Variable air volume device with multiple measuring modules

Abstract

The utility model discloses a variable air volume device comprising a plurality of measuring modules, which can be used for air volume measurement and control in an air pipe system in the field of industrial and civil air conditioning. The variable air volume device comprises a valve body, a plurality of measuring modules and an air volume adjusting component, the measuring module is used for collecting the regional pressure difference of a local region and is connected with the pressure difference sensor through a sampling pipe channel to achieve regional pressure difference measurement, the air volume adjusting component comprises a valve rod limited on the valve body and air valve blades arranged on the valve rod, and the air volume is adjusted through rotation of the valve rod. The utility model also designs a rectifying part for reducing the turbulence of the measured cross section. The device is reasonable in structure, improves the measurement control precision and the measuring range ratio under adverse working conditions, and can be widely applied.

Description

Technical Field

[0001] The present invention relates to the field of industrial and civil fluid measurement, and in particular to a fluid flow test, a measurement method, a device and applications thereof. Background Art

[0002] In the field of industrial and civil pipeline fluid measurement, various average pressure difference measurement components developed based on various pitot tubes or averaging tubes are widely used to measure average flow velocity and fluid flow. The measured fluid types include air, industrial gas, industrial fluid, etc. Applications include air volume control valves, mobile air volume hoods, fluid measurement control, etc. The basic measurement principle of the average pressure difference measurement component is the Bernoulli equation, which describes the conservation characteristics of the sum of kinetic energy, potential energy and pressure energy of the flow section of an incompressible fluid. After ignoring the potential energy change in fluid measurement, the equation describes the conservation characteristics of the sum of kinetic energy and pressure energy. The average pressure difference measurement component is simple to manufacture and fast to measure, and is widely used in fluid flow measurement.

[0003] The Pitot tube can adopt a matrix design to form multi-point average measurement, and by measuring the average total pressure and average static pressure of the cross section, the average dynamic pressure is calculated, and the average flow velocity is obtained by the Bernoulli equation. For example, the device described in US3685355A is a design form of a total pressure branch pipe plus multiple static pressure branch pipes.

[0004] In the ideal flow measurement, one of the more accurate ways to measure the underdeveloped flow is to calculate the average flow velocity by measuring point by point with a Pitot tube after the rectifier:

[0005]

[0006] ρ: fluid density (kg / m 3 ), where ΔP1......ΔP n is the dynamic pressure at each measuring point (Pa)

[0007] The formula for calculating the average flow rate through the average total pressure and the average static pressure can be summarized as:

[0008] In the formula, ΔP1+ΔP2+.....+ΔP n It can be simplified to measure the difference between the average total pressure and the average static pressure of the cross section.

[0009] When the cross-sectional velocity non-uniformity is within a certain range, the second formula above has a higher measurement accuracy. The error mainly depends on the deviation between the root mean square of the velocity at each point of the measurement section and the arithmetic mean. This error is referred to as the velocity distribution error in the present invention. When the average pressure difference measuring device is in the non-fully developed section of the fluid turbulence and the cross-sectional velocity is seriously non-uniform, the velocity distribution error increases. At the same time, the serious non-uniformity of the cross-sectional velocity has an adverse effect on the pressure averaging performance of the detection tube. When the average pressure difference measuring component adopts an S-type pitot tube, the same problem exists.

[0010] The average pressure difference measurement component uses an average velocity tube with a square, oval, etc. shape, and the average velocity tube is arranged perpendicular to the axis of the measurement channel. The average velocity tube generally has a high-pressure cavity and a low-pressure cavity to form a detection tube. The average pressure difference measurement component is composed of a single or multiple average velocity tubes. When multiple tubes are used, the high-pressure cavities and low-pressure cavities are connected by pipes. The high-pressure cavity of the average velocity tube is provided with multiple total pressure measurement holes on the frontal surface. The measurement of multiple total pressure measurement holes realizes the measurement of the average high pressure, and the measured value of the average high pressure is approximately equal to the average total pressure of the measurement cross section; the low-pressure cavity is provided with multiple low-pressure measurement holes on the side or rear of the average velocity tube. When the flow stream passes through the average velocity tube, the side or rear thereof forms a low-pressure distribution area due to the local flow velocity enhancement or the appearance of a large number of fluid vortices. The average low pressure value collected by the average velocity tube is significantly lower than the average static pressure of the measurement cross section. The average pressure difference measured by the average pressure difference measurement component is generally greater than the average dynamic pressure at the measurement cross section by more than 1.5 times. In an approximately fully developed circular fluid pipeline, a single velocity averaging tube is usually used for measurement, such as a flute-shaped velocity averaging tube or a Verabar velocity averaging tube. In some cases, a single low-pressure measurement hole is used.

[0011] The calculation of the average pressure difference measurement component of the averaging tube type can be summarized as follows:

[0012]

[0013] where v m is the average flow velocity of the measurement channel, K is the flow coefficient, Δp is the average pressure difference, and ρ is the fluid density. Factors affecting the flow coefficient include structural coefficient, blockage coefficient, Reynolds number, flow velocity distribution, etc. The serious unevenness of the measured cross-sectional flow velocity has a greater impact on it than the average pressure difference measurement component of the Pitot tube. In the field of industrial and civil pipeline fluid measurement, most of the measurement conditions are underdeveloped flow states, large turbulence and serious uneven flow velocity distribution. The asymmetry greatly reduces the measurement feasibility and accuracy of the average pressure difference measurement component. For example, when some air volume hoods measure smaller air outlets, the cross-sectional flow velocity deviation is too large. The test results that often appear are larger than the actual values, and the stability of the measurement readings decreases; the measurement feasibility, stability, and accuracy of the variable air volume device are greatly reduced when the straight pipe section in front is insufficient.

[0014] In the field of industrial and civil pipeline fluid measurement, the use conditions and requirements have brought other challenges to the average pressure difference measurement components. Some use conditions require a relatively large range, such as the measurement and control of the fresh air duct of ventilation and air conditioning, which has a wide control and measurement range; some measurement components have a serious shortage of straight pipe sections in the fluid pipeline, and even after the use of rectifiers, there are still large turbulence and measurement errors; the rectifiers used in conjunction with the components are prone to dust accumulation during use, which reduces the practicality of the rectifier.

[0015] In view of the above-mentioned deficiencies of the average pressure difference measuring component, the present invention addresses various aspects to improve the measuring accuracy and measuring range of the average pressure difference measuring component under adverse working conditions. Summary of the invention

[0016] One of the problems to be solved by the present invention is to improve the measurement accuracy of the average pressure difference measurement component under unfavorable working conditions and to improve its range ratio. For this purpose, a modular flow measurement method is proposed.

[0017] As a further improvement of the present invention, the total pressure measurement points are arranged in the sector-shaped or circular measurement area by using an unequal annular measurement point arrangement method. The present invention combines the modular flow measurement method to design a variable air volume device, which includes a valve body, multiple measurement modules, and an air volume adjustment component; the air volume adjustment component includes a valve stem limited on the valve body and a wind valve blade arranged on the valve stem, and the air volume is adjusted by rotating the valve stem; the detection tube of the measurement module is fixed in the valve body and located in front of the air volume adjustment component, and the measurement module is used to collect the regional pressure difference in the local area, and is connected to the pressure difference sensor through the sampling channel to realize the regional pressure difference measurement. The pressure difference sensor transmits the pressure difference signal to the control device, and the control device performs calculations and adjusts the air volume of the corresponding air volume adjustment component by controlling the wind valve actuator.

[0018] As a further improvement of the variable air volume device, a rectifying component is arranged in front of the plurality of measuring modules to reduce the turbulence of the measuring cross section. As a further improvement of the variable air volume device, the rectifying component comprises a plurality of straight channels through which the air flows to reduce the turbulence of the measuring cross section, the straight channels through which the air flows are arranged from the inside to the outlet are straight channels, the hydraulic diameter of the straight channels is less than 0.2 times the hydraulic diameter of the measuring channels, and the length of the straight channels is greater than 0.2 times the hydraulic diameter of the straight channels.

[0019] As a further improvement of the variable air volume device, a hardening film is provided on the surface of the rectifying component to reduce the surface roughness.

[0020] As a further improvement of the variable air volume device, the variable air volume device includes a switching component, and the switching component is actuated by the control device to realize cyclic measurement of at least part of the measurement sub-area. As a further improvement of the variable air volume device, the multiple measurement modules include at least one average pressure difference measurement component, and the high pressure value of the average pressure difference measurement component is averaged by multiple total pressure measurement holes in the high pressure cavity.

[0021] As a further improvement of the variable air volume device, the multiple measurement modules include at least one static pressure measurement module; the low pressure measurement hole of the static pressure measurement module is located above the cylinder, and the straight generatrix of the cylinder is parallel to the axis of the measurement channel.

[0022] As a further improvement of the variable air volume device, the multiple measurement modules include at least one non-static pressure measurement module, and the low-pressure measurement hole of the non-static pressure measurement module is arranged on the low-pressure cavity of the detection tube, which is used to measure the pressure of the low-pressure distribution area generated by the fluid flowing around the detection tube.

[0023] As a further improvement of the variable air volume device, the variable air volume device includes a spacing component inside, and the spacing component separates the measurement channel to reduce the turbulence of the measurement areas on both sides. As a further improvement of the variable air volume device, the control device closes at least one measurement sub-area through the blocking component and the spacing component, and cuts off the sampling channel between the corresponding measurement module of the measurement sub-area and the pressure difference sensor by the action of the switching component, and then measures the regional pressure difference of each measurement sub-area.

[0024] As mentioned above, after the variable air volume device adopts the modular flow measurement method and related design, the measurement control accuracy and range ratio under adverse conditions are improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Example 1 of multiple average differential pressure measurement components for rectangular measurement channels

[0026] Figure 2 Part of the measuring module in the form of a Pitot tube

[0027] Figure 3 Example 1 for installation of multiple average differential pressure measurements for rectangular measuring channels

[0028] Figure 4 Example 1 of the rectangular measurement channel with multiple average pressure difference measurement components. Side view of the total pressure measurement part Figure 5 Multiple average differential pressure measurements for rectangular measuring channels Parts Example 1 Installation Example 2

[0029] Figure 6 Example of a honeycomb partition

[0030] Figure 7Example 1 of multiple average differential pressure measurement components for circular measuring channels

[0031] Figure 8 Part of the measurement module in the form of a single measurement channel Pitot tube

[0032] Fig. 9 Example of a circular measuring channel with multiple average differential pressure measurement components. Side view of the total pressure measurement section Fig.10 Example of arranging points for a sector-shaped measurement area

[0033] Fig.11 Example of point arrangement in a circular measurement area

[0034] Fig.12 Example 2 of multiple average differential pressure measurement components for circular measurement channels

[0035] Fig.13 Example 2 of multiple average differential pressure measurement components for rectangular measurement channels

[0036] Fig.14 Example 3 of multiple average differential pressure measurement components for rectangular measurement channels

[0037] Fig.15 Example 3 of multiple average differential pressure measurement components for circular measurement channels

[0038] Fig.16 Example of a removable honeycomb rectifier for a rectangular measurement channel

[0039] Fig.17 Example of a removable measuring channel spacer

[0040] Fig.18 Design example for a spacer valve

[0041] Fig.19 Design example for spacer box

[0042] Fig. 20 Example of designing for circular measuring channel spacing

[0043] Fig.21 Example of a cross-sectional view of the installation of multiple mean differential pressure measuring components for a circular measuring channel

[0044] Fig. 22 This is an example of a multi-sensor measurement method.

[0045] Fig.23 Example 1 for the cycle measurement method

[0046] Fig.24 Example 2 for cycle measurement method

[0047] Fig.25 Example of a rectangular variable air volume device

[0048] Fig.26 Example of a circular variable air volume device

[0049] Fig. 27 An example of a rectangular variable air volume device with air volume adjustment components

[0050] Fig.28 Part 1 of the transmission example of the air volume adjustment component of the circular variable air volume device

[0051] Fig.29 Example of air volume adjustment components for circular variable air volume devices

[0052] Fig.30 Part 2 of the transmission example of the air volume adjustment component of the circular variable air volume device

[0053] Fig.31 Part 3 of the transmission example of the air volume adjustment component of the circular variable air volume device DETAILED DESCRIPTION

[0054] In the present invention, the component used to measure the overall average pressure difference of the fluid in the measuring channel is called a single average pressure difference measurement component, which is characterized in that it collects the overall average pressure difference of the measuring channel, including multiple total pressure measurement holes connected through a high-pressure cavity, for the measurement of average high pressure; unlike the Venturi tube, it does not change the contour of the fluid measurement channel, and the average low pressure collects the static pressure of the fluid or the pressure of the low-pressure distribution area generated by the fluid flowing around the detection tube. The high-pressure cavity and the low-pressure cavity described below include the internal cavity of the detection tube and the internal cavity in the connecting pipe of the detection tube; the high-pressure cavity and the low-pressure cavity are separated from each other. In the present invention, the module used to measure the pressure difference of a local area in the measurement channel is called a measurement module; the measurement module includes one or more detection tube combinations, and the measurement module has a total pressure measurement hole for measuring the high pressure value of the corresponding measurement sub-area; the low pressure value collects the static pressure of the fluid or the pressure of the low-pressure distribution area generated by the fluid flowing around the detection tube. The measurement module can have only one total pressure measurement hole, such as an L-type Pitot tube.

[0055] Figure 1 The figure shows a static pressure type average pressure difference measurement component, wherein the first high-pressure main pipe 101ha and its three connected high-pressure branch pipes 11, the first low-pressure main pipe 101la and its two connected low-pressure branch pipes 12, and four low-pressure branch pipes 13 constitute a measurement module. There are 7 measurement modules in total in the figure. Fig.14 The non-static pressure type average pressure difference measurement component is shown in the figure. The diamond-shaped average velocity tube where the 7th total pressure measurement hole 7h, the 8th total pressure measurement hole 8h, the 9th total pressure measurement hole 9h, and the 10th total pressure measurement hole 10h are located constitutes the second detection tube 1rl; a single second detection tube 1rl, and its connected high-pressure branch pipe 11, low-pressure branch pipe 12, and two solenoid valves 10800 constitute a measurement module and a measurement sub-area. The example in the figure can have up to 9 measurement modules during measurement.

[0056] When the measuring module has multiple total pressure measuring holes, it is called an average pressure difference measuring module. The multiple total pressure measuring holes are connected through the high pressure cavity. The measuring module includes corresponding connecting pipes and measuring switching valves; the corresponding connecting pipes include corresponding branch pipes, branch pipes, high pressure main pipes, low pressure main pipes, etc. Figure 1 and Fig.14 The ones in the figure are average differential pressure measurement modules.

[0057] The low pressure collected by the measurement module is divided into two types: static pressure and non-static pressure. One of the characteristics of the static pressure measurement module is that the low pressure measurement hole is located on the cylinder, the straight generatrix of the cylinder is parallel to the axis of the measurement channel, the directrix can be a straight line segment, and the straight generatrix has a certain length to eliminate the influence of the streamline flow in front; the low pressure value measured is close to the average static pressure of the measurement cross section. The non-static pressure measurement module uses various average velocity tubes and S-type Pitot tubes as detection tubes to measure the pressure of the low-pressure distribution area caused by the fluid flow around the detection tube; for the Fechheimer type Pitot tube, although the low pressure value is close to the static pressure of the fluid in front, it also measures the pressure of the low-pressure distribution area caused by the fluid flow around the detection tube, and also belongs to the non-static pressure type. Its measurement value is easily affected by the blockage of the detection tube on the measurement channel. Similarly, the average pressure difference measurement module is divided into static pressure type and non-static pressure type.

[0058] Common shapes of velocity-averaging tubes include square, oval, etc. The velocity-averaging tube is arranged perpendicular to the axis of the measurement channel. The velocity-averaging tube generally has a high-pressure cavity and a low-pressure cavity to form a detection tube. The average pressure difference measurement component can be composed of a single or multiple velocity-averaging tubes. When multiple tubes are used, the high-pressure cavities and low-pressure cavities are connected by pipes. The high-pressure cavity of the velocity-averaging tube is provided with multiple total pressure measurement holes on the frontal surface. The total pressure of the fluid is averaged in the high-pressure cavity to obtain an average high pressure, which is approximately equal to the average total pressure of the measurement cross section; the low-pressure cavity is provided with multiple low-pressure measurement holes on the side or rear of the velocity-averaging tube. When the flow stream passes through the velocity-averaging tube, the side or rear thereof forms a low-pressure distribution area due to the local flow velocity enhancement or the appearance of a large number of vortices. The average low pressure value collected by the velocity-averaging tube is significantly lower than the average static pressure of the measurement cross section, and the average pressure difference is generally greater than 1.5 times the average dynamic pressure at the measurement cross section. The high-pressure cavity and the low-pressure cavity of the velocity-averaging tube can be designed separately during manufacturing to form two detection tubes. The velocity averaging tube in the present invention can adopt other various cross-sectional shapes. When the average differential pressure measurement module adopts an S-type Pitot tube combination, multiple total pressure holes of the S-type Pitot tube are connected through a pipeline, and multiple low-pressure measurement holes are connected through a pipeline; the average differential pressure is measured by measuring the difference between high pressure and low pressure. In the components using the S-type Pitot tube combination, the low pressure value is also the low pressure value of the vortex zone behind the detection tube. The average differential pressure is generally greater than 1.3 times the average dynamic pressure at the measurement cross section, and the specific shapes of the detection tube are also various.

[0059] The average differential pressure measuring component in the present invention adopts a modular design, which has multiple measuring modules and multiple measuring sub-areas. Each measuring module contains at least multiple average differential pressure measuring modules. This component can be defined as multiple average differential pressure measuring components; the measuring sub-area refers to the measuring area undertaken by a single measuring module in the measuring channel, including the area occupied by the detection tube. In a single total flow measurement process, the sum of the areas of all measuring sub-areas is equal to the total cross-sectional area of ​​the measuring channel; multiple measuring sub-areas in the measuring channel can be opened by the measuring switching valve to form a combined measuring sub-area, so the measuring channel can only contain The measuring module includes a measuring sub-area; each measuring module can be combined with each other through the action of the measuring switching valve, and the measuring channel can include only one measuring module; the pressure difference value provided by each measuring sub-area is called the regional pressure difference, which is obtained by the pressure difference sensor and transmitted to the flow measurement circuit for calculation; each regional pressure difference contains multiple average pressure differences, and the high pressure value of the average pressure difference is obtained by averaging multiple total pressure measuring holes in the high pressure cavity, and the low pressure value of the average pressure difference collects the static pressure of the fluid or the pressure of the low-pressure distribution area generated by the fluid flowing around the detection tube; a single regional pressure difference can be measured by only one total pressure measuring hole, and the regional pressure difference does not belong to the average pressure difference.

[0060] The detection tube in the present invention refers to a hollow tube with a total pressure measurement hole or a low pressure measurement hole in the measurement channel, which is used for total pressure value measurement or low pressure value measurement, and has a specific cross-sectional shape. The definition of high-pressure branch pipe and low-pressure branch pipe in the present invention refers to branch pipes connected to the high-pressure main pipe and the low-pressure main pipe, and the definition of branch branch pipe refers to all branch pipes connected to the branch pipe. The high-pressure main pipe in the present invention refers to the main pipe used for total pressure measurement and averaging, on which a sensor pressure sampling port is provided; the low-pressure main pipe refers to the main pipe used for low-pressure measurement and averaging, on which a sensor pressure sampling port is provided; the high-pressure collection pipe refers to the sampling main pipe directly connected to the high-pressure end of the differential pressure sensor, and the low-pressure collection pipe refers to the sampling main pipe directly connected to the low-pressure end of the differential pressure sensor. In actual engineering, each part can adopt a compact design. For example, the high-pressure cavity and the low-pressure cavity in the detection tube can be directly connected to the main pipe. In form, there are no high-pressure branch pipes and low-pressure branch pipes. At this time, the high-pressure cavity and the low-pressure cavity in the detection tube are equivalent to the high-pressure branch pipe and the low-pressure branch pipe; when the detection tube in the measuring channel has a pressure sampling port that is directly connected to the differential pressure sensor, the high-pressure cavity and the low-pressure cavity of the detection tube are the high-pressure main pipe and the low-pressure main pipe.

[0061] Figure 1 , Figure 7 , Fig.12 , Fig.13 , Fig.14 , Fig.15 The following are examples of average pressure difference measurement components, which are applied to rectangular and circular measurement channels. For non-rectangular and non-circular fluid channels, the following designs can be used to manufacture average pressure difference measurement components of different shapes.

[0062] Figure 1 The multiple average pressure difference measurement components are suitable for rectangular measurement channels, and are composed of 6 static pressure type average pressure difference measurement modules, with 6 measurement sub-areas, and the device has 6 pairs of low-pressure main pipes and high-pressure main pipes, namely the first high-pressure main pipe 101ha, the first low-pressure main pipe 101la, the second high-pressure main pipe 102hb, the second low-pressure main pipe 102lb, the third high-pressure main pipe 103ha, the third low-pressure main pipe 103la, the fourth high-pressure main pipe 104ha, the fourth low-pressure main pipe 104la, the fifth high-pressure main pipe 105ha, the fifth low-pressure main pipe 105la, the sixth high-pressure main pipe 106ha, and the sixth low-pressure main pipe 106la. The low-pressure main pipe in the example collects the average static pressure in the measurement sub-area, a single low-pressure main pipe is connected to two low-pressure branch pipes 12, and a single low-pressure branch pipe is connected to two low-pressure branch pipes 13. The low-pressure branch pipe 13 uses a single-channel pipe pitot tube to collect static pressure, and multiple measurement holes are set on it. The high-pressure main pipe collects the average total pressure in the measurement sub-area. A single high-pressure main pipe connects three high-pressure branch pipes 11. The single high-pressure branch pipe is arranged perpendicular to the axial direction of the measurement channel and adopts a thin-walled circular pipe design. A plurality of total pressure measurement holes are arranged on it, which can be called a total pressure average pipe. In the example, the low-pressure branch pipe is located behind the cross section of the high-pressure branch pipe, which can effectively reduce the impact on its measurement and reduce fluid resistance.

[0063] When using a total pressure average tube, the static pressure measurement point needs to be kept at a certain distance from the total pressure measurement point because the static pressure measurement value is affected by the stagnation of the streamline in front of the tube. At the same time, since the flow beam continues to develop with distance, the static pressure values ​​at each axial point are different, so it is necessary to control the distance between the static pressure and total pressure measurement points to ensure measurement accuracy.

[0064] Figure 3 Shown Figure 1 The example is installed in the measuring channel 5a, and a honeycomb rectifier is designed in the front. The connection between the detection tube and the measuring channel can be achieved by welding, threaded connection, socket connection, etc. Thin and fine materials can be used to strengthen the structure in the middle of the channel, and at the same time, they can be arranged reasonably to minimize the impact on the flow field. The detection tubes can be connected to each other by welding and connectors to enhance the structural strength. The manufacturing method and details are applicable to other examples in the present invention. In the present invention, the front and the rear are determined according to the flow direction of the fluid, and the direction from front to back is along the flow direction. Figure 4 for Figure 1Side view of the example high-pressure detection tube in a rectangular channel. In the example, the measurement channel 5a is divided into 6 rectangular areas as measurement sub-areas. The arrangement of the total pressure measurement points in the measurement sub-areas can be based on the traditional small rectangle division method. The measurement sub-area klmn is divided into 9 measurement small rectangles by dotted lines 1001a, 1002a, 1003a, and 1004a, and has 9 total pressure measurement points. For example, the 6th total pressure measurement point 6h is in the center of the mrpq small rectangle, and the same is true for other total pressure measurement points. The arrangement method of the static pressure measurement points is the same as that of the total pressure measurement points. When a honeycomb rectifier is used, the consistency of the static pressure is improved. The number of distributions can be adjusted according to the consistency of the static pressure distribution and the measurement accuracy requirements. In the example, each sub-area has 4 static pressure measurement points.

[0065] Figure 7 The multiple average pressure difference measurement components 1 are suitable for circular measurement channels, and are composed of 7 static pressure type average pressure difference measurement modules, with 1 central circle measurement sub-area and 6 sector measurement sub-areas, and the component has 7 pairs of low-pressure mains and high-pressure mains, namely the seventh high-pressure main 101ha, the seventh low-pressure main 101la, the eighth high-pressure main 102hb, the eighth low-pressure main 102lb, the ninth high-pressure main 103ha, the ninth low-pressure main 103la, the tenth high-pressure main 104ha, the tenth low-pressure main 104la, the eleventh high-pressure main 106ha, the eleventh low-pressure main 106la, the twelfth high-pressure main 107ha, the twelfth low-pressure main 107la, and the thirteenth high-pressure main 105ha and the thirteenth low-pressure main 105la connected to the central circle measurement sub-areas. Figure 7 The examples in this section use the same type of tubes as Figure 1 The example is the same as that in the above example, except that the high-pressure branch pipe 11 and the low-pressure branch pipe 12 are arc-shaped and are sealed at the ends with plugs, and the structures can be welded to each other for reinforcement.

[0066] Fig. 9 Shown Figure 7 Side view of the high-pressure branch pipe and the total pressure measurement point in the example. The dividing points i, j, a, and b in the figure constitute a sector-shaped measurement sub-area, which is the sum of the measurement areas of all measurement points in the area and is also the measurement dividing line between measurement modules. The arc where the dividing points a and b are located constitutes the central circle measurement sub-area. In actual engineering, the central circle measurement sub-area can be cancelled and not designed.

[0067] In actual design, multiple sector-shaped measurement sub-areas can form a sector-shaped measurement sub-area. The characteristic of the sector-shaped measurement area is that the boundary line of the measurement area is composed of two concentric arc-shaped boundaries and two radial line segments passing through the center of the circle; in the case of the small arc boundary part, the radius can be 0, and the small arc becomes 1 point, which also belongs to the sector-shaped measurement area. In the example, the total pressure measurement points of the central circle measurement sub-area are arranged according to the equal annular surface method. A total of 3 concentric rings are selected and 18 measurement points are arranged.

[0068] This example optimizes the design of the total pressure arrangement points in the sector measurement area. The sector area surrounded by the demarcation points i, j, a, and b in the figure is 1 / 7S, which is equal to the area of ​​the other five sector areas. S is the total cross-sectional area of ​​the measurement channel. In actual engineering design, the measurement areas of each sector can be adjusted, and their respective areas can be different. The sector measurement area surrounded by the demarcation points i, j, a, and b has 14 total pressure measurement points designed, with 4 measurement arcs, and the measurement arcs have 5, 4, 3, and 2 measurement points respectively. The first total pressure measurement point 1h, the second total pressure measurement point 2h, the third total pressure measurement point 3h, the fourth total pressure measurement point 4h, and the fifth total pressure measurement point 5h are on one of the measurement arcs, with the endpoints being the demarcation points s and t; the measurement areas of the five measurement points form a measurement ring domain, with endpoints i, j, g, and h; the other three measurement arcs correspond to their respective measurement ring domains.

[0069] When the measurement areas of the 14 total pressure measurement points are equal, the boundary line of the measurement ring area can be calculated. The radii of the arc where point g is located, the arc where point e is located, the arc where point c is located, and the arc where point a is located are 0.833R, 0.670R, 0.515R, and 0.378R, respectively. The positions of the measurement arcs in each measurement ring area can be arranged by equally dividing the measurement ring area area, such as Fig. 9 The ijts annular area and the sthg annular area shown in the figure have the same area; the radii of each measuring arc are calculated to be 0.920R, 0.756R, 0.598R, and 0.452R, respectively, where R is the radius of the measurement channel. In the present invention, the measurement arc refers to the arc with the sector-shaped measurement area as the center of the measurement point, and the arc has the boundary of the measurement area of ​​the measurement point as the endpoint; the measurement annular domain is the area formed by the sum of the measurement areas of all measurement points on the measurement arc. In the example, the measurement arc between the dividing points s and t is divided into 10 equal parts to determine the specific positions of the 5 measurement points; the arc lengths between each measurement point are equal, so that the measurement area of ​​each measurement point is equal. The static pressure measurement points of the static pressure type average pressure difference measurement module can be arranged in the same way as above. In the example, each sector-shaped sub-area has 2 measurement arcs and 6 static pressure measurement points. In actual engineering design, the number of distributions can be adjusted according to the consistency and accuracy requirements of the static pressure distribution, and a single static pressure measurement point can be used as needed.

[0070] The total number of measurement points in the sector measurement area, the number of measurement arcs, and the number of measurement points on each measurement arc can be determined based on the measurement accuracy. The number of measurement arcs and the number of measurement points on each measurement arc can be reasonably divided so that the measurement area borne by each measurement point is as close to a square or regular triangle as possible; for example, the measurement area of ​​point 1h in the figure is surrounded by the measurement boundary and the dotted line, which is close to a square. The number of measurement arcs and the number of points on each measurement arc in the example can be further optimized based on this principle.

[0071] The calculation of the radius of the measuring arc of the sector-shaped measuring sub-area and the measuring ring boundary line in the present invention can be summarized into a mathematical calculation formula. Fig.10 As shown in the figure, the sector measurement area has N measurement points, and the radius of the boundary line of the area is R min , R max， There are n i The number of measuring points between the measuring arc or measuring ring boundary and the minor diameter is n1, and the number of measuring points between the measuring arc or measuring ring boundary and the major diameter is n2. It can be deduced that the radius of the measuring arc is Measuring ring area The minor diameter of the measurement area can be 0, that is, the area is the center of the circle as the end point. In this case, there is no center circle in the measurement channel, which can also be used in engineering.

[0072] Similarly, for the central circle measurement area, it can be considered as a sector area with an angle of 360 degrees, and the measurement points can also be divided according to the above method and formula. Specifically, the circular area can be divided into several measurement rings and small central circles to arrange the total pressure layout points. Fig.11 As shown, there is a small center circle and two measurement rings, and the boundary line is a dotted line. The small center circle has a total pressure measurement point located at the center of the circle. The two measurement rings have 3 and 6 measurement points respectively, which are evenly distributed on their respective measurement arcs. The measurement arcs are represented by dotted lines. Calculate the boundary line R of the two measurement rings r1 for for The measured arc R1 is The measured arc R2 is The measuring arc of a circular area can also be called the measuring circle.

[0073] The specific steps of arranging the measuring points of the sector or circular measuring area may be: S1 determines the total number of measuring points outside the center of the circle in the area and the number of measuring points on each measuring arc according to the measuring accuracy, and the number of measuring points on each measuring arc is not completely equal. S2 determines the radius of the measuring arc according to the radius formula. S3 evenly distributes the measuring points on the measuring arc.

[0074] When different layout schemes need to be optimized, the f of different layout schemes can be calculated. aValue, which represents the average similarity between the measurement area of ​​all measurement points outside the center of the circle and the equilateral triangle or square. The specific method can be, S1: Determine the geometric center, that is, the centroid, of the measurement area of ​​each measurement point. S2: Draw an equilateral triangle with an area equal to the area of ​​the measurement area, and the geometric center coincides with the above center. Rotate the equilateral triangle so that one vertex of the equilateral triangle is located in the radial direction of the geometric center and the vertex is close to the center of the circle. S3: Compare the ratio of the area of ​​overlap between the measurement area and the equilateral triangle to the area of ​​the measurement area, that is, the similarity f1. S4: Draw a square with an area equal to the area of ​​the measurement area, and the geometric center coincides with the above center, and the midpoint of one side of the square is located in the radial direction of the geometric center. Compare the ratio of the area of ​​overlap between the measurement area and the square to the area of ​​the measurement area, that is, the similarity f2. S5: Take the maximum value of f1 and f2. That is f0. S5: Calculate the similarity f0 of each measurement point and calculate the average value f a , its value can be the arithmetic mean or other types of average values; when a certain f0 is lower than a certain minimum limit, its related average value fa and layout scheme can be judged as invalid and will not participate in the optimization comparison.

[0075] Under the same total number of measurement points, the number of measurement points on each measurement arc can be changed to compare the average similarity f in different schemes. a , find the optimal arrangement corresponding to the maximum value. In actual calculation, the above formula can be input into the computer, and the optimal solution can be obtained by assuming conditions and performing manual or program optimization. In actual engineering, when there are spacing components around the sector measurement area, the boundaries and boundary connections of the sector area will be displaced or deformed, and approximate processing can be done in the actual measurement point arrangement.

[0076] When a non-static pressure measurement module is used, the measurement point layout can be consistent with the above method. Compared with the conventional circular measurement area layout method, this method is similar in that the measurement area area of ​​each measurement point is equal, and the difference is that the number of measurement points on each measurement arc in this method is not the same or not completely the same, and the measurement points can be arranged in the center of the pipeline. This method can be called the unequal annular point layout method. When the number of points is the same or close, the unequal annular point layout method has a wider range of applicability for measurement situations where the fluid development is seriously insufficient and the flow velocity distribution is diversified, and the measurement accuracy is higher under some conditions. The formula of this layout method is clear and suitable for computer or manual calculation. The measurement point layout of circular and sector-shaped measurement areas can also be arranged according to other layout methods such as logarithmic linear method.

[0077] After the rectifier components are used under unfavorable working conditions, the flow velocity distribution characteristics are different. At this time, the unequal annular point distribution method has advantages. In actual engineering, flow velocity measurement is not limited to Pitot tube type probes. One or more probes can be used, mechanical rotating probes, various hot ball type, hot wire type, hot film type and other probes based on the heat dissipation principle, vortex street type probes, etc. When the probe is combined with advanced automatic positioning function, one probe can measure one or more measurement areas point by point, and the results are calculated by arithmetic average, so as to achieve high-precision and low-cost measurement. Probes that can perform simultaneous multi-point average measurement can also be used in the measurement.

[0078] In actual engineering design, a static pressure measurement module in the form of a Pitot tube can also be used. Figure 2 A partial example of this type is shown. The basic structure of the four Pitot branch pipes 16 is consistent with the detection tube structure of an ordinary L-type Pitot tube, with a total pressure measurement hole and four static pressure measurement holes at the front. The structure of the Pitot branch pipe 15 is consistent with the main tube structure of the L-type Pitot tube, which is a double-layer tube structure. The total pressure channel of the Pitot branch pipe 16 is connected to the total pressure channel of the Pitot branch pipe 15, and the static pressure channel of the Pitot branch pipe 16 is connected to the static pressure channel of the Pitot branch pipe 15. The opening at the bottom of the Pitot branch pipe exports the total pressure to the high-pressure branch pipe 11, and the opening on the side of the Pitot branch pipe exports the static pressure to the low-pressure branch pipe 12. The high-pressure branch pipe 11 and the low-pressure branch pipe 12 are respectively connected to the corresponding high-pressure main pipe and low-pressure main pipe for averaging. Due to the consistency of static pressure distribution after the rectifier, the above four static pressure measurement holes can be designed as one; at the same time, the double-layer structure of the Pitot tube can be optimized to reduce flow resistance.

[0079] In actual engineering, the static pressure type average pressure difference measurement module can also use a single-channel Pitot tube to collect total pressure. Figure 8 As part of this design, three high-pressure branch pipes 14 are connected to the high-pressure branch pipe 11, and the high-pressure branch pipe adopts a single-channel Pitot tube design. In the design, the total pressure measurement hole can be arranged after the static pressure measurement hole to reduce the impact on the static pressure distribution. Similarly, the static pressure measurement point can have only one measurement hole.

[0080] When the rectifier is used, the consistency of static pressure is improved, the pressure difference between the static pressure measurement holes of the static pressure type average pressure difference measurement module is reduced, the fluid flow in the low-pressure cavity slows down, and the static pressure average measurement accuracy of the component is improved. Since the measurement accuracy of the static pressure type measurement module is mainly affected by the flow velocity distribution error and the average performance of the detection tube when the number of measurement points is certain; compared with the non-static pressure type average pressure difference measurement module, the measurement accuracy is less affected by the factors, and it can be used preferentially in the flow field where the flow velocity is seriously insufficient; the shape of the detection tube of the static pressure type measurement module can be other shapes besides the circular tube; in the measurement, the static pressure type average pressure difference measurement module can be used in combination with other types of modules. Due to the manufacturing relationship of the static pressure type measurement module, the static pressure measurement points do not have to be arranged strictly according to the above measurement point arrangement method; in some cases, some or all of the static pressure measurement points can be offset relative to the theoretical arrangement points as needed to meet the principle of measurement accuracy. Connecting pipes can be added between each high-pressure branch pipe, each low-pressure branch pipe, and each low-pressure branch pipe of the static pressure type measurement module to improve the pressure average performance. This design is suitable for non-static pressure type measurement modules. In the present invention, the static pressure measurement point refers to the geometric center of the small holes around a single detection tube, that is, the center of gravity; when accuracy allows, the measurement hole group can actually only design one measurement hole to improve the average performance and anti-blocking performance of the component. At this time, the center of gravity of the single measurement hole becomes the accurate position of the measurement point; the center of gravity of the total pressure measurement hole is the accurate position of the total pressure measurement point.

[0081] In actual engineering, the relative average deviation of the flow velocity of the fluid behind local resistance parts such as elbows and tees is too large, resulting in excessive errors in the flow velocity distribution during the measurement process. The flow velocity distribution of the fluid behind local resistance parts often shows high consistency in the local area. If the channel is divided into multiple measurement sub-areas, the measurement module is used to perform separate regional pressure difference measurements, and the average flow velocity related variables of the measurement sub-areas are calculated separately. The total flow is calculated based on the area parameters of the measurement sub-areas. The measurement accuracy will be significantly improved relative to a single average pressure difference measurement component; the improvement effect is also obvious for non-static pressure measurement modules; one of the improvement factors is that the relative average deviation of the flow velocity in a single measurement sub-area is reduced; the second improvement factor is that the relative average deviation of the flow velocity in a single measurement sub-area is reduced. At the same time, there are relatively few full-pressure measurement holes and low-pressure measurement holes in a single measurement sub-area, which leads to a slowdown in the flow of fluids in high-pressure and low-pressure cavities, and improves the average pressure measurement accuracy of the components. Figure 3 In the example, after the measurement channel is divided into 6 measurement sub-areas, a honeycomb rectifier is set in the front to improve the measurement accuracy. After being divided into multiple measurement sub-areas, the Reynolds number of each point in a single area is relatively uniform. For the non-static pressure type average pressure difference measurement module, the error caused by the fluctuation of the structural coefficient is reduced.

[0082] Fig.12The example of the average velocity tube type used in the circular measurement channel is shown. The measuring component is composed of several first detection tubes 1rt, and the cross section of the first detection tube 1rt is an elongated ellipse. The device has a total of 6 sector-shaped measurement sub-areas and 1 central circle measurement sub-area, including 7 high-pressure main pipes 100h, 7 low-pressure main pipes 100l, 7 high-pressure sampling tubes 10901, and 7 low-pressure sampling tubes 10902. Each sector-shaped measurement sub-area is composed of several detection tubes in different directions, including 3 high-pressure branch pipes 11, 3 low-pressure branch pipes 12, and 3 measurement ring areas. The inner measurement ring area includes 2 full-pressure measurement holes 0h, the middle measurement ring area includes 3 full-pressure measurement holes 0h, and the outer measurement ring area includes 4 full-pressure measurement holes 0h. There is a low-pressure measurement hole corresponding to the back of each full-pressure measurement hole.

[0083] The center circle measurement sub-area includes a center connection block 110, three groups of first detection tubes 1rt, and two measurement annular areas. The inner measurement annular area includes three total pressure measurement holes, and the outer measurement annular area includes six total pressure measurement holes. The center connection block 110 is designed with a partition inside, which is divided into a high-pressure cavity and a low-pressure cavity. The three groups of detection tubes are connected to average the total pressure measurement value and the low-pressure measurement value. The center connection block is connected to the high-pressure sampling tube 10901 and the low-pressure sampling tube 10902. At this time, the center connection block 110 is equivalent to the high-pressure main pipe and the low-pressure main pipe.

[0084] When the non-static pressure measurement module uses an averaging tube, the structural coefficient of the averaging tube can be understood as the ratio of the flow velocity in the area not disturbed by the averaging tube when the averaging tube is placed in an infinite straight uniform flow field to the flow velocity calculated by the Bernoulli equation according to the high and low pressure difference of the averaging tube, which can be expressed as K1 is the structural coefficient, v i is the flow velocity in the area not disturbed by the averaging tube, P in is the total pressure value of the velocity averaging tube, P io is the low pressure value of the velocity averaging tube. K1 is the Reynolds number Re calculated by the velocity relative to the cross-sectional width of the velocity averaging tube. i The cross-sectional width here refers to the maximum width of the velocity-averaging tube blocking the fluid, and the direction of the cross-sectional width is perpendicular to the axis of the channel in the velocity-averaging tube.

[0085] In the actual measurement of non-static pressure type measurement module, due to the influence of blockage, the flow coefficient K of the measurement module can be obtained by experiment or theoretical calculation. In the present invention, the measurement subchannel where the measurement module is located is placed in a straight uniform flow field, and the obtained flow coefficient is called the theoretical flow coefficient; the relevant expression can be Among them, K0 is its theoretical flow coefficient, ΔP is the pressure difference measured by the measurement module, V0 is the flow velocity of the uniform direct current, and the factors affecting K0 include the factors affecting the Reynolds number: flow velocity V0, kinematic viscosity coefficient ν. K0 can be obtained by performance experiments. The measurement module and the measurement subchannel can be placed in a straight uniform flow field, keeping ρ and ν constant, and the flow velocities of different streamlines in the front flow field except for the near-wall laminar flow are approximately equal. The theoretical flow coefficient is calculated as K0 based on ΔP, ρ and V0; the flow velocity V0 is continuously changed, and different K0 values ​​are measured and calculated; ΔP and K0 are recorded to form a sample database, and then the function K0=f(ΔP) with ΔP as the independent variable and K0 as the function value can be established by interpolation or fitting and applied to the measurement. The above function has high accuracy when the flow velocity unevenness of the flow field in which the measurement module is actually used is within a certain range. Furthermore, experiments can be conducted under different ρ and ν conditions to obtain a function K0=f(ΔP, ρ, ν) with ΔP, ρ and ν as independent variables and K0 as the function value. The function can be a piecewise fitting function. Fig.21 In the example, the measurement modules of the three total pressure measurement holes connected to the 14th solenoid valve 10814 and the 23rd solenoid valve 10823 can be measured and collated using the above method to obtain the calculation function of their theoretical flow coefficient K0.

[0086] The above expression and experimental method are applicable to the static pressure measurement module, in which case K0 is close to 1 under different conditions;

[0087] In actual engineering, the measurement module can be partially improved to make it more flexible. Fig.13 As shown, there are 54 full-pressure measuring holes 0h and 24 low-pressure measuring holes 0l in the figure; there are 9 high-pressure branch pipes 11 connected to the high-pressure main pipe 100h; there are 6 low-pressure branch pipes 12 connected to the low-pressure main pipe 1001; 30 electromagnetic ball valves are used in the figure to control the branch pipes to achieve conduction or cut-off. During the measurement, each high-pressure branch pipe can be controlled by the control device and the conduction and cut-off of the high-pressure main pipe; the low-pressure branch pipe is operated accordingly to form a measurement module. This control method for branch pipes or branch pipes can be called a branch pipe controllable type; in actual engineering, the solenoid valve can be changed to a manual valve, a pneumatic valve, or various types of valves. In the figure, the first solenoid valve 10801, the second solenoid valve 10802, the third solenoid valve 10803, the fourth solenoid valve 10804, and the fifth solenoid valve 10805 are turned on, and the other solenoid valves are closed to form a measurement module, and the pressure difference sensor can first measure the pressure difference in this area. In the process of controlling 30 solenoid valves, various solenoid valve opening combinations can be formed, forming various measurement modules and measurement sub-areas; cyclic measurement can be performed by the differential pressure sensor.

[0088] Attached Fig.14The design example of diamond-shaped average velocity tube in a rectangular channel is shown. Nine average velocity tubes are connected to the high-pressure manifold 100h and the low-pressure manifold 100l through the high-pressure manifold 11 and the low-pressure manifold 12. A total of 18 solenoid valves are designed on the manifolds. The 18 solenoid valves can be opened in various combinations to form various measurement modules and measurement sub-areas. For example, when the solenoid valve 10800 on the low-pressure manifold where the two average velocity tubes including the 7th full-pressure measurement hole 7h, the 8th full-pressure measurement hole 8h, the 9th full-pressure measurement hole 9h, the 10th full-pressure measurement hole 10h, the 11th full-pressure measurement hole 11h, the 12th full-pressure measurement hole 12h, the 13th full-pressure measurement hole 13h, and the 14th full-pressure measurement hole 14h are connected, and the other solenoid valves are closed, a measurement module including two average velocity tubes is formed. Similarly, the cyclic measurement of the pressure difference is realized by the control of the solenoid valve.

[0089] Fig.15 Examples are Fig.12 Design changes have been made based on the examples. Fig.15 The number and distribution of measurement points in the center remain unchanged. The 6 high-pressure main pipes in the periphery are merged into 1; the 6 low-pressure main pipes are merged into 1; 1 solenoid valve is added to each of the 3 high-pressure branch pipes in a single sector area; 1 solenoid valve is added to each of the 3 low-pressure branch pipes in a single sector area; the original high-pressure sampling pipe of the measurement module in the central circle area is connected to the 24th solenoid valve 10824, and the original low-pressure sampling pipe is connected to the 25th solenoid valve 10825. At the same time, the diameter of the sampling pipe is thickened to make it a branch pipe. By controlling multiple solenoid valves, a variety of different measurement module combinations can be achieved to form more or fewer measurement sub-areas.

[0090] The valves arranged on the branch pipes mentioned above can be called measurement switching valves. The measurement switching valves can also be arranged on the branch pipes. They and the switch valves, valve islands and other components arranged on the sampling pipes described later can be collectively referred to as switching components. The action of the measurement switching valve can make a measurement module be split into multiple measurement modules, and multiple measurement modules can be merged at the same time. The measurement switching valve also includes a valve arranged between the main pipes. When the two measurement modules each have a high-pressure main pipe and a low-pressure main pipe, a switching valve can be arranged between the high-pressure main pipe and the low-pressure main pipe. When the switching valve is opened, the two measurement modules are merged into one measurement module, and the two measurement sub-areas are merged into one measurement sub-area. In the controllable design of the branch pipe, since a single measurement module can use a small number of detection tubes, the number of measurement holes is relatively small, which reduces the average performance degradation in the measurement tube caused by the pressure difference imbalance between the areas. Other advantages are that it can form a good match with the spacing component, which can be opened as needed to merge the measurement sub-areas for rapid measurement.

[0091] It is recommended that multiple average pressure difference measuring components be used together with rectification components in an underdeveloped fluid state. The rectification components are used to reduce the turbulence at the rear. The rectification components commonly used in engineering are: the components contain multiple straight channels for passing fluids, which are used to reduce the turbulence of the measuring cross section. The straight channel from the inside to the outlet of the straight channel for passing fluids is a straight channel, and the length of the straight channel is at least 1 times or more of the hydraulic diameter of the straight channel, and the hydraulic diameter of the straight channel is less than 0.2 times the hydraulic diameter of the measuring channel. The straight channel through which the fluid passes can be referred to as a flow channel unit, and its flow cross section can be a rectangle, a regular hexagon, or any other shape. The flow cross section area of ​​each flow channel unit may not be equal, and multiple flow pipes may be combined. This flow component can be called a honeycomb rectifier. Due to the manufacturing process, the straight channel is allowed to have a certain degree of roughness and deformation, that is, the inner surface of the straight channel is allowed to be not completely a smooth cylinder. The advantage of this rectifier is that while reducing the turbulence, a more consistent static pressure distribution can be obtained at the rear. The honeycomb rectifier can drill small holes on the honeycomb unit wall to form an open hole wall. Experiments have shown that the open hole wall has different degrees of effect on reducing the turbulence at the measuring point. Figure 5 The middle rectifier component 2 is made of stainless steel sheet, the honeycomb wall 32 is 0.1mm thick, the honeycomb unit is 5mm*5mm square, and the length of a single flow channel unit 31 is 25mm. In this example, the honeycomb unit has a thin wall thickness, which can be called a thin-walled honeycomb rectifier. The thin-walled honeycomb rectifier is characterized by a thin cell wall thickness, a large ratio of net flow area to total channel area, and a preferred ratio greater than 0.88. The thin-wall design of the honeycomb rectifier helps to reduce the rear turbulence.

[0092] In engineering, the hydraulic diameter of the flow channel unit is preferably selected based on the Reynolds number of the measured flow velocity being less than the critical Reynolds number of laminar flow, 2000. The Reynolds number of the fluid in the honeycomb unit is greatly reduced, the velocity component in the cross-sectional direction of the fluid is greatly constrained, and the lateral turbulence is greatly reduced.

[0093] The axial average velocity of the fluid at the spatial point at the outlet of the honeycomb rectifier fluctuates along the cross-sectional direction, and the axial average velocity oscillates with the honeycomb unit diameter as a period, and the distribution unevenness does not meet the measurement requirements. With the disappearance of the laminar shear layer and the increase in the distance between the spatial point and the honeycomb outlet, the distribution unevenness weakens until the measurement accuracy requirements are met. The effective distance between the rectifier outlet and the measuring point, which can ensure a certain flow velocity measurement accuracy, can be expressed as x / d. x is the distance between the rectifier outlet surface and the measuring point, and d is the hydraulic diameter of the honeycomb unit. The distance between the static pressure point of the average pressure difference measurement component and the honeycomb outlet can be greater than x. In engineering applications, a smaller ratio of honeycomb length to honeycomb unit hydraulic diameter can be used. Practice has shown that in some cases, the use of a rectifier with a smaller ratio helps to reduce the x / d value and reduce the measurement space. At the same time, the turbulence meets the measurement accuracy requirements of the average pressure difference measurement component.

[0094] It can be changed on the basis of the design of honeycomb rectifier, and a honeycomb rectifier disc is used. The component contains multiple straight channels for passing fluid, which are used to reduce the turbulence of the measuring cross section. The straight channel from the inside to the outlet of the straight channel for passing fluid is a straight channel, and the length of the straight channel is at least 0.2 to 1 times the hydraulic diameter of the straight channel, and the hydraulic diameter of the straight channel is less than 0.2 times the hydraulic diameter of the measuring channel. Honeycomb rectifier discs can be used under partial measurement accuracy; the combination of multiple rectifier discs can reduce the x / d value, optimize the measurement space and optimize the test conditions. The shape of the flow cross section of the honeycomb rectifier disc can be various, which is consistent with the design of the aforementioned honeycomb rectifier, and small holes can also be drilled in its internal channel. Due to the manufacturing process, the straight channel is allowed to have a certain degree of roughness and deformation, that is, the inner surface of the straight channel is allowed to be not completely a smooth cylinder. Its thin-wall design and smaller flow channel diameter can also reduce the rear turbulence to varying degrees.

[0095] Honeycomb rectifiers and honeycomb rectifier discs focus on reducing the turbulence in the direction of the fluid cross section, while significantly improving the static pressure consistency of the subsequent flow field, which can effectively reduce the possibility of blockage in the average channel and the blockage effect of the average pressure difference measurement component that collects static pressure; at the same time, due to the reduction in turbulence, the measurement results of static pressure and non-static pressure measurement components are stable, creating conditions for the correction of the results. The inlet of the honeycomb rectifier can selectively design orifice plates, grids, mesh plates and other flow equalization components to improve the uniformity of flow velocity distribution. The solid materials used in the honeycomb flow components include solids formed by cooling, curing agents and other methods.

[0096] The rectifying component can be a combination of multiple honeycomb rectifiers or honeycomb rectifying disks to improve performance. Honeycomb rectifiers and honeycomb rectifying disks are referred to as honeycomb current passing components in this invention.

[0097] Honeycomb type flow components can be equipped with a honeycomb partition plate design to increase ease of use. Figure 6 As shown, the rectifier 3 has a transverse partition plate 301 and a first longitudinal partition plate 302 inside, and a second longitudinal partition plate 303 runs through the rectifier. One function of the partition plate is to strengthen the structure, and the second function is to facilitate the separation and closure of the flow beam. The position of the cross section of the partition plate is generally consistent with the position of the cross section of the subsequent channel partition plate.

[0098] Furthermore, the rectifying component can be designed to be detachable, such as Fig.16 As shown. The measurement channel in the figure is designed with 6 rectifier modules 304, and the figure shows 3 modules located at the upper part of the channel. In the example, a disassembly port is opened at the corresponding channel position, and the rectifier module is extracted after removing the cover plate 306, and can be reinstalled afterwards. This design facilitates the inspection and cleaning of the rectifier module. The cover plate 306 can be fixed with fasteners such as screws.

[0099] The fixing bracket for limiting the installation of the rectifier module can be in the form of a slot 305. In actual engineering, it is necessary to minimize the cross-sectional area of ​​the fixing bracket to reduce the impact on the rear streamline. The fixing bracket of the rectifier module can adopt different mechanical strengths according to the fluid pressure.

[0100] The internal channels of honeycomb flow components are small, and dust accumulation needs to be avoided in practical applications. Internal structural gaps, front face and high surface roughness are all unfavorable factors, especially the front face is prone to form tiny burrs and high roughness due to manufacturing. The internal structural gaps of flow components include gaps at the overlap of the fluid channel unit partition plate, gaps at the overlap of the outer wall of the tube bundle, etc. Various polishing processes can be used to polish the end faces and surfaces of honeycomb flow components, so that the average roughness Ra value of the front face area and the channel surface in the unit is less than 2um.

[0101] The flow-through parts can also be filled or coated with a heated sealing liquid to fill the internal structure gaps or the surface. The sealing liquid solidifies after cooling, so that a hardened film is formed on the surface, and the roughness meets the use requirements. After that, it can be further polished to achieve the aforementioned roughness. The main component of the sealing liquid can be a polymer such as resin. The flow-through parts can be pre-degreased with an organic solvent, cleaned and dried. The flow-through parts can also be filled or coated with a sealing liquid containing a curing agent. The sealing liquid forms a hardened film on the surface after solidification, and then it can be further polished. The main component of the sealing liquid can be a polymer such as resin. After that, it can be further polished to achieve the aforementioned roughness. This kind of honeycomb flow-through parts treated with sealing liquid can be used to measure various fluids. Including water, industrial fluids. Suitable for a variety of pipe shapes.

[0102] A camera can be set at the front end of the flow component to monitor whether the honeycomb flow channel unit is blocked. A small maintenance hole can be set on the pipeline to clamp or vacuum absorb larger foreign objects when necessary.

[0103] In some working conditions, modular flow measurement devices need to use spacer components to further reduce the turbulence in the measurement channel and improve measurement stability and accuracy. Figure 5 The static pressure type multiple differential pressure measuring components are arranged in the rectangular channel 5a using a spacing component, such as Figure 5 As shown. The spacing component 2 uses a thin solid plate to separate the measurement sub-area. Six independent measurement sub-channels are formed. The measurement sub-channel in the present invention refers to a local channel surrounded by a spacing component or a measurement channel wall, which is used for the measurement of the measurement module.

[0104] In the example, the channel partition plate 2 can be made of three thin plates. After the thin plates are slotted, they can be fixed by mutual welding, socket joints, riveting, bonding or other methods. The channel partition plate and the fluid channel can be fixed by welding, socket joints, riveting, threaded connection or other methods. The gaps between the channel partition plates need to be sealed as much as possible.

[0105] The main function of the channel partition is to form a measurement sub-channel, reduce the turbulence of the flow beam, and improve the static pressure consistency of the local area. The channel partition can be arranged in small quantities, so that the number of measurement sub-channels is less than the number of measurement sub-areas. Its other function is to fix the measurement module. Some high-pressure main pipes and low-pressure main pipes can be fixed on the channel partition in various ways to increase the use strength. In actual engineering, a detachable design can also be used, such as Fig.17 As shown, rectangular openings 518 are arranged around the rectangular channel, wherein a plurality of mounting keels 515 and a plurality of slide grooves 517 are arranged; some slide grooves are fixed on the keels. The first channel partition plate 501, the second channel partition plate 502, the third channel partition plate 503, the fourth channel partition plate 504, the fifth channel partition plate 505, the sixth channel partition plate 506, the seventh channel partition plate 505, the eighth channel partition plate 508, the ninth channel partition plate 509, the tenth channel partition plate 510, the eleventh channel partition plate 511, the twelfth channel partition plate 512, the thirteenth channel partition plate 513, and the fourteenth channel partition plate 514 can all be removed and reinstalled. In the example, a plurality of mounting cover plates 519 are arranged, and the mounting openings can be closed with fasteners.

[0106] In order to pass through the detection tube in the channel, the channel partition plate in the example is relative to Figure 5 The design in the above is split. At the same time, the middle partition 516 is fixed in the channel to partially divide the flow channel, and a slide groove is fixed on it. The above channel partitions are connected by connecting studs 520 to facilitate the removal and installation of the channel partitions. In actual projects, the connection between the plates can be further designed to form more channel partitioning methods.

[0107] The same channel spacer design can also be implemented in circular measuring channels.

[0108] The spacer components and the rectifying components can achieve better turbulence reduction effect, which greatly improves the measurement. Figure 5In the process, after the fluid passes through the honeycomb rectifier and is separated by the channel partition, due to the relatively uniform flow velocity distribution in a single measuring sub-channel, the fluid at the outlet of the honeycomb rectifier, with the disappearance of the laminar shear layer, the kinetic energy of the higher velocity flow beam decreases relatively little during the development process; at the same time, the channel partition can reduce the disturbance of the flow beam by local resistance components such as the rear elbow and tee. Near the same total pressure measurement point, compared with the case without the spacing component, the static pressure consistency will be improved and the turbulence will be reduced, which is beneficial to the improvement of the measurement accuracy of the measurement module. In measurement places with large pipe diameters and very short straight channels, such as air conditioning and ventilation fields, the measurement conditions of the honeycomb rectifier will deteriorate to varying degrees without the cooperation of the channel partition. At the same time, the spacing component can be used together with the blocking component to improve the measurement range ratio of the device.

[0109] In actual engineering, the spacer valve 21 can also be used. Fig.18 As shown in the figure, an example of the design of the interval valve is shown, in which a cylindrical partition plate 202 is used for partitioning at the center circle, and 6 interval valves are used for partitioning at the periphery. The interval valve is characterized in that it has a plurality of long strip interval valve units 201, and the first column 203 and the second column 204 can be designed on both sides for fixing. When the interval valve is opened, the flow beams on both sides are conducted, which can reduce the number of measuring sub-channels; when the interval valve is closed, the number of measuring sub-channels can be increased. The interval valve unit 201 is designed with an interval valve leaf 20102, an interval gear 20103, and an interval valve stem 20101; the interval valve leaf can be fixed on the interval valve stem in a variety of ways, such as fastening, welding, or adopting an integrated molding process, and the interval valve stem and the channel axial direction are consistent. In the example, the gears of multiple interval valve units mesh with each other in the hollow second column 204 for transmission; the first column 203 and the second column 204 can be designed with corresponding bearings and limit support components to limit the above-mentioned valve stem; the measuring channel is opened at the corresponding position, and gears, drive shafts, motors and other components are used to actuate the valve unit, and pneumatic action can be used to achieve automatic control or remote manual operation.

[0110] When the interval valve behind the honeycomb rectifier is opened, the average static pressure of the measuring sub-areas on both sides is close or slightly different, which is conducive to the measurement of the average pressure difference measuring component. After the interval valve is closed, the static pressure difference on both sides is close. This feature allows the interval valve to adopt a low-strength mechanical design; at the same time, the interval valve occupies a small space, which has the advantage of being small.

[0111] The design of the interval valve can be applied to rectangular and other shaped fluid pipelines, and can achieve a wide range of flow measurement and control functions when combined with automatic control. The interval valve leaf of the interval valve can achieve a more airtight performance by adopting a suitable contour design or adding sealing materials. It can be applied to a wide range of fluid measurement and control by adopting suitable materials and strength design.

[0112] The spacer components can also be used Fig.19design. Fig.19 Two spacer boxes 22 are fixed around the surface of the circular valve body, and the spacer box 22 includes a box body 205, a box body cover 206, a cover screw 209, and a movable spacer 207. The inside of the box is used to install the movable spacer 207, and the movable spacer can be manually installed and fixed. Spacer racks 208 are designed on both sides of the movable spacer 207. The movable spacer can be limited by fixing methods such as guide rails inside the spacer box. At the same time, a driving hole 210 is designed at the lower part of the spacer box cover, which can be installed with gears, drive shafts, motors and other components, and the controller can remotely drive and adjust the movable partition at the driving hole. The surface of the box body cover 206 is designed with a cover screw 209 for easy installation and maintenance. The movement direction of the movable spacer is perpendicular to the axis of the measuring channel. In actual engineering, the movable spacer can be optimized on this basis, such as using a retractable movable spacer to reduce the design size.

[0113] The above-mentioned channel partition plates, partition valves, and partition plate boxes are collectively referred to as partition components in the present invention. In actual engineering, the above-mentioned different types of partition components can be used in combination. The partition valve and the partition plate box are characterized in that they have an actuator that can be electrically or communicatively connected to a control device and controlled by the control device to perform actions.

[0114] In modular measurement, under some working conditions, it is necessary to close some low-speed measuring sub-areas and increase the measuring flow rate of adjacent areas for measurement. This measurement method becomes feasible in the measurement using rectifying components. In actual fluid pipelines, after local resistance components such as elbows and tees, the static pressure of the local fluid area is relatively small. Closing some low-speed measuring sub-areas does not cause obvious pressure loss. On the contrary, the advantage of the higher flow rate of the local fluid area can be utilized. The definition of closing the measuring sub-area in the present invention is to set a blocking component in front of or behind the relevant measuring sub-channel so that the flow rate of the measuring sub-area is close to zero, so that it does not participate in the measurement. The difference in fluid flow rate of this measurement method relative to the fluid flow rate in the state before the measuring sub-area is closed is related to the weight of the resistance of the test device in the total pressure head of the system. Under some working conditions, the above flow difference does not affect the measurement accuracy at all. The method of closing some measuring sub-areas can generally be achieved by setting a baffle or a closed valve in front of or behind the average pressure difference measuring component. In the present invention, the component that blocks the backward flow of fluid is called a blocking component, and its function is to close the fluid measurement space together with the measuring channel or the spacing component.

[0115] Fig.16 The baffle 307 in the figure is of fixed design. In engineering, a detachable baffle can be provided in front of the rectifying component to achieve low-cost measurement. Fig.16In the embodiment, three slidably removable baffles 307 can be used in conjunction with the rectifier module 304. After the blocking component is installed, the sampling channel between the corresponding differential pressure measuring module and the differential pressure sensor can be cut off by the action of the switching component, and then the regional pressure difference of each measuring sub-area can be measured.

[0116] When the blocking component adopts a rotating valve stem design, it can be designed behind the average pressure difference measuring component to reduce its influence on the measurement accuracy.

[0117] The pressure difference measurement method of multiple average pressure difference measurement components can adopt a multi-sensor measurement method or a cycle measurement method; the aforementioned branch pipe controllable pressure difference measurement method belongs to a cycle measurement method. Examples of multi-sensor measurement methods are as follows Fig. 22 Each low-pressure main pipe and high-pressure main pipe are connected to a separate sensor 6 through a sampling pipe, and each sensor transmits a voltage or other signal to the flow measurement circuit. An example of a cyclic measurement method is as follows Fig.23 , each low-pressure main pipe and high-pressure main pipe share a differential pressure sensor through a sampling pipe, and the flow measurement circuit and valve island 18 are measured in turn through the differential pressure sensor and the flow measurement circuit 17 within a certain period of time. Since the manufacturing cost of a high-precision differential pressure sensor is high, the cyclic measurement method uses one or fewer differential pressure sensors to reduce the maintenance, calibration and manufacturing costs of the device, and at the same time allows some differential pressure sensors to be automatically calibrated during idle time. When the cyclic measurement method is measured on the sampling pipe, the small valve size makes the cost low and the reliability high.

[0118] The flow measurement circuit measures the regional pressure difference of each measuring sub-area, uses the regional pressure difference of each measuring sub-area and the area parameters of the measuring sub-area to participate in the calculation, and obtains the total flow; during the calculation process, the average flow velocity related variables of each measuring sub-area can be calculated according to the above theoretical flow coefficient or the following measurement function, and the total flow is calculated by combining the area and other parameters of each measuring sub-area; the area parameters include parameters such as the actual area and the area weight; the average flow velocity related variables include the average flow velocity of the measuring sub-area, the flow rate and other related parameters. The flow measurement circuit in the present invention refers to a circuit containing comprehensive functions such as signal measurement amplification circuit and flow calculation, which can be one part or multiple parts in appearance, and can include integrated circuits and chips such as signal conversion, signal processing and calculation, and signal output. The differential pressure sensor in the present invention can be replaced by a differential pressure sensor transmitter, and the transmitter circuit becomes a part of the flow measurement circuit; at the same time, the differential pressure sensor 6 and the valve island 18 can add a communication module, and wireless communication is used to connect with the flow measurement circuit; the flow measurement circuit in the modular flow measurement device can increase the collection of parameters such as fluid temperature and pressure, and realize multi-faceted result correction.

[0119] The valve island 18 responsible for switching the high and low pressure sampling pipelines may also use other sampling control components, collectively referred to as sampling switching components; Fig.25 The variable air volume device shown in the figure has four solenoid valves 10800 installed on the sampling pipeline, which also belong to the sampling switching component. The design idea is that each high-pressure main pipe is connected to the high-pressure main pipe by connecting to a common sampling channel or through a pipeline equipped with a switch valve, and each low-pressure main pipe is connected to the low-pressure main pipe by a common sampling channel or through a pipeline equipped with a switch valve. The sampling channel is provided with moving internal parts such as a controllable piston, a controllable diaphragm or a controllable valve core; the switch valve or moving internal part is driven by an electromagnetic coil, controllable compressed air, controllable pressurized liquid, etc. through a flow measurement circuit; the flow measurement circuit controls the connection or disconnection of each sampling channel through the switch valve control or the moving internal part to realize pipeline switching: when one of the high-pressure main pipes is connected to the high-pressure main pipe, the low-pressure main pipe and the low-pressure main pipe in the same measurement sub-area are connected at the same time, and the other high-pressure main pipes are disconnected from the high-pressure main pipe, and the other low-pressure main pipes are disconnected from the low-pressure main pipe; the action time and duration of the moving internal part or the switch valve are controlled by electrical components or programmed. The sampling channel in the present invention refers to the channel used by the differential pressure sensor for pressure sampling. Valves or moving internals can be set in the channel for cyclic measurement. The sampling channel does not need to have the average function of the full pressure value and the low pressure value; it includes the sampling hose frequently used in engineering.

[0120] The cyclic measurement method can use a single sensor, which reduces the manufacturing cost. In actual engineering, two or more differential pressure sensors can also be used. A single differential pressure sensor corresponds to multiple measurement sub-areas for cyclic measurement. This design has a faster measurement speed than the method of using only one differential pressure sensor. Fig.24 When two or more differential pressure sensors are used in the cyclic measurement method, different ranges can be used to adapt to different flow rate ranges. Furthermore, the switching component can have an automatic selection function, and a single differential pressure sensor can automatically switch to a measurement sub-area with the same range, so that sensors with different ranges correspond to corresponding measurement sub-areas.

[0121] When the modular flow measurement device adopts the cyclic measurement method, the measurement sub-areas can be combined, and the flow coefficient for measurement can be obtained and used to speed up the measurement speed while ensuring a certain measurement accuracy. Fig. 20 This is an example of circular measuring channel spacing design, which includes a cylindrical partition plate 202, four radial partition plates 211, and two partition valves 21; the columns of the partition valves are fixed on the cylindrical partition plates. Fig.21 This is a cross-sectional view of an example of installing multiple average pressure difference measurement components in a circular measurement channel. The device uses Fig.15 The differential pressure measurement component in Fig. 20The spacing components in the honeycomb rectifier, two baffles 307 are set in front of the honeycomb rectifier to close the central circle measurement sub-area and the three measurement sub-channels below, and the relevant 20 measurement switching valves are closed accordingly; when the two spacing valves 21 are closed, the effective measurement channel is divided into three measurement sub-channels; 18 solenoid valves are controlled to form multiple measurement modules. It is assumed that before the following process of obtaining the flow coefficient for measurement, the aforementioned performance test has been carried out on each measurement module, and the experiment has obtained: the fitting function of the theoretical flow coefficient corresponding to each of the following 9 measurement modules; before the measurement, all the solenoid valves are opened, and the two spacing valves 21 are opened to form a large measurement module, including 27 full-pressure measurement holes, which is hereinafter referred to as the 27-hole measurement module, and the measurement module has also obtained the fitting function of the theoretical flow coefficient.

[0122] The process of obtaining the flow coefficient for measurement can be performed when the total flow of the measurement channel does not change, and ρ and ν are not changed. The flow measurement circuit can perform cyclic measurement with only two solenoid valves turned on to complete the regional pressure difference measurement of 9 measurement modules, and open the 6th solenoid valve 10806 and the 15th solenoid valve 10815 in sequence; open the 7th solenoid valve 10807 and the 16th solenoid valve 10816; open the 8th solenoid valve 10808 and the 17th solenoid valve 10817; open the 9th solenoid valve 10809 and the 18th solenoid valve 10818; open the 10th solenoid valve 10810 and the 19th solenoid valve 10819; open the 11th solenoid valve 10811 and the 20th solenoid valve 10820; open the 12th solenoid valve 10812 and the 21st solenoid valve 1082 1; open the 13th solenoid valve 10813 and the 22nd solenoid valve 10822; open the 14th solenoid valve 10814 and the 23rd solenoid valve 10823; the flow measurement circuit calculates the average flow rate of each measurement module according to the pressure difference value of each area and the respective theoretical flow coefficient function, and obtains the average flow rate V1 of the measurement channel by weighted average; then open all the related solenoid valves, open the two interval valves 21, form a 27-hole measurement module, measure its regional pressure difference to obtain ΔP, obtain the theoretical flow coefficient according to its theoretical flow coefficient function, and further calculate the average flow rate V2; calculate V1 / V2 to obtain the flow coefficient correction factor K corresponding to ΔP Q . K Q The value actually fluctuates with different total flow rates. The flow measurement circuit can measure and calculate K at different total flow rates. Q , and record the corresponding ΔP to form a database, and establish K with ΔP as the independent variable through difference or fitting. Q K is the function value of Q =f(ΔP). This function can be applied to the flow test of the 27-hole measurement module in practice. It only needs to measure the ΔP value and calculate K through the function. QK0, and then the total flow rate is calculated. This method can be called the flow coefficient correction method, which multiplies the theoretical flow coefficient K0 by K Q Correction is performed to obtain the flow coefficient for measurement, which can be expressed as K m =K Q K0 = f(ΔP)·K0. This method can be applied to rapid fluid measurement and control. Furthermore, if ρ and ν have large fluctuations, K can be obtained through the same measurement steps. Q The database corresponding to ΔP, ρ and ν is organized into K Q The fitting function can be applied, and the function can be a piecewise fitting function. The flow coefficient correction method can be applied to the flow coefficient correction of the combination of different measurement modules.

[0123] The flow measurement circuit can also use other methods to obtain the flow coefficient K for measurement m As mentioned above, when the total flow rate ρ and ν of the measurement channel remain unchanged, after obtaining V1 and ΔP, change the total flow rate, record multiple average flow rates V1 and ΔP, and calculate K m Form a database. Then directly calculate the flow coefficient K m The difference function or fitting function corresponding to ΔP. This method requires more sample data than the flow coefficient correction method. Furthermore, if ρ and ν have large fluctuations, K can be obtained through the same measurement steps. m The database corresponding to ΔP, ρ and ν is organized into K m The fitting function is applied. This method can be called the direct calculation method of the flow coefficient.

[0124] In the above operation, the two spacing valves 21 are opened for measurement, the unblocked measurement modules are merged, and the pressure difference measurement of the entire measurement channel is performed. In actual operation, only one spacing component can be opened to merge some measurement modules to obtain the actual K of the merged measurement sub-area. m The above method is also applicable to the case where there is no spacing component between the measurement modules.

[0125] The similarities between the above-mentioned flow coefficient correction method and the flow coefficient direct calculation method are that the function of the flow coefficient corresponding to ΔP of the larger measurement module is measured and calculated. Furthermore, in actual engineering, a function of the average flow velocity corresponding to ΔP can be established and applied to the total flow calculation; essentially, the flow coefficient can be expressed as a function of the average flow velocity, so the above-mentioned methods are all to obtain the function of the average flow velocity related variable corresponding to ΔP. The above process can be summarized as follows: S1: Under the same measurement conditions, measure and record the regional pressure difference of the measurement module and the multiple regional pressure differences corresponding to the multiple measurement modules formed after the measurement module is split. S2: When the measurement condition parameters change, repeat step S1. S3: Using the regional pressure difference of the measurement module in steps S1 and S2, the sample data of the multiple regional pressure differences corresponding to the multiple measurement modules formed after the measurement module is split participate in the calculation to establish the measurement function corresponding to the measurement module, the independent variable of the measurement function includes the regional pressure difference ΔP of the measurement module, and the function value is the corresponding average flow velocity related variable of the measurement module; the different measurement conditions include different total flow rates of the measurement channel, or different fluid densities, or different kinematic viscosity coefficients; the average flow velocity related variables include parameters or variables such as average flow velocity, flow rate, and flow coefficient, and the average flow velocity related variables have a clear functional relationship with the average flow velocity, which reflects the size of the average flow velocity. The total flow rate in the present invention refers to the volume flow rate;.

[0126] It can be carried out under a single measurement condition to obtain the coefficient of the regional pressure difference corresponding to the average flow rate related variable. It can be used for applications with low accuracy requirements.

[0127] The modular flow measurement method can be applied to a variety of occasions, such as natural gas pipelines, ventilation and air conditioning systems, and various industrial fluid pipelines. The advantage is that the manufacturing cost is low and the accuracy is significantly improved. When the cyclic differential pressure measurement is used in the measurement method, although the measurement speed decreases, it can still be widely used in most fields; since there is no fluid flow in the differential pressure sampling tube itself, after setting a filter component at the front end of the sampling tube, the influence of blockage can be completely eliminated.

[0128] Typical application devices of modular measurement method can be variable air volume valve, air volume hood, etc. Variable air volume valve is a device for measuring and controlling air volume in air conditioning ventilation duct. Traditional variable air volume valve has a single average pressure difference measurement component, and most variable air volume valves do not have rectifiers, which limits its wider use. When the variable air volume valve adopts modular flow measurement method, its measurement accuracy and applicability are greatly improved; many applications of variable air volume valve do not require high measurement speed. Many air ducts belong to the slow adjustment state of adapting to load or the state of slow change with resistance. It is suitable to adopt cyclic measurement and combined measurement sub-area adjustment. Most of the traditional variable air volume valves have an installation width greater than 300mm. The modularly designed variable air volume valve can realize ultra-thin valve design for large-size valves and realize a large range ratio adjustment. It can be used to replace traditional manual regulating valves to achieve comprehensive automation management.

[0129] Fig.25 A cross-sectional view of a rectangular variable air volume valve application. Fig. 27 As its air volume adjustment component, the cross section of the valve body 521 is 250*200mm, the installation width is 210mm, and it is made of 0.75mm galvanized steel plate. It can also be made of thin plates of other materials and thicknesses. In this embodiment, the valve body 521 is a combination of a measuring part valve body and a wind valve body. The two parts of the valve body are fixedly connected by bolts, and other fastening methods such as clamps can also be used. The valve body 521 can also adopt an integrated design, designing the measuring part valve body and the wind valve body as a whole. In the example, the end face of the valve body is connected to the rectangular air duct using a flange.

[0130] In the example, multiple average pressure difference measuring components are used, which have two measuring modules in total. The two measuring sub-areas correspond to their own air volume adjustment components 9 and air valve actuators 8. A honeycomb rectifier is provided at the front of the measuring component. The flow channel unit is 5mm*5mm and the length is 15mm. The rectifier can also be used as follows: Fig.16The multi-piece detachable design shown. A channel partition plate 2 is welded in the measuring channel. The sampling tube of the 14th high-pressure main pipe 107ha is provided with a solenoid valve 10800, and the sampling tube of the 15th high-pressure main pipe 108ha is provided with a solenoid valve 10800, and the two sampling tubes are connected to the high-pressure collection tube 10903; the sampling tube of the 14th low-pressure main pipe 107la is provided with a solenoid valve 10800, and the sampling tube of the 15th low-pressure main pipe 108la is provided with a solenoid valve 10800, and the two sampling tubes are connected to the low-pressure collection tube 10904; the high-pressure collection tube and the low-pressure collection tube are connected to the differential pressure sensor transmitter 4. The four solenoid valves can be controlled by the controller to sample the pressure difference of the measuring sub-area in a cycle, and the controller 7 measures the average pressure difference of the two measuring sub-areas, performs calculations, drives the air volume adjustment unit, and adjusts the air volume. For example, the controller can close one air volume adjustment component to close the corresponding measuring sub-area to increase the measuring flow rate. In actual engineering, the same air volume adjustment component and air valve actuator can be used for the two measuring sub-areas, and the air valve actuator can adjust the two measuring sub-areas at the same time when it is actuated, thereby reducing manufacturing costs. The channel partition plate 2 can be eliminated and is not a necessary design component.

[0131] Each air volume regulating component 9 includes an active valve stem 902 and three driven valve stems 901, and the active valve stem and the driven valve stem are meshed and connected with each other through gears; the gears of each air volume regulating component are located at different heights, and each is driven by the actuator 7 through the active valve stem, and the two air volume regulating components share a wind valve partition plate 906 and a dust cover 929.

[0132] The valve stem is provided with air valve blades 905, and a number of air valve partitions 906 are provided in the component; the air valve partitions 906 divide the air duct into 16 modular cavities, and the installation width of the air volume adjustment component 4 is 40mm. The air valve partitions can be welded to each other and positioned in the air valve body. The 32 air valve blades are welded to the active valve stem and the driven valve stem to form 8 valve stems with air valve blades. The active valve stem and the driven valve stem are provided with sliding bearings 907 at the places where they pass through the air valve body and the air valve partition to reduce air leakage and resistance. The connection between the air valve blades 905 and the valve stem can be made by various welding and fastening methods, or by processing and forming the same material; the air valve partition can also be installed by bonding or mechanical fastening.

[0133] The design of the above-mentioned multiple valve stems realizes an ultra-thin design. Specifically, the ultra-thin design mentioned here refers to a wind valve width of no more than 50m. The above-mentioned design adopts the design of multiple valve stems and wind valve partitions to disperse the air flow channel, which has a direct effect on reducing the turbulence of the upper airflow and improving the uniformity of the static pressure at the measuring point. When space is limited, the total width of the wind valve blades of a single active valve stem and a driven valve stem can be selected to be no more than 1 / 4 times the hydraulic diameter of the measuring sub-channel. The total width refers to the total closing width borne by the valve leaf in the direction perpendicular to the valve stem. The material of the air volume regulating component 9 can be metal or other materials. When the number of valve stems increases, the diameter of the valve stem decreases, and the wind valve blades adopt a lightweight design, the rotational inertia moment of the wind valve can be effectively reduced.

[0134] The air valve partition plate 906 can enhance the mechanical strength of the air volume adjustment component. Part of the air valve partition plate can be aligned with and in contact with the front channel partition plate to form a tight partition of the measurement sub-channel, such as Fig.25 The channel partition plate and the air valve partition plate may not be in contact with each other, but may be spaced a certain distance apart so that the measuring sub-channels are connected in front of the air valve.

[0135] In actual engineering design, the valve stem can be driven in a variety of ways, such as using gear bars, synchronous belt drive, etc. After using gear bars and synchronous belts, the gears can be small-diameter gears, and the aforementioned gears do not need to mesh with each other for transmission. In the design of the adjustment unit with an active valve stem, the gears are more susceptible to wear, and the design of the gear bars and synchronous belts is more wear-resistant. In actual engineering design, the valve stem can also be driven by other drive methods other than gears, such as connecting rod drive. Please refer to the relevant design of the circular variable air valve. The air volume adjustment component can also adopt an ordinary single-piece or multi-piece valve leaf design without an air valve partition.

[0136] like Fig.26 The partial cross-sectional view of a circular variable air volume valve example, the valve body 521 is partitioned by a cylindrical partition plate 202 and six radial partition plates 211 in the sector area, forming a central circle measurement sub-area and six sector measurement sub-areas. Fig.12 In the example, each of the seven high-pressure sampling tubes is designed with a solenoid valve 10800, and each sampling tube is connected to the high-pressure collection tube 10903; the seven low-pressure sampling tubes adopt the same design, and each sampling tube is connected to the low-pressure collection tube 10904. The valve body 521 also adopts the combination of the measuring part valve body and the air valve body, and the valve body is connected to the circular air duct for use. The central circle measurement sub-area can be eliminated and is not a necessary design component; the partition plate is also not a necessary design component.

[0137] Fig.29 for Fig.26The cross-sectional view of the exemplary air valve regulating component shows that each sector area has five valve stems, including an active valve stem 902 and four driven valve stems 901. The central circle area has eight valve stems, one of which passes through the hollow keel plate 912 of the sector area and is driven by the air valve actuator 8. The air valve actuator can be fixed on the dust cover 929.

[0138] A corresponding air valve blade is fixed on each valve stem for rotation adjustment. A air valve blade is provided on each valve stem in the fan-shaped area and is separated by an air valve partition plate 907; a air valve blade is provided on each valve stem in the central circle area and is separated by an air valve partition plate 907. The function of the air valve partition plate is to strengthen the valve body structure and further separate the airflow to reduce the turbulence in front, but the air valve partition plate is not a necessary design component in the present invention and can be omitted. The blade width shape in the example is adjusted according to the specific size of the adjustment area, and contacts with the air valve partition plate to form a closure during adjustment. Each valve stem is limited and supported by the air valve body and the hollow fixed cylinder 915. In actual engineering, sliding bearings, seals and other components can be designed for in-depth design. The fixed cylinder is fixed on the air valve body by 5 radial keel plates 913 and hollow keel plates 912, and is aligned with the radial partition plate to form airflow separation.

[0139] The eight small bevel gears 914 connected to the eight valve stems in the center circle area mesh with the large bevel gear 918 located in the center. The active valve stem 919 drives the small gear to rotate, driving the other small bevel gears to rotate, thereby realizing the opening and closing of the air valve blades. The bevel gear set is limited and fixed by the gear box 916, and the gear box is fixed by the air valve partition plate 907 and sealed by the gear box cover plate 917 for dust prevention. The appearance of the gear box is a regular 8-sided shape, and the outer surface is partially flat, and the corresponding part of the air valve blade is also flat to eliminate the matching clearance with the air valve unit blade.

[0140] The gear transmission in the center circle area can be further optimized. For example, the active valve stem can be eliminated, and the driving torque can be applied to the large conical gear, which can drive the small bevel gears to move; this will reduce the stress caused by gear meshing and increase the working life of the gears. When this design is adopted, the corresponding drive shaft needs to be used, and it should be driven by a motor fixed inside the valve or by other forms of external torque.

[0141] The first bevel gear 903 is fixed to the outer end of the valve stem of the air valve unit in each sector area, meshing with each other and driven by the active valve stem. The bevel gear adopts an involute tooth profile bevel gear with a shaft angle of 12 degrees and a pressure angle of 20 degrees, and is made of POM or nylon.

[0142] The local valve body surface near the valve stem in the figure can be processed into a flat surface to install the sliding bearing and bevel gear. The dust cover 929 installed in each sector area protects the bevel gear set. In the design of the fan-shaped area air valve, the part where the fixed cylinder 915 and the blade of the air valve unit match is a flat surface, and the blade at this part is also a flat surface to eliminate the matching gap. The edge of the air valve blade of the air valve unit can be provided with sealing material to improve the air tightness of the closure.

[0143] The valve stem in each sector area can be equipped with an equal number of bevel gears to achieve transmission, and the number of bevel gears can also be increased to reduce the size of the bevel gears.

[0144] Each sector area can also eliminate the design of active valve stem, and configure a pair of bevel gears for each valve stem, which can convert radial gear rotation into axial gear rotation, such as Fig.30 As shown. In the figure, a second bevel gear 922 is set at the outer end of each valve stem, forming a 90-degree axial angle with the third bevel gear 923. The third bevel gear is connected to the drive shaft 921, and the drive shaft 921 is meshed with the arc-shaped rack through the driving spur gear 924. The arc-shaped rack 925 is driven from the outside. In this design, the driving torque of the air valve unit in the fan-shaped area is dispersed on the arc-shaped rack, which has better stress distribution characteristics. The above-mentioned arc-shaped rack can be replaced by a synchronous belt for a more flexible design. The above-mentioned arc-shaped rack and synchronous belt are collectively referred to as arc-shaped belt toothed components.

[0145] The transmission part of the air valve unit in the fan-shaped area can also adopt a connecting rod transmission design, such as Fig.31 As shown in the figure, each valve stem is fixed on a swing arm 926, and a groove is opened in the swing arm to limit the sliding pin 928. The sliding pin 928 is fixed on a rotating crank arm 927, and the rotating crank arm 927 can be driven by a motor or pneumatic components through various transmission methods.

[0146] The advantage of the fan-shaped regulating valve design is that it realizes perfect coordination with the aforementioned spacing components and can form independent air volume regulation for the measuring sub-channel. The installation width of the valve can be greatly reduced while achieving good sealing performance. Another advantage is that it can achieve an ultra-thin design.

[0147] The air volume adjustment component can adopt other transmission designs. Fig.28 The transmission component is designed to match the common circular air valve with multiple parallel air valve blades; the active valve stem on the circular air valve can be connected to the active valve stem 902 in the figure by a continuous connection; the driven valve stem on the circular air valve is connected to the driven valve stem 901 in the figure; the valve stem end face in the figure is designed to be connected in the form of a non-circular hole shaft connection, which is fixed by screws, and the design can also use key connection and other methods. The active valve stem 902 and the driven valve stem 901 are fixed to the corresponding gear 904 in the open gear box 91,

[0148] The open gearbox 91 includes a base 908, a sliding bearing, a fixed seat, and a gear 904. The open gearbox can be fixed to the gearbox base 92 by a nut 909, and a mounting stud 911 is provided on the gearbox base. The open gearbox can be adjusted on the gearbox base, and the positioning accuracy of the air valve stem is high, and the friction resistance is reduced. The gearbox base 92 can be fixed to the valve body by bolts, and the above-mentioned transmission part is protected by a dust cover.

[0149] In actual engineering design, the open gearbox can also add a shell and adopt a semi-enclosed design; the design of the gearbox enhances the interchangeability of valve manufacturing. The open gearbox can also refer to the design of the above-mentioned circular air volume adjustment component and adopt a gear bar and synchronous belt drive; after adopting the gear bar and synchronous belt, the aforementioned gears do not need to mesh with each other for transmission.

[0150] The above-mentioned variable air volume valve belongs to a variable air volume device, and the variable air volume device can adopt any design method in modular design; the variable air volume device can adopt a variety of average pressure difference measuring components in modular design, among which the static pressure type measuring component is more suitable for an ultra-thin valve body, and one or more static pressure type average pressure difference measuring modules can be used in the valve body; since the pressure difference measured by the non-static pressure type measuring module is large, it can be used or used in combination with the static pressure type measuring module; the variable air volume device can adopt a variety of switching components in modular design, so that its action can cyclically measure the pressure difference of at least part of the measuring sub-areas, and a branch pipe controllable average pressure difference measuring component can be used to realize the merging of the measuring sub-areas and perform rapid measurement and adjustment. Section; it can adopt a variety of honeycomb-type flow components in modular design, and one or more are arranged in front of the pressure difference measuring component; the variable air volume device can adopt a variety of spacing components in modular design to separate the measuring channel to reduce the turbulence of the measuring areas on both sides; the spacing component can have an actuator and be opened by the control device, and the control device combines the relevant measuring sub-areas through the measurement switching valve action to measure the regional pressure difference and use it for the calculation of the average flow velocity related variables of the measuring sub-area; the spacing component can be electrically or communicatively connected to the control device to become a part of the control, or a wireless communication connection method can be adopted; the variable air volume device can adopt any design of the sampling channel in the modular design.

[0151] The control device can adopt any measurement and control method in the modular design; multiple average pressure difference measuring components are connected to the pressure difference sensor through the sampling channel, the pressure difference sensor transmits the pressure difference signal to the control device, the control device transmits the control signal to the air volume adjustment component, the control device measures the regional pressure difference of each measuring sub-area, performs calculations and drives the air volume adjustment unit to adjust the air volume passing through the valve body until the target air volume is reached, and the target air volume is within the error range of the air volume required by the air conditioning and ventilation system; the control device can close at least one measuring sub-area through the air volume adjustment component and the spacing component, and cut off the sampling channel between the corresponding measuring module of the above-mentioned measuring sub-area and the pressure difference sensor by the action of the switching component, and then measures the regional pressure difference of each measuring sub-area, and separately calculates the pressure difference. Calculate the average flow velocity related variables of the measuring sub-area. For example, when the set air volume of the variable air volume device is too small, the air volume adjustment component corresponding to the measuring sub-channel can be closed; the variable air volume device can add a multi-leaf closed air valve or a plug valve in front of or behind the measuring sub-channel in the design to close the measuring sub-area when the function requires it. At the same time, the air volume adjustment component in the example is designed as an ordinary air volume adjustment component without a closed function, so as to have better practicality; the control device can actuate the measurement switching valve in multiple average pressure difference measurement components, measure and record the regional pressure difference of at least one measurement module and the multiple regional pressure differences corresponding to the multiple measurement modules formed after the measurement module is split, calculate the flow coefficient for measurement, and apply it to the calculation of the average flow velocity related variables of the measuring sub-area. During the measurement process, when the air volume adjustment component closes the auxiliary measurement, its function is equivalent to the blocking component; when the plug valve or the closed closing valve is designed to close the auxiliary measurement, they are the blocking components.

[0152] The above-mentioned damper actuator can adopt pneumatic control components, which can specifically include angular stroke or linear stroke actuators and positioners. This design can achieve fast control or explosion-proof control. The angular stroke actuator can act on the active valve stem or gear bar, and the linear stroke actuator can act on the gear bar. The addition of pneumatic angular stroke or linear stroke actuators can achieve faster drive. The valve stem position positioning feedback mechanism optionally matched with the damper actuator is called a positioner. The functions and forms of the three parts of the differential pressure sensor transmitter, controller, and damper actuator in the example can be integrated with each other. For example, the motor and other components in the electric damper actuator and the matching positioner can be hidden in the dustproof cavity, so that there is no need to design an external high-protection level damper actuator. At this time, a built-in electric damper actuator and positioner are formed; the differential pressure sensor transmitter can be integrated with the controller into one component; the differential pressure sensor transmitter design can be divided into a differential pressure sensor and a transmitter. The differential pressure sensor and the controller are electrically connected through the transmitter circuit. The differential pressure sensor is a necessary component in this variable air volume device.

[0153] The controller in the example includes an air volume calculation circuit and a control circuit. In fact, its functions can be simplified. The controller can only include sending action signals to the air valve actuator and receiving pressure difference signals from the sensor. Other air volume calculations and control calculations are completed by remote control equipment through wired communication or wireless communication. The controller controls the air valve actuator after receiving the control signal through the network. The above-mentioned remote control equipment or local controller that actuates the air valve actuator through wired communication or wireless communication, or through electrical connection can be collectively referred to as a control device. The control device includes an air volume calculation circuit and a control circuit. The control device can also include a network communication module; the control device is electrically connected to the pressure difference sensor, or wired communication connection, or wireless communication connection, and the control device is electrically connected to the air valve actuator, or wired communication connection, or wireless communication connection; the device that transmits control signals to the spacing component in the variable air volume device is also a part of the control device; the control device can be one or more in appearance, and can use a variety of control hardware such as PLC, single-chip microcomputer, computer, etc.

[0154] The control logic and method of the control device of the variable air volume device may include all the contents of the above-mentioned modular flow measurement method. Its basic control method may be to measure the air volume by multi-sensor measurement or cyclic method. When the total air volume does not reach the set value, the valve remains fully open; when the air volume is too large, the air volume adjustment component may adjust the measurement channel with the same opening synchronously, or may adopt different opening adjustment methods; during the measurement, the measurement sub-area with too low wind speed may be closed in time, and then adjusted; the variable air volume device using cyclic measurement may timely adopt the following air volume coefficient method to calculate the total flow or accelerate the measurement speed by merging the measurement sub-areas to calculate the total flow.

[0155] For variable air volume valves using cyclic measurement, the control speed can be accelerated by optimizing the control logic. Fig.25For example, assuming that the total air volume target value is L0, and the two air volume adjustment components are in full open state in the initial state, the controller can use the air volume of the measurement sub-area with larger average wind speed as the control target, and adjust the two measurement sub-areas with the same opening synchronously; record the air volume L11 of the measurement sub-area with larger average wind speed, measure the air volume of the other measurement sub-area to obtain L21, add the two to obtain the total air volume LT1, record the air valve opening α1, and calculate the air volume coefficient C1=LT1 / L11, C1 is the corresponding α1, L11 air volume coefficient; calculate the control target value L12' of the larger average wind speed measurement sub-area based on C1, LT1, L0, continue to adjust the two measurement sub-areas with the same opening synchronously, stop adjusting when the air volume of the larger average wind speed measurement sub-area approaches the target value, record the air volume L12, and measure the air volume of another channel to obtain L22, calculate the total air volume LT2, record the air valve opening α2, calculate C2 = LT2 / L12, C2 is the air volume coefficient corresponding to α2, L12. Calculate the control target value L13' of the larger average wind speed measurement sub-area based on C2, LT2, L0, and continue to adjust according to this method until the total air volume is within the control error range of the set air volume.

[0156] The control device counts the air volume coefficient C and related parameters, including C1, C2, C3, ....C n , which corresponds to different valve opening α i , L1 i , a database can be established. A function with α, L1 as independent variables and C as function value can be established by interpolation or fitting through manual or machine learning. The function can be applied to participate in control in the next adjustment process to speed up the adjustment speed. The above control method uses the control method of adjusting the air volume of the measurement sub-area and multiplying it by the air volume coefficient to adjust the total air volume. It can be called the air volume coefficient method, which is suitable for designing programs for related calculations and controls. The wind speed in the air duct is often larger in some measurement sub-areas after local resistance components such as elbows and tees, such as near the large radius of the elbow; when the air volume adjustment components are adjusted synchronously with the same opening, when the L1 value is fixed, the air volume coefficient C value has a certain curve characteristic with the distribution of the α value, so the air volume coefficient method is accurate in practice. When the average pressure difference measurement component is located in the air duct branch close to the air duct main pipe, the function of the C value is affected to varying degrees by the main pipe wind speed Vd. At this time, the main pipe wind speed can be obtained by counting the air volume of each branch, and further, the air volume coefficient C corresponding to α is established. i , L1 i , Vd i The database is used to establish a ternary interpolation function or a ternary fitting function of C corresponding to α, L1, and Vd by artificial or machine learning, thereby improving the control accuracy and speed. The use of the above-mentioned air volume coefficient method can also reduce the action frequency of the switching components and further improve reliability.

[0157] The above-mentioned air volume coefficient method and the method of calculating the total flow by merging the measurement sub-areas can both speed up the measurement. The difference is that when there are spacing components in the measurement channel, the air volume coefficient method can obtain better monitoring and measurement accuracy without opening the spacing components, which has advantages in manufacturing costs.

[0158] In the application of the above variable air volume valve, the air volume adjustment component may not be installed in the valve body, but may be installed in the air duct through accessories; the air volume adjustment component is not limited to a rotatable valve stem; and the honeycomb type rectifying component may also be installed in the air duct. The above variable air volume valve example is only for demonstration, and the modular flow measurement method can be applied to make various changes and improvements thereto.

[0159] The terms “first”, “second”, “third”, etc. appearing in this document are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0160] Finally, it should be noted that: the embodiments are described in detail herein. For those skilled in the art, they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A variable air volume device containing multiple measurement modules, characterized in that It includes a valve body, multiple measuring modules, and air volume adjustment components; The air volume regulating component includes a valve stem limited on the valve body and a wind valve blade arranged on the valve stem, and the air volume is adjusted by rotating the valve stem; the detection tube of the measuring module is fixed inside the valve body and located in front of the air volume regulating component. The measuring module is used to collect the regional pressure difference in the local area, and is connected to the pressure difference sensor through a sampling channel to realize the regional pressure difference measurement.

2. A variable air volume device according to claim 1, characterized in that The pressure difference sensor transmits the pressure difference signal to the control device, and the control device performs calculations and adjusts the air volume of the corresponding air volume adjustment component by controlling the air valve actuator.

3. A variable air volume device according to claim 1, characterized in that A rectifying component is arranged in front of the plurality of measuring modules to reduce the turbulence of the measuring cross section.

4. The variable air volume device according to claim 3, characterized in that The rectifying component comprises a plurality of straight channels through which the air flows, and is used to reduce the turbulence of the measuring cross section; the straight channels through which the air flows are passed are straight channels from the inside to the outlet, the hydraulic diameter of the straight channels is less than 0.2 times the hydraulic diameter of the measuring channel, and the length of the straight channels is greater than 0.2 times the hydraulic diameter of the straight channels.

5. A variable air volume device according to claim 4, characterized in that A hardening film is provided on the surface of the rectifying component to reduce the surface roughness.

6. A variable air volume device according to claim 1, characterized in that The variable air volume device comprises a switching component, and the switching component is activated by a control device to realize cyclic measurement of at least part of the measurement sub-areas.

7. A variable air volume device according to claim 1, characterized in that The multiple measurement modules include at least one average pressure difference measurement component, and the high pressure value of the average pressure difference measurement component is averaged by multiple total pressure measurement holes in the high pressure cavity.

8. A variable air volume device according to claim 1, characterized in that The multiple measurement modules include at least one static pressure measurement module, the low pressure measurement hole of the static pressure measurement module is located on the cylindrical surface, and the straight generatrix of the cylindrical surface is parallel to the axis of the measurement channel.

9. A variable air volume device according to claim 1, characterized in that The multiple measurement modules include at least one non-static pressure measurement module, and the low-pressure measurement hole of the non-static pressure measurement module is arranged on the low-pressure cavity of the detection tube, which is used to measure the pressure of the low-pressure distribution area generated by the fluid flowing around the detection tube.

10. A variable air volume device according to claim 1, characterized in that The variable air volume device comprises a spacing component inside, and the spacing component separates the measurement channel to reduce the turbulence of the measurement areas on both sides.

11. A variable air volume device according to claim 10, characterized in that The control device closes at least one measuring sub-area through the blocking component and the spacing component, and cuts off the sampling channel between the corresponding measuring module of the measuring sub-area and the pressure difference sensor by operating the switching component, and then measures the regional pressure difference of each measuring sub-area.

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