Full-diameter slot-shaped box type uniform-speed fluid flow measuring device

Abstract

The invention relates to the technical field of fluid flow measuring devices, in particular to a full-diameter slot-shaped box-type uniform-speed fluid flow measuring device, which is characterized in that a slot-shaped uniform-speed box is arranged in a measured pipeline, the height of the uniform-speed box is the same as the diameter of the measured pipeline, an air inlet is formed in a windward side, and the uniform-speed box is connected to a pressure leading-out mother pipe in the uniform-speed box through a positive pressure leading-out pipe; an air outlet is formed in the slot-shaped uniform-speed box; the air outlet is used for discharging air flow entering the strip-seam-shaped uniform-speed box, and the air outlet is connected to a pressure leading-out pipe at the position of an exhaust strip seam opening of the uniform-speed box through a negative pressure leading-out pipe. The requirement for the straight pipe section of the measured pipeline is greatly reduced, the measurement precision is greatly improved, the fluid flow in the pipeline can be accurately measured under the condition that the measured pipeline is not provided with the straight pipe section and only provided with an elbow, the arrangement flexibility is high, and the device is suitable for various pipelines, high in precision and suitable for various fluids. The flow meter is especially suitable for flow measurement of dusty gas or dirty liquid.

Description

Technical Field

[0001] The invention relates to the technical field of fluid flow measurement devices, in particular to a full-diameter slit-shaped box-type average-speed fluid flow measurement device. Background Art

[0002] At present, domestic bar-type differential pressure elements for measuring gas flow have been widely used in all walks of life. Bar-type differential pressure elements mainly include domestic Annubar, American Viabar, German Deltabar, etc. The measurement principle of bar-type differential pressure elements is actually based on the measurement principle of flute tubes. One tube has several pressure-sensing holes on the windward side to sense the positive pressure in the pressure tube. Another tube is arranged behind the previous tube, and several pressure-sensing holes are opened on its side. The static pressure (also known as negative pressure), positive pressure and negative pressure in the sensing pipeline are uniformly distributed through their respective mother tubes and then output from their respective ends to the differential pressure transmitter. The size of the differential pressure also reflects the size of the gas flow in the tube. Figure 1 It is a structural diagram of an ordinary bar-type flow meter. Figure 2 It is a cross-sectional schematic diagram of an ordinary bar-type flow meter.

[0003] Through the application tracking and analysis of existing bar products, it is found that bar products still have the following defects in the process of use: a. Bar products have high requirements for the straight pipe section of the measured air duct. When the straight pipe section is short, the velocity distribution of the same end face in the measured pipe will cause a large deviation. At this time, because the number of measurement points on the windward side of bar products is too small, and the diameter of the measuring mother pipe itself is relatively thin, the pressures of each point measured by each sensing hole cannot be evenly distributed in the measuring mother pipe. Moreover, the pressure output of bar products is at one end of the measuring pipe. Usually, the output pressure is the average of several sensing holes near the output end, rather than the average pressure sensed by the entire mother pipe, which often causes a large error in the measurement. b. When encountering dusty airflow, dust will enter the measuring mother through the pressure sensing hole. The dust that enters the main pipe cannot get out and will accumulate in the pipe. The more it accumulates, the more likely it is that the entire measuring main pipe will be blocked. In order to ensure its use, maintenance personnel have to use compressed air to blow out the measuring device regularly or irregularly. The maintenance workload is large, and most of the dust accumulated in the main pipe cannot be blown out after a long time. Summary of the invention

[0004] In order to overcome the shortcomings of existing bar products, the present invention provides a full-diameter slit-shaped box-type uniform-speed fluid flow measurement device.

[0005] The technical solution adopted by the present invention to solve its technical problems is: a full-diameter slit-type box-type uniform fluid flow measuring device, including a slit-type uniform velocity box arranged in the pipeline to be measured, a pressure lead-out main pipe in the uniform velocity box, a pressure lead-out pipe at the exhaust slit opening of the uniform velocity box, a slit-type air inlet of the uniform velocity box, and a slit-type air outlet of the uniform velocity box; the slit-type uniform velocity box is arranged in the pipeline to be measured, and is a flat box with a height of D, a width of H 1 , a length of L, and the height D is the same as the diameter of the pipeline to be measured. The windward surface is provided with a slit-type air inlet of the uniform velocity box with a height of D and a width of H 1 , and at least three positive pressure measuring points are respectively arranged at the upper, middle, and lower positions along the height direction of the inner edge and are connected to the pressure lead-out main pipe in the uniform velocity box through positive pressure lead pipes; the slit-type uniform velocity box is provided with a slit-type air outlet of the uniform velocity box with a height of D and a width of H 2 ; the slit-type air outlet of the uniform velocity box is used to discharge the air flow entering the slit-type uniform velocity box, and at least three negative pressure measuring points are arranged at a position avoiding the air flow impact beside the slit-type air outlet of the uniform velocity box and are connected to the pressure lead-out pipe at the exhaust slit opening of the uniform velocity box through negative pressure lead pipes; it is characterized in that the ratio of the width of the slit-type air outlet of the uniform velocity box to the width of the air inlet of the uniform velocity box H 2 / H 1 = 0.15 - 0.25, and the ratio of the width to the height of the slit-type uniform velocity box H 1 / D = 0.065 - 0.110.

[0006] According to another embodiment of the present invention, it further includes that the average gas velocity in the upper part of the pipeline to be measured is V 上 , and the average gas velocity in the lower part is V 下 ; the ratio of the length to the height of the slit-type uniform velocity box L / D increases with the increase of the flow velocity distribution value V 上 / V 下 .

[0007] According to another embodiment of the present invention, it further includes that the positive pressure lead pipes and the negative pressure lead pipes are perpendicular to the ground or form an angle between 45° and 90° with the ground.

[0008] According to another embodiment of the present invention, it further includes that the cross-section of the pipeline to be measured is circular or rectangular.

[0009] According to another embodiment of the present invention, it further includes that when the pipeline to be measured is an elbow, the positive pressure measuring points are arranged at the 45° center line of the elbow, and the negative pressure measuring points are arranged at the left, middle, and right positions in the diameter direction of the downstream pipeline. Among them, the slit-type air inlet of the uniform velocity box is at the entrance of the horizontal section of the elbow into the elbow, and the slit-type air outlet of the uniform velocity box is at the pipeline vertically downward after passing through the elbow.

[0010] According to another embodiment of the present invention, further comprising that when the slit-shaped air outlet of the constant-speed box is installed on the side surface of the constant-speed box, the bottom surface of the slit-shaped constant-speed box is an inclined surface, and the slit-shaped air outlet of the constant-speed box is arranged at the lower position of the inclined surface for guiding.

[0011] According to another embodiment of the present invention, further comprising that when the slit-shaped air outlet of the constant-speed box is arranged corresponding to the bottom surface and the windward surface of the slit-shaped constant-speed box, the bottom surface of the slit-shaped constant-speed box suddenly changes inward to form symmetric inclined surfaces.

[0012] The beneficial effects of the present invention are as follows: The "full-diameter slit-shaped box-type constant-speed fluid flow measurement device" of the present invention completely solves the problem that the measurement elements, especially the measurement elements of the bar-type products, are easily blocked in current industrial applications. At the same time, due to its unique measurement principle and structure, the requirement for the straight pipe section of the measured pipeline is greatly reduced, and the measurement accuracy is greatly improved. Even in the case of no straight pipe section and only elbows, the accurate measurement of the fluid flow in the pipeline can be realized, with strong layout flexibility, and it can be applied to pipelines in any direction. The illustrated examples of the present invention are only based on the structure when the measured pipeline is a circular pipeline, and its structure can actually be fully applied to the measurement when the cross-section of the measured pipeline is rectangular. In addition, the principle and structure of the present invention can be fully applied to other fluids, such as water, oil, etc., especially applicable to dusty gases and contaminated liquids. The measurement instruments that can be replaced by it are not limited to bar-type measurement instruments, and can completely replace other fluid flow measurement instruments such as Venturi, orifice plate, and long-radius nozzle. Brief Description of the Drawings

[0013] The present invention will be further described below in conjunction with the drawings and embodiments.

[0014] Figure 1 is a schematic structural diagram of a common bar-type flowmeter;

[0015] Figure 2 is a schematic cross-sectional view of a common bar-type flowmeter;

[0016] Figure 3 is a front view of the present invention applied to a horizontal measured pipeline;

[0017] Figure 4 is a right view of the present invention applied to a horizontal measured pipeline;

[0018] Figure 5 is a top view of the present invention applied to a horizontal measured pipeline;

[0019] Figure 6 is Figure 5 a cross-sectional view of;

[0020] Figure 7 is a front view of the measured pipeline being a vertical pipeline;

[0021] Figure 8 It is the right view of the pipeline under test when the pipeline is vertical;

[0022] Figure 9 It is the top view of the pipeline under test when the pipeline is vertical;

[0023] Figure 10 It is the front view of the measurement structure when the pipeline under test is an elbow;

[0024] Figure 11 It is the left view of the measurement structure when the pipeline under test is an elbow;

[0025] Figure 12 It is the cross-sectional view of the dust-free airflow fluid structure.

[0026] In the figure, 1 is the pipeline under test, 2 is the slit-shaped uniform velocity box, 3 is the pressure lead-out main pipe inside the uniform velocity box, 4 is the pressure lead-out pipe at the exhaust slit opening of the uniform velocity box, 5 is the slit-shaped air inlet of the uniform velocity box, and 6 is the slit-shaped air outlet of the uniform velocity box. Specific implementation manner

[0027] As Figures 3 to 12 It is the structural schematic diagram of the present invention. A full-diameter slit-shaped box-type uniform velocity fluid flow measurement device includes a slit-shaped uniform velocity box 2, a pressure lead-out main pipe 3 inside the uniform velocity box, a pressure lead-out pipe 4 at the exhaust slit opening of the uniform velocity box, a slit-shaped air inlet 5 of the uniform velocity box, and a slit-shaped air outlet 6 of the uniform velocity box arranged in the pipeline under test 1; the slit-shaped uniform velocity box 2 is arranged in the pipeline under test 1 and is a flat box with a height D, a width of H 1 , and a length of L, and the height D is the same as the diameter of the pipeline under test 1. The windward side is provided with a slit-shaped air inlet 5 of the uniform velocity box with a height of D and a width of H 1 . At least three positive pressure measurement points are respectively arranged at the upper, middle, and lower positions along the height direction inside and are connected to the pressure lead-out main pipe 3 inside the uniform velocity box through positive pressure lead pipes; a slit-shaped air outlet 6 of the uniform velocity box with a height of D and a width of H is opened on the slit-shaped uniform velocity box 2 2 ; the slit-shaped air outlet 6 of the uniform velocity box is used to discharge the airflow entering the slit-shaped uniform velocity box 2. At least three negative pressure measurement points are arranged at a position avoiding the airflow impact beside the slit-shaped air outlet 6 of the uniform velocity box and are connected to the pressure lead-out pipe 4 at the exhaust slit opening of the uniform velocity box through negative pressure lead pipes; it is characterized in that the ratio of the width of the slit-shaped air outlet 6 of the uniform velocity box to the width of the air inlet of the uniform velocity box H 2 / H 1 = 0.15 - 0.25, and the ratio of the width to the height of the slit-shaped uniform velocity box 2 is H 1 / D = 0.065 - 0.110.

[0028] Specifically, one of the reasons for the low measurement accuracy of the bar-type product is that the number of pressure-sensing holes arranged along the diameter direction is not large enough. In principle, if the pressures measured by each pressure-sensing hole can be fully mixed and homogenized in the measurement main pipe of the bar-type product, then the more pressure-sensing points, the better. In fact, the number of pressure-sensing points of the bar-type product cannot be too many because the diameter of its measurement main pipe is small, and the pressures measured by the pressure-sensing holes at each point simply do not have enough time to be homogenized. To improve the measurement accuracy, it is necessary to increase the diameter of the measurement main pipe and the volume of the mixing chamber. However, the increase in diameter is also limited because too large a diameter will affect the flow area of the measured pipeline 1. Without increasing the flow area, and yet increasing the volume of the mixing chamber, only by changing the shape of the measurement pipe from circular to a flat box shape and extending the length in the air flow direction. Since there is enough mixing space, this creates conditions for increasing the number of pressure-sensing holes on the windward surface. When the pressure-sensing holes are numerous enough, they almost connect together to form a slit. This is the process of this invention. Figure 3 , Figure 4 , Figure 5 and Figure 6 shows the structure of the present invention when applied to a horizontally measured pipeline. A slit-shaped uniform velocity box 2 is arranged in the horizontal circular pipeline. The slit-shaped uniform velocity box 2 is a flat box with a height equal to the diameter D of the measured pipeline 1 and a width of H 1 . The windward surface of the slit-shaped uniform velocity box 2 is a uniform velocity box slit-shaped air inlet 5 with a height of D and a width of H 1 . Its surrounding areas on the top, bottom, left, and right are sealing bodies, and its leeward surface is provided with an opening with a height of D and a width of H 2For the slotted air outlet 6 of the averaging chamber, when the gas in the measured pipeline 1 flows vertically towards the slotted averaging chamber 2, since the inlet area of the slotted averaging chamber 2 is larger than the outlet area, a pressure higher than the static pressure in the measured pipeline 1 will be generated inside the slotted averaging chamber 2. The pressure difference between the two can fully reflect the magnitude of the gas flow in the measured pipeline 1. The larger the flow rate, the larger the pressure difference, and the magnitude of the flow rate is proportional to the root mean square of the pressure difference. As long as the pressures inside and outside the slotted averaging chamber 2 are led out through the pressure guiding output pipe to the outside of the measured pipeline 1, the gas flow in the measured pipeline 1 can be measured. When laying out the pressure guiding pipes, considering that the averaging chamber is relatively high and the pressures at the upper and lower parts inside the chamber may not be exactly the same, in order to further improve the measurement accuracy, three pressure output holes are respectively opened at the upper, middle, and lower parts in the middle of the averaging chamber, and are connected to the pressure leading-out main pipe 3 inside the averaging chamber through three pressure guiding pipes. The " + " pressure is output from the pressure leading-out main pipe 3 inside the averaging chamber. Similarly, pressures are led out from the upper, middle, and lower parts at the slotted air outlet, and after mixing, they are led out through the pressure leading-out pipe 4 at the slotted air outlet of the averaging chamber as the " - " pressure output inside the pipeline. The three negative pressure leading-out points are arranged at the slotted air outlet part, but the pressure taking port cannot be directly facing the exhaust port and should not be affected by the airflow impact, and is arranged beside the air outlet. Due to the jet action of the outlet airflow, a pressure lower than the static pressure inside the pipeline will be generated beside it. Taking out the pressure at this part as the " - " pressure output can obtain a larger differential pressure, which is beneficial to improving the measurement accuracy.

[0029] Specifically, in order to reduce the disturbance of the measuring device to the gas in the measured pipeline 1 and reduce the flow resistance, the width H of the slotted windward surface of the measuring device 1 should not be too wide, but also should not be too narrow. If it is too narrow, the flow velocity inside the chamber will be too low, causing dust accumulation inside the chamber. Practice has proved that the ratio of the slit width H 1 to the diameter D of the measured pipeline 1 is more reasonable at 0.065 - 0.110; in order to prevent dust accumulation caused by too low flow velocity inside the averaging chamber, on the one hand, the inlet width H 1 cannot be too small, and at the same time the outlet width H 2 also cannot be too small, but H 2 also cannot be too large, because if H 2 is too large, there will be no pressure difference inside and outside the chamber. The reasonable H 2 / H 1 should be between 0.15 - 0.25;

[0030] According to another embodiment of the present invention, it further includes that the average gas flow velocity at the upper part inside the measured pipeline 1 is V 上 , and the average gas flow velocity at the lower part is V 下 ; the ratio L / D of the length to the height of the slotted averaging chamber 2 increases with the increase of the flow velocity distribution value V 上 / V 下 increases.

[0031] Specifically, the device of the present invention measures the air intake in a slit shape in the diameter direction of the pipeline 1 to be measured. In order to obtain accurate measurement accuracy, the air flow entering the equalizing chamber must be fully mixed, which requires the equalizing chamber to have a large mixing space. When the width H of the device 1 is limited, it can only be achieved by extending the length L along the air flow direction. In principle, the longer the L, the larger the mixing space and the better the mixing effect. However, in actual use, due to the limited pipeline length, L cannot be designed to be very long, but the length of L must have a minimum value. When the gas flow velocities at the upper and lower parts of the same end face in the pipeline 1 to be measured are the same, the required length is the shortest at this time. A large number of test experiments show that the minimum value of L / D is 0.158. As the air flow deviation between the upper and lower parts of the pipeline 1 to be measured becomes larger, the value of L / D must also increase accordingly to ensure sufficient mixing space. After a large number of experiments, the following table gives the minimum value of L / D under the multiple of the air flow deviation between the upper and lower parts.

[0032]

[0033]

[0034] According to another embodiment of the present invention, it further includes that the positive pressure guiding pipe and the negative pressure guiding pipe are perpendicular to the ground or form an angle between 45° and 90° with the ground.

[0035] Specifically, in order to ensure the reliable performance of the device of the present invention, in addition to preventing dust accumulation inside the equalizing chamber, it is also necessary to ensure that the output guiding pipeline cannot be blocked by dust accumulation. Therefore, when designing the pressure guiding pipeline of this device, all are arranged perpendicular to the ground or at a large angle with the ground, so that the dust will fall back into the air duct to be measured due to its own gravity.

[0036] According to another embodiment of the present invention, it further includes that the cross-section of the pipeline 1 to be measured is circular or rectangular.

[0037] Specifically, the structure of the device of the present invention is almost applicable to any pipeline 1 to be measured. Whether the pipeline 1 to be measured is horizontal, vertical or inclined, it can be adopted, and whether the slit of the device itself is vertical or horizontal is not affected. As long as it is ensured that the pressure guiding pipeline led out from the device is arranged vertically or at a large angle upward. Figure 7 、 Figure 8 、 Figure 9 is the layout situation when the pipeline to be measured is a vertical pipeline.

[0038] According to another embodiment of the present invention, further comprising that when the pipeline 1 to be measured is an elbow, the positive pressure measuring point is arranged at the 45° center line of the elbow, and the negative pressure measuring point is arranged at the left, middle, and right positions in the diameter direction of the downstream pipeline. Among them, the slotted air inlet 5 of the averaging pitot tube is at the place where the horizontal section of the elbow enters the elbow, and the slotted air outlet 6 of the averaging pitot tube is at the pipeline vertically downward after passing through the elbow.

[0039] Specifically, due to the adoption of the whole slotted measurement arrangement along the diameter direction in the device structure of the present invention, combined with the measurement principle of this device, the requirement for the straight pipe section length of the pipeline 1 to be measured is greatly shortened. It can be arranged on a shorter straight pipe section. Even in the extreme case where there is no straight pipe section but only an elbow, it is still possible to accurately measure the fluid flow rate in the pipeline. Figure 10 and Figure 11 is the measurement structure designed to be arranged at the elbow. Its air inlet is at the place where the horizontal section of the elbow enters the elbow, and the air outlet is at the pipeline vertically downward after the elbow. Three positive pressure measuring points are arranged at the averaging pitot tube part along the 45-degree center line of the elbow, and three negative pressure measuring points are arranged along the diameter at the left, middle, and right positions at the part downward at the outlet. All positive and negative pressure lead pipes should be arranged perpendicular to the ground or at a large angle to the ground.

[0040] According to another embodiment of the present invention, further comprising, as Figure 6 shown, when the slotted air outlet 6 of the averaging pitot tube is installed on the side of the averaging pitot tube, the bottom surface of the slotted averaging pitot tube 2 is an inclined surface, and the slotted air outlet 6 of the averaging pitot tube is arranged at the lower position of the inclined surface for guiding.

[0041] According to another embodiment of the present invention, further comprising, as Figure 12 shown, when the slotted air outlet 6 of the averaging pitot tube is arranged corresponding to the bottom surface and the windward surface of the slotted averaging pitot tube 2, the bottom surface of the slotted averaging pitot tube 2 suddenly changes inward to form a symmetric inclined surface.

[0042] Specifically, Figure 6 、 Figure 12 shows the situation when the slotted averaging pitot tube 2 is vertically erected in the pipeline 1 to be measured. The slotted averaging pitot tube 2 can be placed horizontally in the pipeline 1 to be measured. At this time, there are steps at the bottom, which are prone to dust accumulation. When the slotted averaging pitot tube 2 is placed horizontally in the pipeline 1 to be measured, impurities and dust in the contaminated liquid or dusty gas are likely to accumulate in the box body and cause blockage. However, the arrangement of the outlet of the slotted averaging pitot tube 2 biased to one side can solve this problem, ensuring that the bottom of the box body is flat and there are no steps, which is beneficial to better preventing dust or dirt accumulation in the box body. In most cases, the outlet is arranged symmetrically with the center line. However, when the slotted averaging pitot tube 2 is placed horizontally in the pipeline 1 to be measured and the fluid is a contaminated liquid or dusty gas, in order to prevent dust accumulation, the outlet on one side is adopted.

[0043] Specifically, Figures 3 to 12Taking a dusty gas as an example, the device is also applicable to various fluids.

[0044] Specific operation process: 1. Device installation: Place the slotted uniform velocity box 2 vertically inside the measured pipeline 1, ensuring that its height D is the same as the pipeline diameter, and the width H of the air inlet on the windward side 1 satisfies H 1 / D = 0.065 - 0.110, and the width H of the air outlet 2 satisfies H 2 / H 1 = 0.15 - 0.25.

[0045] 2. Measuring point layout: Positive pressure measuring points: At least three measuring points are set at the upper, middle, and lower positions along the height direction inside the slotted uniform velocity box 2, and are connected to the pressure extraction main pipe 3 inside the uniform velocity box through positive pressure guiding pipes, outputting "+ pressure". Negative pressure measuring points: At least three measuring points are arranged beside the slotted air outlet 6 of the uniform velocity box, avoiding the airflow impact area, and are connected to the pressure extraction pipe 4 at the exhaust slotted opening of the uniform velocity box through negative pressure guiding pipes, outputting "- pressure".

[0046] 3. Mixing space adjustment: According to the flow velocity ratio V 上 / V 下 inside the measured pipeline 1, adjust the ratio of the box length L to the height D according to the test data (such as when V 上 / V 下 = 1.0, L / D ≥ 0.158, and L / D increases correspondingly when the flow velocity difference increases).

[0047] 4. Pressure guiding pipe arrangement: The positive and negative pressure guiding pipes are perpendicular to the ground or form an angle of 45 - 90° with the ground to prevent dust deposition and blockage.

[0048] 5. Elbow working condition adaptation: If the measured pipeline is an elbow, the positive pressure measuring points are arranged at the 45° center line of the elbow, and the negative pressure measuring points are arranged at the left, middle, and right positions in the diameter direction of the downstream pipeline.

[0049] 6. Flow rate calculation: Collect the differential pressure signal between the inside and outside of the uniform velocity box through a differential pressure transmitter, and calibrate the output value in combination with the flow velocity distribution data; for short straight pipe sections or elbow working conditions, dynamically correct the measurement result according to the preset relationship table of L / D and V 上 / V 下 .

[0050] The above description is illustrative rather than restrictive for the present invention. Those of ordinary skill in the art understand that many modifications, variations, or equivalents can be made without departing from the spirit and scope defined by the appended claims, and all of them will fall within the protection scope of the present invention.

Claims

1. A full-diameter slit-shaped box-type average velocity fluid flow measurement device, comprising a slit-shaped average velocity box (2) arranged in a measured pipeline (1), a pressure outlet main pipe (3) in the average velocity box, a pressure outlet pipe (4) at the exhaust slit of the average velocity box, a slit-shaped air inlet (5) of the average velocity box and a slit-shaped air outlet (6) of the average velocity box; the slit-shaped average velocity box (2) is arranged in the measured pipeline (1) and is a flat box body with a height of D, a width of H1 and a length of L, and the height D is the same as the diameter of the measured pipeline (1), and the windward side is provided with a slit-shaped air inlet (5) of the average velocity box with a height of D and a width of H1. , at least three positive pressure measuring points are respectively arranged at the upper, middle and lower positions along the height direction of the inner edge and are connected to the pressure outlet main pipe (3) in the speed averaging box through a positive pressure lead pipe; the slit-shaped speed averaging box (2) is provided with a slit-shaped air outlet (6) of a height D and a width H2; the slit-shaped air outlet (6) of the speed averaging box is used to discharge the airflow entering the slit-shaped speed averaging box (2), and at least three negative pressure measuring points are arranged beside the slit-shaped air outlet (6) of the speed averaging box at a position avoiding the impact of the airflow and are connected to the pressure outlet pipe (4) at the exhaust slit of the speed averaging box through a negative pressure lead pipe; it is characterized in that The ratio of the width of the slit-shaped air outlet (6) of the average velocity box to the width of the air inlet of the average velocity box is H2 / H1=0.15-0.25, and the ratio of the width to the height of the slit-shaped average velocity box (2) is H1 / D=0.065-0.

110.

2. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: The average gas velocity in the upper part of the measured pipeline (1) is V 上 , the average gas velocity in the lower part is V 下 The ratio of the length to the height of the slit-shaped velocity box (2) L / D varies with the velocity distribution value V 上 / V 下 Increase and increase.

3. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: The positive pressure-guiding pipe and the negative pressure-guiding pipe are perpendicular to the ground or form an angle between 45° and 90° with the ground.

4. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: The cross section of the measured pipeline (1) is circular or rectangular.

5. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: When the measured pipeline (1) is an elbow, the positive pressure measuring point is arranged at the 45° center line of the elbow, and the negative pressure measuring point is arranged at the left, middle and right positions in the diameter direction of the downstream pipeline; wherein the average velocity box slit-shaped air inlet (5) is at the horizontal section of the elbow entering the elbow, and the average velocity box slit-shaped air outlet (6) is at the pipeline vertically downward after passing the elbow.

6. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: When the slit-shaped air outlet (6) of the speed averaging box is installed on the side of the speed averaging box, the bottom surface of the slit-shaped speed averaging box (2) is an inclined surface, and the slit-shaped air outlet (6) of the speed averaging box is arranged at the lower position of the inclined surface for guidance.

7. The full-diameter slot-shaped box-type average velocity fluid flow measurement device according to claim 1, characterized in that: When the slit-shaped air outlet (6) of the velocity averaging box is arranged on the bottom surface of the slit-shaped velocity averaging box (2) corresponding to the windward surface, the bottom surface of the slit-shaped velocity averaging box (2) suddenly changes inward to form a symmetrical inclined surface.

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