CN110081319A - A kind of design method of controllable transient flow leak detection system - Google Patents
A kind of design method of controllable transient flow leak detection system Download PDFInfo
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- CN110081319A CN110081319A CN201910457001.1A CN201910457001A CN110081319A CN 110081319 A CN110081319 A CN 110081319A CN 201910457001 A CN201910457001 A CN 201910457001A CN 110081319 A CN110081319 A CN 110081319A
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
- F17D—PIPE-LINE SYSTEMS; PIPE-LINES
- F17D5/00—Protection or supervision of installations
- F17D5/02—Preventing, monitoring, or locating loss
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
- G01M3/00—Investigating fluid-tightness of structures
- G01M3/02—Investigating fluid-tightness of structures by using fluid or vacuum
- G01M3/26—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors
- G01M3/28—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds
- G01M3/2807—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes
- G01M3/2815—Investigating fluid-tightness of structures by using fluid or vacuum by measuring rate of loss or gain of fluid, e.g. by pressure-responsive devices, by flow detectors for pipes, cables or tubes; for pipe joints or seals; for valves ; for welds for pipes using pressure measurements
Abstract
The present invention relates to a kind of design methods of controllable transient flow leak detection system, comprising: the calculating of the frictional resistant coefficient of pipeline to be detected；The calculating of the frictional resistant coefficient of connecting pipe；Collect pipeline data to be detected；Determine the intensity of controllable transient flow when detection；The calculating of pipe flow speed variation to be detected；The calculating of transient flow exciting bank pressure；Initial compression amount calculates；The calculating of pressurizing chamber volume；The calculating of the diameter of pressurizing piston；The calculating of pressurization cavity length.System designed by design method of the present invention can apply the leak detection in aqueducts such as hydraulic engineering, municipal water supplies, design for controllable transient flow exciting bank provides theory support, also provides technical basis for the application of controllable transient flow leak detection.
Description
Technical field
It is a kind of for determining water conservancy work the present invention relates to a kind of design method of controllable transient flow leak detection system
The indirect problem analytic approach of canonical parameter involved by the controllable transient flow leak detection of journey, municipal water supply aqueduct, is a kind of pipeline
System soil's rigidity, assessment and leak point positioning system design method.
Background technique
Leakage is a kind of generally existing phenomenon in pipeline liquid process, causes a large amount of resources loss, energy wave
Take and environmental pollution.According to statistics, the average leakage ratio about 17.9% of public supply mains, urban has been even more than 25%,
Thus caused annual loss fluid loss has been more than 5,000,000,000 m3.How in pipeline water delivery engineering, water distributing network, urban drainage pipe network
Leakage quick and precisely positioned, become current social a hot spot demand and Constructing Water-saved Society there is an urgent need to
One of critical issue of solution.
Transient flow detection method makes system generate transient flow, according to exemplary position by artificially manufacturing disturbance in pipeline
The distortion of pressure signal and attenuation characteristic recognize leakage information.Since pipe can be made small leakage under transient condition
The hydraulic pressure waveform in road generates significant difference, and therefore, the accuracy and reliability of transient flow detection method is higher.
For transient flow leak detection method, form based on transient pressure wave distortion and attenuation characteristic identification leak
The theoretical method of information, and ideal application effect is achieved in laboratory.But transient flow generally by quickly or
Come what is excited, this absolutely not allows in engineering actual motion for periodic disturbance pipeline head end, centre or the valve of end.
Therefore, controllable transient flow leak detection method becomes the research hotspot of the technical field.
How controllable transient flow to be excited, and how according to the characteristic feature of pipeline to be detected, including pipe range, caliber, confession
The hydraulic parameters such as water pressure determine the parameter attribute of each structure of exciting bank, can excite the controllable transition for meeting leak detection
Stream, and can guarantee the structure safety of pipeline, become the matter of utmost importance that the technology needs to solve applied to engineering practice.
Summary of the invention
Of the existing technology in order to overcome the problems, such as, the invention proposes a kind of setting for controllable transient flow leak detection system
Meter method.The method is based on controllable transient flow exciting bank, proposes a kind of controllable transient flow of use to leakage point position
The design method for carrying out pinpoint system keeps leak point positioning more accurate, detects more convenient.
The object of the present invention is achieved like this: a kind of design method of controllable transient flow leak detection system, described
System includes: the controllable transient flow exciting bank being connected to by connecting pipe with pipeline to be detected, the connecting pipe with to
The junction for detecting pipeline is equipped with pressure sensor；The controllable transient flow exciting bank includes: adding with pressurizing piston
Chamber is pressed, the pressurizing chamber is connected to energy-storing chamber, and the energy-storing chamber is connected by the check valve and test chamber opened to test chamber
Logical, the check valve adjusts the opening force of check valve by spring adjustment mechanism, and the energy-storing chamber is equipped with to be connected with inlet valve
Logical water inlet, the test chamber are equipped with the water outlet being connected to by outlet valve with pipeline to be detected；
The step of the method, is as follows:
Step 1, pipe range, caliber, tubing and the part of pipeline to be detected the calculating of the frictional resistant coefficient of pipeline to be detected: are collected
Drag characteristic determines absolute roughness according to pipeline material, and calculates the frictional resistant coefficient of pipeline to be detectedλ 0:
In formula:For pipe diameter to be detected；For the absolute roughness of pipeline to be detected；
Step 2, pipe range, caliber, tubing and the local resistance of connecting pipe the calculating of the frictional resistant coefficient of connecting pipe: are determined
Characteristic determines absolute roughness according to pipeline material, and calculates the frictional resistant coefficient of connecting pipeλ 1:
In formula:For connecting pipe diameter；For the absolute roughness of connecting pipe；
Step 3, it collects pipeline data to be detected: collecting the head of the connected reservoir of pipeline to be detectedIt can with pipeline to be detected
The pressure of receiving；
Step 4, the intensity of controllable transient flow when detection is determined:
In formula:For transient flow maximum boost amplitude；For transient flow maximum reducing amplitude；
In formula:ρFor the density of water；gFor acceleration of gravity；
Step 5, pipe flow speed variation to be detectedCalculating:
In formula:For the velocity of wave of pipeline to be detected, calculation formula is as follows:
In formula:For the bulk modulus of water；For the Young's modulus of elasticity of pipeline to be detected；For pipeline to be detected
Wall thickness；
Step 6, transient flow exciting bank pressureP a Calculating:
Intermediate parametersmAre as follows:
In formula:For duct length to be detected；For pipeline coefficient of partial resistance summation to be detected；For pipeline to be detected
Flow velocity,；For connecting pipe length；For connecting pipe coefficient of partial resistance summation；For pipeline to be detected
Area,；For the area of connecting pipe,；
Step 7, initial compression amount calculates: calculating the initial compression amount Δ of spring adjustment mechanismx:
In formula:For flap area,；For flap diameter；The institute moved for flap and together with flap
There is the total quality of part；For the coefficient of elasticity of spring；
Step 8, pressurizing chamber volumeCalculating:
In formula:For the period of controllable transient flow leak detection system,；
Step 9, the diameter of pressurizing pistonD P Calculating:
In formula:For the active force applied to piston；
Step 10, pressurize cavity lengthCalculating:
。
The beneficial effect comprise that: the present invention is rubbed using duct length to be detected, pressure-bearing, bore, velocity of wave, waterpower
The canonical parameters such as resistance, the indirect problem analysis means calculated by Hydraulic Transient, under the premise of without earth works such as excavations,
So that it is determined that whether aqueduct leaks and its design method of the system of position.System designed by the design method can
To apply the leak detection in aqueducts such as hydraulic engineering, municipal water supplies, the design for controllable transient flow exciting bank is provided
Theory support also provides technical basis for the application of controllable transient flow leak detection.
Detailed description of the invention
Present invention will be further explained below with reference to the attached drawings and examples.
Fig. 1 is the schematic diagram of meter systems set by the embodiment of the present invention the method；
Fig. 2 is controllable transient flow exciting bank structural schematic diagram described in the embodiment of the present invention；
Fig. 3 is the flow chart of method described in the embodiment of the present invention；
Fig. 4 is transient flow leak detection time domain method schematic diagram；
Fig. 5 is the design example leak detection system effect of method described in the embodiment of the present invention.
Specific embodiment
Embodiment:
The present embodiment is a kind of design method of controllable transient flow leak detection system, and the system (see figure 1) includes: to pass through
The controllable transient flow exciting bank 03 that connecting pipe 01 is connected to pipeline 02 to be detected, the connecting pipe and pipeline to be detected
Junction be equipped with pressure sensor 04；The controllable transient flow exciting bank (see figure 2) includes: with pressurizing piston 1
Pressurizing chamber 2, the pressurizing chamber are connected to energy-storing chamber 3, and the energy-storing chamber passes through the check valve 5 opened to test chamber 4 and inspection
Survey chamber connection, the check valve by spring adjustment mechanism 6 adjust check valve opening force, the energy-storing chamber be equipped with into
The water inlet that water valve 7 is connected to, the test chamber are equipped with the water outlet being connected to by outlet valve 8 with pipeline to be detected.
Detection system described in the present embodiment is mainly by controllable transient flow exciting bank, connecting pipe and pressure sensor structure
At controllable transient flow exciting bank is mainly used for motivating transient flow, generates a pressure in pipeline to be detected via connecting pipe
Power shock wave recycles propagation state of the pressure sensor monitoring pressure shock wave in pipeline to be detected, to analyze pressure shock wave spy
Property, to judge whether pipeline to be detected leaks, then leak 05 can also be obtained to be detected by analysis if there is leaking
Position on pipeline.
The source of pipeline to be detected is reservoir 06, and reservoir described here is the general name at water source, can be water tank, pond
Deng.It usually there is provision of one section of connecting pipe between pipeline to be detected and transient flow exciting bank, in the design side of the system
In method, the drag effects of this section of connecting pipe be can not be ignored.
The transient flow exciting bank is the key that generate transient flow, and many of these elements all influence entire detection system
The efficiency and precision of system.
Since piston to be had moves wherein, the shape of pressurizing chamber generally uses cylindrical shape, is similar to a hydraulic cylinder.Circle
The side of piston in cylinder is water, and the other side is then communicated with the atmosphere.Piston is equipped with pressure rod, is equivalent to the cylinder rod of hydraulic cylinder,
When pressurization, to cylinder rod applied force, piston is made to apply pressure to water, form pressurization.
Energy-storing chamber and test chamber shape can be square box, are also possible to cylindrical shape, are connected between the two using check valve
It is logical.Energy-storing chamber and test chamber can be the square box welded together, form one, and setting is unidirectional on partition between the two
Valve.Also short tube connection can be used between energy-storing chamber and test chamber, check valve is set on short tube, but design can generate one in this way
A little head loss should pay attention in calculating.
Check valve is closed type check valve, i.e., is being to close, and maintain normally off using spring under normal conditions.Check valve
Unlatching is to be applied with pressure to water due to pressurizing piston, and promoting the hydraulic pressure in energy-storing chamber is more than the active force of one-way valve spring.
When energy-storing chamber and test chamber are set together, check valve need to be designed specially, to adapt to the connection between two chambers
Mode.The form of check valve can be traditional truncated cone-shaped flap and the valve seat to match therewith or other forms.The valve of check valve
Valve is pressed by spring, generates the effect of control output water pressure.
It can directly be pressed with manpower to piston when to pressurizing chamber pressurization.Due to being directly to press, active force is small, this side
Formula is suitable for the lesser pipeline of measured diameter.When needing compared with noticeable effort, lever can be connected on piston, passes through lever
Amplification is generated compared with noticeable effort.
Pressurizing chamber is connected to by pipeline with energy-storing chamber or open connection.Opening connection refers to what pressurizing chamber was connect with energy-storing chamber
Position is not closed, but by cylinder body connection in a manner of completely it is open connect with energy-storing chamber, as shown in Figure 2.It can also will pressurize
Chamber it is closed at both ends, formed be similar to hydraulic cylinder form, connect by hydraulic tube with energy-storing chamber.
For gas vent swimmingly can be arranged full of each chamber in water on energy-storing chamber and test chamber, when water-filling, opens exhaust
Hole, water be full of after by vent closure.Bolt can be used on gas vent as obstruction piece, can also be installed on gas vent
Exhaust valve or common valve, only common valve needs to be turned off manually after water is full of energy-storing chamber and test chamber.
Spring adjustment mechanism such as using the guide part of the stem movement of guidance check valve, and can be utilized there are many form
Spring or drawing or pressure are turned round to valve rod application active force.Whether it draws, press, turn round, the direction of active force is all to close check valve
It closes.A variety of different spring adjustors can be set according to different force directions, it is unidirectional to use adjusting for adjustment spring elastic force
The opening force of valve.
Shown in Fig. 2 is the schematic diagram of controllable transient flow exciting bank, should also have these parts of connection to want in practice
The bracket of element, adjustment spring and its regulating part are fixed together with pressurizing chamber, energy-storing chamber and test chamber, form one completely
It is whole.Pressurizing chamber, energy-storing chamber and test chamber are arranged successively a kind of only mode of arrangement from top to bottom in Fig. 2, it can also be from
Upper arrangement or transversely arranged downwards, how arranging need to design according to structure, as long as and specific structure can be realized its function
?.
The specific design process of the present embodiment the method and it is analyzed as follows (process of step is as shown in Figure 3):
One, basic data is collected
Including three steps:
Step 1, pipe range, caliber, tubing and the part of pipeline to be detected the calculating of the frictional resistant coefficient of pipeline to be detected: are collected
Drag characteristic determines absolute roughness according to pipeline material, calculates frictional resistant coefficient using following formula:
(1)
In formula:For pipe diameter (see figure 1) to be detected, m；For the absolute roughness of pipeline to be detected, m.
Step 2, the calculating of the frictional resistant coefficient of connecting pipe: transient flow exciting bank can pass through the sky on water supply line
Air valve or maintenance valve pit are connected to main pipeline, access situation according to scene, determine the pipe range, caliber, tubing of connecting pipe, according to
Pipeline material determines absolute roughness, calculates frictional resistant coefficient using following formula:
(2)
In formula:For connecting pipe diameter (see figure 1), m；For the absolute roughness of connecting pipe, m.
Step 3, it collects pipeline data to be detected: collecting the connected reservoir head of pipeline to be detected(see figure 1), it is to be checked
Test tube road allowable stress。
Two, pipeline transition intensity of flow to be detected determines
Pipeline transition intensity of flow to be detected must be limited within zone of reasonableness, and transient pressure is excessively high, may generate booster, shadow
Ring engineering safety and piped water supply；Transient pressure is too low, and signal-to-noise ratio is also lower, and pressure sensor is not easy to capture.It analyzed
Journey is as follows:
(1) transient flow is pressurized amplitude
For enhance signal-to-noise ratio, improve transient flow leak detection pressure signal can identification, transient flow pressurization lower limit be
(3)
In formula:The transient flow of pipeline to be detected is caused to be pressurized amplitude, m for exciting bank work.
For the engineering safety for ensuring pipeline to be detected, the upper limit of transient flow pressurization are as follows:
(4)
In formula:For the density of water, kg/m3；For acceleration of gravity, m/s2。
Therefore, controllable transient flow maximum boost amplitude are as follows:
(5)
(2) transient flow Amplitude of Hypotensive
During transient flow leak detection, water hammer negative pressure cannot be reduced to steam pressure hereinafter, in order to avoid liquid vaporizes to form steaming
Vapour hole, referred to as water column separation, later, water column, which makes up, can generate bigger water hammer pressure, increase booster risk.For guarantee to
Detect the engineering safety of pipeline, the lower limit of transient flow decompression are as follows:
(6)
In formula:The transient flow of pipeline to be detected is caused to be depressured amplitude, m for exciting bank work.
(3) transition intensity of flow
Therefore, the intensity of controllable transient flow are as follows:
(7)
Constraint condition is formula (5) and formula (6).Meet formula (5) ~ (6) requirement,The larger value may be selected.
Summarize above-mentioned 3 points of conclusions are as follows: step 4, determine the intensity of controllable transient flow when detection:
(7)
In formula:For transient flow maximum boost amplitude；For transient flow maximum reducing amplitude.
(5)
(6)
In formula:ρFor the density of water；gFor acceleration of gravity.
Three, calculation of pressure needed for transient flow exciting bank
Pressure needed for calculating transient flow exciting bank first has to calculate pipe flow speed variation to be detected.
(1) step 5, the calculation formula of pipe flow speed variation to be detected:
(8)
In formula:For the change in flow of pipeline to be detected, m/s；For the velocity of wave of pipeline to be detected, m/s.
Pipeline velocity of wave calculation formula to be detected are as follows:
(9)
In formula:For the bulk modulus of water, Pa；For the Young's modulus of elasticity of pipeline to be detected, Pa；It is to be detected
The wall thickness of pipeline, m.
(2) transient flow exciting bank pressureP a Calculating, analytic process is as follows:
Under steady flow situation, column energy equation is exported to reservoir, pipeline to be detected, connecting pipe and exciting bank:
(10)
In formula:For duct length (see figure 1) to be detected, m；For pipeline coefficient of partial resistance summation to be detected；For to
The flow velocity of detection pipeline, m/s,；For connecting pipe length (see figure 1), m；For connecting pipe local resistance system
Number summation；For the flow velocity of connecting pipe, m/s.
Pipeline to be detected and connecting pipe meet continuity equation:
(11)
In formula:For the area of pipeline to be detected, m2,；For the area of connecting pipe, m2,。
Joint type (10) and formula (11) can obtain:
(12)
In formula:。
Above-mentioned analytic induction are as follows: step 6, transient flow exciting bank pressureP a Calculating:
(12)
Intermediate parametersmAre as follows:
In formula:For duct length to be detected；For pipeline coefficient of partial resistance summation to be detected；For pipeline to be detected
Flow velocity,；For connecting pipe length；For connecting pipe coefficient of partial resistance summation；For pipeline to be detected
Area,；For the area of connecting pipe,。
Four, the controllable transient flow exciting bank design of constant pressure
It calculates below and is related to the specific calculating of some hardware key parameters of the controllable transient flow exciting bank of constant pressure, comprising: spring
Initial compression amount calculates, pressurizing chamber volume calculates, piston size calculates, pressurization cavity length.
(1) spring initial compression amount calculates
Analytic process are as follows: valve opening meets following relational expression between test chamber and energy-storing chamber:
(13)
In formula:For flap area, m2,；For flap diameter (see figure 2), m；For flap, valve rod and lead
This unitarily formed quality, kg to cylinder；For the coefficient of elasticity of spring, N/mm；For the initial compression amount of spring, mm.
Coefficient of elasticity calculation formula are as follows:
(14)
In formula:For the shear modulus of spring material, Pa；For spring material diameter, mm；For mean diameter of coil, mm；For
Active spring coils number.
Therefore, the calculation formula of spring initial compression amount are as follows:
(15)
Above-mentioned analytic induction are as follows: step 7, initial compression amount calculates: calculating the initial compression amount Δ of spring adjustment mechanismx:
()
In formula:For flap area,；For flap diameter；The institute moved for flap and together with flap
There is the total quality of part；For the coefficient of elasticity of spring.
(2) pressurizing chamber volume calculates
Analytic process is as follows:
The length of connecting tube is usually 1 ~ 2m, and the pressure propagation time is much smaller than pipeline to be detected, therefore, transient flow detection system
Period are as follows:
(16)
In formula:For the period of transient flow detection system, s.
Pressurizing chamber volume are as follows:
(17)
In formula:For pressurizing chamber volume, m3。
The above analytic induction are as follows: step 8, pressurizing chamber volumeCalculating:
()
In formula:For the period of controllable transient flow leak detection system,。
(3) piston size calculates
Step 9, the diameter of pressurizing pistonD P Calculating:
(18)
In formula:For piston diameter (see figure 2), m；For the active force that engineering site can apply, N.
(4) pressurizing chamber length computation
Step 10, pressurize cavity lengthCalculating:
(19)
In formula:For cavity length (see figure 2) of pressurizeing, m.
Five, mathematical model
(1) pipeline
The equation of momentum and continuity equation of pipeline are as follows:
(20)
(21)
In formula:For piezometric head, m；For along the distance in pipe centerline direction, m；For flow rate of water flow, m/s；For
Acceleration of gravity, m/s2；For time, s；For stable state frictional resistance；For unsteady friction losses；For water-hammer wave speed, m/s；For
Pipeline inclination angle, °.
The calculation formula of stable state frictional resistance are as follows:
(22)
In formula:For frictional resistant coefficient；For pipe diameter, m.
The calculation formula of unsteady friction losses are as follows:
(23)
In formula:For coefficient,；；For Reynolds number.
(2) upper pond
When ducts upstream is reservoir, the variation of water level is that slowly, can ignore not compared to entire Hydraulic Transient process
Meter, therefore it can be assumed that reservoir level is constant:
(24)
In formula:For the piezometric head of pipeline start node, m；For reservoir level, m.
(3) valve in pipeline
The calculation formula of valve flow is in pipeline
(25)
In formula:For valve flow, m3/s；For valve flow coefficient；For valve opening area, m2；For valve
The pressure head of import and export is poor, m.
(4) leak
For the leak in pipeline, leak flow are as follows:
(26)
In formula:For the flow of leak, m3/s；For the discharge coefficient of leak；For the area of leak, m2；
For the head of leak, m.
Time domain method, distance of the leak away from exciting bank are detected according to transient flowL(see figure 4) are as follows:
(27)
In formula:The time of pressure tap, s are back to for decompression wave；For unidirectional valve opening time, s.
(5) the controllable transient flow exciting bank of controllable constant-pressure:
(28)
In formula:H PN For the piezometric head of pipe end node, m；
Design example:
(1) basic data is collected:
Pipeline to be detected, length 300m, caliber 0.1m, thickness of pipe wall 5mm, tubing are coating steel pipe, and equivalent roughness is 0.15mm,
According to formula (1), frictional resistant coefficient 0.0217.
(2) connecting pipe, length 2m, caliber 0.008m, thickness of pipe wall 1mm, tubing are steel pipe, and equivalent roughness is
0.046mm, according to formula (2), frictional resistant coefficient 0.0317.
Reservoir level is 5m, and pipeline allowable stress to be detected is 1.0MPa.
(3) pipeline transition intensity of flow to be detected determines
According to formula (3) and formula (4), controllable transition intensity of flow, maximum boost amplitude is。
According to formula (6), controllable transient flow maximum reducing amplitude is
According to formula (7), the intensity of controllable transient flow is, selection
(4) calculation of pressure needed for exciting bank
The elasticity modulus of water is 2.19 × 109Pa, steel pipe Young's modulus of elasticity is 2.0 × 1011Pa, to be detected according to formula (9)
The velocity of wave of pipeline。
According to formula (8), pipe flow speed variation to be detectedm/s。
According to formula (12), pressure needed for exciting bank=178201.15 Pa。
(5) the controllable transient flow exciting bank design of constant pressure
Flap, valve rod and guide cylinder single piece quality are 2.0kg, and exciting bank pressure isWhen, spring force 204.33N.
The shear modulus of spring material is 7 × 104MPa, material diameter 4.1mm, mean diameter of coil 30.1mm, number of active coils are
7 circles, according to formula (14), spring rate is 12.95 N/mm, and according to formula (15), the initial compression amount of spring is 15.77mm.
According to formula (16), the period of transient flow detection system is 0.895s；Determine that pressurizing chamber volume is by (17) formula
0.26L。
It is assumed that pressure rod acting surface diameter 0.04m, pushes away required thrust according to formula (18) is counterOnly 224N, much smaller than normal
Adult can apply 500 ~ 600N of active force, and according to formula (19), pressurization cavity length is 0.20m.
(6) detection effect
It is assumed that leakage point is located at away from upstream 67m, design controllable transient flow leak detection system using the above method, have leakage and
The pressure waveform of No leakage operating condition is as shown in Figure 5.When water soot blower propagates to leakage point, decompression wave reflexes to pressure tap, when the two
Between it is poor=0.249s, away from downstream side 233.9m, the identification distance away from upstream is 66.1m, and the deviation of actual range is only
0.9m.It can be seen that according to the controllable transient flow leak detection system that the above method designs, meet controllable, constant pressure, low-intensity and
The requirement of high-precision detection.
Claims (1)
1. a kind of design method of controllable transient flow leak detection system, the system include: by connecting pipe with it is to be checked
The junction of the controllable transient flow exciting bank of test tube road connection, the connecting pipe and pipeline to be detected is equipped with pressure sensing
Device；The controllable transient flow exciting bank includes: the pressurizing chamber with pressurizing piston, and the pressurizing chamber and energy-storing chamber connect
Logical, the energy-storing chamber is connected to by the check valve opened to test chamber with test chamber, and the check valve is adjusted by spring
Mechanism adjusts the opening force of check valve, and the energy-storing chamber is equipped with the water inlet being connected to inlet valve, and the test chamber is equipped with
The water outlet being connected to by outlet valve with pipeline to be detected；
It is characterized in that, the step of the method, is as follows:
Step 1, pipe range, caliber, tubing and the part of pipeline to be detected the calculating of the frictional resistant coefficient of pipeline to be detected: are collected
Drag characteristic determines absolute roughness according to pipeline material, and calculates the frictional resistant coefficient of pipeline to be detectedλ 0:
In formula:For pipe diameter to be detected；For the absolute roughness of pipeline to be detected；
Step 2, pipe range, caliber, tubing and the local resistance of connecting pipe the calculating of the frictional resistant coefficient of connecting pipe: are determined
Characteristic determines absolute roughness according to pipeline material, and calculates the frictional resistant coefficient of connecting pipeλ 1:
In formula:For connecting pipe diameter；For the absolute roughness of connecting pipe；
Step 3, it collects pipeline data to be detected: collecting the head of the connected reservoir of pipeline to be detectedIt can with pipeline to be detected
The pressure of receiving；
Step 4, the intensity of controllable transient flow when detection is determined:
In formula:For transient flow maximum boost amplitude；For transient flow maximum reducing amplitude；
In formula:ρFor the density of water；gFor acceleration of gravity；
Step 5, pipe flow speed variation to be detectedCalculating:
In formula:For the velocity of wave of pipeline to be detected, calculation formula is as follows:
In formula:For the bulk modulus of water；For the Young's modulus of elasticity of pipeline to be detected；For pipeline to be detected
Wall thickness；
Step 6, transient flow exciting bank pressureP a Calculating:
Intermediate parametersmAre as follows:
In formula:For duct length to be detected；For pipeline coefficient of partial resistance summation to be detected；For pipeline to be detected
Flow velocity,；For connecting pipe length；For connecting pipe coefficient of partial resistance summation；For pipeline to be detected
Area,；For the area of connecting pipe,；
Step 7, initial compression amount calculates: calculating the initial compression amount Δ of spring adjustment mechanismx:
In formula: for flap area,；For flap diameter；All zero moved for flap and together with flap
The total quality of part；For the coefficient of elasticity of spring；
Step 8, pressurizing chamber volumeCalculating:
In formula:For the period of controllable transient flow leak detection system,；
Step 9, the diameter of pressurizing pistonD P Calculating:
In formula:For the active force applied to piston；
Step 10, pressurize cavity lengthCalculating:
。
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