Flow calibration system and determination method of temperature uncertainty

Abstract

The present application relates to the technical field of flow measurement, and particularly relates to a flow calibration system and a temperature uncertainty determination method, comprising a flow calibration device, a control module and a plurality of temperature detection units, the flow calibration device comprises a to-be-measured fixed pipeline and a standard fixed pipeline, the standard fixed pipeline is provided with a plurality of standard venturi nozzles; the temperature detection unit penetrates through the standard fixed pipeline, and the control module is configured to determine the temperature uncertainty of the standard fixed pipeline based on the position of the standard fixed pipeline and the temperature detection depth of the temperature detection unit. The present application analyzes the detection data of the temperature detection unit which can measure the most accurate temperature data, reduces the deviation between the detection temperature data and the actual environmental temperature data, reduces the temperature uncertainty, thereby reducing the temperature measurement error, realizing accurate detection and calculation of the actual flow of each standard venturi nozzle, and effectively improving the flow calibration precision.

Description

Technical Field

[0001] This invention relates to the field of flow measurement technology, and in particular to a flow calibration system and a method for determining temperature uncertainty. Background Technology

[0002] High-pressure Venturi nozzles refer to the high-flow-rate high-pressure Venturi nozzles commonly used in dynamic model testing, with a flow rate range of 0.5 kg / s to 5.5 kg / s and an operating pressure range of 0.5 MPa to 6 MPa. High-pressure Venturi nozzles must be calibrated before use to accurately measure gas flow. However, in the process of developing this invention, the applicant discovered that existing calibration devices capable of calibrating high-flow-rate high-pressure Venturi nozzles have low temperature detection accuracy during calibration testing, resulting in lower-than-expected calibration accuracy. Summary of the Invention

[0003] The purpose of this invention is to provide a flow calibration system and a method for determining temperature uncertainty to solve the aforementioned technical problems in the prior art, mainly including the following two aspects:

[0004] The first aspect of this invention provides a flow calibration system for a Venturi nozzle, including a flow calibration device, a control module, and multiple temperature detection units. The flow calibration device includes a test fixed pipe and a standard fixed pipe coaxially arranged along the airflow direction. A first mounting seat is provided inside the standard fixed pipe, and multiple first fixing channels are provided on the first mounting seat for installing and fixing the standard Venturi nozzle. The distance between the axes of two adjacent first fixing channels is greater than four times the throat diameter of the standard Venturi nozzle. A second mounting seat is provided inside the test fixed pipe for installing and fixing the test Venturi nozzle. Multiple mounting holes are provided on the peripheral wall of the standard fixed pipe, and the temperature detection units are disposed through the mounting holes. The temperature detection units and the standard fixed pipe have a sliding stroke along the radial direction of the standard fixed pipe to adjust the temperature detection depth of the temperature detection unit in the standard fixed pipe. The control module is connected to the temperature detection units and is configured to determine the temperature uncertainty of the standard fixed pipe based on the position of the standard fixed pipe and the temperature detection depth of the temperature detection unit.

[0005] Furthermore, the peripheral wall of the standard fixed pipe has at least one detection area along the axial direction of the standard fixed pipe, and multiple mounting holes are provided in the detection area, with the multiple mounting holes in the same detection area located on the same circumference;

[0006] And / or, the axial direction of the fixed pipe to be tested on the peripheral wall of the fixed pipe to be tested has at least one detection area, and multiple mounting holes are provided in the detection area, with multiple mounting holes in the same detection area located on the same circumference.

[0007] Furthermore, the inner diameter ratio of the fixed pipe to be tested and the standard fixed pipe is 3:10. The first mounting base is provided with 15 first fixing channels, of which one first fixing channel is located on the axis of the standard fixed pipe, four first fixing channels are located on the first circumference around the axis of the standard fixed pipe, and ten first fixing channels are located on the second circumference around the axis of the standard fixed pipe. The first circumference is located within the second circumference.

[0008] Furthermore, the flow calibration device also includes a sealing end cap, which is provided in a one-to-one correspondence with the first fixed channel. The sealing end cap is detachably connected to the back flow surface of the first mounting base, and the sealing end cap is used to seal the output end of the first fixed channel.

[0009] Furthermore, the venturi nozzle to be tested is coaxially arranged with the fixed pipe to be tested, and the axis of the first fixed channel is parallel to the axis of the standard fixed pipe.

[0010] Furthermore, the control module is configured to: when the difference in detection data from different temperature detection units is within a preset value, determine the temperature uncertainty of each standard Venturi nozzle based on the average value of the detection data from all temperature detection units;

[0011] When the difference in detection data from different temperature detection units is outside the preset value, the temperature uncertainty of the standard Venturi nozzle is determined based on the detection data from the temperature detection unit closest to the axis of the standard Venturi nozzle.

[0012] Furthermore, the calibration system also includes an adjustment mechanism, which comprises a base, a fastener, and an adjustment body. The base is correspondingly arranged with the mounting hole. The distal end of the fastener is connected to the peripheral wall of a standard fixed pipe through the base, and the proximal end of the fastener is connected to the adjustment body. The base has a first channel, the fastener has a second channel with an inner diameter matching the temperature detection unit, and the adjustment body has a third channel. The first, second, and third channels, along with the mounting hole, constitute an adjustment channel for housing the temperature detection unit. An adjustment cavity is provided between the fastener and the adjustment body, and a fastening tube and at least two mating parts are provided within the adjustment cavity. The mating parts surround the temperature detection unit and have wedge-shaped surfaces that engage with the distal end of the fastening tube. The fastener and the adjustment body have a movable stroke along the axial direction of the adjustment channel to adjust the clamping force of the mating parts on the temperature detection unit. The proximal end of the fastening tube is connected to the adjustment body, and a gap is provided between the distal end of the fastening tube and the fastener.

[0013] Furthermore, a heat insulation cavity is provided on the inner wall of the distal end of the first channel.

[0014] A second aspect of the present invention provides a method for determining temperature uncertainty, which verifies the temperature uncertainty based on the above-mentioned flow calibration system, including the following steps:

[0015] Step S100: Obtain the detection data of all temperature detection units;

[0016] Step S200: When the difference in detection data from different temperature detection units is within a preset value, determine the Type A temperature uncertainty of each standard venturi nozzle based on the average value of the detection data from all temperature detection units.

[0017] When the difference in detection data from different temperature detection units exceeds a preset value, the Type A temperature uncertainty of the standard Venturi nozzle is determined based on the detection data from the temperature detection unit closest to the axis of the standard Venturi nozzle.

[0018] Step S300: Combine the Type A and Type B temperature uncertainties of the standard Venturi nozzle to obtain the standard temperature uncertainty of the standard Venturi nozzle.

[0019] Furthermore, the method includes step S400, which involves averaging the temperature standard uncertainty of all standard venturi nozzles in the flow calibration system that are in the open state to obtain the temperature standard uncertainty of the flow calibration system.

[0020] Compared with the prior art, the present invention has at least the following technical effects:

[0021] This invention analyzes the detection data of a temperature detection unit that can measure the most accurate temperature data by rationally selecting such a unit. This reduces the deviation between the detected temperature data and the actual ambient temperature data, and also reduces temperature uncertainty, thereby reducing temperature measurement error. This enables accurate detection and calculation of the actual flow rate of each standard Venturi nozzle, effectively improving the flow calibration accuracy. Attached Figure Description

[0022] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram of the flow calibration system of the present invention;

[0024] Figure 2 yes Figure 1 Sectional view along line AA;

[0025] Figure 3 yes Figure 1 A magnified view of a section at point B in the middle;

[0026] Figure 4 This is a schematic diagram of the structure of the first mounting base of the present invention on a standard fixed pipe (showing the back flow surface);

[0027] Figure 5 This is a schematic diagram of the structure of the first mounting base of the present invention on a standard fixed pipe (showing the flow-facing side);

[0028] Figure 6 This is a schematic diagram of the adjustment mechanism of the present invention;

[0029] Figure 7 This is a schematic diagram of the internal structure of the adjusting mechanism of the present invention;

[0030] Figure 8 This is a schematic diagram of the connection structure between the adjustment mechanism and the standard fixed pipe of the present invention;

[0031] Figure 9 This is a schematic diagram of the structure of the fixed pipe to be tested in this invention;

[0032] Figure 10 This is a flowchart of the method for determining the temperature uncertainty of the present invention;

[0033] Figure 11 This is a state diagram of the flow calibration system of the present invention when selecting four standard Venturi nozzles for flow calibration;

[0034] In the picture:

[0035] 110. Standard fixed pipe; 111. First mounting base; 112. Standard venturi nozzle; 113. Sealing end cap; 114. First fixed channel; 120. Fixed pipe to be tested; 121. Second mounting base; 122. Venturi nozzle to be tested; 20. Temperature detection unit; 210. Base; 211. First channel; 212. Insulation cavity; 220. Fastening body; 221. Second channel; 222. Connecting part; 230. Adjusting body; 231. Third channel; 232. Adjusting cavity; 233. Fastening tube; 234. Mating part. Detailed Implementation

[0036] The following description provides many different embodiments or examples for implementing various features of the invention. The elements and arrangements described in the specific examples below are only for concise expression of the invention and are merely examples, not intended to limit the invention.

[0037] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.

[0038] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances. Furthermore, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0039] In this invention, unless otherwise expressly specified and limited, "above or below" a first feature may include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on" the first feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the first feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0040] High-pressure Venturi nozzles refer to the high-flow-rate high-pressure Venturi nozzles commonly used in dynamic model testing, with a flow rate range of 0.5 kg / s to 5.5 kg / s and an operating pressure range of 0.5 MPa to 6 MPa. High-pressure Venturi nozzles must be calibrated before use to accurately measure gas flow. Existing technologies for calibrating high-flow-rate high-pressure Venturi nozzles, such as the critical flow Venturi nozzle method gas flow calibration device disclosed in Chinese Patent Publication No. CN210774272U, employ a scheme of multiple critical flow Venturi nozzles connected in parallel to increase the upper limit of the calibration flow rate. Simultaneously, the temperature data of the stagnation container is collected as the calibration temperature parameter for all critical flow Venturi nozzles. Since gas flow calibration devices are generally in high-pressure environments, to ensure the structural safety of the device, the temperature sensor is fixedly mounted on the stagnation container, resulting in a fixed temperature acquisition point. Furthermore, for multiple critical flow Venturi nozzles connected in parallel, the relationship between the critical flow Venturi nozzle and the temperature sensor... The spacing between nozzles varies; the larger the spacing, the greater the difference between the temperature data used by the temperature sensor and the actual ambient temperature corresponding to the critical flow Venturi nozzle. This is especially true for calibration devices used with high-flow-rate, high-pressure Venturi nozzles. To achieve high-flow-rate detection, more critical flow Venturi nozzles need to be connected in parallel. However, when applying this to low-flow-rate calibration (where some parallel critical flow Venturi nozzles need to be closed), and when selecting critical flow Venturi nozzles with larger spacing (the axial spacing between open critical flow Venturi nozzles is relatively large), the deviation between the data detected by the temperature sensor and the actual ambient temperature data of the critical flow Venturi nozzle further increases, leading to a decrease in calibration accuracy. Therefore, this application provides a Venturi nozzle flow calibration system and a method for determining temperature uncertainty that can reduce temperature detection deviation and improve the accuracy of calculating calibration temperature parameters for standard Venturi nozzles, as detailed in the following embodiments.

[0041] Example 1:

[0042] This application provides a flow calibration system for a venturi nozzle, such as... Figures 1-5As shown, the device includes a flow calibration device, a control module, and multiple temperature detection units 20. The flow calibration device includes a test fixed pipe 120 and a standard fixed pipe 110 arranged coaxially along the airflow direction. A first mounting base 111 is provided inside the standard fixed pipe 110. The first mounting base 111 is provided with multiple first fixing channels 114 for installing and fixing a standard Venturi nozzle 112. The distance between the axes of two adjacent first fixing channels 114 is greater than four times the throat diameter of the standard Venturi nozzle 112. A second mounting base 121 is provided inside the test fixed pipe 120. The standard fixed pipe 110 is used to install and fix the venturi nozzle 122 to be tested; multiple mounting holes are provided on the peripheral wall of the standard fixed pipe 110, and the temperature detection unit 20 is disposed through the mounting holes. The temperature detection unit 20 and the standard fixed pipe 110 have a sliding stroke along the radial direction of the standard fixed pipe 110 to realize the adjustment of the temperature detection depth of the temperature detection unit 20 in the standard fixed pipe 110. The control module is connected to the temperature detection unit 20 and is configured to determine the temperature uncertainty of the standard fixed pipe 110 based on the position of the standard fixed pipe 110 and the temperature detection depth of the temperature detection unit 20.

[0043] When calibrating and testing a Venturi nozzle, the Venturi nozzle 122 to be tested is installed on the second mounting base 121, and the standard Venturi nozzle 112 is installed on the first mounting base 111. Then, the temperature detection unit 20 is adjusted so that it slides radially along the standard fixed pipe 110, allowing multiple temperature detection units 20 to perform tests at different detection depths. Figure 2As shown, a standard Venturi nozzle 112 is adapted to fit different positions. Then, a stable airflow is introduced into the input end of the fixed pipe 120 to be tested. The airflow flows sequentially along the fixed pipe 120 and the standard fixed pipe 110, passing through the Venturi nozzle 122 to be tested and the standard Venturi nozzle 112 respectively. Temperature data during the calibration test is collected by the temperature detection unit 20. When it is necessary to calculate the actual flow rate data of each standard Venturi nozzle 112, the difference between different temperature detection units 20 is first determined based on the detection data of all temperature detection units 20. If the difference in detection data between different temperature detection units 20 is within a preset value, then... Assuming the temperature distribution within the standard fixed pipe 110 is uniform, the experimental standard deviation of each standard Venturi nozzle 112 during the calibration and testing process is taken as the Type A temperature uncertainty. If the difference in the detection data of different temperature detection units 20 is outside the preset value, it can be considered that the temperature distribution within the standard fixed pipe 110 is non-uniform. For a certain standard Venturi nozzle 112, the detection data of the temperature detection unit 20 closest to the axis of the standard Venturi nozzle 112 is selected as the corresponding detection temperature, and the experimental standard deviation of the corresponding closest temperature detection unit 20 during the calibration and testing process is taken as the Type A temperature uncertainty of the standard Venturi nozzle 112.

[0044] Then, the Type A and Type B temperature uncertainties of the standard Venturi nozzle 112 are combined to obtain the standard temperature uncertainty of each standard Venturi nozzle 112. The Type B uncertainty mainly comes from the systematic error of the temperature detection unit 20, which can be directly obtained from the technical specification of the temperature detection unit 20. Then, the stagnation temperature is determined based on the standard temperature uncertainty corresponding to the standard Venturi nozzle 112, and the actual flow rate of each standard Venturi nozzle 112 is calculated. That is, for the standard Venturi nozzles 112 at different positions in the standard fixed pipeline 110, by reasonably selecting the detection data of the temperature detection unit 20 that can measure the most accurate temperature data for analysis, the deviation between the detected temperature data and the actual ambient temperature data can be reduced, and the temperature uncertainty can be reduced, thereby reducing the temperature measurement error and realizing the accurate detection and calculation of the actual flow rate of each standard Venturi nozzle 112, effectively improving the flow calibration accuracy. Furthermore, by summing the actual flow rates of all standard Venturi nozzles 112, the total actual gas flow rate can be obtained.

[0045] Furthermore, since all standard Venturi nozzles 112 are centrally installed in a single pipe, the piping structure of the calibration device is simplified compared to parallel piping, facilitating the management and maintenance of the standard Venturi nozzles 112. On the other hand, because all standard Venturi nozzles 112 are in the same airflow environment, the increased diameter of the standard fixed pipe 110 results in a smaller proportion of the temperature detection unit 20 in the gas flow cross-section when it is installed in the airflow environment for testing. Compared to the prior art where one branch corresponds to one standard Venturi nozzle 112, the temperature detection unit 20 has almost no impact on airflow. Therefore, not only can the temperature detection unit 20 be placed close to the first mounting base 111 to achieve accurate detection of the ambient temperature of the standard Venturi nozzle 112, but the standard fixed pipe 110 can also provide more installation positions for the temperature detection unit 20 on the same circumference, enabling multi-point detection, reducing temperature detection errors, and thus improving detection accuracy.

[0046] It should be noted that the difference in detection data between different temperature detection units 20 is within a preset value, which is 0.05℃~0.5℃. In this embodiment, the preset value is preferably 0.1℃.

[0047] To achieve accurate temperature measurement within the standard fixed pipe 110, at least one detection zone can be provided on the peripheral wall of the standard fixed pipe 110 along its axial direction. Multiple mounting holes are provided within the detection zone, with the multiple mounting holes located on the same circumference. This increases the number of installation positions for the temperature detection unit 20, enabling multi-point detection, reducing temperature detection errors, and thus improving detection accuracy.

[0048] To achieve accurate measurement of the temperature within the fixed pipe 120, such as Figure 9 As shown, the circumferential wall of the fixed pipe 120 to be tested has at least one detection area along its axial direction. Multiple mounting holes are provided in the detection area, and multiple mounting holes in the same detection area are located on the same circumference. This increases the number of installation positions of the temperature detection unit 20, realizes multi-point detection, reduces temperature detection error, and thus improves detection accuracy.

[0049] To improve space utilization, the inner diameter ratio of the test-to-be-fixed pipe 120 to the standard fixed pipe 110 is 3:10. The first mounting base 111 is provided with 15 first fixing holes 114, such as... Figures 3-5 As shown (in) Figure 4 and Figure 5For ease of understanding, only one standard Venturi nozzle 112 and its corresponding sealing end cap 113 are shown on the first mounting base 111. One first fixing channel 114 is located on the axis of the standard fixing pipe 110, four first fixing channels 114 surround the axis of the standard fixing pipe 110 on the first circumference, and ten first fixing channels 114 surround the axis of the standard fixing pipe 110 on the second circumference. The first circumference is located within the second circumference. The distance between the axes of two adjacent first fixing channels 114 is greater than four times the throat diameter of the standard Venturi nozzle 112. On the one hand, this makes the mutual influence between adjacent standard Venturi nozzles 112 negligible even in the same environment. On the other hand, it achieves the maximum installation limit of as many standard Venturi nozzles 112 as possible within the limited installation space of the standard fixing pipe 110. By increasing the space utilization rate of the standard fixing pipe 110, the upper limit of flow calibration is increased. High flow and high pressure calibration is achieved within the smallest possible standard fixing pipe 110, meeting the requirements of high flow and high pressure Venturi nozzles.

[0050] To facilitate the system's ability to meet the high-precision calibration requirements of different flow rates, such as Figures 3-5 As shown, the flow calibration device also includes a sealing end cap 113, which is configured one-to-one with the first fixing channel 114. The sealing end cap 113 is detachably connected to the back flow surface of the first mounting base 111, and is used to seal the output end of the first fixing channel 114. During flow calibration, the number of standard venturi nozzles 112 that need to be in the open state is determined according to the calibration flow requirements. When the sealing end cap 113 is not installed on the back flow surface of the first mounting base 111, a predetermined number of standard venturi nozzles are blocked by installing the sealing end cap 113 on the back flow surface of the first mounting base 111. When the sealing end cap 113 is pre-installed on the back flow surface of the first mounting base 111 and the standard venturi nozzles 112 have been blocked, the planned number of nozzles are removed from the first mounting base 111. The sealing end cap 113 leaves the standard venturi nozzle 112 in an open state, meeting the calibration flow requirements, thus enabling flexible adjustment of the calibration flow. For the blocked standard venturi nozzle 112, the direct end-face sealing method ensures efficient sealing under high pressure differential, avoiding the problem of poor sealing performance of valves in high-pressure environments in existing technologies. Furthermore, the sealing end cap 113 is located on the back flow surface of the first mounting base 111, so it will not affect the gas flow of other standard venturi nozzles. Preferably, the sealing end cap 113 is connected to the back flow surface of the first mounting base 111 by screws.

[0051] To improve calibration accuracy, the venturi nozzle 122 to be tested can be coaxially arranged with the fixed pipe 120 to be tested, and the axis of the first fixing channel 114 is parallel to the axis of the standard fixed pipe 110. Preferably, the second mounting base 121 is provided with a second fixing channel for placing the venturi nozzle 122 to be tested.

[0052] Specifically, since the installation position of the standard venturi nozzle 112 is determined, the insertion depth of the temperature detection unit 20 can also be obtained by measurement. In order to improve the calibration accuracy and calibration efficiency, the control module can be configured to determine the temperature uncertainty of each standard venturi nozzle 112 based on the average value of the detection data of all temperature detection units 20 when the difference in the detection data of different temperature detection units 20 is within a preset value.

[0053] When the difference in detection data from different temperature detection units 20 is outside the preset value, the temperature uncertainty of the standard venturi nozzle 112 is determined based on the detection data from the temperature detection unit 20 closest to the axis of the standard venturi nozzle 112.

[0054] To enable the temperature sensing unit 20 to slide radially along the standard fixed pipe 110, a calibration system can be provided, which also includes an adjustment mechanism, such as... Figures 6-8 As shown, the adjustment mechanism includes a base 210, a fastener 220, and an adjustment body 230. The base 210 is correspondingly arranged with the mounting hole. The distal end of the fastener 220 is connected to the peripheral wall of the standard fixed pipe 110 through the base 210, and the proximal end of the fastener 220 is connected to the adjustment body 230. The base 210 is provided with a first channel 211, the fastener 220 is provided with a second channel 221, the inner diameter of the second channel 221 matches the temperature detection unit 20, and the adjustment body 230 is provided with a third channel 231. The first channel 211, the second channel 221, the third channel 231, and the mounting hole constitute an adjustment channel. The adjustment channel is used for... A temperature detection unit 20 is placed therein. An adjustment cavity 232 is provided between the fastening solid 220 and the adjustment body 230. A fastening tube 233 and at least two mating parts 234 are provided in the adjustment cavity 232. The mating parts 234 are arranged around the temperature detection unit 20. A wedge-shaped surface is provided on the mating parts 234. The wedge-shaped surface is used to mate with the distal end of the fastening tube 233. The fastening solid 220 and the adjustment body 230 have a movable stroke along the adjustment channel axis to realize the adjustment of the clamping force of the mating parts 234 on the temperature detection unit 20. The proximal end of the fastening tube 233 is connected to the adjustment body 230, and a gap is provided between the distal end of the fastening tube 233 and the fastening solid 220.

[0055] When the insertion depth of the temperature detection unit 20 needs to be adjusted, the adjusting body 230 is controlled so that the mating part 234 does not directly clamp the temperature detection unit 20. At this time, the operator can adjust the position of the temperature detection unit 20 within the adjusting channel along the axial direction of the adjusting channel, allowing the sensor at the far end of the temperature detection unit 20 to move radially along the standard fixed pipe 110. This achieves the adjustment of the temperature detection position within the standard fixed pipe 110, aligning the detection position of the temperature detection unit 20 with the standard Venturi nozzle 112 in the open state. This allows for accurate detection of the temperature data of the standard Venturi nozzle 112, avoiding the problems caused by the existing technology. A deviation in the temperature detection position can lead to errors in the temperature detection data, thus affecting calibration accuracy. This necessitates flexible adjustment of the temperature detection position. Furthermore, after adjusting the position of the temperature detection unit 20, the adjusting body 230 is controlled again to change the distance between the adjusting body 230 and the fastening solid 220. During the adjustment process, as the distance between the adjusting body 230 and the fastening solid 220 decreases, the adjusting body forces the fastening tube 233 to move towards the fastening solid 220. Based on the engagement between the distal end of the fastening tube 233 and the wedge-shaped surface on the mating part 234, the mating part 234 is forced to move towards the axis of the adjustment channel. Multiple mating parts 234 work together... As the distance between the adjusting body 230 and the fastening solid 220 decreases, the temperature detection unit 20 in the adjusting channel is gradually tightened, thus locking the position of the temperature detection unit 20. That is, under high pressure, the position-adjustable temperature detection unit 20, locked by the adjusting body 230 and the fastening solid 220, can withstand the internal and external pressure difference without slipping, ensuring that the temperature detection unit 20 stably performs detection at the target position. At the same time, based on the sealed fit between the second channel 221 on the fastening solid 220 and the temperature detection unit 20, not only can air be prevented from flowing out of the adjusting channel, but the stress area of ​​the temperature detection unit 20 is also not limited. The mating part 234 also includes the interaction force between the inner wall of the second channel 221 and the peripheral wall of the temperature detection unit 20. The second channel 221 increases the frictional resistance of the temperature detection unit 20 moving axially along the adjustment channel. This can prevent the temperature detection unit 20 from accidentally slipping when adjusting its position, improve the structural stability of the temperature detection unit 20 after the position is locked, and use the inner wall of the second channel 221 to disperse the stress on the temperature detection unit 20 caused by the internal and external pressure difference, so as to avoid stress concentration at the corresponding part of the mating part 234, protect the structural safety of the temperature detection unit 20, and improve the ease of use of the device.

[0056] It should be noted that the temperature detection unit 20 is existing technology and can be purchased directly from the market. The specification of the temperature detection unit 20 specifies Type B uncertainty. Specifically, the temperature detection unit 20 can be a cylindrical structure. The sensor for temperature detection is located at the far end of the cylinder, inside the standard fixed pipe 110, while the signal connector for transmitting the detection data is located at the near end of the cylinder, outside the standard fixed pipe 110. The cylinder is preferably made of metal, specifically steel. When selecting the detection data from the temperature detection unit 20 closest to the axis of the standard Venturi nozzle 112 as the corresponding detection temperature, this specifically means that the sensor at the far end of the cylinder is closest to the axis of the standard Venturi nozzle 112.

[0057] To improve temperature detection accuracy, a heat insulation cavity 212 can be provided on the inner wall of the far end of the first channel 211. To achieve a stable connection between the temperature detection mechanism and the standard fixed pipe 110, the base 210 is generally made of metal. Since metal has good thermal conductivity, and the base 210 is close to the sensor at the far end of the temperature detection unit 20, to avoid the external ambient temperature being conducted to the temperature detection unit 20 through the base 210 and affecting the detection accuracy of the temperature detection unit 20, a heat insulation cavity 212 is provided on the inner wall of the far end of the first channel 211. The heat insulation cavity 212 reduces the heat transfer between the base 210 and the temperature detection unit 20, thereby reducing the impact of the external environment on the detection accuracy of the temperature detection unit 20, improving the accuracy of temperature detection, and achieving precise calibration.

[0058] To achieve the locking state adjustment of the temperature detection unit 20, an adjustment groove can be provided at the distal end of the third channel 231. A connecting part 222 is provided at the proximal end of the fastening solid 220. The distal end of the adjustment groove and the connecting part 222 are threadedly connected to achieve the adjustment of the axial distance between the fastening solid 220 and the adjusting body 230 along the adjustment channel. The inner wall of the adjustment groove and the connecting part 222 cooperate to form an adjustment cavity 232. By rotating the adjusting body 230, the distance between the fastening solid 220 and the adjusting body 230 is changed. When the distance between the fastening solid 220 and the adjusting body 230 is reduced, the fastening force of the fastening tube 233 on the temperature detection unit 20 through the mating part 234 increases. When the distance between the fastening solid 220 and the adjusting body 230 is increased, the fastening force of the fastening tube 233 on the temperature detection unit 20 through the mating part 234 decreases.

[0059] In some embodiments, a first rectifier is provided in the standard fixed pipe 110, and the first rectifier is located at the front end of the first mounting base 111. A second rectifier is provided in the fixed pipe 120 to be tested, and the second rectifier is located at the front end of the second mounting base 121. The fixed channel 120 to be tested is connected to the standard fixed pipe 110 through a transition channel. The flow calibration system also includes a pressure detection unit for detecting the pressure in the fixed channel 120 to be tested and the standard fixed pipe 110.

[0060] Example 2:

[0061] This application provides a method for determining temperature uncertainty, based on the flow calibration system in Embodiment 1, to confirm the temperature uncertainty. Figure 9 As shown, the steps include:

[0062] Step S100: Obtain the detection data of all temperature detection units 20;

[0063] Step S200: When the difference in detection data of different temperature detection units 20 is within a preset value, determine the Type A temperature uncertainty of each standard venturi nozzle 112 based on the average value of the detection data of all temperature detection units 20.

[0064] When the difference in detection data from different temperature detection units 20 is outside a preset value, the Type A temperature uncertainty of the standard Venturi nozzle 112 is determined based on the detection data from the temperature detection unit 20 closest to the axis of the standard Venturi nozzle 112.

[0065] Step S300: Combine the Type A temperature uncertainty and Type B temperature uncertainty of the standard Venturi nozzle 112 to obtain the standard temperature uncertainty of the standard Venturi nozzle 112.

[0066] Specifically, it also includes step S400, which takes the average of the temperature standard uncertainty of all standard Venturi nozzles 112 in the open state in the flow calibration system to obtain the temperature standard uncertainty of the flow calibration system.

[0067] For standard Venturi nozzles 112 at different locations within the standard fixed pipeline 110, by rationally selecting the detection data from the temperature detection unit 20 that can measure the most accurate temperature data, the deviation between the detected temperature data and the actual ambient temperature data can be reduced, and the temperature uncertainty can be reduced, thereby reducing the temperature measurement error. This enables accurate detection and calculation of the actual flow rate of each standard Venturi nozzle 112, effectively improving the flow calibration accuracy. By summing the actual flow rates of all standard Venturi nozzles 112, the total actual gas flow rate can be obtained.

[0068] In some embodiments, during flow calibration, four standard Venturi nozzles 112 located on the first circumference of the first mounting base are selected for calibration according to the calibration flow requirements. The remaining eleven standard Venturi nozzles 112 are sealed with sealing end caps 114, and four temperature detection units 20 are controlled to extend into the corresponding (e.g., ...) temperature detection units 20. Figure 11As shown, the temperature detection unit 20 corresponds one-to-one with the standard Venturi nozzle 112. Data from n measurements taken by the four temperature detection units 20 are collected, and the average temperature value of each temperature detection unit 20 is calculated.

[0069]

[0070] Where x is the xth temperature detection unit 20, 1≤x≤4;

[0071] Next, calculate the experimental standard deviation of the average value of more than 20 measurements taken by the temperature detection unit.

[0072]

[0073] Among them, s(T xi ) represents the experimental standard deviation of the nth measurement performed by the xth temperature detection unit 20;

[0074] Then, the experimental standard deviation of the x-th temperature detection unit 20 The Type A temperature uncertainty of the temperature detection unit 20 is,

[0075]

[0076] The Type B uncertainty u of the x-th temperature detection unit 20 B (T x The error is the systematic error of the temperature detection unit, which can be obtained directly from the technical specification of the temperature detection unit 20.

[0077] Type A temperature uncertainty u for the x-th temperature detection unit 20 A (T x Type B uncertainty u B (T x The temperature standard uncertainty u of the x-th temperature detection unit 20 is obtained by combining the results. c (T x ),

[0078]

[0079] After evaluating the temperature uncertainty of each standard Venturi nozzle 112, the standard temperature uncertainty u measured by the four temperature detection units 20 was evaluated. c (T x By averaging, the combined temperature standard uncertainty u of the entire flow calibration system can be obtained. c (T),

[0080]

[0081] The stagnation temperature is then determined based on the standard temperature uncertainty corresponding to the standard Venturi nozzle 112. The actual flow rate of each standard Venturi nozzle 112 is calculated, and the actual flow rates of the four standard Venturi nozzles 112 are summed to obtain the total actual gas flow rate of the flow calibration system.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A flow calibration system for a venturi nozzle, characterized in that, The system includes a flow calibration device, a control module, and multiple temperature detection units. The flow calibration device comprises a test fixed pipe and a standard fixed pipe coaxially arranged along the airflow direction. A first mounting base is provided within the standard fixed pipe, and the first mounting base has multiple first fixing channels for mounting and fixing a standard Venturi nozzle. The distance between the axes of two adjacent first fixing channels is greater than four times the throat diameter of the standard Venturi nozzle. A second mounting base is provided within the test fixed pipe for mounting and fixing the test Venturi nozzle. Multiple mounting holes are provided on the peripheral wall of the standard fixed pipe, and the temperature detection units pass through these mounting holes. The temperature detection units and the standard fixed pipe have a sliding stroke along the radial direction of the standard fixed pipe to adjust the temperature detection depth of the temperature detection unit within the standard fixed pipe. The control module is connected to the temperature detection units and is configured to determine the temperature uncertainty of the standard fixed pipe based on the position of the standard fixed pipe and the temperature detection depth of the temperature detection unit.

2. The flow calibration system as described in claim 1, characterized in that, The standard fixed pipe has at least one detection area along the axial direction of the standard fixed pipe on its peripheral wall. Multiple mounting holes are provided in the detection area, and the multiple mounting holes in the same detection area are located on the same circumference. And / or, the axial direction of the fixed pipe to be tested on the peripheral wall of the fixed pipe to be tested has at least one detection area, and multiple mounting holes are provided in the detection area, with multiple mounting holes in the same detection area located on the same circumference.

3. The flow calibration system as described in claim 2, characterized in that, The inner diameter ratio of the fixed pipe to be tested to the standard fixed pipe is 3:

10. The first mounting base is provided with 15 first fixing channels, of which one first fixing channel is located on the axis of the standard fixed pipe, four first fixing channels are located on the first circumference around the axis of the standard fixed pipe, and ten first fixing channels are located on the second circumference around the axis of the standard fixed pipe. The first circumference is located inside the second circumference.

4. The flow calibration system as described in claim 1, characterized in that, The flow calibration device also includes a sealing end cap, which is provided in a one-to-one correspondence with the first fixed channel. The sealing end cap is detachably connected to the back flow surface of the first mounting base. The sealing end cap is used to seal the output end of the first fixed channel.

5. The flow calibration system as described in claim 4, characterized in that, The venturi nozzle to be tested is coaxially arranged with the fixed pipe to be tested, and the axis of the first fixed channel is parallel to the axis of the standard fixed pipe.

6. The flow calibration system according to any one of claims 1 to 5, characterized in that, The control module is configured to: when the difference in detection data from different temperature detection units is within a preset value, determine the temperature uncertainty of each standard venturi nozzle based on the average value of the detection data from all temperature detection units; When the difference in detection data from different temperature detection units is outside the preset value, the temperature uncertainty of the standard Venturi nozzle is determined based on the detection data from the temperature detection unit closest to the axis of the standard Venturi nozzle.

7. The flow calibration system as described in claim 6, characterized in that, The calibration system further includes an adjustment mechanism, which comprises a base, a fastener, and an adjustment body. The base is correspondingly positioned to the mounting hole. The distal end of the fastener is connected to the peripheral wall of a standard fixed pipe via the base, and the proximal end of the fastener is connected to the adjustment body. The base has a first channel, and the fastener has a second channel with an inner diameter matching the temperature detection unit. The adjustment body has a third channel. The first, second, and third channels, along with the mounting hole, constitute an adjustment channel for housing the temperature detection unit. An adjustment cavity is provided between the fastener and the adjustment body, containing a fastening tube and at least two mating parts. The mating parts surround the temperature detection unit and have wedge-shaped surfaces that engage with the distal end of the fastening tube. The fastener and the adjustment body have a axial travel along the adjustment channel to adjust the clamping force of the mating parts on the temperature detection unit. The proximal end of the fastening tube is connected to the adjustment body, and a gap exists between the distal end of the fastening tube and the fastener.

8. The flow calibration system as described in claim 7, characterized in that, A heat insulation cavity is provided on the inner wall of the distal end of the first channel.

9. A method for determining temperature uncertainty, characterized in that, The verification of temperature uncertainty based on the flow calibration system according to any one of claims 1 to 8 includes the following steps: Step S100: Obtain the detection data of all temperature detection units; Step S200: When the difference in detection data from different temperature detection units is within a preset value, determine the Type A temperature uncertainty of each standard venturi nozzle based on the average value of the detection data from all temperature detection units. When the difference in detection data from different temperature detection units exceeds a preset value, the Type A temperature uncertainty of the standard Venturi nozzle is determined based on the detection data from the temperature detection unit closest to the axis of the standard Venturi nozzle. Step S300: Combine the Type A and Type B temperature uncertainties of the standard Venturi nozzle to obtain the standard temperature uncertainty of the standard Venturi nozzle.

10. The determination method as described in claim 9, characterized in that, It also includes step S400, which averages the temperature standard uncertainty of all standard Venturi nozzles in the flow calibration system that are in the open state to obtain the temperature standard uncertainty of the flow calibration system.

Images