CN117433594A - Differential pressure type gas flow measuring device and optimal design method - Google Patents
Differential pressure type gas flow measuring device and optimal design method Download PDFInfo
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- CN117433594A CN117433594A CN202311754014.8A CN202311754014A CN117433594A CN 117433594 A CN117433594 A CN 117433594A CN 202311754014 A CN202311754014 A CN 202311754014A CN 117433594 A CN117433594 A CN 117433594A
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- 238000000034 method Methods 0.000 title claims abstract description 20
- 238000013461 design Methods 0.000 title claims abstract description 16
- 238000009530 blood pressure measurement Methods 0.000 claims abstract description 9
- 238000005457 optimization Methods 0.000 claims abstract description 3
- 238000005259 measurement Methods 0.000 claims description 21
- 230000001133 acceleration Effects 0.000 claims description 3
- 230000005484 gravity Effects 0.000 claims description 3
- 239000011148 porous material Substances 0.000 claims description 3
- 238000003466 welding Methods 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 21
- 230000003247 decreasing effect Effects 0.000 description 2
- 210000003437 trachea Anatomy 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012938 design process Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
Classifications
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/05—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects
- G01F1/34—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure
- G01F1/36—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using mechanical effects by measuring pressure or differential pressure the pressure or differential pressure being created by the use of flow constriction
- G01F1/40—Details of construction of the flow constriction devices
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/28—Design optimisation, verification or simulation using fluid dynamics, e.g. using Navier-Stokes equations or computational fluid dynamics [CFD]
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/08—Fluids
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2113/00—Details relating to the application field
- G06F2113/14—Pipes
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- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
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- Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Geometry (AREA)
- Fluid Mechanics (AREA)
- Evolutionary Computation (AREA)
- Pure & Applied Mathematics (AREA)
- Computer Hardware Design (AREA)
- Mathematical Optimization (AREA)
- General Engineering & Computer Science (AREA)
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- Measuring Volume Flow (AREA)
Abstract
The invention discloses a differential pressure type gas flow measuring device which comprises an air inlet hole, a differential pressure measuring part and an air outlet hole which are connected in sequence; the air inlet and the air outlet are connected with measuring air paths on two sides; the differential pressure measuring part comprises a first measuring air passage, a differential pressure hole, a conical hole and a second measuring air passage which are communicated in sequence; the invention also provides a taper hole cone opening gradient optimization design method aiming at the problems of the pressure loss and the turbulence intensity of the pipeline, and the accurate pipeline gas flow can be obtained by exploring the relation between the pressure loss and the cone opening gradient and the turbulence intensity at the second differential pressure measurement point under different cone opening gradients, finally obtaining the gas flow measuring device with stable differential pressure measurement and controllable pipeline pressure loss and combining the pipeline absolute pressure obtained from the rear end to carry out pressure compensation.
Description
Technical Field
The invention belongs to the technical field of gas flow measurement, and particularly relates to a differential pressure type gas flow measurement device and an optimal design method.
Background
The flow measuring devices commonly used in the market at present can be classified into a speed type flowmeter, a differential pressure type flowmeter, a volumetric flowmeter, a mass flowmeter and the like according to the structural principle. The differential pressure type flowmeter is used as a common flowmeter, has a relatively simple structure and a wide application range, is convenient to maintain, and can often solve the problem that the flowmeter is not accurate enough on the basis of the traditional calculation principle when in actual use. The inaccuracy of differential pressure flow meters has been mainly addressed by:
(1) The turbulence intensity is greatly improved after the air flow passes through the differential pressure hole, the differential pressure fluctuation is large, and the differential pressure value cannot be accurately read;
(2) The pressure loss exists in the pipeline;
how to comprehensively solve the problems of pipeline pressure loss and overlarge turbulence intensity of a pressure difference measuring point is an important research direction for improving the measuring precision of a differential pressure type gas flow measuring device.
Disclosure of Invention
The invention aims to: aiming at the problems in the background art, the invention provides a differential pressure type gas flow measuring device and an optimal design method, and provides a gas flow measuring structure capable of effectively improving measuring precision.
The technical scheme is as follows: a differential pressure type gas flow measuring device comprises an air inlet, a differential pressure measuring part and an air outlet which are connected in sequence; the air inlet and the air outlet are connected with measuring air paths on two sides; the differential pressure measuring part comprises a first measuring air passage, a differential pressure hole, a conical hole and a second measuring air passage which are communicated in sequence; the side face of the first measuring air passage is vertically provided with a first differential pressure measuring hole, the side face of the conical hole, which is close to the differential pressure hole, is provided with a vertical second differential pressure measuring hole, and one side, which is close to the air outlet hole, of the second measuring air passage is vertically provided with an absolute pressure measuring hole.
Further, the first differential pressure measuring hole and the second differential pressure measuring hole are respectively connected to the differential pressure sensor through air pipes and used for reading differential pressure values; the absolute pressure measuring hole is connected to the absolute pressure sensor through an air pipe and is used for measuring absolute pressure and performing pressure compensation on a differential pressure measured value.
Further, the air inlet and the air outlet are respectively connected into the measuring air path through self-locking connectors.
The design method of the differential pressure type gas flow measuring device comprises the following steps of:
step S1, obtaining the relation between the pressure loss and the cone inclination according to the Darcy-Weisbach formula as follows:
；
wherein the method comprises the steps ofRepresenting pressure loss->Representing the resistance coefficient>Representing the density of the gas in the pipeline,/-, and>represents the gas flow rate,/->Acceleration of gravity, ++>Representing a second measured airway length,/>Representing a second measured airway diameter. With the increase of D, the pressure lossGradually decreasing.
The expression for D is given based on cone slope α, differential pore aperture D, and cone height h as follows:
；
substituting the pressure loss formula can obtain:
；
s2, acquiring turbulence intensity at a second differential pressure measurement point under different cone inclination alpha according to an actual welding working condition, and solving a fitting relation between the cone inclination and the turbulence intensity; the greater the cone pitch value, the higher the turbulence intensity;
and S3, determining a turbulence intensity threshold Imax allowed at a second differential pressure measurement point based on the measurement precision of a fluctuation device of the differential pressure type gas flow measurement device, substituting Imax into the fitting relation in the step S2 to obtain an optimal solution of the cone inclination, and calculating a pressure loss value according to the pressure loss formula in the step S1.
Compared with the prior art, the technical scheme adopted by the invention has the following beneficial effects:
according to the invention, the output air flow is transited by arranging the conical holes on the basis of the traditional differential pressure type air flow measuring device, so that the turbulence intensity at the differential pressure measuring hole is reduced, meanwhile, the optimal cone inclination is given by combining the pipeline pressure loss result, the optimal cone inclination can be given according to the welding actual working condition by the design method, the low turbulence intensity and the low pipeline pressure loss are considered, the absolute pressure obtained by combining the rear end measurement can be effectively improved, and the accurate measurement of the air flow is finally realized.
Drawings
FIG. 1 is a schematic diagram of a differential pressure type gas flow measuring device according to the present invention.
Description of the embodiments
The invention provides a differential pressure type gas flow measuring device and an optimal design method, which aims at solving the problems that the turbulence of the existing differential pressure type flowmeter near a differential pressure measuring hole is serious, the pressure loss is increased, meanwhile, the turbulence of the differential pressure measuring hole can continuously influence the pressure reading of a measuring point, the reading is fluctuated and inaccurate measurement is caused, and provides a gas flow measuring structure capable of effectively improving the measuring precision, and meanwhile, a design method is provided, and an optimal design principle is provided from the two directions of the pressure loss and the turbulence intensity.
The gas flow measuring device and the optimal design method provided by the invention are explained in detail below with reference to the attached drawings.
The differential pressure type gas flow measuring device has a specific structure shown in figure 1 and comprises an air inlet hole, a differential pressure measuring part and an air outlet hole which are connected in sequence. The air inlet holes and the air outlet holes on the two sides are respectively connected into the measuring air path through self-locking connectors. The differential pressure measurement part comprises a first measurement air passage, a differential pressure hole, a conical hole and a second measurement air passage which are communicated in sequence. A vertical first differential pressure measuring hole A is formed in one side, close to the differential pressure hole, of the first measuring air passage, and a vertical second differential pressure measuring hole B is formed in one side, close to the differential pressure hole, of the conical hole. An absolute pressure measuring hole C for measuring absolute pressure is vertically formed in one side, close to the air outlet hole, of the second measuring air passage. Wherein the taper of the tapered hole has a taper angle alpha.
Wherein first differential pressure measuring hole and second differential pressure measuring hole are connected to outside differential pressure sensor through the trachea, and absolute pressure measuring hole is connected to outside absolute pressure sensor through the trachea and is used for measuring absolute pressure, carries out pressure compensation to differential pressure measurement.
In the actual measurement process, the streamline of the outlet section on the right side of the differential pressure hole is disordered, and serious turbulence occurs at the outlet. The turbulence intensity at the second differential pressure measuring hole is obviously improved, and the turbulence intensity at the absolute pressure measuring hole C can reach 50%. Therefore, the pressure loss can be increased, and meanwhile, the pressure measured at the second differential pressure measuring hole B and the absolute pressure measuring hole C can be frequently fluctuated due to the existence of turbulence, so that the measurement accuracy is seriously affected.
Turbulence occurs when fluid flows from the differential pressure orifice to the large diameter outlet orifice. The general solutions for reducing turbulence intensity include: (1) changing the aperture ratio of the differential pressure hole to the rear end measuring pipeline; (2) And a conical hole is arranged between the differential pressure hole and the rear end measuring pipeline, and the turbulence intensity of the differential pressure measuring point is changed by changing the inclination of the conical hole. The invention provides a design method for comprehensively controlling the pressure loss and the turbulence intensity of a pipeline, which is characterized in that the aperture of a differential pressure hole of a general differential pressure type gas flow measuring device is determined, and the method comprises the following steps:
according to the Darcy-Weisbach formula, the pipeline pressure loss expression is as follows:
；
wherein the method comprises the steps ofRepresenting pressure loss->Representing the resistance coefficient>Representing the density of the gas in the pipeline,/-, and>represents the gas flow rate,/->Acceleration of gravity, ++>Representing a second measured airway length,/>Representing a second measured airway diameter. With the increase of D, the pressure lossGradually decreasing.
The expression for D is given based on cone slope α, differential pore aperture D, and cone height h as follows:
；
substituting the pressure loss formula can obtain:
；
when D is gradually increased, the taper inclination is gradually increased as the aperture of the differential pressure hole is unchanged and the height of the taper hole is kept unchanged. Under the same external conditions, the turbulence intensity of the point B under different cone inclinations is measured, and the relationship between the cone inclination and the turbulence intensity of the point B is fitted, as shown in the following table 1, and it can be seen that the turbulence intensity of the point B is continuously increased when the cone inclination is gradually increased.
TABLE 1 correspondence between B Point turbulence intensity and cone inclination
In the actual design process, because the turbulence intensity of the point B is directly related to the measurement accuracy, the larger the turbulence intensity is, the more the fluctuation of the pressure difference measurement value is serious, the turbulence intensity of the point B is generally below 5 percent according to the actual calculation result, and the inclination of a proper cone opening selected in the embodiment is 15-20 degrees in consideration of the condition of lowest pressure loss.
The invention provides a measuring device structure with a conical opening, which aims at solving the problems that the existing differential pressure type gas flow measuring device has overlarge turbulence intensity and influences measuring precision. Meanwhile, the problem that the pressure loss in the pipeline cannot be excessive is considered, and a design method for comprehensively controlling the turbulence intensity and the pressure loss is provided. And aiming at external conditions such as different gases and pressures, fitting the relationship between the cone inclination and the second differential pressure measuring hole, and combining with the turbulence intensity requirement required by the measurement precision of an actual differential pressure flowmeter, providing the cone inclination alpha meeting the precision requirement. The design method provided by the invention can reduce the pressure loss of the pipeline as much as possible while meeting the measurement precision of differential pressure, and has higher measurement precision and measurement stability compared with the prior art.
The foregoing is merely a preferred embodiment of the present invention and it should be noted that it will be apparent to those skilled in the art that several optimizations and modifications can be made without departing from the principle of the present invention, and these should also be regarded as the protection scope of the present invention.
Claims (4)
1. The differential pressure type gas flow measuring device is characterized by comprising an air inlet hole, a differential pressure measuring part and an air outlet hole which are connected in sequence; the air inlet and the air outlet are connected with measuring air paths on two sides; the differential pressure measuring part comprises a first measuring air passage, a differential pressure hole, a conical hole and a second measuring air passage which are communicated in sequence; the side face of the first measuring air passage is vertically provided with a first differential pressure measuring hole, the side face of the conical hole, which is close to the differential pressure hole, is provided with a vertical second differential pressure measuring hole, and one side, which is close to the air outlet hole, of the second measuring air passage is vertically provided with an absolute pressure measuring hole.
2. The differential pressure type gas flow rate measurement device according to claim 1, wherein the first differential pressure measurement hole and the second measurement hole are respectively connected to a differential pressure sensor through gas pipes for reading differential pressure values; the absolute pressure measuring hole is connected to the absolute pressure sensor through an air pipe and is used for measuring absolute pressure and performing pressure compensation on a differential pressure measured value.
3. The differential pressure type gas flow measuring device according to claim 1, wherein the gas inlet hole and the gas outlet hole are respectively connected to the measuring gas path through self-locking connectors.
4. An optimization design method based on the differential pressure type gas flow measuring device as claimed in any one of claims 1 to 3, wherein the taper hole inclination design method specifically comprises the following steps:
step S1, obtaining the relation between the pressure loss and the cone inclination according to the Darcy-Weisbach formula as follows:
；
wherein the method comprises the steps ofRepresenting pressure loss->Representing the resistance coefficient>Representing the density of the gas in the pipeline,/-, and>represents the gas flow rate,/->Acceleration of gravity, ++>Representing a second measured airway length,/>Representing a second measured airway diameter; with increasing D, pressure loss->Gradually lowering;
the expression for D is given based on cone slope α, differential pore aperture D, and cone height h as follows:
；
substituting the pressure loss formula can obtain:
；
s2, acquiring turbulence intensity at a second differential pressure measurement point under different cone inclination alpha according to an actual welding working condition, and solving a fitting relation between the cone inclination and the turbulence intensity; the greater the cone pitch value, the higher the turbulence intensity;
and S3, determining a turbulence intensity threshold Imax allowed at a second differential pressure measurement point based on the measurement precision of the differential pressure type gas flow measurement device, substituting Imax into the fitting relation in the step S2 to obtain an optimal solution of the cone opening inclination, and calculating a pressure loss value according to the pressure loss formula in the step S1.
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| CN202311754014.8A CN117433594B (en) | 2023-12-20 | 2023-12-20 | Differential pressure type gas flow measuring device and optimal design method |
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| CN117433594B CN117433594B (en) | 2024-03-05 |
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201034643Y (en) * | 2007-02-02 | 2008-03-12 | 刘志壮 | Venturi type differential pressure liquid flowmeter |
| CN201434737Y (en) * | 2009-07-15 | 2010-03-31 | 重庆市伟岸测器制造有限公司 | Differential pressure type heat meter throttling device |
| CN104019853A (en) * | 2014-06-05 | 2014-09-03 | 唐力南 | Diffusion tube type rectangular flow meter |
| CN204241043U (en) * | 2014-12-05 | 2015-04-01 | 浦瑞斯仪表（上海）有限公司 | Rectangle differential pressure flowmeter |
| CN106197576A (en) * | 2016-07-18 | 2016-12-07 | 邵朋诚 | Venturi conical pipe flowmeter |
| CN113358319A (en) * | 2021-08-09 | 2021-09-07 | 中国空气动力研究与发展中心低速空气动力研究所 | Air inlet simulation system and method |
| CN117148877A (en) * | 2023-11-01 | 2023-12-01 | 苏芯物联技术(南京)有限公司 | High-precision pipeline flow measurement control device and design method |
-
2023
- 2023-12-20 CN CN202311754014.8A patent/CN117433594B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201034643Y (en) * | 2007-02-02 | 2008-03-12 | 刘志壮 | Venturi type differential pressure liquid flowmeter |
| CN201434737Y (en) * | 2009-07-15 | 2010-03-31 | 重庆市伟岸测器制造有限公司 | Differential pressure type heat meter throttling device |
| CN104019853A (en) * | 2014-06-05 | 2014-09-03 | 唐力南 | Diffusion tube type rectangular flow meter |
| CN204241043U (en) * | 2014-12-05 | 2015-04-01 | 浦瑞斯仪表（上海）有限公司 | Rectangle differential pressure flowmeter |
| CN106197576A (en) * | 2016-07-18 | 2016-12-07 | 邵朋诚 | Venturi conical pipe flowmeter |
| CN113358319A (en) * | 2021-08-09 | 2021-09-07 | 中国空气动力研究与发展中心低速空气动力研究所 | Air inlet simulation system and method |
| CN117148877A (en) * | 2023-11-01 | 2023-12-01 | 苏芯物联技术(南京)有限公司 | High-precision pipeline flow measurement control device and design method |
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