Liquid pressure measuring device and method based on five-hole probe

Abstract

The invention discloses a liquid pressure measuring device and method based on a five-hole probe, and the device comprises the five-hole probe, a housing supporting rod, miniature pressure transmitters, a lead, and a tail conical head, the five miniature pressure transmitters are respectively connected in each hole of the five-hole probe through threads, and the bottom of the threads is provided with a sealing rubber ring. The five-hole probe is in threaded connection with the head of the shell supporting rod to form a water-drop-shaped head structure, the tail conical head is in threaded connection with the tail of the shell supporting rod to form a water-drop-shaped tail structure, the wire is connected with the miniature pressure transmitter, and the miniature pressure transmitter converts collected pressure signals into electric signals. The electric signal is transmitted to a data acquisition card through a wire, and the liquid pressure is obtained according to the electric signal in the data acquisition card. The miniature pressure transmitter is directly arranged in the five-hole probe, so that the use of a pressure pipeline can be avoided, and the pressure in the water flow direction can be directly measured. In addition, the response speed of the sensor can be remarkably improved through a very small cavity in the five-hole probe.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid pressure measurement, and in particular to a liquid pressure measurement device and method based on a five-hole probe. Background Art

[0002] At present, there are many test instruments to measure the velocity in both air and liquid, such as pitot tube, anemometer, flow meter, etc. Since these measuring devices are generally used for pipeline measurement, there is no requirement for velocity vector measurement. Therefore, these devices can usually only measure the magnitude of velocity, but not the direction of velocity.

[0003] There are also five-hole, three-hole, and seven-hole probes in the air that can be used to measure the velocity vector of the gas. Taking the five-hole probe as an example, when measuring, the probe is facing the airflow, and the five pressure holes on the probe lead the airflow pressure to five pressure transmitters through the pressure pipe. Then the pressure transmitter transmits the electrical signal to the data acquisition card, and finally the size and direction of the airflow can be obtained through the five-hole probe algorithm on the computer. This method is already very mature in the field of gas measurement, but due to the density, gravity, and cavity effect of the liquid, this method cannot measure the velocity vector in the liquid. If the five-hole probe measurement method is used directly in water to measure the velocity vector of the liquid, it is necessary to ensure that: ① The entire pressure pipeline is completely filled with the measured liquid and no bubbles exist. ② The five-hole probe and the pressure transmitter are completely at the same height to avoid the pressure difference caused by gravity. ③ Ensure that the length of the pressure pipeline is consistent to reduce the measurement error caused by the viscosity of the fluid. This method is theoretically feasible, but there are problems in the actual measurement process that the results are inaccurate and are greatly affected by the measurement environment. Summary of the invention

[0004] The present invention provides a liquid pressure measuring device and method based on a five-hole probe to overcome the above technical problems.

[0005] A liquid pressure measuring device based on a five-hole probe comprises a five-hole probe, a shell support rod, a micro pressure transmitter, a wire and a tail cone head, wherein the five-hole probe comprises five pressure holes, namely a first hole, a second hole, a third hole, a fourth hole and a fifth hole; five micro pressure transmitters are respectively connected to the five pressure holes of the five-hole probe through threads, a sealing rubber ring is arranged at the bottom of the thread, the five-hole probe and the head of the shell support rod are connected through threads to form a water drop-shaped head structure, the tail cone head and the middle part of the shell support rod are connected through threads to form a water drop-shaped tail structure, the wire is connected to the micro pressure transmitter, and the micro pressure transmitter converts the collected pressure signal into an electrical signal , the electrical signal is transmitted to the data acquisition card through the wire, and the liquid pressure is obtained according to the electrical signal in the data acquisition card. The five-hole probe is the front half of the teardrop-shaped head structure separated along the maximum radius. The shell support rod includes the remaining part of the teardrop-shaped head structure divided along the maximum radius, the middle part and a support rod. The connection between the middle part and the remaining part is the first edge of the middle part, and the connection between the middle part and the tail cone head is the second edge of the middle part. The middle part and the support rod are both hollow shells and are wrapped with wires. The tail cone head is the tail part of the teardrop-shaped tail structure divided along the second edge of the middle part, and is installed on the tail part of the second edge of the middle part through threads.

[0006] Preferably, the measuring range of the micro pressure transmitter is determined by the pressure of the measured liquid, and the pressure range of the measured liquid is estimated, and the pressure range of the measured liquid is set to 1 / 3 to 2 / 3 of the measuring range of the micro pressure transmitter to determine the measuring range of the micro pressure transmitter.

[0007] Preferably, the axis of the second hole coincides with the center line of the five-hole probe; the first hole, the third hole, the fourth hole, and the fifth hole are evenly distributed on a circle centered on the second hole, and the axes of the first hole, the third hole, the fourth hole, and the fifth hole are all perpendicular to the outer wall surface of the five-hole probe.

[0008] A liquid pressure measuring method based on a liquid pressure measuring device, comprising:

[0009] S1. Calibrate the liquid pressure measuring device in the standard flow field, obtain the pressure values ​​of the five pressure holes at different deflection angles and pitch angles, calculate the directional calibration coefficient, total pressure coefficient and static pressure coefficient corresponding to the deflection angle and pitch angle according to the pressure values ​​of the five pressure holes at different deflection angles and pitch angles, and plot K according to the pressure values ​​and the corresponding directional calibration coefficient, total pressure coefficient and static pressure coefficient. α -K β Curve, C pt Calibration curve and C ps Calibration curve;

[0010] S2. Place the calibrated liquid pressure measuring device at the measuring point of the liquid to be measured, wherein the liquid pressure measuring device is parallel to the flow direction of the liquid to be measured, and the placement direction of the water drop-shaped head structure is opposite to the flow direction, and obtain data in the data acquisition card, wherein the data in the data acquisition card includes pressure values ​​respectively obtained by five micro pressure transmitters in the five-hole probe;

[0011] S3, based on K α -K β Curve, C pt Calibration curve, C ps The liquid pressure and velocity vector at the measuring point are calculated based on the calibration curve and the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes of the five-hole probe.

[0012] Preferably, said S3 includes,

[0013] S31. Express the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes as p1, p2, p3, p4, and p5, and calculate the deflection calibration coefficient K of the measuring point according to equations (1) and (2): α and the pitch calibration factor K β ;

[0014]

[0015] in, p1, p2, p3, p4, and p5 represent the pressure values ​​obtained from the first hole, the second hole, the third hole, the fourth hole, and the fifth hole, respectively;

[0016] S32, according to K α and K β The value of K α -K β The curve obtains the airflow angle a and β based on C pt Calibration curve, C ps The calibration curve obtains the total pressure calibration coefficient C of the measuring point pt and static pressure calibration factor C ps ;

[0017] S33, according to the total pressure calibration coefficient C pt and static pressure calibration factor C ps , calculate the total pressure P0 and static pressure P at the measuring point according to equations (3) and (4);

[0018]

[0019] S34. Based on the total pressure P0 and the static pressure P, the velocity of the measuring point is calculated according to the isentropic Mach number formula, wherein α is the deflection angle, β is the pitch angle, and the deflection angle α and the pitch angle β are used to represent the spatial direction of the velocity of the measuring point.

[0020] The present invention provides a liquid pressure measuring device and method based on a five-hole probe, wherein a micro pressure transmitter is directly built into the five-hole probe, thereby avoiding the use of a pressure pipe. During measurement, the liquid directly enters the micro pressure transmitter through the holes on the five-hole probe, and acts on the micro pressure transmitter to generate an electrical signal. In this way, the pressure in the direction of the water flow can be directly measured. Thus, the density and gravity of the liquid can be avoided, and a serious cavity effect can be generated in the pressure pipe. In addition, the extremely small cavity inside the five-hole probe can significantly improve the response speed of the sensor. The mounting part of the micro pressure transmitter is a threaded structure, which is convenient for processing and replacement. It can be replaced with sensors of different ranges according to different liquid depths and fluid velocities. To adapt to different measurement conditions. The five-hole probe adopts a water droplet-shaped streamlined shape, which can effectively reduce underwater resistance. The axes of the first hole, the third hole, the fourth hole, and the fifth hole on the five-hole probe are all perpendicular to the outer wall surface of the five-hole probe, which can better measure the static pressure of the fluid. The support rod also adopts a water droplet-shaped streamlined shape, which can significantly reduce underwater resistance underwater. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0022] Figure 1 It is a structural diagram of the device of the present invention;

[0023] FIG2( a ) is a cross-sectional view of the liquid pressure measuring device in an embodiment of the present invention;

[0024] FIG2( b ) is a front view of the liquid pressure measuring device in an embodiment of the present invention;

[0025] Figure 3 is an appearance view of a micro pressure transmitter in an embodiment of the present invention;

[0026] FIG4( a) is a front view of a five-hole probe in an embodiment of the present invention;

[0027] FIG4( b ) is a side view of a five-hole probe in an embodiment of the present invention;

[0028] FIG4( c ) is a top view of a five-hole probe in an embodiment of the present invention;

[0029] FIG4( d ) is a cross-sectional view of a five-hole probe in an embodiment of the present invention;

[0030] Figure 5 is a schematic diagram of five-hole probe measurement in an embodiment of the present invention;

[0031] FIG. 6( a ) is a diagram of the direction calibration coefficient K according to an embodiment of the present invention. α -K β curve;

[0032] FIG. 6( b ) is a diagram of the total pressure calibration coefficient C according to an embodiment of the present invention. pt Calibration curve;

[0033] FIG. 6( c ) is a diagram of the static pressure calibration coefficient C according to an embodiment of the present invention. ps Calibration curve.

[0034] Description of Figure Numbers:

[0035] 1. Five-hole probe; 2. Shell support rod; 3. Miniature pressure transmitter; 4. Sealing rubber ring; 5. Wire; 6. Tail cone head; 7. Teardrop-shaped head structure; 8. Teardrop-shaped tail structure; 9. Middle part; 10. Support rod; 11. Remaining parts. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0037] Figure 1 It is a structural diagram of the device of the present invention, such as Figure 1 As shown, the method of this embodiment includes:

[0038] A liquid pressure measuring device based on a five-hole probe comprises a five-hole probe 1, a shell support rod 2, a micro pressure transmitter 3, a wire 5 and a tail cone head 6, wherein the five-hole probe comprises five pressure holes, namely a first hole, a second hole, a third hole, a fourth hole and a fifth hole; five micro pressure transmitters are respectively connected to the five pressure holes of the five-hole probe by threads, a sealing rubber ring 4 is arranged at the bottom of the thread to prevent water from entering the probe, the five-hole probe and the head of the shell support rod are connected by threads to form a water drop-shaped head structure 7, which can effectively reduce the influence of the probe on the flow of liquid underwater and improve the measurement accuracy, the tail cone head and the middle part of the shell support rod are connected by threads to form a water drop-shaped tail structure 8 for reducing underwater resistance, the cross-sectional view of the present invention is shown in FIG2(a), and the front view is shown in FIG2(b). As shown in 2(b), the wire is connected to a micro pressure transmitter, which converts the collected pressure signal into an electrical signal, transmits the electrical signal to a data acquisition card through the wire, and obtains the liquid pressure according to the electrical signal in the data acquisition card. The five-hole probe is the front half of the teardrop-shaped head structure separated along the maximum radius, the outer shell support rod comprises the remaining part 11, the middle part 9 and a support rod 10 separated along the maximum radius of the teardrop-shaped head structure, the connection between the middle part and the remaining part is the first edge of the middle part, the connection between the middle part and the tail cone head is the second edge of the middle part, the middle part and the support rod are both hollow shells, and both are wrapped with wires, the tail cone head is the tail of the teardrop-shaped tail structure separated along the second edge of the middle part, and is installed on the tail of the second edge of the middle part by threads.

[0039] Specifically, the range of the micro pressure transmitter is determined by the pressure of the measured liquid. The pressure range of the measured liquid is set to 1 / 3 to 2 / 3 of the range of the micro pressure transmitter. The pressure range of the measured liquid is estimated and the range of the micro pressure transmitter is determined. Specifically, in order to obtain a more accurate pressure value, the pressure range of the measured liquid is usually required to be between 1 / 3 and 2 / 3 of the sensor range during measurement. At this time, the value measured by the sensor is the most accurate. For example, if we estimate that the pressure of the measured liquid is between 1kPa-2kPa, we can choose a sensor with a range of 0-3kPa to measure. The appearance of the micro pressure transmitter is as follows Figure 3 The axis of the second hole of the five-hole probe coincides with the center line of the five-hole probe; the first hole, the third hole, the fourth hole, and the fifth hole are evenly distributed on a circle centered on the second hole, and the axes of the first hole, the third hole, the fourth hole, and the fifth hole are perpendicular to the outer wall of the five-hole probe. The angle views of the five-hole probe are as shown in FIG. Figure 4(a) , 4(b) , 4(c), and the cross-sectional view is shown in Figure 4(d).

[0040] Specifically, the outer shell support rod is only shown for schematic display. In actual application, the thickness, length and width can be designed according to the measurement conditions. When measuring, directly place the probe in the measured liquid and make the probe head face the fluid. Figure 5 The liquid will directly impact the central part of the underwater probe head, i.e. the second hole, and generate pressure values ​​in the five measuring holes.

[0041] A liquid pressure measuring method based on a liquid pressure measuring device, comprising:

[0042] S1. Calibrate the liquid pressure measuring device in the standard flow field, obtain the pressure values ​​of the five pressure holes at different deflection angles and pitch angles, calculate the directional calibration coefficient, total pressure coefficient and static pressure coefficient corresponding to the deflection angle and pitch angle according to the pressure values ​​of the five pressure holes, and plot K according to the pressure values ​​and the corresponding directional calibration coefficient, total pressure coefficient and static pressure coefficient. α -K β Curve, C pt Calibration curve and C ps Calibration curve, the calibration of the liquid pressure measuring device in the standard flow field includes defining the five pressure values ​​measured by the probe as p1, p2, p3, p4, and p5 respectively. The coordinate axis is constructed with the second hole as the origin, the line connecting the fourth and fifth holes as the X-axis, and the line connecting the first and third holes as the Y-axis. The angle between the probe and the X-axis is α (deflection angle), and the angle with the Y-axis is β (pitch angle). During calibration, the five-hole probe is directly placed in the standard flow field (referring to an artificial flow field with known speed, size, direction, and pressure) so that the center direction of the five-hole probe is exactly the same as the axis direction of the standard fluid. After that, the probe head is used as the rotation center, and the probe is rotated from -30° to +30° at intervals of 5° in the X and Y directions respectively. Record the pressure values ​​of the five pressure holes of the probe at each calibration point.

[0043] The non-opposing calibration coefficients for the five-hole probe are defined as follows, where

[0044] Pitch calibration factor:

[0045]

[0046] Deflection calibration factor:

[0047]

[0048] Total pressure calibration factor:

[0049]

[0050] Static pressure calibration factor:

[0051]

[0052] Through the above calibration method, the direction calibration coefficient K as shown in Figure 6(a) can be obtained α -K β The total pressure calibration coefficient C shown in the curve and Figure 6(b) pt The calibration curve and the static pressure calibration coefficient C shown in Figure 6(c) ps Calibration curve. This method is simple to operate in actual measurement. The probe does not need to be adjusted during measurement. Data can be directly collected to calculate the pitch calibration coefficient K. β , deflection calibration coefficient K α , total pressure calibration coefficient and static pressure calibration coefficient, the deflection angle α and pitch angle β are calculated according to the above three curves, that is, the direction of the fluid is obtained. The corresponding measurement time is greatly shortened. Generally speaking, the measurement angle range of the five-hole probe is within ±40°, otherwise the probe reading fluctuates greatly, the measurement accuracy decreases, and the value obtained is no longer reliable. Therefore, when applying this measurement method, the range of α and β during probe calibration should be within ±30°.

[0053] S2. Place the calibrated liquid pressure measuring device at the measuring point of the liquid to be measured, wherein the liquid pressure measuring device is parallel to the flow direction of the liquid to be measured, and the placement direction of the water drop-shaped head structure is opposite to the flow direction, and obtain data in the data acquisition card, wherein the data in the data acquisition card includes pressure values ​​respectively obtained by five micro pressure transmitters in the five-hole probe;

[0054] S3, based on K α -K β Curve, C pt Calibration curve, C ps The liquid pressure and velocity vector at the measuring point are calculated based on the calibration curve and the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes of the five-hole probe.

[0055] The S3 includes:

[0056] S31. Express the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes as p1, p2, p3, p4, and p5, and calculate the deflection calibration coefficient K of the measuring point according to equations (1) and (2): α and the pitch calibration factor K β ,

[0057]

[0058] in, p1, p2, p3, p4, and p5 represent the pressure values ​​obtained from the first hole, the second hole, the third hole, the fourth hole, and the fifth hole, respectively.

[0059] S32, according to K α and K βThe value of K α -K β The airflow angles α and β are obtained from the curve, and the pt Calibration curve, C ps The total pressure calibration coefficient C of the measuring point is obtained from the calibration curve pt and static pressure calibration factor C ps ,

[0060] S33, according to the total pressure calibration coefficient C pt and static pressure calibration factor C ps , calculate the total pressure P0 and static pressure P at the measuring point according to equations (3) and (4),

[0061]

[0062] S34. Based on the total pressure P0 and the static pressure P, the velocity of the measuring point is calculated according to the isentropic Mach number formula, wherein α is the deflection angle, β is the pitch angle, and the deflection angle α and the pitch angle β are used to represent the spatial direction of the velocity of the measuring point.

[0063] Among them, the isentropic Mach number formula is

[0064] Overall beneficial effects:

[0065] The present invention provides a liquid pressure measurement device and method based on a five-hole probe, wherein a micro pressure transmitter is directly built into the five-hole probe, thereby avoiding the use of a pressure pipe. During measurement, the liquid directly enters the micro pressure transmitter through the holes on the five-hole probe, and acts on the diffused silicon to generate an electrical signal. In this way, the pressure in the direction of the water flow can be directly measured. Thus, the density and gravity of the liquid can be avoided, and a serious cavity effect can be generated in the pressure pipe. In addition, the extremely small cavity inside the five-hole probe can significantly improve the response speed of the sensor. The mounting part of the micro pressure transmitter is a threaded structure, which is convenient for processing and replacement. It can be replaced with sensors of different ranges according to different liquid depths and fluid velocities to adapt to different measurement conditions. The five-hole probe adopts a water droplet-shaped streamlined shape, which can effectively reduce underwater resistance. The axes of the first hole, the third hole, the fourth hole, and the fifth hole on the five-hole probe are all perpendicular to the outer wall surface of the five-hole probe, which can better measure the static pressure of the fluid. The support rod also adopts a water droplet-shaped streamlined shape, which can significantly reduce underwater resistance underwater.

[0066] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. 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 replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid pressure measuring device based on a five-hole probe, characterized in that: The invention comprises a five-hole probe, a shell support rod, a micro pressure transmitter, a wire and a tail cone head. The five-hole probe comprises five pressure holes, namely a first hole, a second hole, a third hole, a fourth hole and a fifth hole. The five micro pressure transmitters are respectively connected to the five pressure holes of the five-hole probe through threads, and a sealing rubber ring is arranged at the bottom of the thread. The five-hole probe and the head of the shell support rod are connected through threads to form a water drop-shaped head structure, and the tail cone head and the middle part of the shell support rod are connected through threads to form a water drop-shaped tail structure. The wire is connected to the micro pressure transmitter, and the micro pressure transmitter converts the collected pressure signal into an electrical signal, and transmits the electrical signal through the wire. The five-hole probe is the front half of the teardrop-shaped head structure separated along the maximum radius, the outer shell support rod comprises the remaining part of the teardrop-shaped head structure separated along the maximum radius, the middle part and a support rod, the connection between the middle part and the remaining part is the first edge of the middle part, the connection between the middle part and the tail cone head is the second edge of the middle part, the middle part and the support rod are both hollow shells, and are wrapped with wires, the tail cone head is the tail part of the teardrop-shaped tail structure separated along the second edge of the middle part, and is installed on the tail part of the second edge of the middle part by threads.

2. A liquid pressure measuring device based on a five-hole probe according to claim 1, characterized in that: The measuring range of the micro pressure transmitter is determined by the pressure of the measured liquid. The pressure range of the measured liquid is estimated and the pressure range of the measured liquid is set to 1 / 3 to 2 / 3 of the measuring range of the micro pressure transmitter to determine the measuring range of the micro pressure transmitter.

3. A liquid pressure measuring device based on a five-hole probe according to claim 1, characterized in that: The axis of the second hole coincides with the center line of the five-hole probe; the first hole, the third hole, the fourth hole, and the fifth hole are evenly distributed on a circle centered on the second hole, and the axes of the first hole, the third hole, the fourth hole, and the fifth hole are all perpendicular to the outer wall of the five-hole probe.

4. A method for measuring liquid pressure based on the liquid pressure measuring device according to claim 1, characterized in that: include: S1. Calibrate the liquid pressure measuring device in the standard flow field, obtain the pressure values ​​of the five pressure holes at different deflection angles and pitch angles, calculate the directional calibration coefficient, total pressure coefficient and static pressure coefficient corresponding to the deflection angle and pitch angle according to the pressure values ​​of the five pressure holes at different deflection angles and pitch angles, and plot K according to the pressure values ​​and the corresponding directional calibration coefficient, total pressure coefficient and static pressure coefficient. α -K β Curve, C pt Calibration curve and C ps Calibration curve; S2. Place the calibrated liquid pressure measuring device at the measuring point of the liquid to be measured, wherein the liquid pressure measuring device is parallel to the flow direction of the liquid to be measured, and the placement direction of the water drop-shaped head structure is opposite to the flow direction, and obtain data in the data acquisition card, wherein the data in the data acquisition card includes pressure values ​​respectively obtained by five micro pressure transmitters in the five-hole probe; S3, based on K α -K β Curve, C pt Calibration curve, C ps The liquid pressure and velocity vector at the measuring point are calculated based on the calibration curve and the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes of the five-hole probe.

5. The method for measuring liquid pressure according to claim 4, characterized in that: The S3 includes, S31. Express the pressure values ​​obtained by the five micro pressure transmitters in the five pressure holes as p1, p2, p3, p4, and p5, and calculate the deflection calibration coefficient K of the measuring point according to equations (1) and (2): α and the pitch calibration factor K β ; in, p1, p2, p3, p4, and p5 represent the pressure values ​​obtained from the first hole, the second hole, the third hole, the fourth hole, and the fifth hole, respectively; S32, according to K α and K β The value of K α -K β The curve obtains the airflow angle a and β based on C pt Calibration curve, C ps The calibration curve obtains the total pressure calibration coefficient C of the measuring point pt and static pressure calibration factor C ps ; S33, according to the total pressure calibration coefficient C pt and static pressure calibration factor C ps , calculate the total pressure P0 and static pressure P at the measuring point according to equations (3) and (4); S34. Based on the total pressure P0 and the static pressure P, the velocity of the measuring point is calculated according to the isentropic Mach number formula, wherein α is the deflection angle, β is the pitch angle, and the deflection angle α and the pitch angle β are used to represent the spatial direction of the velocity of the measuring point.

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