclination angle comprises 30-60°. 5.The mixer of claim 3, wherein in the orthographic projection of each blade in the direction of the blade array, the width of the projection of the bent portion and the vertical portion is the same as the spacing between adjacent two blades. 6.The mixer of claim 1, wherein the length of each blade in the plurality of inner ring blade arrays is 0.1-0.3 times the width of the mixer. 7.The mixer of claim 1, wherein the thickness of the mixer in the air flow inlet direction is 0.2-0.3 times the width of the mixer. 8.Use of the double helical flow mixer according to any one of claims 1-7 as an air flow mixing device in enthalpy difference measurement.

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