CN106323184A - Method for three-dimensionally and dynamically measuring diameter of slipping bubble - Google Patents
Method for three-dimensionally and dynamically measuring diameter of slipping bubble Download PDFInfo
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- CN106323184A CN106323184A CN201611029639.8A CN201611029639A CN106323184A CN 106323184 A CN106323184 A CN 106323184A CN 201611029639 A CN201611029639 A CN 201611029639A CN 106323184 A CN106323184 A CN 106323184A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/08—Measuring arrangements characterised by the use of optical techniques for measuring diameters
- G01B11/10—Measuring arrangements characterised by the use of optical techniques for measuring diameters of objects while moving
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Abstract
The invention discloses a method for three-dimensionally and dynamically measuring diameter of a slipping bubble. The method comprises the following steps, shoot scale plates with scales by using two vertical high-speed cameras, and obtain a clear scale plate image; transfer effective pixel of the scale plate image to real physical dimension, and shoot a background picture when there is no bubble; shoot the slipping bubble generated at a bubble nucleating point from the front face and the side face; peel off the slipping bubble image; filter the peeled bubble image; perform the binarization processing on the filtered image, and obtain a black-and-white image; calculate equivalent diameter of the bubble in real time. Through two high-speed cameras, the slipping bubble is three-dimensionally shot from the front face and the side face, and the slipping bubble image is obtained; through analyzing and processing the collected image in real time, the dynamic change process of diameter during the bubble slipping process can be accurately measured, so as to lay a foundation for the subsequent movement behavior analysis of the slipping bubble and a boiling heat transfer mechanism model.
Description
Technical field
The invention belongs to experimental technique, particularly to a kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method, for accurately
Measure steam bubble dia in steam bubble slipping dynamically to change.
Background technology
In Narrow Rectangular Channel, the research of boiling heat transfer mechanism is for thermal technology's water in the reactor of employing Plate-type Fuel Elements
Force system safety and economy have meaning, and sliding bubbles diameter is the foundation of boiling heat transfer mechanism model and benchmark analysis
The middle key parameter that must input, it is therefore necessary in accurately measuring Narrow Rectangular Channel by laboratory facilities, sliding bubbles is straight
Footpath.Existing experiment often uses high-speed camera instrument from just shooting in the face of steam bubble, and calculates steam bubble dia by the method for equal effect, but
When steam bubble is constantly swung by turbulence prediction, its certainty of measurement is the highest.
The present invention is based on above-mentioned application background, proposes a kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method, can essence
Really measuring steam bubble dia dynamic changing process in steam bubble slipping, the foundation for follow-up boiling heat transfer mechanism model provides basis
Test data support.
Summary of the invention
In order to overcome the disadvantages mentioned above of prior art, the invention provides a kind of sliding bubbles diameter Three-Dimensional Dynamic measurement side
Method, can obtain 3 d image data in steam bubble slipping, and accurately measures steam bubble dia in steam bubble slipping and dynamically change
Process, the foundation for follow-up boiling heat transfer mechanism model provides basic test data supporting.
The technical solution adopted for the present invention to solve the technical problems is: a kind of sliding bubbles diameter Three-Dimensional Dynamic measurement side
Method, comprises the steps:
Step one, utilize two vertically disposed high-speed camera instrument shooting scale with a scale, obtain scale map clearly
Picture, is changed into actual physical size by the valid pixel of scale map picture；
Step 2, two the high-speed camera instrument utilizing step one to arrange shoot background picture when not having steam bubble；
Step 3, utilize two high-speed camera instrument that step one arranges respectively from front and side simultaneously to bubble nucleation point
The sliding bubbles that position produces shoots；
Step 4, sliding bubbles image is peeled off；
Step 5, to peel off after steam bubble image be filtered；
Step 6, filtered image is carried out binary conversion treatment, it is thus achieved that black white image；
The equivalent diameter of step 7, in real time calculating steam bubble.
Compared with prior art, the positive effect of the present invention is:
The present invention carries out three-dimensional shooting from front and side to sliding bubbles by two high-speed camera instrument simultaneously, the most sharp
Carry out synchronizing Real-time Collection to the image that two high-speed camera instrument shoot with image capturing system, and utilize the poster processing soft to adopting
The image of collection is analyzed in real time and processes, and can accurately measure steam bubble dia dynamic changing process in steam bubble slipping, for rear
Continuous sliding bubbles motor behavior analysis and boiling heat transfer mechanism model are set up and are laid the foundation.
Use the inventive method can obtain front and side image data in steam bubble slipping, can be according to the image obtained
Data obtain steam bubble dia in steam bubble slipping and dynamically change.Steam bubble nucleation and the spy that develops in narrow channel can be applied to
Property visualized experiment.
Accompanying drawing explanation
Examples of the present invention will be described by way of reference to the accompanying drawings, wherein:
Fig. 1 is the measurement system composition schematic diagram of the present invention；Wherein, 1, bubble nucleation point, 2,1# high-speed camera instrument, 3,2#
High-speed camera instrument, 4, image variants system；
Fig. 2 is the sliding bubbles diameter dynamic changing process figure using the inventive method to obtain.
Detailed description of the invention
First, for shooting small steam bubble clearly, two high-speed camera instrument all select micro-lens, preferred micro-lens
Model is Nikon/200mmF/4D/macro.Under conditions of guaranteeing to photograph bubble growth and slipping, Ying Jinke
Less pixel can be selected to reduce the amount of calculation of later stage process, for Phantom V9.0 high-speed camera instrument, preferably shoot
Pixel is 576 × 288 (high × wide).
Afterwards, by regulation 1# high-speed camera instrument 2 micro-lens aperture, making shooting image become clear, secondly, regulation 1# is at a high speed
Video camera 2 micro-lens focal length, makes 1# high-speed camera instrument 2 focus on bubble nucleation point 1, now, for guaranteeing to photograph steam bubble
Growth and the whole process of sliding, highly make bubble nucleation point 1 be in the middle part of shooting window by regulation 1# high-speed camera instrument 2 and close
Right position is put, and shooting window top is S to bottom distance, and nucleating point 1 is s away from bottom position, then s/S span is 0.3-0.5,
It is 0.4 as preferred value.Hereafter, 2# high-speed camera instrument 3 micro-lens focal length is arranged to and 1# high-speed camera instrument 2 one
Cause, make the nucleating point 1 position in shooting window with 1# high-speed camera instrument 2 the most partially by regulation 2# high-speed camera instrument 3 position
Difference is less than ± 10%, and can photograph picture rich in detail.For obtaining smooth steam bubble dynamic image, two high-speed camera instrument frame numbers
Need consistent, and scope should be 500-3000 frame, is 1000 frames as preferred value.
Hereafter, keep high-speed camera instrument focal length constant, respectively with 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 shooting band
The scale of scale, obtains scale map picture clearly.The valid pixel of shooting picture can be changed into actual physical size by this step,
Its concrete grammar is, measures the valid pixel at 1mm interval in scale, and result is d, in shooting picture between 2 effectively
Pixel is d1, then point-to-point transmission actual physical a size of d in shooting picture1/d mm。
The relation input picture of two the high-speed camera instrument valid pixels obtained with actual physical size is gathered and processes
System, the benchmark measured as steam bubble dia.
Afterwards, 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 is utilized to shoot background picture when not having a steam bubble respectively
It is input in image variants system 4, then uses 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 simultaneously to steam bubble nucleation
The sliding bubbles that point 1 position produces shoots, and the view data collected is real-time transmitted to image variants
In system 4.
Afterwards, the image that 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 is shot by image variants system 4 is utilized
Carrying out integrated treatment, its concrete grammar is:
First steam bubble in the synchronization image of 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 shooting is peeled off, its
Concrete grammar is to be subtracted each other with background picture corresponding element, after the difference of gained is for peeling off by the picture having steam bubble that experiment shooting obtains
Steam bubble image.
Generally, the steam bubble image outline after stripping is the most coarse, and can there are some random noises, as preferably, to stripping
Steam bubble image after from is filtered, and preferred filtering method is medium filtering, can make steam bubble edge more by medium filtering
Smooth, and eliminate the noise in image.
As preferably, filtered image is carried out binary conversion treatment, it is thus achieved that black white image.Processed at image binaryzation
Cheng Zhong, need to determine suitable threshold value f, and when gray value is more than threshold value f, picture point is white；During less than threshold value f, picture point is
Black.
For steam bubble image, preferably determine that the method for threshold value f is maximum variance between clusters, its ideal calculated, with
Time to calculate speed fast, meet the requirement of kinetic measurement.Maximum variance between clusters principle is: by the grey level histogram of image a certain
Being divided into two groups at threshold value, when the variance maximum of this gray value of two groups, cut-point is threshold value.For typical grayscale figure
Picture, it is assumed that f is threshold value of first and second group, the most now first group of image is counted and accounted for the total pixel ratio of image is x0, averagely ash
Degree is y0, second group of image is counted and accounted for the total pixel ratio of image is x1, average gray is y1, then image grand mean gray scale is:
Y=x0×y0+x1×y1 (1)
The most now variance yields z expression formula is as follows:
Z=x0×(y0-y)2+x1×(y1-y)2 (2)
Threshold value f is enumerated (intensity value ranges is 0～255), and making f maximum for variance yields z is the best cutting point.
As an example, the shooting of synchronization 1# high-speed camera instrument 2 obtains the original image and two in bubble nucleation point front
Image after value process, the shooting of 2# high-speed camera instrument 3 obtains original image and the binary conversion treatment thereof of bubble nucleation point side
After image.
Afterwards, utilize image variants system 4 that the image after processing is carried out post processing, straight to obtain steam bubble equivalence
Footpath real-time change, specific implementation method is as follows:
Image after the original image binary conversion treatment of bubble nucleation point front is laterally progressively scanned, it is thus achieved that every a line
Leftmost side black image point and distance D of rightmost side black image pointx1,Dx2,Dx3...Dxn, taking wherein maximum is Dx.Afterwards,
Image after the original image binary conversion treatment of bubble nucleation point front is longitudinally scanned by column, it is thus achieved that every string top side is black
Chromatic graph picture point and distance D of lower side black image pointy1,Dy2,Dy3...Dyn, taking wherein maximum is Dy。
Image after the original image binary conversion treatment of bubble nucleation point side is laterally progressively scanned, it is thus achieved that every a line
Leftmost side black image point and distance D of rightmost side black image pointz1,Dz2,Dz3...Dzn, wherein maximum is set to Dz。
The most now steam bubble equivalent diameter DbFor:
Use said method, the image of 1# high-speed camera instrument 2 and 2# high-speed camera instrument 3 shooting is processed, i.e. in real time
Steam bubble dia in steam bubble slipping can be obtained dynamically change.
Use said method, it is thus achieved that typical sliding steam bubble dia dynamic changing process as in figure 2 it is shown, in figure the time be 0
Moment be the moment that steam bubble just starts sliding.
Claims (8)
1. a sliding bubbles diameter Three-Dimensional Dynamic measuring method, it is characterised in that: comprise the steps:
Step one, utilize two vertically disposed high-speed camera instrument shooting scale with a scale, obtain scale map picture clearly, will
The valid pixel of scale map picture is changed into actual physical size；
Step 2, two the high-speed camera instrument utilizing step one to arrange shoot background picture when not having steam bubble；
Step 3, utilize two high-speed camera instrument that step one arranges respectively from front and side simultaneously to bubble nucleation point position
The sliding bubbles produced shoots；
Step 4, sliding bubbles image is peeled off；
Step 5, to peel off after steam bubble image be filtered；
Step 6, filtered image is carried out binary conversion treatment, it is thus achieved that black white image；
The equivalent diameter of step 7, in real time calculating steam bubble.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: two high speeds
Video camera all selects micro-lens, and the height of the high-speed camera instrument of shooting bubble nucleation point direct picture is it is ensured that make steam bubble nucleation
Point is in correct position in the middle part of shooting window, and two high-speed camera instrument frame numbers are consistent, and scope is 500-3000 frame.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: by scale map
The valid pixel of picture is changed into the method for actual physical size: measures the valid pixel at 1mm interval in scale, obtains
Measurement result d, if between 2, valid pixel is d in scale map picture1, then actual physical size between these 2 in scale map picture
For d1/ d, unit is mm.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: to sliding vapour
The method that bubble image carries out peeling off is: the Background that sliding bubbles picture step 3 shooting obtained obtains with step 2 shooting
The corresponding element of sheet subtracts each other, and the difference of gained is the steam bubble image after stripping.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: described filtering
Method is medium filtering.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: after filtering
Image carry out the method for binary conversion treatment and be: first determine threshold value f, then judge the gray value of picture point whether more than threshold value f,
If more than, determine that picture point is white；Otherwise, it is determined that picture point is black.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 6, it is characterised in that: use maximum
Ostu method determines threshold value f, comprises the steps:
Assuming that threshold value that f is first and second group, the most now first group of image is counted and accounted for the total pixel ratio of image is x0, averagely ash
Degree is y0, second group of image is counted and accounted for the total pixel ratio of image is x1, average gray is y1, then image grand mean gray scale is:
Y=x0×y0+x1×y1
The most now variance yields z expression formula is as follows:
Z=x0×(y0-y)2+x1×(y1-y)2
Threshold value f is enumerated, makes f maximum for variance yields z i.e. be defined as threshold value.
A kind of sliding bubbles diameter Three-Dimensional Dynamic measuring method the most according to claim 1, it is characterised in that: calculate in real time
The method of steam bubble equivalent diameter is:
(1) direct picture real-time to the bubble nucleation point after binary conversion treatment laterally progressively scans, it is thus achieved that every a line is the most left
Side black image point and distance D of rightmost side black image pointx1,Dx2,Dx3...Dxn, take wherein maximum and be designated as Dx；
(2) direct picture real-time to the bubble nucleation point after binary conversion treatment longitudinally scans by column, it is thus achieved that every string is gone up most
Side black image point and distance D of lower side black image pointy1,Dy2,Dy3...Dyn, take wherein maximum and be designated as Dy；
(3) side image real-time to the bubble nucleation point after binary conversion treatment laterally progressively scans, it is thus achieved that every a line is the most left
Side black image point and distance D of rightmost side black image pointz1,Dz2,Dz3...Dzn, it is designated as D to wherein maximumz；
(4) steam bubble equivalent diameter D it is calculated as followsb:
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| CN106989672A (en) * | 2017-04-17 | 2017-07-28 | 天津大学 | A kind of workpiece measuring based on machine vision |
| CN110544241A (en) * | 2019-08-22 | 2019-12-06 | 云南电网有限责任公司 | matching system for power cable metal cross section trace feature recognition degree |
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