Wind tunnel flow field total temperature measuring device and measuring system thereof

Abstract

The utility model discloses a wind tunnel flow field total temperature measuring device and a measuring system thereof, the measuring device comprises a stagnation chamber, a thermocouple assembly and a support part, and the support part is internally provided with a through wiring channel; the stagnation chamber is of a cylindrical structure, one end of the stagnation chamber is an open end, the other end of the stagnation chamber is fixedly connected with the supporting part, and overflow holes are formed in the side wall, close to the supporting part, of the stagnation chamber in the circumferential direction. The thermocouple assembly comprises a first thermocouple wire and a second thermocouple wire which are made of different materials, and the first thermocouple wire and the second thermocouple wire are arranged in a channel, communicated with the wiring channel, of the stagnation chamber; one end of the first thermocouple wire and one end of the second thermocouple wire are connected to form a contact, and the contact is arranged on the axis in the stagnation chamber between the open end and the overflow hole; the thermocouple assembly is fixed at the joint of the stagnation chamber and the supporting part through the fixing part, and one end, located in the stagnation chamber, of the fixing part is a closed end. The measuring device provided by the utility model solves the technical problem that the thermocouple wire is easy to damage in the prior art.

Description

Technical Field

[0001] This utility model belongs to the field of airflow total temperature measurement technology, specifically relating to a wind tunnel flow field total temperature measurement device and its measurement system. Background Technology

[0002] Because high-speed pulse wind tunnels operate for very short periods, typically less than 500ms, determining the total temperature of the flow field within this short time is a significant challenge in wind tunnel calibration. Traditional temperature sensors generally have response times in the second range and can only measure the static temperature of the flow field, failing to meet the requirements for measuring the total temperature of the wind tunnel flow field. Chinese invention patent application publication number CN108917963A discloses a fast-response, high-precision total temperature thermocouple head structure, including a protective sheath, an insulating layer, two thermocouple wires of different materials, and a wire junction. The windward side of the wire junction includes a planar or concave airflow stagnation structure. This invention uses the wire junction as an incoming flow stagnation chamber, and the thermocouple wires are installed perpendicular to the high-temperature, high-speed airflow. During use, the thermocouple wires have a large stress area, making them prone to damage. If thicker thermocouple wires are used to meet strength requirements, the response time will be longer, failing to meet the application requirements. Utility Model Content

[0003] In view of the existing technical problems, the present invention aims to provide a wind tunnel flow field total temperature measuring device and its measuring system, which can solve the technical problem of easy damage to thermocouple wires in the prior art.

[0004] To achieve the above objectives, the technical solution adopted by this utility model is as follows:

[0005] A wind tunnel flow field total temperature measurement device, characterized by the following structural features: It includes a stagnation chamber, a thermocouple assembly, and a support portion, the support portion having a through-flow channel; the stagnation chamber is a cylindrical structure, one end of which is open, and the other end is fixedly connected to the support portion, and the stagnation chamber is connected to the wiring channel; at least one overflow hole is provided circumferentially on the side wall of the stagnation chamber near the support portion; the thermocouple assembly includes a first thermocouple wire and a second thermocouple wire of different materials, which are disposed within the channel connecting the stagnation chamber and the wiring channel; one end of the first thermocouple wire and the second thermocouple wire are connected to form a contact point, which is located on the axis of the stagnation chamber between the open end and the overflow hole; the outer ends of the first thermocouple wire and the second thermocouple wire are disposed along the wiring channel; the thermocouple assembly is fixed to the connection between the stagnation chamber and the support portion by a fixing part, the fixing part being a closed end located at one end of the stagnation chamber.

[0006] When using the wind tunnel flow field total temperature measurement device of this application, the device is fixed within the uniform airflow zone at the nozzle outlet of the wind tunnel equipment, with the stagnation chamber's axis parallel to the nozzle's axis. The outer ends of the first and second thermocouple wires are connected to a data acquisition module to form a closed loop. This data acquisition module is an existing product and can be a temperature transmitter, etc. High-speed, high-temperature airflow enters the stagnation chamber through the open end and exits through the overflow hole. Through the cooperation of the stagnation chamber and the overflow hole, the high-speed, high-temperature airflow forms a shock wave that stagnates at the junction of the thermocouple wires. At this stagnation point, the airflow velocity is essentially zero, and according to the law of conservation of energy, all the airflow kinetic energy is converted into internal energy (temperature). Because the first and second thermocouple wires are made of different materials, a voltage is generated after sensing a temperature change at the junction. This voltage is transmitted to the data acquisition module to form a measurement signal, thereby achieving rapid measurement of the total temperature of the high-temperature, high-speed airflow. This invention relates to a wind tunnel flow field total temperature measurement device with a stagnation chamber. This chamber stagnates the airflow as it passes through the junctions, preventing damage to the thermocouple wires and their junctions, thus enabling the measurement of the total temperature of the wind tunnel flow field. An overflow hole is used to discharge the airflow, preventing shock wave reflection and propagation from interfering with the airflow stagnation area at the thermocouple wire junctions, which would otherwise result in low temperature measurement accuracy. The materials of the first and second thermocouple wires can be selected according to the temperature of the measured airflow, enabling measurements across different temperature ranges, thus making it widely applicable to various temperature stages.

[0007] Preferably, the stagnation chamber is a cylindrical structure with an inner diameter of D1 and a distance of L1 between the contact point and the opening end, where L1 = 2D1 to 3D1. By setting the position of the contact point, the impact on the total temperature measurement results of the wind tunnel flow field is reduced.

[0008] Preferably, the distance between the overflow hole and the fixing part is L2, where L2 = 0.27D1 to 0.4D1; the distance between the overflow hole and the contact point is L3, where L3 = 0.44D1 to 0.58D1. By setting the position of the overflow hole, the influence on the total temperature measurement results of the wind tunnel flow field is reduced.

[0009] Preferably, multiple overflow holes are provided, and the ratio of the sum of the areas of the multiple overflow holes to the inlet area of ​​the open end is 0.1 to 0.2. The airflow velocity in the stagnation chamber has a significant impact on the total temperature measurement results of the wind tunnel flow field. The airflow velocity in the stagnation chamber depends on the ratio of the overflow hole area to the stagnation chamber inlet area, and this area ratio should be controlled between 0.1 and 0.2.

[0010] Preferably, the diameters of the first and second thermocouple wires are equal, both being D2, where D2 = 0.2–0.3 mm. By setting the diameters of the first and second thermocouple wires, the impact on the total temperature response time of the wind tunnel flow field is reduced.

[0011] Preferably, the diameter of the contact is The junction can be formed by welding the first thermocouple wire and the second thermocouple wire.

[0012] Preferably, the wall thickness of the stagnation chamber is no more than 0.5 mm. The outer wall thickness of the stagnation chamber should be as thin as possible, as the airflow will radiate heat onto the outer shell of the stagnation chamber when passing through it, and thermal equilibrium needs to be reached as quickly as possible to reduce measurement errors.

[0013] Preferably, the fixing part includes an insulating tube disposed at the connection between the stagnation chamber and the support part; the first thermocouple wire and the second thermocouple wire pass through the insulating tube, and the passage is filled with sealant. Sealant is also filled between the outer wall of the insulating tube and the stagnation chamber, and between the outer wall of the insulating tube and the support part. The insulating tube can be made of ceramic, and the sealant can be a high-temperature adhesive resistant to at least 100°C. By setting up the insulating tube and sealant, the rear lead-out portions of the first and second thermocouple wires are isolated and sealed, reducing the impact on the measurement results.

[0014] Preferably, the outer wall of the end of the support unit connected to the stagnation chamber is provided with a guide surface, the diameter of which gradually increases in the direction away from the stagnation chamber, and a connector is provided at the outer end of the support unit. The connector facilitates the fixing of the support unit; it can be a structure that facilitates connection, such as an external thread or a snap-fit. By providing a guide surface, the airflow outside the measuring device is guided, preventing the airflow from affecting the measuring device.

[0015] Based on the same inventive concept, this application also provides a wind tunnel flow field total temperature measurement system, including a wind tunnel equipment nozzle, wherein the wind tunnel equipment nozzle outlet airflow uniform zone is provided with the wind tunnel flow field total temperature measurement device as described above, the axis of the stagnation chamber is parallel to the axis of the wind tunnel equipment nozzle, and the outer ends of the first thermocouple wire and the second thermocouple wire are connected to the data acquisition module.

[0016] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0017] 1. The wind tunnel flow field total temperature measurement device of this utility model solves the problem of easy damage to thermocouple wires by setting a stagnation chamber, which causes the airflow to be stagnant when passing through the junction inside the stagnation chamber.

[0018] 2. The wind tunnel flow field total temperature measurement device of this utility model, by setting up a stagnation chamber, makes the high-speed airflow form a stagnation area at the thermocouple assembly, and measures the total temperature of the high-speed airflow by thermocouple in the stagnation area, so as to realize the rapid and accurate measurement of the total temperature of the airflow in the high-speed airflow.

[0019] 3. The wind tunnel flow field total temperature measurement device of this utility model has a simple structure. The materials of the first thermocouple wire and the second thermocouple wire can be selected according to the different temperatures of the measured airflow to realize the measurement of different temperature ranges, thus making it widely applicable to various temperature stages. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the wind tunnel flow field total temperature measurement device of this utility model.

[0021] In the figure

[0022] 1-Stagnation chamber; 101-Open end; 102-Overflow hole; 2-Thermocouple assembly; 201-First thermocouple wire; 202-Second thermocouple wire; 203-Contact; 3-Support part; 301-Wire routing channel; 302-Guide surface; 303-Connector; 4-Fixing part; 401-Insulating tube; 402-Sealant. Detailed Implementation

[0023] The present invention will be described in detail below with reference to the accompanying drawings and embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other. For ease of description, the terms "upper," "lower," "left," and "right" appearing below only indicate that they correspond to the upper, lower, left, and right directions in the accompanying drawings and do not limit the structure.

[0024] like Figure 1 As shown, the wind tunnel flow field total temperature measurement device of this embodiment includes a stagnation chamber 1, a thermocouple assembly 2, and a support 3. The support 3 has a through-hole wiring channel 301 with a diameter D1 of 3.6 mm. The stagnation chamber 1 is a cylindrical structure with a wall thickness of 0.2–0.3 mm, an outer diameter of 5.1 mm, and an inner diameter of 4.5 mm. The left end of the stagnation chamber 1 is an open end 101, and the right end of the stagnation chamber 1 is fixedly connected to the support 3. The inner cavity of the stagnation chamber 1 communicates with the wiring channel 301. Four overflow holes 102 with a diameter of 0.9 mm are circumferentially provided on the side wall of the stagnation chamber 1 near the support 3. Thermocouple assembly 2 includes a first thermocouple wire 201 and a second thermocouple wire 202 made of different materials. The first thermocouple wire 201 is made of platinum-rhodium 30 material, and the second thermocouple wire 202 is made of platinum-rhodium 6 material. The first thermocouple wire 201 and the second thermocouple wire 202 have the same diameter, D2, which is 0.2-0.3 mm. The first thermocouple wire 201 and the second thermocouple wire 202 are disposed in a channel connecting the stagnation chamber 1 and the wiring channel 301. One end of the first thermocouple wire 201 and the second thermocouple wire 202 are welded together to form a contact 203, the diameter of which is [missing information]. Contact 203 is located on the axis within the stagnation chamber 1 between the open end 101 and the overflow hole 102. The outer ends of the first thermocouple wire 201 and the second thermocouple wire 202, i.e., the other ends of the first thermocouple wire 201 and the second thermocouple wire 202, are arranged along the wiring channel 301, and these ends are used to connect to the data acquisition module. The horizontal distance between contact 203 and the open end 101 is 11 mm, and the horizontal distance between contact 203 and the overflow hole 102 is 2.3 mm. Thermocouple assembly 2 is fixed to the connection between the stagnation chamber 1 and the support part 3 by fixing part 4. One end of fixing part 4 in the stagnation chamber 1 is a closed end, and the horizontal distance between the overflow hole 102 and the end of fixing part 4 is 1.5 mm. Fixing part 4 includes an insulating tube 401, which is disposed within the connection between the stagnation chamber 1 and the support part 3. The first thermocouple wire 201 and the second thermocouple wire 202 pass through the insulating tube 401, and the passage is sealed with sealant 402. The outer wall of the insulating tube 401 is also sealed with sealant 402 between it and the stagnation chamber 1, and between it and the support portion 3. The insulating tube 401 is made of ceramic, and the sealant 402 is a high-temperature sealant resistant to 100℃. The outer wall of the end of the support portion 3 connected to the stagnation chamber 1 has a guide surface 302, the diameter of which gradually increases in the direction away from the stagnation chamber 1. The guide surface 302 is a frustum, with a major diameter of 15mm, and a horizontal distance of 26.77mm between the major diameter of the frustum and the opening end 101. The outer end of the support portion 3 has a diameter of 6.6mm, and a connector 303 with an M6 external thread is provided on this end.

[0025] This embodiment also provides a wind tunnel flow field total temperature measurement system, including a wind tunnel equipment nozzle. The wind tunnel equipment nozzle outlet airflow uniform zone is provided with the wind tunnel flow field total temperature measurement device as described above. The measurement device can be fixedly connected to a fixed end set in the wind tunnel flow field by a thread. The axis of the stagnation chamber 1 is parallel to the axis of the wind tunnel equipment nozzle. The outer ends of the first thermocouple wire 201 and the second thermocouple wire 202 are connected to the data acquisition module to form a closed loop.

[0026] High-speed, high-temperature airflow enters the stagnation chamber 1 through the opening 101 and exits through the overflow hole 102. Through the interaction of the stagnation chamber 1 and the overflow hole 102, the high-speed, high-temperature airflow forms a shock wave that stagnates at the junction 203 of the thermocouple wires. At this stagnation point, the airflow velocity is essentially zero, and according to the law of conservation of energy, all the kinetic energy of the airflow is converted into internal energy (temperature). Due to the different materials of the first thermocouple wire 201 and the second thermocouple wire 202, a voltage is generated at the junction 203 after sensing a temperature change. This voltage is transmitted to the data acquisition module to form a measurement signal, thereby enabling rapid measurement of the total temperature of the high-temperature, high-speed airflow. The basic principle of temperature measurement using the thermocouple assembly 2 is the Seebeck effect. When two different conductors (or semiconductors) A and B form a closed circuit, and their junctions are at different temperatures, a thermoelectric potential is generated in the circuit. This phenomenon is called the Seebeck effect. The magnitude of the thermoelectric potential is proportional to the temperature difference at the junctions. By collecting the potential difference and combining it with the temperature characteristic curve of the thermocouple wires used, the total temperature of the incoming flow is determined. By setting an overflow hole 102 to discharge the airflow, it prevents shock wave reflection and forward propagation from interfering with the airflow stagnation area at the thermocouple wire junction 203, thus avoiding low temperature measurement accuracy. The materials of the first thermocouple wire 201 and the second thermocouple wire 202 can be selected according to the different temperatures of the measured airflow, enabling measurements within different temperature ranges, thus making it widely applicable to various temperature stages. Verification has shown that this total temperature measurement system can measure a maximum total temperature of 2000K with a response time of approximately 10ms, meeting the requirements for measuring the total temperature of high-temperature, high-speed airflows.

[0027] The above embodiments should be understood as being used only to illustrate the utility model more clearly, and not to limit the scope of the utility model. After reading this utility model, any modifications of the embodiments by those skilled in the art in various equivalent forms fall within the scope defined by the appended claims.

Claims

1. A wind tunnel flow field total temperature measurement device, characterized in that: It includes a stagnation chamber (1), a thermocouple assembly (2) and a support (3), wherein the support (3) is provided with a through wiring channel (301); The stagnation chamber (1) is a cylindrical structure. One end of the stagnation chamber (1) is an open end (101), and the other end of the stagnation chamber (1) is fixedly connected to the support part (3). The stagnation chamber (1) is connected to the wiring channel (301). At least one overflow hole (102) is provided on the side wall of the stagnation chamber (1) near the support part (3) in the circumferential direction. The thermocouple assembly (2) includes a first thermocouple wire (201) and a second thermocouple wire (202) of different materials. The first thermocouple wire (201) and the second thermocouple wire (202) are arranged in the channel connecting the stagnation chamber (1) and the wiring channel (301). One end of the first thermocouple wire (201) and the second thermocouple wire (202) are connected to form a contact (203). The contact (203) is located on the axis of the stagnation chamber (1) between the open end (101) and the overflow hole (102). The outer ends of the first thermocouple wire (201) and the second thermocouple wire (202) are arranged along the wire routing channel (301). The thermocouple assembly (2) is fixed at the connection between the stagnation chamber (1) and the support (3) by a fixing part (4), and the fixing part (4) is a closed end at one end of the stagnation chamber (1).

2. The wind tunnel flow field total temperature measurement device according to claim 1, characterized in that: The stagnation chamber (1) is a cylindrical structure with an inner diameter of D1 and a distance of L1 between the contact point (203) and the opening end (101), where L1 = 2D1 ~ 3D1.

3. The wind tunnel flow field total temperature measurement device according to claim 2, characterized in that: The distance between the overflow hole (102) and the fixing part (4) is L2, L2 = 0.27D1 ~ 0.4D1; the distance between the overflow hole (102) and the contact (203) is L3, L3 = 0.44D1 ~ 0.58D1.

4. The wind tunnel flow field total temperature measurement device according to claim 3, characterized in that: The overflow hole (102) is provided in multiple ways, and the ratio of the sum of the areas of the multiple overflow holes (102) to the inlet area of ​​the opening end (101) is 0.1 to 0.

2.

5. The wind tunnel flow field total temperature measurement device according to claim 1, characterized in that: The first thermocouple wire (201) and the second thermocouple wire (202) have the same diameter, D2, which is 0.2 to 0.3 mm.

6. The wind tunnel flow field total temperature measurement device according to claim 5, characterized in that: The diameter of the contact (203) is 7. The wind tunnel flow field total temperature measurement device according to claim 1, characterized in that: The wall thickness of the stagnation chamber (1) is no more than 0.5 mm.

8. The wind tunnel flow field total temperature measurement device according to claim 1, characterized in that: The fixing part (4) includes an insulating tube (401), which is disposed in the connection between the stagnation chamber (1) and the support part (3); the first thermocouple wire (201) and the second thermocouple wire (202) pass through the insulating tube (401), and the penetration is filled with sealant (402). The outer wall of the insulating tube (401) and the stagnation chamber (1) and the outer wall of the insulating tube (401) and the support part (3) are both filled with sealant (402).

9. The wind tunnel flow field total temperature measurement device according to claim 1, characterized in that: The outer wall of the support part (3) connected to the stagnation chamber (1) is provided with a guide surface (302), the diameter of which gradually increases in the direction away from the stagnation chamber (1), and the outer end of the support part (3) is provided with a connector (303).

10. A wind tunnel flow field total temperature measurement system, comprising a wind tunnel equipment nozzle, characterized in that: The wind tunnel equipment nozzle outlet airflow uniform zone is provided with a wind tunnel flow field total temperature measuring device as described in any one of claims 1 to 9. The axis of the stagnation chamber (1) is parallel to the axis of the wind tunnel equipment nozzle. The outer ends of the first thermocouple wire (201) and the second thermocouple wire (202) are connected to the data acquisition module.

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