Standard flow measuring device and multi-test-bed flow consistency evaluation method

Abstract

The invention relates to a flow measurement precision evaluation method, in particular to a standard flow measurement device and a multi-test-bed flow consistency evaluation method. The method mainly solves the technical problem that an existing liquid oxygen flow measurement method cannot carry out transverse comparison evaluation on the liquid oxygen flow measurement precision of all test bed. The standard flow measuring device comprises a rectifying tube, a differential pressure tube, a pressure regulating tube, a pressure and temperature measuring unit and a heat preservation structure. The method comprises the following steps: 1, metering calibration of a standard flow measuring device; 2, on-site in-situ calibration of the standard flow measuring device; and 3, evaluating the consistency of the liquid oxygen flow of each test bed. According to the method, the corrected flow coefficient is obtained based on the standard flow measuring device, then the standard flow measuring device is adopted to conduct comparison evaluation on the liquid oxygen flow on different test bed bodies based on the corrected flow coefficient, and therefore transverse comparison evaluation of the liquid oxygen flow measuring precision of all the test bed bodies is achieved.

Description

Technical Field

[0001] This invention relates to a method for evaluating the accuracy of flow measurement, specifically to a standard flow measurement device and a method for evaluating the consistency of flow across multiple test benches. Background Technology

[0002] When conducting ground tests of liquid engines, it is usually necessary to perform in-situ calibration of liquid oxygen flow measurement.

[0003] However, existing liquid oxygen flow measurement methods are limited by differences in test systems of different test benches, differences in in-situ calibration devices and flow measurement devices, and individual engine differences, making it impossible to conduct a comparative evaluation of the liquid oxygen flow measurement accuracy of different test benches.

[0004] Therefore, there is an urgent need for a method that can evaluate the consistency of flow rates across multiple test benches. Summary of the Invention

[0005] To address the technical problem that existing liquid oxygen flow measurement methods are limited by differences in different test bench systems, in-situ calibration devices and flow measurement devices, and individual engine variations, making it impossible to conduct a comparative evaluation of the liquid oxygen flow measurement accuracy across different test benches, this invention provides a standard flow measurement device and a method for evaluating the consistency of flow across multiple test benches.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: On one hand, the present invention provides a standard flow measurement device, comprising: Differential pressure lines are made using Venturi tubes. The rectifier tube is installed upstream of the differential pressure tube along the direction of medium flow and adopts a porous plate structure. The pressure regulating pipe is installed downstream of the differential pressure pipe along the direction of medium flow and adopts a porous plate structure. Multiple pressure and temperature measurement units are installed on the differential pressure tube, rectifier tube, and regulator tube respectively, for measuring the pressure and temperature at different locations within the differential pressure tube, rectifier tube, and regulator tube.

[0007] Furthermore, the pressure and temperature measurement unit includes a pressure measuring element and a temperature sensor, wherein the pressure measuring element includes a pressure sensor or a differential pressure sensor.

[0008] Furthermore, the differential pressure tube has multiple pressure tapping holes on its wall, and an outer tube is provided on the differential pressure tube. A pressure stabilizing cavity is formed between the outer tube and the differential pressure tube. Pressure measuring elements corresponding to the number of pressure tapping holes are installed in the circumferential direction of the outer tube, and the installation points of the pressure measuring elements are staggered from the pressure tapping holes.

[0009] Furthermore, temperature sensors are provided at the top of the differential pressure tube and at 120° intervals around its circumference.

[0010] Furthermore, the device also includes: The thermal insulation structure is fitted over the differential pressure pipe, rectifier pipe, and pressure regulating pipe; The measurement and control system is used to collect data from the pressure and temperature measurement units, as well as the flow rate of the medium passing through the differential pressure tube, rectifier tube, and pressure regulating tube, and to process the data.

[0011] On the other hand, the present invention provides a method for evaluating the consistency of flow rates across multiple test benches based on the standard flow measurement device described above, comprising the following steps: Step 1: Calibrate the standard flow measurement device to determine the standard flow coefficient C of the standard flow measurement device; Step 2: Perform on-site in-situ calibration of the standard flow measurement device after metrological calibration; Step 3: Use a standard flow measurement device calibrated on-site to compare and evaluate the liquid oxygen flow rate of the liquid oxygen release system mounted on different test stands, so as to achieve a consistent evaluation of the flow rate across multiple test stands.

[0012] Furthermore, step 2 includes the following specific steps: The calibrated standard flow measuring device was installed in the liquid oxygen discharge system pipeline on the No. 1 test stand; a segmented level gauge was installed in the liquid oxygen discharge system pipeline on the No. 1 test stand to measure the flow rate of liquid oxygen passing through the standard flow measuring device. The temperature and pressure data of different parts of the differential pressure tube, rectifier tube, and pressure regulating tube in the standard flow measurement device are monitored. Linear fitting is performed on the standard flow measurement device for on-site in-situ calibration to obtain the fitting coefficients. The linear fitting formula is: ; In the formula, and Here, is the fitting coefficient, a is the intercept, and b is the slope; To correct the throat area of ​​the differential pressure tube. The density of liquid oxygen, To correct the pressure difference between the inlet and outlet of the differential pressure pipe.

[0013] Furthermore, the throat area of ​​the differential pressure tube is corrected. The calculation method is as follows ; Liquid oxygen density Calculations are performed using the differential pressure inlet temperature t: ; Correction differential pressure pipe inlet and outlet pressure difference The calculation method is as follows: ; P hwql =0.011052t+2.112563; Where t is the inlet temperature of the differential pressure tube, and P iwql P is the inlet pressure of the differential pressure pipe. hwql The pressure at the throat of the differential pressure tube is denoted by d; d represents the inner diameter of the throat of the differential pressure tube. is the linear expansion coefficient of the differential pressure pipe material.

[0014] Furthermore, step 3 includes the following specific steps: The standard flow measurement device, calibrated in situ, was installed in the liquid oxygen discharge pipeline of other test benches. Sectional level gauges were installed in the liquid oxygen discharge pipelines, and the liquid oxygen flow measurement values ​​from the section level gauges and the calculated liquid oxygen flow values ​​from the standard flow measurement device were obtained. The uncertainties of the liquid oxygen flow measurement values ​​and the calculated liquid oxygen flow values ​​were calculated. Then, based on the normalized error En number calculation formula, the flow consistency across multiple test benches was analyzed. The normalized error En number calculation formula is as follows: ; In the formula: This is the calculated value for liquid oxygen flow rate; This is the measured value of liquid oxygen flow rate; The uncertainty in the calculated liquid oxygen flow rate; This represents the uncertainty of the liquid oxygen flow rate measurement.

[0015] The beneficial effects of this invention are: This invention is based on a standard flow measurement device. By calibrating the standard flow measurement device and performing on-site calibration, a corrected flow coefficient is obtained. Based on the corrected flow coefficient, the liquid oxygen flow rate is compared and evaluated on different test benches using the standard flow measurement device. This overcomes the limitations of differences between different test bench systems, differences in on-site calibration devices and flow measurement devices, and individual engine differences. It enables a horizontal comparative evaluation of the liquid oxygen flow measurement accuracy of each test bench, and ultimately achieves a consistent flow rate evaluation across multiple test benches. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the standard flow measurement device in an embodiment of the present invention; Figure 2 yes Figure 1 BB cross-sectional view; Figure 3 yes Figure 1 DD sectional view; Figure 4 yes Figure 1 FF sectional view; Figure 5yes Figure 1 CC and EE sectional views; Figure 6 yes Figure 1 AA and GG sectional views; Figure 7 This is a simulation diagram of the flow resistance distribution of the standard flow measurement device in an embodiment of the present invention; Figure 8 This is a fitted curve of the pressure difference between the inlet and outlet of the differential pressure tube in an embodiment of the present invention.

[0017] The attached figures are labeled as follows: 1-Rectifier tube, 2-Differential pressure tube, 3-Pressure regulating tube, 4-Pressure tap, 5-Pressure stabilizing chamber, 6-Pressure measuring element, 7-Outer sleeve. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0019] See Figure 1 This embodiment provides a standard flow measurement device, which mainly includes the following structure: Rectifier tube 1, differential pressure tube 2, pressure regulating tube 3, pressure and temperature measuring unit, and insulation structure.

[0020] Specifically, the direction of medium flow is taken into account: The rectifier tube 1 is located upstream of the differential pressure tube 2, and the pressure regulating tube 3 is located downstream of the differential pressure tube 2. The three are connected in series coaxially to form an integral structure.

[0021] See Figure 2 In this embodiment, the rectifier tube 1 adopts a porous plate structure. Since the rectifier tube 1 is located upstream of the differential pressure tube 2, the porous plate structure can ensure the conditions for the full development of flow in the tube under different flow field environments.

[0022] See Figure 4 Similarly, in this embodiment, the pressure regulating pipe 3 adopts the same porous plate structure as the rectifier pipe 1. Since the pressure regulating pipe 3 is located downstream of the differential pressure pipe 2, the porous plate structure allows the outlet of the differential pressure pipe 2 to be fully filled, and the fluid in the differential pressure pipe 2 is not disturbed by the downstream flow field.

[0023] See Figure 3 In this embodiment, considering that the Venturi tube has the highest precision and the lowest flow resistance, the differential pressure tube 2 is selected as a Venturi tube.

[0024] The pressure and temperature measurement unit is installed on the aforementioned overall structure. In this embodiment, the pressure and temperature measurement unit includes a pressure measuring element 6 and a temperature sensor. Its function is to achieve accurate measurement of pressure / pressure difference and medium temperature while minimizing interference with the flow field inside the measuring device. On the one hand, the measurement point structure is optimized through the simulation results of the pressure field and temperature field. On the other hand, the parameters are accurately measured through the high-precision pressure measuring element 6 and temperature sensor, thereby obtaining the pressure and temperature data of the required location through the pressure and temperature measurement unit.

[0025] Specifically, a set of pressure measuring elements 6 is provided on the outer circumferential surface of rectifier tube 1 and pressure regulating tube 3, and a set of temperature sensors is provided on the outer circumferential surface of rectifier tube 1 and pressure regulating tube 3 at the inlet and outlet; a set of pressure measuring elements 6 is provided on the outer circumferential surface of differential pressure tube 2 at the inlet and throat.

[0026] The pressure measuring element 6 is a pressure sensor or a differential pressure sensor. The number of pressure measuring elements 6 in each group is M, where M≥2; the number of temperature sensors in each group is N, where N≥2; the M pressure measuring elements 6 and the N temperature sensors in the same group are evenly distributed along the circumference.

[0027] Taking differential pressure tube 2 as an example: Preferably, due to pressure fluctuations within the differential pressure tube 2, to improve the stability of pressure measurement, in this embodiment, four individual pressure taps 4 are evenly distributed circumferentially on the wall of the differential pressure tube 2, with a 90° interval between adjacent pressure taps 4. An outer sleeve 7 is fitted over the differential pressure tube 2, forming a pressure stabilizing cavity 5 between the outer sleeve 7 and the differential pressure tube 2. Pressure measuring elements 6, corresponding to the number of pressure taps 4, are installed circumferentially on the outer sleeve 7, with the mounting points of the pressure measuring elements 6 offset from the pressure taps 4 by 45°. The pressure measuring elements 6 are connected to the pressure taps 4 through the pressure stabilizing cavity 5, thereby achieving stable pressure measurement within the differential pressure tube 2, avoiding measurement data errors caused by pressure fluctuations, and improving the reliability of the measurement data. (See attached...) Figure 6 In the middle, the interface at the top is the vent, and the interface at the bottom is the drain.

[0028] Preferably, in this embodiment, three temperature measuring points are set at the top and 120° intervals around the differential pressure pipe 2. A high-precision temperature sensor is installed at each temperature measuring point to measure the temperature of the medium. In actual use, if the measurement accuracy requirement is lower, temperature sensors can be installed at only two temperature measuring points at 120° intervals around the circumference.

[0029] See Figure 5The temperature sensors are arranged in the same way on the rectifier tube 1, differential pressure tube 2, and pressure regulating tube 3, all located at the top and at 120° intervals around the perimeter. In this embodiment, they will not be described in detail. The pressure measuring elements 6 on the rectifier tube 1 and pressure regulating tube 3 are arranged in the same way as the temperature sensors, except that they are offset from the temperature sensors in the axial direction.

[0030] In addition, it should be noted that the specific configuration of the pressure measuring element 6 and the temperature sensor described above are only some preferred embodiments of the present invention. In other embodiments of the present invention, those skilled in the art can configure the pressure measuring element 6 and the temperature sensor according to actual needs, and are not limited to the preferred embodiments of the present invention.

[0031] In this embodiment, considering that the working medium is mainly cryogenic liquid oxygen, the heat insulation structure is set on the outer circumferential surface of the integral structure formed by the rectifier tube 1, the differential pressure tube 2, and the pressure regulating tube 3. In this way, the heat insulation structure reduces the influence of radial temperature stratification of the measuring device caused by heat transfer loss, which helps to improve the accuracy of medium temperature measurement.

[0032] Preferably, from the perspective of economy and convenience, the insulation structure in this embodiment uses polyurethane foam as the cold insulation material, is wrapped with glass ribbon, and coated with low-temperature adhesive as a moisture-proof layer, and is covered with stainless steel sheet on the outermost layer.

[0033] In other embodiments of the present invention, the measuring device further includes a measurement and control system for acquiring data from the pressure measuring element 6 and the temperature sensor, as well as the flow rate of the medium passing through the device, and performing data processing.

[0034] Specifically, the aforementioned measurement and control system mainly includes a chassis, a CRIO (Cellular Radio Interchange) unit, and a touchscreen. The CRIO's primary function is to collect data from the pressure measuring element 6 and the temperature sensor, as well as system status parameters such as the flow rate of the medium passing through the measuring device, and to receive timing signals. The touchscreen's main function is to display system status parameters and record them in real time. The chassis adopts a portable and movable design, encapsulating the CRIO unit inside and integrating the touchscreen onto the chassis. The touchscreen and CRIO unit are connected via cables, ensuring rapid deployment and convenient use in different locations.

[0035] The technical specifications of the standard flow measurement device in this embodiment include: (1) Rated flow rate: 290 kg / s; (2) Flow measurement range: (65%~110%) rated flow; (3) Uncertainty: ≤1%.

[0036] See Figure 7To ensure that the standard flow measurement device in this embodiment operates within the rated flow range of 65%~110%, the flow resistance of each stage of the pipeline is allocated based on the overall flow resistance requirements of the measurement device. The orifice shape of the rectifier tube 1 and the pressure regulating tube 3, as well as the throat diameter of the differential pressure tube 2, are designed. Simulation analysis shows that the overall flow resistance is approximately 0.378 MPa under rated operating conditions.

[0037] Table 1 Flow resistance distribution of standard flow measurement device The flow resistance of the porous plate structure of the pressure regulating tube 3 increases the back pressure of the venturi tube. Therefore, under actual flow conditions, the rectifier tube 1 and the pressure regulating tube 3 are in a fully liquid flow state, and the differential pressure tube 2 is a scaling structure. The overall flow resistance is about 0.03 MPa. Since the back pressure of the three-stage porous plate is atmospheric pressure, liquid oxygen generates cavitation in the orifice plate and downstream, and the flow resistance is significantly greater than that of the single-stage structure under the fully liquid flow state.

[0038] When using the aforementioned standard flow measurement device to evaluate the flow consistency across multiple test benches, the following steps can be followed: Step 1: Calibration of the standard flow measurement device; The standard flow measurement device is sent to a metrology unit for water medium flow coefficient calibration to obtain the standard flow coefficient C of the standard process measurement device. This process is existing technology and will not be described in detail in this invention.

[0039] Step 2: On-site calibration of the standard flow measurement device; The calibrated standard flow measuring device was installed in the liquid oxygen discharge system pipeline on the No. 1 test stand. In the liquid oxygen discharge system pipeline on the No. 1 test stand, liquid oxygen is recovered from the main container to the collection container through the supply pipeline and the discharge pipeline. A segmented level gauge was installed in the main liquid oxygen pipeline to measure the flow rate of liquid oxygen passing through the standard flow measuring device. The temperature and pressure data of different parts of the differential pressure tube, rectifier tube and pressure regulating tube in the standard flow measurement device are monitored, and the linear fitting of the on-site in-situ calibration is performed using the following formula (1) to obtain the fitting coefficient of the formula.

[0040] (1) In the formula, and Here, is the fitting coefficient, a is the intercept, and b is the slope; To correct the throat area of ​​the differential pressure tube. The density of liquid oxygen, To correct the pressure difference between the inlet and outlet of the differential pressure pipe.

[0041] density of liquid oxygen The calculation is performed using the differential pressure inlet temperature t, and the formula is as follows: (2) In the formula, t is the inlet temperature of the differential pressure tube.

[0042] In practical use, since the pressure measuring element 6 will have a certain zero drift after channel calibration, zero-point correction is performed first before data processing in order to accurately calculate the differential pressure. The average pressure between -10s and 0s is calculated, with the differential pressure tube inlet pressure P as the averaging factor. iwql Using the parameters as a reference, calculate the zero-point deviation, and then calculate the differential pressure inlet pressure P. iwql Differential pressure throat pressure P hwql The difference between them is used as the correction differential pressure difference between the inlet and outlet of the differential pressure pipe. That is, to correct the pressure difference between the inlet and outlet of the differential pressure pipe. The calculation is performed in the following manner: (3) In the formula, P iwql P is the inlet pressure of the differential pressure pipe. hwql This refers to the pressure at the throat of the differential pressure tube.

[0043] As a throttling element, the differential pressure tube 2 is affected by the significant difference in cavitation pressure and coverage area caused by the liquid oxygen temperature, which in turn affects the flow state within the differential pressure tube 2. Table 2 shows the throat pressure P of the differential pressure tube during the actual liquid discharge process in each test area. hwql The value of the differential pressure pipe inlet temperature t. Figure 8 The fitted curve is given, and the relationship between the throat pressure and the inlet temperature of the differential pressure tube can be obtained from the fitting results: P hwql =0.011052t+2.112563 (4) Table 2. Correspondence between differential pressure tube throat pressure and differential pressure tube inlet temperature Considering that the throat area of ​​the differential pressure tube will shrink at low temperatures, in this embodiment, the throat area of ​​the differential pressure tube is corrected according to the inlet temperature of the differential pressure tube using the following formula. ,get ; (5) In the formula: d represents the inner diameter of the throat of the differential pressure tube. The linear expansion coefficient of the differential pressure pipe material is 14.78 × 10⁻⁶. -6 / ℃.

[0044] By measuring pressure, temperature, and liquid oxygen flow rate data under different operating conditions, and combining the above equations (1)-(5), the fitting coefficient can be obtained. and .

[0045] Step 3: Use a standard flow measurement device that has been calibrated on-site to measure and compare the liquid oxygen flow rate of the liquid oxygen release system on other test stands, so as to achieve a consistent flow rate evaluation across multiple test stands.

[0046] Specifically, the standard flow measurement device after on-site calibration was installed in the liquid oxygen discharge pipeline of the No. 2 test stand. Similarly, a segmented level gauge was set in the liquid oxygen discharge pipeline of the No. 2 test stand. The liquid oxygen flow measurement value of the segmented level gauge and the liquid oxygen flow calculation value of the standard flow measurement device were obtained respectively. The uncertainty of the liquid oxygen flow measurement value and the liquid oxygen flow calculation value were calculated. Then, the flow consistency of multiple test stands was analyzed according to the normalized error En number calculation formula (formula (6)).

[0047] (6) In the formula: This is the calculated value for liquid oxygen flow rate; This is the measured value of liquid oxygen flow rate; The uncertainty in the calculated liquid oxygen flow rate; This represents the uncertainty of the liquid oxygen flow rate measurement.

[0048] The measurement and calculation results for this step on the test bench are shown in Table 3-4 below: Table 3 Number of En on Test Stand #2 Table 4. Number of En on Test Stand #3 As can be seen from the En number in the table above, when the standard flow measurement device is applied to test bench #2 and test bench #3, the En number is less than 1, indicating that the accuracy is within the 1% confidence range, and the comparison results are reliable.

[0049] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present invention should be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A standard flow measurement device, characterized in that, include: Differential pressure tube (2) is a Venturi tube; The rectifier tube (1) is installed upstream of the differential pressure tube (2) along the direction of medium flow and adopts a porous plate structure. The pressure regulating pipe (3) is installed downstream of the differential pressure pipe (2) along the direction of medium flow and adopts a porous plate structure. Multiple pressure and temperature measurement units are installed on the differential pressure tube (2), rectifier tube (1) and pressure regulating tube (3) respectively, for measuring the pressure and temperature at different locations in the differential pressure tube (2), rectifier tube (1) and pressure regulating tube (3).

2. The standard flow measurement device according to claim 1, characterized in that, The pressure and temperature measurement unit includes a pressure measuring element (6) and a temperature sensor. The pressure measuring element (6) includes a pressure sensor or a differential pressure sensor.

3. The standard flow measurement device according to claim 2, characterized in that, The differential pressure tube (2) has multiple pressure tapping holes (4) on its wall, and an outer tube (7) is provided on the differential pressure tube (2). A pressure stabilizing cavity (5) is formed between the outer tube (7) and the differential pressure tube (2). Pressure measuring elements (6) corresponding to the number of pressure tapping holes (4) are installed on the circumference of the outer tube (7), and the installation point of the pressure measuring elements (6) is staggered from the pressure tapping holes (4).

4. The standard flow measurement device according to claim 3, characterized in that, Temperature sensors are provided at the top and at 120° intervals around the differential pressure tube (2).

5. The standard flow measurement device according to any one of claims 1-4, characterized in that, The device further includes: The heat insulation structure is sleeved outside the differential pressure pipe (2), rectifier pipe (1) and pressure regulating pipe (3); The measurement and control system is used to collect data from the pressure and temperature measurement units, as well as the flow rate of the medium passing through the differential pressure tube (2), rectifier tube (1) and pressure regulating tube (3), and to perform data processing.

6. A method for evaluating the consistency of flow rates across multiple test benches based on the standard flow measurement device according to any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Calibrate the standard flow measurement device to determine the standard flow coefficient C of the standard flow measurement device; Step 2: Perform on-site in-situ calibration of the standard flow measurement device after metrological calibration; Step 3: Use a standard flow measurement device calibrated on-site to compare and evaluate the liquid oxygen flow rate of the liquid oxygen release system mounted on different test stands, so as to achieve a consistent evaluation of the flow rate across multiple test stands.

7. The method for evaluating the consistency of flow rates across multiple test benches according to claim 6, characterized in that, Step 2 includes the following steps: The calibrated standard flow measuring device was installed in the liquid oxygen discharge system pipeline on the No. 1 test stand; a segmented level gauge was installed in the liquid oxygen discharge system pipeline on the No. 1 test stand to measure the flow rate of liquid oxygen passing through the standard flow measuring device. The temperature and pressure data of different parts of the differential pressure tube, rectifier tube, and pressure regulating tube in the standard flow measurement device are monitored. Linear fitting is performed on the standard flow measurement device for on-site in-situ calibration to obtain the fitting coefficients. The linear fitting formula is: ； In the formula, and Here, is the fitting coefficient, a is the intercept, and b is the slope; To correct the throat area of ​​the differential pressure tube. The density of liquid oxygen, To correct the pressure difference between the inlet and outlet of the differential pressure pipe.

8. The method for evaluating the consistency of flow rates across multiple test benches according to claim 7, characterized in that, Corrected differential pressure tube throat area The calculation method is as follows ； Liquid oxygen density Calculations are performed using the differential pressure inlet temperature t: ； Correction differential pressure pipe inlet and outlet pressure difference The calculation method is as follows: ； P hwql =0.011052t+2.112563; Where t is the inlet temperature of the differential pressure tube, and P iwql P is the inlet pressure of the differential pressure pipe. hwql The pressure at the throat of the differential pressure tube is denoted by d; d represents the inner diameter of the throat of the differential pressure tube. is the linear expansion coefficient of the differential pressure pipe material.

9. The method for evaluating the consistency of flow rates across multiple test benches according to claim 8, characterized in that, Step 3 includes the following steps: The standard flow measurement device, calibrated in situ, was installed in the liquid oxygen discharge pipeline of other test benches. Sectional level gauges were installed in the liquid oxygen discharge pipelines, and the liquid oxygen flow measurement values ​​from the section level gauges and the calculated liquid oxygen flow values ​​from the standard flow measurement device were obtained. The uncertainties of the liquid oxygen flow measurement values ​​and the calculated liquid oxygen flow values ​​were calculated. Then, based on the normalized error En number calculation formula, the flow consistency across multiple test benches was analyzed. The normalized error En number calculation formula is as follows: ； In the formula: This is the calculated value for liquid oxygen flow rate; This is the measured value of liquid oxygen flow rate; The uncertainty in the calculated liquid oxygen flow rate; This represents the uncertainty of the liquid oxygen flow rate measurement.

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