Portable modularized three-dimensional pitot tube flow velocity automatic measuring device and measuring method

Abstract

The invention provides a portable modularized three-dimensional pitot tube flow velocity automatic measuring device and method, and the device comprises a pitot tube, one end of the pitot tube is spherical and is provided with five measuring tubes capable of measuring static pressure, the other end of the pitot tube is connected with an air tube in a clamping manner, and the air tube is internally provided with a thin tube which can be connected with the five measuring tubes of the pitot tube. The surface of the gas pipe is sleeved with a control unit capable of driving the gas pipe to rotate and move, one end, far away from the pitot tube, of the gas pipe is fixedly connected with a quick connection unit, and the gas pipe is fixedly connected with an extension pipe through the quick connection unit. According to the invention, a plurality of transverse points in the flue can be measured, the flow velocity in the flue can be accurately measured, the pitot tube can be conveniently and rapidly prolonged in a narrow flue and other places, and the use experience can be further improved.

Description

Technical Field

[0001] The present invention relates to the field of flow velocity measurement, and in particular to a portable modular three-dimensional pitot tube automatic flow velocity measuring device and a measuring method. Background Art

[0002] A Pitot tube flowmeter is a classic tool for calculating flow velocity by sensing the difference between total and static pressures. It is widely used in aerospace applications, such as airspeed monitoring, airflow control in industrial pipelines, and wind field research in the environmental field. Its core principle is to use a total pressure probe at the front end to capture the dynamic pressure generated by fluid impact, while using a static pressure port to collect static pressure. The difference between the two is converted into flow velocity data using a formula.

[0003] Traditional large-scale fixed measurement equipment often requires advance installation and debugging. When encountering temporary monitoring needs, such as industrial leak investigation and field meteorological emergency observation, the bulky equipment will seriously slow down the response speed, especially when multi-point and multi-time comparative measurements are required. Engineers may need to measure wind speed in narrow air-conditioning ducts or collect exhaust gas flow at large outdoor chimneys. The bulky equipment will further slow down the response speed. Traditional measurement equipment mostly relies on manual adjustment and cannot maintain accuracy for a long time when measuring multiple points. Summary of the Invention

[0004] In response to the problems existing in the prior art, the purpose of the present invention is to provide a portable modular three-dimensional Pitot tube automatic flow velocity measuring device and measurement method: it can be easily carried, and thus can quickly respond to sudden detection needs, and can automatically adjust the feed amount and angle of the Pitot tube spherical probe, can provide stable accuracy during multi-point measurement, thereby improving the user experience, and can quickly extend the length when measuring in narrow pipes, which can effectively improve portability and applicability.

[0005] The present invention provides a portable modular three-dimensional pitot tube automatic flow velocity measuring device, comprising a pitot tube, one end of the pitot tube being spherical and provided with five measuring tubes capable of measuring static pressure, the other end of the pitot tube being clamped with an air pipe, the air pipe being provided with a thin tube capable of connecting with the five measuring tubes of the pitot tube, the surface of the air pipe being provided with a control unit capable of driving the air pipe to rotate and move, the end of the air pipe away from the pitot tube being fixedly connected with a quick-connect unit, and the air pipe being fixedly connected to an extension tube via the quick-connect unit;

[0006] The control unit includes a shell, a rotating drum is provided inside the shell, a rotating unit capable of controlling the angle of the pitot tube is provided inside the shell, the rotating drum is rotatably connected to the shell through the rotating unit, a moving unit capable of controlling the forward and backward displacement of the pitot tube is provided inside the rotating drum, and the air pipe is slidably installed in the shell through the moving unit.

[0007] A portable modular three-dimensional pitot tube flow velocity automatic measurement method, using a portable modular three-dimensional pitot tube flow velocity automatic measurement device, includes the following steps:

[0008] Step 1: Before the test, the device needs to be leveled to ensure that it is in a horizontal state when installed, and then the device flange and the on-site flue flange are fixed with a clamp;

[0009] Step 2: Determine the number of points to be measured and the locations of the measuring points based on the inner diameter of the flue on site. Then, determine the distance between the end of the spherical probe and the end of the device to determine the distance between the ball head and the first traversal point to be measured. The control unit then automatically advances or retracts to the first traversal point as the reference zero point for movement.

[0010] Step 3: The control unit drives the spherical probe of the pitot tube to advance. When it reaches the midpoint of the flue inner diameter, it reaches the static pressure measurement point. At this time, the static pressure value is also the variable to be measured. After reaching this point, the control unit drives the spherical probe of the pitot tube to perform yaw zeroing, that is, rotate to the position where P1-P2 is 0;

[0011] Step 4: At this time, rotate 90 degrees and point P3 to the air. The value of the P2-P3 differential pressure gauge is the measured static pressure value. Then it is fed to the second half of the traverse point for sampling in sequence. After sampling at each traverse point is completed, the flow rate at the current point can be calculated;

[0012] Step 5: After measuring the last point in the second half, start to retreat and measure the cross-points in the first half. For example, if the number of cross-points is n, measure the static pressure value at 1 / 2 of the inner diameter d, then measure the cross-point n / 2+1, and continue to point n. Then retreat to point n / 2 and continue to measure until point 1. The flow velocity value of each point can be obtained, and then the average value is calculated as the flow velocity reference value for this measurement, and then the flow rate is calculated.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0014] (1) The present invention can drive the movement of the spherical probe of the Pitot tube through the moving unit in the control unit, thereby controlling the feeding amount of the spherical probe of the Pitot tube in the flue, and can accurately control the feeding of the spherical probe of the Pitot tube to various measuring points in the flue, which can effectively improve the positioning accuracy, and can also accurately control the angle of the spherical probe of the Pitot tube in the flue through the rotating unit, which can further improve the accuracy.

[0015] (2) The present invention can quickly connect multiple extension tubes at the tail end of the trachea through a quick-connect unit, thereby enabling the spherical probe of the Pitot tube to feed in a narrow flue, and can quickly adapt to more measurement locations, thereby improving the user experience.

[0016] (3) The present invention can accurately control the position and angle of the spherical probe of the Pitot tube in the flue through the control unit, and thus can measure multiple cross-points in the flue, and can accurately measure the flow velocity in the flue, conveniently obtain the flow velocity value of each point, and then calculate the average value as the flow velocity reference value of this measurement, and then calculate the flow rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the positions of the P1-P5 crossing points of the present invention;

[0019] Figure 3 This is a schematic structural diagram of the rotating unit of the automatic measuring device of the present invention;

[0020] Figure 4 Schematic diagram of the internal structure of the automatic measuring device of the present invention;

[0021] Figure 5 This is a schematic structural diagram of the quick-connect unit of the automatic measuring device of the present invention;

[0022] Figure 6 The automatic measuring device of the present invention Figure 5 A schematic diagram of the structure at point A;

[0023] Figure 7 This is a schematic structural diagram of the control unit of the automatic measuring device of the present invention;

[0024] Figure 8 This is a schematic diagram of the internal cross-sectional structure of the automatic measuring device of the present invention;

[0025] Figure 9 This is a schematic diagram of the internal structure of the trachea of ​​the automatic measuring device of the present invention;

[0026] Figure 10 The automatic measuring device of the present invention Figure 9 Enlarged schematic diagram of the structure at point B.

[0027] Explanation of the numbers in the figure: 1. Pitot tube; 12. Air pipe; 13. Housing; 14. Rotating drum; 15. Extension tube; 16. First outer cover; 17. First hinge; 18. Second outer cover; 19. Second hinge; 101. Hose; 102. Thermocouple; 103. Second quick-connect sealing head; 2. Rotating unit; 21. First bracket; 22. First motor; 23. First driving wheel; 24. Second bracket; 25. First driven wheel; 26. First meter wheel; 27. First encoder; 3. Moving unit; 31. Second motor; 32. Second driving wheel; 33. Second driven wheel; 34. Second meter wheel; 35. Second encoder; 4. Quick-connect unit; 41. Connecting hole; 42. Cable management chuck; 43. First quick-connect sealing head; 44. Tapered hole; 45. Top ball; 46. Spring; 47. Block. DETAILED DESCRIPTION

[0028] The above and other technical contents, features and effects of the present invention are described below with reference to the attached Figures 1 to 10 It can be clearly presented in the detailed description of the embodiments that the structural contents mentioned in the following embodiments are all referenced to the drawings in the specification.

[0029] Example 1, as Figure 1 、 Figure 2 and Figure 4 A portable modular three-dimensional pitot tube automatic flow velocity measuring device is shown, comprising a pitot tube 1. One end of the pitot tube 1 is spherical and has five measuring tubes (P1 to P5) capable of measuring static pressure. The other end of the pitot tube 1 is clamped to an air pipe 12. The air pipe 12 contains a thin tube capable of connecting to the five measuring tubes of the pitot tube 1. The surface of the air pipe 12 is provided with a control unit capable of driving the air pipe 12 to rotate and move. The end of the air pipe 12 away from the pitot tube 1 is fixedly connected to a quick-connect unit 4. The air pipe 12 is fixedly connected to an extension tube 15 through the quick-connect unit 4.

[0030] The control unit includes a shell 13, in which a rotating drum 14 is provided. A rotating unit 2 capable of controlling the angle of the pitot tube 1 is provided in the shell 13. The rotating drum 14 is rotatably connected to the shell 13 through the rotating unit 2. A moving unit 3 capable of controlling the forward and backward displacement of the pitot tube 1 is provided in the rotating drum 14. The air pipe 12 is slidably installed in the shell 13 through the moving unit 3.

[0031] In the specific implementation, it is only necessary to insert the spherical probe of the Pitot tube 1 into the flue to be measured, and then determine the number of points to be measured and the position of the measuring points based on the inner diameter of the flue on site. After the number of points to be measured and the position of the measuring points are determined, the position and angle of the spherical Pitot tube 1 in the flue can be controlled by the control unit to perform sampling.

[0032] Example 2, as Figure 3 、 Figure 7 、 Figure 8 and Figure 9 The rotating unit 2 shown includes a first bracket 21, which is fixedly installed in the housing 13. A first motor 22 is fixedly connected to the first bracket 21. A first driving wheel 23 is fixedly connected to the output end of the first motor 22, and the first driving wheel 23 is in contact with the rotating drum 14. A plurality of second brackets 24 are provided on one side of the first bracket 21. The plurality of second brackets 24 are arranged around the rotating drum 14. A first driven wheel 25 is rotatably connected to each of the plurality of second brackets 24, and the first driven wheel 25 is in contact with the rotating drum 14. A first meter wheel 26 is provided below the first bracket 21. A first encoder 27 is fixedly connected to the shaft end of the first meter wheel 26. The first encoder 27 is fixedly connected to the inner wall of the housing 13.

[0033] In actual use, when it is necessary to control the angle of the spherical probe of the Pitot tube 1, it is only necessary to start the first motor 22. The rotation of the first motor 22 will drive the rotating drum 14 to rotate, and the rotation of the rotating drum 14 will drive the mobile unit 3 to rotate, thereby driving the air pipe 12 to rotate. The rotation of the air pipe 12 will drive the Pitot tube 1 to rotate, thereby changing the angle of the spherical probe of the Pitot tube 1 in the flue. In addition, when the rotating drum 14 rotates, it will drive the first meter wheel 26 to rotate. The rotation of the first meter wheel 26 will give an electrical signal to the first encoder 27, thereby knowing the number of rotations and angle of the first meter wheel 26, and then calculating the rotation angle of the rotating drum 14, thereby accurately controlling the angle of the spherical probe of the Pitot tube 1.

[0034] Example 3, as Figure 3 、 Figure 7 、 Figure 8 and Figure 9 The shown moving unit 3 includes a second motor 31, which is fixedly mounted on the surface of the rotating drum 14. The output end of the second motor 31 passes through the rotating drum 14 and is fixedly connected to a second driving wheel 32. The bottom end of the second driving wheel 32 contacts the air pipe 12. A plurality of second driven wheels 33 are provided below the second driving wheel 32. The plurality of second driven wheels 33 are fixedly mounted on the inner wall of the rotating drum 14. The plurality of second driven wheels 33 are arranged around the rotating drum 14 and all of the plurality of second driven wheels 33 contact the air pipe 12. A second meter wheel 34 is provided below the second motor 31. The shaft end of the second meter wheel 34 is fixedly connected to a second encoder 35. The second encoder 35 is fixedly connected to the rotating drum 14.

[0035] In actual use, when it is necessary to control the spherical probe of the Pitot tube 1 to move to the position of the measured point, it is only necessary to start the second motor 31. The rotation of the second motor 31 will push the air pipe 12 to move, and the movement of the air pipe 12 will drive the spherical probe of the Pitot tube 1 to move, so as to control the position of the spherical probe of the Pitot tube 1 in the flue. In addition, the movement of the air pipe 12 will drive the second meter wheel 34 to rotate. The rotation of the second meter wheel 34 will give an electrical signal to the second encoder 35, and then the number of rotations and angles of the second meter wheel 34 will be known, and the moving distance of the air pipe 12 will be calculated, so as to accurately control the angle of the spherical probe of the Pitot tube 1. The first encoder 27 and the second encoder 35 can both adopt models such as JK72S. This model adopts photoelectric encoding, which can convert the mechanical geometric displacement on the output shaft into pulses or digital quantities, thereby facilitating the calculation of angles and feed amounts.

[0036] Example 4, as Figure 5 and Figure 6 The quick-connect unit 4 shown includes a connecting hole 41, which is opened on the surface of the extension tube 15. The extension tube 15 is sleeved on the surface of the trachea 12 and the trachea 12 is fixedly connected to the extension tube 15 by arranging screws in the connecting hole 41. The extension tube 15 and the trachea 12 are fixedly installed with a wire management chuck 42. The wire management chuck 42 can limit the thin tube in the trachea 12. The thin tube in the trachea 12 and the extension tube 15 are fixedly connected through a first quick-connect sealing head 43. A tapered hole 44 is opened at the tail end of the trachea 12, and a top bead 45 is clamped in the tapered hole 44. A spring 46 is in contact with the bottom of the top column 45, and a block 47 is fixedly connected to the bottom end of the spring 46. The block 47 is adapted to the wire management chuck 42.

[0037] In the specific implementation, it is only necessary to align the tail end of the trachea 12 to be extended with the extension tube 15, and then insert the extension tube 15 into the tail end of the trachea 12. At this time, the block 47 can be connected with the wire management chuck 42 under the thrust of the spring 46, thereby giving the extension tube 15 a weak positioning, so that it is convenient for the user to screw the screw into the connecting hole 41 to complete the fixed connection between the trachea 12 and the extension tube 15, and the trachea 12 and the thin tube in the extension tube 15 can be sealed and connected through the first quick-connect sealing head 43, so that the changes collected by the spherical probe of the Pitot tube 1 can be seamlessly transmitted backwards, thereby facilitating the reading of the differential pressure sensor.

[0038] Example 5, as Figure 1 and Figure 4 As shown, a thermocouple 102 is fixedly mounted at the front spherical measuring end of the Pitot tube 1 .

[0039] In a specific implementation, the thermocouple 102 can read the temperature while the spherical probe of the Pitot tube 1 collects the flow rate, which can effectively improve the user experience under high temperature and high flow rate wind speed measurements such as collecting exhaust gas flow at a large outdoor chimney or in an air-conditioning system.

[0040] Example 6, as Figure 9 and 10 The five measuring tubes in the pitot tube 1 are connected to the thin tube in the trachea 12 via a hose 101 , and the junction between the hose 101 and the thin tube is sealed via a second quick-connect sealing head 103 .

[0041] The first quick-connect sealing head 43 and the second quick-connect sealing head 103 can both adopt models such as XTGS20A, which can be inserted and connected with one click after alignment, and can effectively improve the user experience.

[0042] Example 7, as Figure 1 and Figure 3 A first outer cover 16 is provided on the top of the housing 13 , and the first outer cover 16 is fixedly connected to the housing 13 via a first hinge 17 . A second outer cover 18 is provided in the drum 14 , and the second outer cover 18 is fixedly connected to the drum 14 via a second hinge 19 .

[0043] In a specific implementation, the first outer cover 16 can be opened by unlocking the first hinge 17, thereby facilitating maintenance and repair inside the shell 13. The second outer cover 18 can also be opened by unlocking the second hinge 19, thereby facilitating maintenance and repair inside the drum 14.

[0044] Example 8, working process: In actual use, it is only necessary to insert the spherical probe of the pitot tube 1 into the flue to be measured, and then determine the number of points to be measured and the position of the measuring points according to the inner diameter of the flue on site. After the number of points to be measured and the position of the measuring points are determined, the second motor 31 can be started. The rotation of the second motor 31 will push the air pipe 12 to move, and the movement of the air pipe 12 will drive the spherical probe of the pitot tube 1 to move, so as to control the position of the spherical probe of the pitot tube 1 in the flue, making it convenient for the user to send the spherical probe of the pitot tube 1 to the measuring point to be reached. When the spherical probe of the pitot tube 1 needs to adjust the angle, it is only necessary to start the first motor 22. The rotation of the first motor 22 will The rotating drum 14 is pushed to rotate, and the rotation of the rotating drum 14 will drive the mobile unit 3 to rotate, and then drive the air pipe 12 to rotate. The rotation of the air pipe 12 will drive the pitot tube 1 to rotate, and then change the angle of the spherical probe of the pitot tube 1 in the flue. When an external extension tube 15 is needed, it is only necessary to insert the extension tube 15 into the tail end of the air pipe 12. At this time, the block 47 can be connected with the wire management chuck 42 under the thrust of the spring 46, thereby giving the extension tube 15 a weak positioning, so that the user can screw the screw into the connecting hole 41 to complete the fixed connection between the air pipe 12 and the extension tube 15, and the user can also send the spherical probe of the pitot tube 1 to the correct position in a narrow position.

[0045] Example 9. The present invention also provides a portable modular three-dimensional Pitot tube flow rate automatic measurement method. The overall process of the measurement method is that the device needs to be horizontally zeroed before the test to ensure that the device is in a horizontal state when installed, and then the device flange and the on-site flue flange are fixed with a clamp.

[0046] The number of points to be measured and the position of the measuring points are determined according to the inner diameter of the flue on site. The distance between the end of the spherical probe and the end of the device is then measured to determine the distance between the ball head and the first traversal point to be measured. The control unit then automatically advances or retracts to the first traversal point as the reference zero point for movement.

[0047] The spherical probe of the Pitot tube is driven by the control unit to feed. When it reaches the midpoint of the inner diameter of the flue, it reaches the static pressure measurement point. At this time, the static pressure value is also the variable to be measured. After reaching this point, the spherical probe of the Pitot tube is driven by the control unit to perform yaw zeroing, that is, rotate to the position where P1-P2 is 0.

[0048] At this time, rotate 90 degrees and point P3 to the air. The value of the P2-P3 differential pressure gauge is the measured static pressure value. Then it is fed to the second half of the cross-section points for sampling in sequence. After sampling is completed at each cross-section point, the flow rate at the current point can be calculated.

[0049] After measuring the last point in the second half, it starts to retreat and measure the cross-points in the first half. For example, if the number of cross-points is n, the static pressure value is measured when the feed reaches 1 / 2 of the inner diameter d, and then the cross-point n / 2+1 is measured until point n, and then retreat to point n / 2 and measure until point 1. The flow velocity value of each point can be obtained, and then the average value is calculated as the flow velocity reference value for this measurement, and then the flow rate is calculated.

[0050] Example 10, based on Example 9, details the specific process and principle of the measurement method. Figure 2 The probe shown is a spherical sensing head consisting of five pressure measuring holes. The pressure points are numbered from 1 to 5 and are connected to the differential pressure sensor through a thin tube in the air pipe 12. They are P1-P2, P2-P3, and P4-P5 respectively.

[0051] The pressure data required for the measurement process are these three differential pressure values, of which P2-P3 can be used to adjust the yaw zero and then measure the yaw angle. That is, when P2-P3 is 0, the yaw angle is considered to be 0, indicating that the ball head is facing the direction of the smoke on the plane facing the measurer.

[0052] The ratio of pitch pressure P4-P5 to velocity pressure P1-P2 is F1. Determine F1 at a specific pitch angle, perform multiple repeated calibrations, and then perform curve fitting to generate a curve of F1 with respect to the pitch angle, called the pitch angle calibration curve. This allows F1 to be directly calculated based on the feedback differential pressure value during field measurements, and the pitch angle can be determined from the calibration curve. The curve of velocity calibration coefficient F2 with respect to pitch angle is called the velocity calibration curve. Once the pitch angle is determined from the pitch angle calibration curve, F2 can also be determined from the velocity calibration curve.

[0053] The yaw angle, pitch angle and velocity calibration coefficient F2 are all undetermined parameters of the flow rate calculation formula. The control unit drives the spherical probe of the pitot tube 1 to collect the above undetermined parameters in the flue to calculate the flow rate.

[0054] Before field testing, and when extending the Pitot tube 1 during field testing, the rotational position of the Pitot tube 1 must be checked by the control unit. The thermocouple 102 and the barometric pressure gauge should have a recent and valid calibration before being used in field testing. Before testing the Pitot tube 1, visually verify the physical condition of the front end of the Pitot tube 1. A horizontal straightness check should be performed before the start of each field test. An additional leak check can be performed after any test or group of tests. Pressurize the P1 pressure port of the Pitot tube 1 to at least 7.6cm H2O and record it on the device. Then close the pressure port (the pressure port and pressurizing equipment are field calibration equipment, which is existing conventional technology and is not shown in the figure). The pressure should remain stable at ±2.5mm H2O for at least 15 seconds. Similarly, check the P2, P3, P4, and P5 pressure ports. Before each field test, perform a zero calibration on each differential pressure measuring device.

[0055] When the test is first carried out, the flue or duct diameter and the length of the duct joint, including the pitot tube 1 ball probe joint or any extension of the pitot tube 1 ball probe into the flue, should be verified;

[0056] A distance measuring device such as a laser device is required to measure the dimensions of the flue or duct. The length required for the spherical probe of the Pitot tube 1 to reach each traversal point should be recorded and accurate to ±6.4mm. When determining these lengths, the distance that the port flange extends out of the flue and the depth of any pipe joints extending into the airflow should be considered. The end point position should reflect the actual distance from the inside wall of the flue or duct.

[0057] Transverse points refer to the transverse points distributed on the flue cross section according to specific rules in flue measurement. These points are set to accurately measure parameters such as the flow rate, concentration, temperature or pressure of the gas in the flue. Since the airflow distribution in the flue is usually uneven, single-point measurement alone cannot reflect the overall situation. Therefore, it is necessary to calculate the average value through the data of multiple transverse points to ensure the representativeness of the measurement results.

[0058] There are two methods to determine the cross-points, the equal-area method and the log-linear method, which are applicable to flues of different specifications. The equal-area method simply divides the flue cross-section into several equal areas; the log-linear method is suitable for large-sized flues or situations with complex airflow distribution. Of course, there are also requirements for the number of points. When the flue diameter is less than 0.3 meters, at least 8 points are required, and when the diameter is greater than 0.3 meters, more than 12 points are required.

[0059] After completing the equipment inspection and setting, use the control unit to drive the spherical probe of the Pitot tube 1 to feed in the flue or duct, insert and position the spherical probe of the Pitot tube 1 at any traversal point, and read and record the pressure difference, temperature and running time of the probe P1-P2 at intervals of 15 seconds until stable pressure and temperature readings are achieved.

[0060] Then, sampling is carried out. First, the yaw angle of the spherical probe of the Pitot tube 1 is set to zero, that is, the yaw measurement angle is zero. At each traversal point, the control unit is used to drive the Pitot tube to rotate along the flue axis until its punching pressure port P1 directly faces the positive airflow of the flue and the pressure difference between the ball head pressure holes P2 and P3 pressure ports is zero, that is, the pressure at P2 = the pressure at P3. At this time, the probe is aligned with the flow direction, which is the flow direction of the flue gas in the flue. When P2-P3 is 0, it means that the direction is aligned. The yaw angle, pressure difference and temperature of the traversal point are measured and recorded, and recorded after reaching a stable reading. At the beginning of the test at each sampling port (that is, after the probe is inserted into the flue airflow), at least sufficient response time must be left before starting measurement at the first traversal point approached by the sampling port (the response time is the longer running time of the two time periods). If the probe is not removed from the flue airflow, measurements can be continued at subsequent traversal points from the same test port without waiting for the response time to elapse again.

[0061] Maintain the rotational position of the spherical probe of the Pitot tube 1 established when measuring the yaw angle. Then, record the impact pressure (P1-P2) and pitch angle pressure (P4-P5) readings of the pressure measuring device. These pressure measurements should be made within a sampling period long enough to ensure that representative readings are obtained at each traverse point. If an automatic data acquisition system is used to record the pressure measurements, obtain the integrated average value of all pressure readings at the traverse point. The flue or duct gas temperature measurement should be recorded at least once at each traverse point.

[0062] As for the determination of the pitch angle, since the pitch angle and the pressure difference are not in a linear relationship, the specific value cannot be read out or directly calculated. Therefore, experiments should be carried out in the laboratory before conducting field tests. The ratio of pitch pressure to velocity pressure is defined as F1, that is, F1 = (P4-P5) / (P1-P2), where P1, P2, P3, P4, and P5 are the pressure values ​​of the corresponding pressure holes of the Pitot tube. First, determine F1 at a specific pitch angle, perform repeated calibration multiple times, and then perform curve fitting to generate a curve of F1 with respect to the pitch angle, which is called the pitch angle calibration curve. In this way, when conducting field measurements, F1 can be directly calculated according to the feedback differential pressure value, and then the pitch angle can be known through the calibration curve.

[0063] The velocity calibration coefficient is also required when calculating the final flue gas flow rate. Therefore, this coefficient also needs to be pre-derived through laboratory experiments. The velocity calibration coefficient F2 is defined as Cp[Pstd / (P1-P2)] -1 / 2 , where Cp is the calibration coefficient of the pitot tube, which is equal to 1, P1 and P2 are the pressure values ​​of the two pressure holes of the pitot tube, and Pstd is the dynamic pressure. The same calibration is repeated for curve fitting to obtain the curve of F2 and pitch angle, which is called the speed calibration curve. After the pitch angle is known through the pitch angle calibration curve, the speed calibration coefficient F2 is also known.

[0064] These calculations use the measured yaw angle, the derived pitch angle, and the measured pressure differentials and temperatures at various traverse points to derive the axial stack gas velocity at each point. The axial velocities are then averaged across all traverse points comprising the entire stack or duct to obtain the stack average axial velocity.

[0065] The calculation formula for flue gas flow rate is:

[0066]

[0067] Where: v si is the axial velocity of the flue gas at the measuring point i, in m / s; K c is the conversion factor, 128.9; F 2i is the velocity calibration coefficient of the three-dimensional pitot tube across the measuring point i; t s is the flue gas temperature, in degrees Celsius; P s P is the flue static pressure, in Pascals; a is atmospheric pressure, in Pascal; M s is the molecular weight of wet flue gas, in kilograms per kilogram mole; θ yi is the yaw angle of the flue gas flow, in degrees; θ pi is the flue gas airflow pitch angle, unit: degree.

[0068] Calculate flow rate:

[0069] Q=vs A

[0070] Where: v s is the average flow velocity, in m / s; A is the cross-sectional area of ​​the flue, in m 2 .

[0071] Finally, it should be noted that the embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit them. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some or all of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A portable modular three-dimensional pitot tube automatic flow velocity measuring device, comprising a pitot tube (1), one end of the pitot tube (1) being spherical and having five measuring tubes P1 to P5 capable of measuring static pressure, characterized in that: The other end of the pitot tube (1) is clamped with an air pipe (12), a thin tube capable of being connected to the five measuring tubes of the pitot tube (1) is provided in the air pipe (12), a control unit capable of driving the air pipe (12) to rotate and move is sleeved on the surface of the air pipe (12), one end of the air pipe (12) away from the pitot tube (1) is fixedly connected to a quick-connect unit (4), and the air pipe (12) is fixedly connected to an extension pipe (15) through the quick-connect unit (4); The control unit comprises a housing (13), a rotating drum (14) is provided in the housing (13), a rotating unit (2) capable of controlling the angle of a pitot tube (1) is provided in the housing (13), the rotating drum (14) is rotatably connected to the housing (13) via the rotating unit (2), a moving unit (3) capable of controlling the forward and backward displacement of the pitot tube (1) is provided in the rotating drum (14), and an air pipe (12) is slidably installed in the housing (13) via the moving unit (3).

2. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: The rotating unit (2) comprises a first bracket (21), which is fixedly mounted in a housing (13); a first motor (22) is fixedly connected in the first bracket (21); a first driving wheel (23) is fixedly connected to an output end of the first motor (22); the first driving wheel (23) contacts a rotating drum (14); a plurality of second brackets (24) are provided on one side of the first bracket (21); the plurality of second brackets (24) are arranged around the rotating drum (14); a first driven wheel (25) is rotatably connected in each of the plurality of second brackets (24); the first driven wheel (25) contacts the rotating drum (14); a first meter wheel (26) is provided below the first bracket (21); a first encoder (27) is fixedly connected to an axis end of the first meter wheel (26); and the first encoder (27) is fixedly connected to an inner wall of the housing (13).

3. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: The moving unit (3) comprises a second motor (31), the second motor (31) is fixedly mounted on the surface of the rotating drum (14), an output end of the second motor (31) passes through the rotating drum (14) and is fixedly connected to a second driving wheel (32), the bottom end of the second driving wheel (32) contacts an air pipe (12), a plurality of second driven wheels (33) are provided below the second driving wheel (32), the plurality of second driven wheels (33) are fixedly mounted on the inner wall of the rotating drum (14), the plurality of second driven wheels (33) are arranged around the rotating drum (14), the plurality of second driven wheels (33) all contact the air pipe (12), a second meter wheel (34) is provided below the second motor (31), a second encoder (35) is fixedly connected to the shaft end of the second meter wheel (34), and the second encoder (35) is fixedly connected to the rotating drum (14).

4. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: The quick-connect unit (4) includes a connecting hole (41), which is provided on the surface of the extension tube (15). The extension tube (15) is sleeved on the surface of the air pipe (12) and the air pipe (12) is fixedly connected to the extension tube (15) by arranging a screw in the connecting hole (41). A wire management chuck (42) is fixedly installed in the extension tube (15) and the air pipe (12). The wire management chuck (42) can limit the fine tube in the air pipe (12). The air pipe (12) and the fine tube in the extension tube (15) are fixedly connected through a first quick-connect sealing head (43). A tapered hole (44) is provided at the tail end of the air pipe (12). A top ball (45) is clamped in the tapered hole (44). A spring (46) is contacted below the top column (45). A clamping block (47) is fixedly connected to the bottom end of the spring (46). The clamping block (47) is adapted to the wire management chuck (42).

5. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: A thermocouple (102) is fixedly mounted at the front spherical measuring end of the Pitot tube (1).

6. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: The five measuring tubes in the pitot tube (1) are connected to the thin tube in the trachea (12) through a hose (101), and the junction between the hose (101) and the thin tube is sealed through a second quick-connect sealing head (103).

7. The portable modular three-dimensional pitot tube automatic flow velocity measuring device according to claim 1, characterized in that: A first outer cover (16) is provided on the top of the outer shell (13), and the first outer cover (16) is fixedly connected to the outer shell (13) via a first hinge (17). A second outer cover (18) is provided in the rotating drum (14), and the second outer cover (18) is fixedly connected to the rotating drum (14) via a second hinge (19).

8. A portable modular three-dimensional pitot tube automatic flow velocity measurement method, using a portable modular three-dimensional pitot tube automatic flow velocity measurement device according to claims 1-7, characterized in that: The steps include: Step 1: Before the test, the device needs to be leveled to ensure that it is in a horizontal state when installed, and then the device flange and the on-site flue flange are fixed with a clamp; Step 2: Determine the number of points to be measured and the locations of the measuring points based on the inner diameter of the flue on site. Then, determine the distance between the end of the spherical probe and the end of the device to determine the distance between the ball head and the first traversal point to be measured. The control unit then automatically advances or retracts to the first traversal point as the reference zero point for movement. Step 3: The control unit drives the spherical probe of the pitot tube to advance. When it reaches the midpoint of the flue inner diameter, it reaches the static pressure measurement point. At this time, the static pressure value is also the variable to be measured. After reaching this point, the control unit drives the spherical probe of the pitot tube to perform yaw zeroing, that is, rotate to the position where P1-P2 is 0; Step 4: At this time, rotate 90 degrees and point P3 to the air. The value of the P2-P3 differential pressure gauge is the measured static pressure value. Then it is fed to the second half of the traverse point for sampling in sequence. After sampling at each traverse point is completed, the flow rate at the current point can be calculated; Step 5: After measuring the last point in the second half, start to retreat and measure the cross-points in the first half. For example, if the number of cross-points is n, measure the static pressure value at 1 / 2 of the inner diameter d, then measure the cross-point n / 2+1, and continue to point n. Then retreat to point n / 2 and continue to measure until point 1. The flow velocity value of each point can be obtained, and then the average value is calculated as the flow velocity reference value for this measurement, and then the flow rate is calculated.

9. The portable modular three-dimensional pitot tube automatic flow velocity measurement method according to claim 8, characterized in that: The process of measuring the flow rate in step 4 includes: Step 4-1: Number the pressure points from 1 to 5, connect them to the differential pressure sensor through the thin tube in the trachea, and measure the differential pressures of P1-P2, P2-P3, and P4-P5 respectively. When the differential pressure of P2-P3 is 0, the yaw angle is considered to be 0 at this moment, indicating that the ball head is facing the direction of the smoke on the plane facing the measurer; Step 4-2: Define F1 as the ratio of the pitch pressure P4-P5 differential pressure to the velocity pressure P1-P2 differential pressure, i.e., F1 = (P4-P5) / (P1-P2), where P1, P2, P4, and P5 are the pressure values ​​of the corresponding pressure ports of the pitot tube. This determines F1 at a specific pitch angle. Repeat the calibration multiple times, and then perform curve fitting to generate a curve of F1 with respect to the pitch angle, called the pitch angle calibration curve. During field measurements, F1 can be directly calculated based on the feedback differential pressure value, and the pitch angle can be determined using the calibration curve. Step 4-3: Define F2 as the velocity calibration coefficient, and F2 = Cp[Pstd / (P1-P2)]- 1 / 2 , where Cp is the calibration coefficient of the pitot tube, which is 1, P1 and P2 are the pressure values ​​of the two pressure holes of the pitot tube, and Pstd is the dynamic pressure. Repeat the calibration and perform curve fitting to generate a curve of F2 and pitch angle, which is called the velocity calibration curve. The velocity calibration coefficient F2 is calculated through the pitch angle. Step 4-4: Calculate the flow velocity using the yaw angle, pitch angle, and velocity calibration coefficient F2. The flue gas flow velocity calculation formula is: Where vsi is the axial velocity of the flue gas at measuring point i, in m / s; Kc is the conversion factor, 128.9; F2i is the velocity calibration coefficient of the three-dimensional pitot tube across measuring point i, i.e. F2; ts is the flue gas temperature, in degrees Celsius; Ps is the flue static pressure, in Pascals; Pa is the atmospheric pressure, in Pascals; Ms is the molecular weight of wet flue gas, in kilograms per kilogram mole; θyi is the yaw angle of the flue gas flow, in degrees; θpi is the pitch angle of the flue gas flow, in degrees. Calculate the flow rate: Q=vsA Where: vs is the average flow velocity, unit is m / s; A is the cross-sectional area of ​​the flue, unit is m 2 .

Images