CN108981867B - The measurement method of any start and stop of high-precision bell-jar gas flow standard equipment - Google Patents
The measurement method of any start and stop of high-precision bell-jar gas flow standard equipment Download PDFInfo
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- CN108981867B CN108981867B CN201810858816.6A CN201810858816A CN108981867B CN 108981867 B CN108981867 B CN 108981867B CN 201810858816 A CN201810858816 A CN 201810858816A CN 108981867 B CN108981867 B CN 108981867B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F25/00—Testing or calibration of apparatus for measuring volume, volume flow or liquid level or for metering by volume
Abstract
The present invention relates to a kind of measurement methods of any start and stop of high-precision bell-jar gas flow standard equipment, the following steps are included: a, setting Digital Photogrammetric System, b, photography mark is pasted, c, photo is shot, d, image procossing, e, coordinate calculate, f, geometrical analysis, g, curve matching, the calculating of h, bell jar decline any position cover orthobaric volume.The present invention measures the inside of bell jar using V-STARS/N Digital Photogrammetric System, obtain the corresponding data of one group of bell jar cover height and cavity radius, Matlab Fitting Toolbox CFtool software is recycled to carry out curve fitting the data, obtain curvilinear function of the cavity radius of cover about cover height, further according to any start and stop position of bell jar cover, the exhaust volume of bell jar can be calculated with definite integral principle, the final measurement for realizing the arbitrary point start and stop of high-precision bell-jar gas flow standard equipment.
Description
Technical field
The present invention relates to a kind of gas flowmeter detection method, specifically a kind of high-precision bell-jar gas flow mark
The measurement method of any start and stop of standard apparatus.
Background technique
Bell-jar gas flow standard equipment is examined and determine gas flowmeter, calibrated and is detected using gas as medium
Metrological Standard Equipment.Many countries are studied and are established as the standard apparatus of low-pressure gas flow.
Bell-jar gas flow standard equipment is generally by bell jar, liquid bath, bell jar falling head measuring device, pressure compensation machine
The composition such as structure, timer, Measurement and Control System, gas source, test pipe and valve.Its working principle is that after outlet valve is opened,
Bell jar uniform descent under self gravity, the accurate orthobaric volume measured inside bell jar, time used can calculate bell jar row
The instantaneous flow of gas out.
Can bell-jar gas flow standard equipment realize that correct amount passes, and key is the accurate mark of cover orthobaric volume
It is fixed.It is provided according to JJG165-2005, volume is the device of 500L (containing) or more, it is recommended to use dimensional metrology demarcates cover mark
Quasi- volume.
Recently as the development of measuring technique, try to explore the novel measurement means based on size method, 20 generation both at home and abroad
It records the eighties, 1000L high-precision bell jar has been demarcated with size method by German federal physical technique research institute.At the beginning of 21 century, China
Metering scientific research institute using volume for 100L bell jar as research object, using π ruler method, laser tracing and outside micrometer method
3 kinds of different experimental methods, respectively measure the outer diameter on bell jar different cross section, and obtaining 3 kinds of measurement methods is all just
True reasonable conclusion.The outside diameter measurings methods such as π ruler method, outside micrometer method and laser tracing belong to indirect measurement, it is necessary to tie
Wall thickness measuring is closed, thus larger uncertainty of measurement (0.02% or so) can be introduced.First two method takes a long time, man's activity
Factor is big, a data group of mean people, cannot effectively restore cross-sectional geometry.Laser tracker measurement method requirement optical path is unobstructed, bows
At ± 45 °, this method is based on Spherical approach for elevation angle control, and spherical mirror is point contact type measurement, is limited by personnel and space,
It is not easy to operate, limit measurement range and application.Shanghai Institute of Measurement and Testing Technology is sat with articulated arm within 2016
Co-ordinate measuring machine is the measurement method that measuring system has studied bell jar device internal capacity.Articulated arm coordinate measuring machine sets for large size
It is standby, it is not suitable for in-site measurement, and also measure for point contact type, is limited by environment temperature and space.
The flow measurement uncertainty of above-mentioned bell jar device is between 0.06% (k=2) to 0.3% (k=2).Cover mark
Quasi- volume is used from the whole section of constant volume of early stage using the sublevel strapping table constant volume refinement developed in recent years, is that fixed point makes
With.This application method limits the lower limit of range of flow, and detection time is long, low efficiency.
To sum up, according to tested bell jar actual size and environment is placed, seeks a kind of contactless, high-precision, efficient and convenient
Measuring device, and under the premise of guaranteeing accuracy, providing a kind of bell jar device scheme that arbitrary point start and stop use is this
One technical problem in field.
Summary of the invention
It is an object of the invention to provide a kind of measurement sides of any start and stop of high-precision bell-jar gas flow standard equipment
Method, to solve the problems, such as traditional measurement method detection time length, low efficiency.
The object of the present invention is achieved like this: a kind of survey of any start and stop of high-precision bell-jar gas flow standard equipment
Amount method, comprising the following steps:
A, Digital Photogrammetric System is set: a set of V- to purchase including measurement camera, station meter and bar shaped photography mark
STARS/N Digital Photogrammetric System；
B, it pastes photography mark: bell jar cover is hung on base support, lower edge keeps horizontal；The mouth under cover
It is interior to indicate along one circle photography of stickup, several vertical photography marks are vertically pasted in cover inner wall, and calibrate the sequence of sequence
Number, circumferentially face is uniformly distributed in cover inner wall for vertical photography mark, the cover inner wall between two neighboring vertical photography mark
Upper to be pasted with splicing photography mark respectively, splicing photography mark is different, if the inner top surface in bell jar cover is also pasted at random
Do different splicing photography mark；Two foundation object staffs are separated and are separately fixed in the cover between vertical photography mark
On wall, two foundation object staffs are parallel with vertical photography mark and abut with a circle photography mark of mouth under bell jar cover；
C, it shoots photo: measurement camera being extend into bell jar cover, different positions, angle and distance are converted, is shot
The photo of one group of cover inner wall and cover inner top surface, all photography marks and station meter should all take；
D, image procossing: opening the V-STAR software in computer, inputs two parameters " station meter length value " and " overproof
The photo of captured cover inner wall and cover inner top surface, is imported the V-STAR software of computer, passes through V- by point accuracy value "
STAR software lookup respectively photograph mark central point and automatic positioning, after matched identification, the photo of shooting, which is spliced into, to be had
One group of picture of " angle value " feature；Wherein, " station meter length value " is the parameter demarcated in certificate of tracing to the source, and " overproof point essence
Angle value " is then the parameter being arranged according to measurement request；
E, coordinate calculates: in V-STAR software, according to " station meter length value " to the picture point and measurement of each photography mark
The position of camera is calculated, to identify the three-dimensional coordinate of each photography mark；
F, geometrical analysis: geometry is carried out in the V-STAR software of computer using the three-dimensional coordinate position of each photography mark
Analysis and calculating, obtain in bell jar cover and amount to 160 different height h at interval of 11mm along short transverseiThe intracavity section at place
Radius size ri, to form the two-dimensional array (h of mask body intracavity height and radiusi, ri)；
G, curve matching: using Matlab Fitting Toolbox CFtool software in a computer to above-mentioned two-dimensional array (hi,
ri) carry out curve fitting, obtain full curve function of the cavity radius r of bell jar cover about cover height h: r=f (h)；
H, the calculating of bell jar decline any position cover orthobaric volume: according to the intracorporal element of volume calculation formula of bell jar cover
DV=π r2Dh=π [f (h)]2Dh calculates the orthobaric volume of bell jar cover are as follows:
In formula: a and b is respectively the height value of bell jar decline front and back.
The present invention breaches the limitation that traditional bell-jar gas flow standard equipment constant volume uses, and realizes arbitrary point
The function of start and stop measurement, while can guarantee flow measurement uncertainty ur(q)≤0.1%, k=2, major advantage are as follows:
(1) measurement method disclosed in this invention is suitable for big volume, high-precision bell-jar gas flow standard equipment
The calibration of cover orthobaric volume, when measurement, only need the time-consuming valid data (height that can be obtained no less than 160 groups for 1 hour of a people
hi, radius ri).A large amount of data source can be quickly and accurately obtained, provides data basis for arbitrary point start stop mode measurement.
(2) present invention is to be carried out curve fitting according to a large amount of measured datas using MATLAB, to obtain mask body intracavity half
Bell jar row is calculated with definite integral principle further according to cover start and stop position in continuous function of the diameter about mask body intracavity height
Air volume, to finally realize the arbitrary point start and stop measurement of high-precision bell-jar gas flow standard equipment.
Detailed description of the invention
Fig. 1 is the setting schematic diagram of bell jar cover and measurement camera.
Fig. 2 is that bell jar cover pastes the expanded view after photography mark.
Fig. 3 is that bell jar cover inner top surface pastes the schematic diagram after photography mark.
Fig. 4 is the plot for surveying Value Data.
Fig. 5 is the contrast schematic diagram of curve-fitting results and measured data.
Fig. 6 is the schematic diagram that bell jar cover orthobaric volume in arbitrary height section is obtained using definite integral.
In figure: 1, bell jar cover, 2, base support, 3, measurement camera, 4, bottom surface photography mark, 5, cover inner wall, 6, perpendicular
Item photography mark, 7, splicing photography mark, 8, station meter, 9, cover inner top surface, 10, wirerope.
Specific embodiment
As shown in Figure 1, bell jar cover 1 is a cylindric container, top closed, lower openings, the inside of cylinder
Diameter is about 1399mm, and height is about 2500mm.
Measurement method of the present invention the following steps are included:
One, V-STARS/N Digital Photogrammetric System is selected to demarcate the orthobaric volume of bell jar cover.V-STARS/N takes the photograph
The composition of shadow measuring system includes: measurement camera 3, station meter 8 and photography mark.The measurement of V-STARS/N Digital Photogrammetric System
Range is 0~60m, and the limits of error are 10 μm+10 μm/m.
Two, it pastes photography mark: bell jar cover 1 is hung on the base support 2 specially made by wirerope 10,
Cover is vertical, and lower edge keeps horizontal (Fig. 1).Mouth is interior along a circle photography mark (Fig. 2) is pasted under cover, constitutes bottom surface photography
Mark 4, as reference datum.12 vertical photography marks are vertically pasted on cover inner wall 5, constitute vertical bar photography mark 6,
Circumferentially face is uniformly distributed (Fig. 2) in cover inner wall for vertical bar photography mark 6, and perpendicular to reference datum.To vertical bar photography mark 6
Sequential calibration goes out the sequencing numbers from No. 1~No. 12.It is glued respectively on cover inner wall 5 between adjacent two vertical bar photography mark 6
Patch splicing photography mark 7, splicing photography mark 7 are different.It is also pasted at random on cover inner top surface 9 several different
Splicing photography mark 7 (Fig. 3).Splicing photography mark 7 indicates random be spliced by several photographies.By two foundation object staffs 8
It separates and is separately fixed on the cover inner wall 5 between vertical bar photography mark 6, two foundation object staffs 8 and vertical bar photography mark 6 are flat
Row, and it is adjacent with the bottom surface photography mark 4 of mouth under bell jar cover.
Three, it shoots photo: measurement camera 3 being extend into bell jar cover 1, different positions, angle and distance are converted, is clapped
The photo of one group of cover inner wall 5 and cover inner top surface 9 is taken the photograph, all photography marks and station meter are intended to take.The photo of shooting
Quantity for digital photo, digital photo will be more than 100.
Four, image procossing: opening the V-STAR software in computer, inputs " station meter length value " and " overproof precision
The two parameters of value ".Then, measurement camera RAM card is taken out, computer interface is inserted into, by captured cover inner wall 5 and cover
The digital photo of internal top surface 9 imports in the V-STAR software of computer.V-STAR software has pixel center identification function, can
According to the difference of measurement point, several groups measurement data is extracted, and according to pixel size, is automatically found the central point of photography mark,
Realize precisely automatic positioning, through splicing photography mark, Auto-matching identifies accurate stitching position, thus by the measurement of shooting
Picture automatic Mosaic is together.According to the setting of accuracy value, false target point Bad point and the biggish Weak point of deviation are identified,
Shooting photo more than the accuracy value setting limit is rejected, one group of picture with " angle value " feature is finally connected into.
Five, coordinate calculates: in V-STAR software, according to " station meter length value " to the picture point and measurement of each photography mark
The position of camera is calculated, and to identify the three-dimensional coordinate of each photography mark, realizes asking to the three-dimensional coordinate of photography mark
Solution.
Six, it geometrical analysis: using the three-dimensional coordinate position of each photography mark, is carried out in the V-STAR software of computer several
What is analyzed and calculates, and obtains in bell jar cover and amounts to 160 different height h at interval of 11mm along short transverseiThe inner cavity at place is cut
Radius surface size ri, to form the two-dimensional array (h of mask body intracavity height and radiusi, ri), i=1,2 ..., 160, measurement result
As shown in table 2, plot is as shown in Figure 4.
Table 2: the measurement result (unit: mm) of digital photography method calibration cover orthobaric volume
Seven, curve matching: using Matlab Fitting Toolbox CFtool software in a computer to above-mentioned two-dimensional array
(hi, ri) carry out curve fitting, concrete mode is:
7-1 is first by two-dimensional array (hi, ri) saved in a computer with the format of EXCEL.
7-2 loads above-mentioned EXCEL file in the MATLABR2014A software of computer, defeated in MATLAB main window
Enter CFtool, after pressing enter key, corresponding tool box software can be called, finds Fourier's fitting function, setting fitting rank
Secondary, there are measurement data points and fitting function figure in window lower right, while obtaining the parameters and fitting mark of fitting function
Quasi- poor (RMSE).
7-3 examines fitting effect by analysis fit standard poor (RMSE), when not meeting fitting and requiring, increases and is fitted
Number, until coincidence loss requires.
The satisfactory fitting function of 7-4 is eight Fourier functions, mathematical model are as follows:
Wherein, each coefficient is respectively as follows: a0=702.1, a1=3.705, b1=3.452, a2=0.2251, b2=-4.503,
a3=-2.418, b3=-2.784, a4=-2.776, b4=-0.2533, a5=-1.429, b5=1.095, a6=-0.1616, b6
=1.018, a7=0.2302, b7=0.3752, a8=0.1108, b8=0.02697, ω=0.002576.Its function curve and
Measured data plot is as shown in Figure 5.
Obtained is full curve function of the cavity radius (r) of bell jar cover about cover height (h): r=f
(h)。
Eight, the calculating of bell jar decline any position cover orthobaric volume:
According to the intracorporal element of volume calculation formula dV=π r of bell jar cover2Dh=π [f (h)]2Dh calculates the mark of bell jar cover
Quasi- volume are as follows:
In formula: a and b is respectively the height value of bell jar decline front and back.
Nine, Definite Integral Calculation cover orthobaric volume:
As shown in fig. 6, the orthobaric volume of cover 1 is by full curve r=f (h) and straight line h=a, h=b and cover
The volume V of trapezoidal the surrounded cylindrical body that rotates a circle around axial line of curl made of axial line surrounds.Wherein, a and b difference
For the height value of bell jar decline front and back.Selection h be integration variable, any selection minizone [h, h+dh] on section [a, b], that
, the approximation i.e. body of bell jar cover 1 of the trapezoidal thin slice volume to rotate a circle around axial line of curl on this minizone
Product element are as follows:
DV=π r2Dh=π [f (h)]2dh (1)
So, the orthobaric volume of bell jar cover is are as follows:
The falling head of bell jar cover uses optical grating ruler measurement, and magnitude is traceable to length unit by laser interferometer,
Its limits of error is ± 20 μm.
Ten, the uncertainty calculation of orthobaric volume:
Rule is propagated by the mathematical model and uncertainty of the orthobaric volume of formula (2), being involutory for orthobaric volume can be obtained
At standard uncertainty:
The radius of bell jar cover is ± 30 μm by up short systematic survey, the limits of error, and radius estimated value isIts introducing is B class uncertainty, is considered by the rectangular distribution,It can obtain:
The radius value of bell jar cover, minimum discharge 6m have been fitted in software using fourier function3When/h, fitting function
Fit standard difference introduce relative standard uncertainty be A class uncertainty, ur2(r)=7.074 × 10-3%.
Height is measured by double grating scale, and the limits of error are ± 20 μm.Bell jar is with minimum discharge 6m3/ h declines 60s
Corresponding cover descending stroke is 65.07mm, and introducing is B class uncertainty, is considered by the rectangular distribution,Under and
The estimated value for dropping height is the average value of double grating scale, so answering multiplying factorIt can obtain:
ur(V)=1.955 × 10-2% (7)
The opposite expanded uncertainty of orthobaric volume are as follows:
ur(V)=0.04% (8)
In view of the uncertainty of measurement of temperature, pressure and time-parameters, bell jar instantaneous flow uncertainty of measurement reaches
ur(q)≤0.1%, k=2.
Claims (2)
1. a kind of measurement method of any start and stop of high-precision bell-jar gas flow standard equipment, characterized in that including following step
It is rapid:
A, Digital Photogrammetric System is set: a set of V- to purchase including measurement camera, station meter and bar shaped photography mark
STARS/N Digital Photogrammetric System；
B, it pastes photography mark: the cover of bell jar is hung on base support, lower edge keeps horizontal；Under cover in mouth
Along a circle photography mark is pasted, several vertical photography marks are vertically pasted in cover inner wall, and the sequence for calibrating sequence is compiled
Number, circumferentially face is uniformly distributed in cover inner wall for vertical photography mark, on the cover inner wall between two neighboring vertical photography mark
Be pasted with splicing photography mark respectively, splicing photography mark is different, the inner top surface of cover also paste at random it is several it is each not
Identical splicing photography mark；Two foundation object staffs are separated and on the cover inner wall that is separately fixed between vertical photography mark,
Two foundation object staffs are parallel with vertical photography mark and abut with a circle photography mark of mouth under cover；
C, it shoots photo: measurement camera being extend into cover, different positions, angle and distance are converted, shoots one group of cover
The photo of inner wall and cover inner top surface, all photography marks and station meter should all take；
D, image procossing: opening the V-STAR software in computer, inputs two parameters " station meter length value " and " overproof point essence
The photo of captured cover inner wall and cover inner top surface is imported the V-STAR software of computer by angle value ", soft by V-STAR
Part searches the central point of each photography mark and automatic positioning, and after matched identification, the photo of shooting, which is spliced into, has " angle
One group of picture of value " feature；
E, coordinate calculates: in V-STAR software, according to " station meter length value " to the picture point and measurement camera of each photography mark
Position calculated, with identify it is each photography mark three-dimensional coordinate；
F, geometrical analysis: geometrical analysis is carried out in the V-STAR software of computer using the three-dimensional coordinate position of each photography mark
And calculating, it obtains in cover and amounts to 160 different height h at interval of 11mm along short transverseiThe intracavity section radius size at place
ri, to form the two-dimensional array (h of mask body intracavity height Yu mask body intracavity radiusi, ri)；
G, curve matching: using Matlab Fitting Toolbox CFtool software in a computer to above-mentioned two-dimensional array (hi, ri) into
Row curve matching obtains full curve function of the mask body intracavity radius r about mask body intracavity height h: r=f (h)；
H, the calculating of bell jar decline any position cover orthobaric volume: according to the intracorporal element of volume calculation formula dV=π r of cover2dh
=π [f (h)]2Dh calculates the orthobaric volume of cover are as follows:
In formula: a and b is respectively the height value of bell jar decline front and back.
2. the measurement method of any start and stop of high-precision bell-jar gas flow standard equipment according to claim 1, step h
The height value a and b of middle bell jar decline front and back measure to obtain using grating scale.
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| CN104061859B (en) * | 2014-07-02 | 2016-09-14 | 华北水利水电大学 | A kind of hydraulic engineering gate high accuracy installs the digital close shot industrial photogrammetry method of detection |
| CN105387828B (en) * | 2015-10-29 | 2017-11-21 | 上海市计量测试技术研究院 | The measurement apparatus of sublevel volume inside high-precision bell-jar gas flow standard equipment |
| CN105444681A (en) * | 2015-11-16 | 2016-03-30 | 安徽省道一电子科技有限公司 | High-precision rail crawling measurement method based on single camera calibration and coding points |
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