CN110320144B - Method for acquiring three-dimensional flow field velocity holographic image in coal rock fracture cavity - Google Patents
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Abstract
A method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity belongs to the technical field of coal rock fracture seepage measurement. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity comprises the following steps: processing a coal rock test piece; fracturing a coal rock test piece; scanning the fracture distribution condition of the coal rock test piece at the fracture through stage and positioning the radial position of the fracture; splitting a coal rock test piece into two parts; scanning the crack surface wall to form a crack surface three-dimensional point cloud model; forming a post-peak fracture coal rock digital model for reducing the three-dimensional fracture appearance by utilizing a CT imaging fracture section diagram; printing the model by using a 3D printer to print a light-transmitting test piece; and (3) testing the simulation test piece in a three-dimensional particle image velocity measurement test system in the coal rock fracture cavity to obtain a three-dimensional flow field velocity holographic image in the fracture cavity. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity is a method for acquiring a three-dimensional particle flow field velocity holographic image taking time and space as functions.
Description
Technical Field
The invention relates to the technical field of coal-rock mass fracture seepage measurement, in particular to a method for acquiring a three-dimensional flow field velocity holographic image in a coal-rock fracture cavity.
Background
The gas extraction is an important measure for controlling mine gas disasters, and because the permeability of the gas reservoir of most coal seams in China is low, the pre-extraction effect before coal seam extraction is not ideal. The mining influence is an effective means for gas extraction, and mining causes the redistribution of the surrounding rock pressure of a mining field and the damage of a coal rock body (namely after peak intensity), and then causes the change of permeability, thereby being beneficial to the gas extraction. The shape of a fracture cavity of the coal rock after the peak is complex, and factors such as the roughness of a fracture surface, the contact area, the fracture opening degree, the seepage diameter fluctuation degree, the goodness of fit, normal and tangential deformation, whether fillers exist in the fracture, the communication rate of the fillers, the material characteristics and the like have great influence on the seepage field distribution rule of the fracture coal rock.
Most of the current researches use linear fracture surface morphological parameters to represent three-dimensional geometrical characteristics of the fracture surface, so that many morphological characteristics of a fracture cavity disappear, and fracture gas seepage characteristics obtained on the basis of the morphological characteristics are inaccurate in many situations. With the development of a microscopic particle tracing speed measurement technology, a 3D printing technology and a reverse engineering, the reconstruction of the complex morphology of a fracture cavity of the coal rock after the peak and the display of the flow state of a seepage field thereof become possible.
The relevant scholars develop a great deal of research on coal-rock structures and seepage characteristics by utilizing the CT technology, but still have some defects, the steady-state seepage is the premise of the coal body seepage simulation research, and the actual seepage is a dynamic change process from instability to gradually trend to stability. Different from the steady-state seepage, the density, the speed and other physical quantities of the unsteady-state seepage in the rock mass are not only functions of space but also functions of time, so that the difficulty of three-dimensional numerical simulation research is greatly increased. And a two-dimensional slice image is obtained by CT scanning, and then a three-dimensional coal rock model is reconstructed by stacking multiple slices, so that the three-dimensional appearance of the fracture surface is distorted to a certain extent in the process, and the three-dimensional appearance of the fracture cavity and the influence of the three-dimensional appearance on the seepage state and characteristics cannot be completely reflected.
Disclosure of Invention
In order to solve the technical problems in the prior art, the invention provides a method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity, and particularly provides a method for acquiring a three-dimensional particle flow field velocity holographic image taking time and space as functions.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity comprises the following steps:
s1: processing the coal rock into a coal rock test piece with a standard size;
s2: on a coal rock thermo-fluid-solid coupling CT experiment system, fracturing the coal rock test piece through triaxial loading and unloading;
s3: scanning the fracture distribution condition of the coal rock test piece in the fracture penetration damage stage and positioning the radial position of the fracture by adopting a CT scanning system;
s4: splitting the coal rock test piece with the through fracture into two parts along the fracture;
s5: scanning the formed plurality of gap surface walls one by using a three-dimensional scanner to form a gap surface three-dimensional point cloud model;
s6: positioning the position relation of each pair of fracture surfaces in the post-peak strain stage on a computer by utilizing a CT imaging fracture section diagram, and introducing the corresponding position relation of the point cloud model of the three-dimensional fracture surface into the computer to form a post-peak fracture coal rock digital model for restoring the appearance of the three-dimensional fracture;
s7: printing the model by using a 3D printer, wherein the printing material is a light-transmitting material, so that a light-transmitting test piece is printed;
s8: testing a simulation test piece in a three-dimensional particle image velocity measurement test system in a coal rock fracture cavity to obtain a three-dimensional flow field velocity holographic image in the fracture cavity;
the whole simulation test piece is a light-transmitting test piece, namely a full-light-transmitting test piece; or the upper part of the simulation test piece is the upper part of the light-transmitting test piece, and the lower part of the simulation test piece is the lower part of the coal rock test piece, namely the semi-light-transmitting test piece.
In the technical scheme, the reverse engineering and the CT technology are applied to coal rock fracture seepage research, a coal rock simulation test piece containing a three-dimensional fracture cavity is reconstructed, then the simulation test piece is placed in a three-dimensional particle image velocity measurement test system in the coal rock fracture cavity to be tested, a three-dimensional flow field velocity holographic image in the fracture cavity is obtained, basic data are provided for developing research on three-dimensional appearance of the fracture cavity and influence of the three-dimensional appearance on seepage states and characteristics, and theoretical guidance and technical prototype are further provided for accurate extraction of gas after mining influence.
Preferably, the coal petrography test piece is cylindrical, and then in step S4, the coal petrography test piece is cut into two semi-cylindrical shapes.
Preferably, in the step S7, the light-transmitting material is a high-light-transmitting three-dimensional light-curing molding resin.
Preferably, the three-dimensional particle image velocimetry test system in the coal rock fracture cavity comprises a rotating disk, a driving mechanism for driving the rotating disk to rotate, a light-transmitting coal rock clamp, a fluid conveying device and an image acquisition device;
the rotary disc is provided with M optical lenses with different focal lengths or different thicknesses, M is a positive integer larger than 1, the end face of the rotary disc is circumferentially provided with N through holes, N is M or N is M +1, the M optical lenses are arranged in the through holes one by one and can rotate along with the rotary disc, and the simulation test piece is positioned right below one of the optical lenses or the through hole when the rotary disc rotates;
the light-transmitting coal rock clamp is provided with a sealed cavity for loading a simulation test piece;
the output port of the fluid conveying device is connected with the inlet of the light-transmitting coal rock clamp, fluid enters the crack cavity of the simulation test piece from one end of the simulation test piece in the sealed cavity and then is discharged from the other end of the simulation test piece, and tracer particles are contained in the fluid passing through the crack cavity of the simulation test piece;
the image acquisition device comprises a visible ray emission device which is positioned above the optical lens and corresponds to the position of the simulation test piece and a CCD camera which is connected with the computer, wherein the light rays emitted by the visible ray emission device irradiate the simulation test piece, are reflected by the tracing particles and then are refracted by the optical lens and then enter the CCD camera.
Among the above-mentioned technical scheme, arrange the optical lens that the focus is different or the thickness is different on the rotary disk, actuating mechanism makes the rotary disk rotate fast to make the CCD camera can shoot the image of the different scenic depths of simulation test piece. The rotating disc rotates one circle rapidly, so that a particle image taking space as a function can be obtained; the rotating disc rotates for a period, the rotating disc periodically rotates to obtain particle images taking time as a function, the images are sorted to obtain three-dimensional particle flow field velocity holographic images taking time and space as functions, and basic data are provided for developing research on three-dimensional appearance of a cavity and influence of the cavity on seepage state and characteristics.
Preferably, the focal lengths of the M optical lenses are different, and the simulation test piece is covered in the longitudinal direction;
or the thicknesses of the M optical lenses have the following characteristics: different incident rays are reflected by tracing particles at different positions on the simulation test piece in the longitudinal direction and then are refracted by the optical lens with corresponding thickness, and emergent rays can enter the CCD camera.
In the technical scheme, the M optical lenses with different thicknesses and the M optical lenses with different focal lengths rotate along with the rotating disk, so that the CCD camera can shoot images of different depths of the simulated test piece, namely the permeation states of fluids in cracks of different planes in the longitudinal direction of the simulated test piece.
Preferably, the fluid conveying device comprises a fluid tank and a trace particle generator, an outlet of the fluid tank is communicated with a fluid inlet of the light-transmitting coal rock clamp through a first pipeline, a first valve is arranged on the first pipeline, and a particle outlet of the trace particle generator is communicated with the first pipeline; a fluid outlet of the light-transmitting coal rock clamp is communicated with a second pipeline, and a second valve is arranged on the second pipeline; a first pressure sensor is arranged on the first pipeline, and a second pressure sensor is arranged on the second pipeline; and/or a first flowmeter is arranged on the first pipeline, and a second flowmeter is arranged on the second pipeline.
In the technical scheme, the tracer particles output by the tracer particle generator enter the light-transmitting coal rock clamp through the first pipeline, then enter the simulated test piece fracture cavity, flow together with the fluid in the fracture cavity, and the seepage state of the tracer particles is shot through the CCD camera, so that the seepage condition of the fluid in the simulated test piece fracture is indirectly reflected. The pressure sensor and the flowmeter are used for detecting the pressure and the flow of the fluid in the first pipeline and the second pipeline, so that the influence of the pressure and the flow of the fluid on the permeability of the fluid in the simulated test piece fracture is researched, and the fracture seepage basic theory is enriched.
Preferably, the image acquisition device further comprises a microscope objective at the front end of the CCD camera, and/or the visible light ray emitting device is a pulsed laser;
the simulation test piece is positioned in the field of view range of the image acquisition device.
In the technical scheme, the microscope objective plays a role in amplification, so that an image shot by the CCD camera is clearer; compare natural light, the laser that pulse laser sent makes the light of tracer particle reflection stronger, and the flowing condition of tracer particle in simulation test piece crack intracavity can be more clear demonstration tracer particle.
Preferably, the number of the CCD cameras is two, and the number of the microscope objectives is also two; the pulse laser is perpendicular to the optical lens, and the two CCD cameras are symmetrically and obliquely arranged on two sides of the pulse laser.
In the technical scheme, when a CCD camera shoots the permeation condition in the fracture cavity of the simulated test piece, the edge of a view field of an image acquisition device is relatively fuzzy, and the edge of the simulated test piece in the image is relatively fuzzy; the two CCD cameras are arranged, so that the field of view of the image acquisition device can be enlarged, the edge of the obtained simulation test piece is clearer, and the integral definition of the image is improved.
Preferably, the light-transmitting coal rock clamp comprises an upper clamp and a lower clamp which form the sealed cavity, the upper part of the simulation test piece is fixedly connected with the upper clamp, and the lower part of the simulation test piece is fixedly connected with the lower clamp; the upper clamp and the lower clamp are connected in a sealing way through a flexible film or an elastic film, and the outer wall of the simulation test piece is connected with the inner wall of the sealing cavity in a sealing way; the distance between the upper clamp and the lower clamp is adjustable, so that the opening width of the crack of the simulated test piece is changed.
In the technical scheme, the elastic membrane is arranged to prevent fluid and trace particles in the crack of the simulation test piece from leaking out from the space between the upper clamp and the lower clamp; by changing the opening width of the crack of the simulation test piece, the permeability characteristics of the fluid under different crack widths can be researched, and the crack seepage basic theory is further enriched. When the influence of the opening width of the simulated test piece crack on the permeation of the fluid is researched, the simulated test piece and the light-transmitting coal rock clamp do not need to be replaced, so that the practicability is high, and the operation is convenient; the outer wall of the simulation test piece is in sealing connection with the inner wall of the sealing cavity, so that the sealing performance around the simulation test piece is guaranteed, fluid and tracer particles can only permeate from the cracks of the simulation test piece, and the accuracy and the authenticity of the crack permeability characteristic are guaranteed.
Preferably, the lower clamp is mounted on the fixing frame through a hinged joint, a stud is fixedly connected to the lower clamp, an elastic part sleeved outside the stud is arranged between the upper clamp and the lower clamp in a pressing mode, the upper portion of the stud penetrates through the upper clamp and is located above the upper clamp, and a nut is connected to the upper portion of the stud through threads.
In the technical scheme, the distance between the upper clamp and the lower clamp can be adjusted by loosening or tightening the nut, so that the opening width of the crack of the simulated test piece is changed; when the crack surface of the simulation test piece is not parallel to the axis of the simulation test piece, the simulation test piece can be inclined by rotating the lower clamp, so that the incident light can be directly opposite to the crack surface.
The invention has the beneficial effects that:
1) the reverse engineering and the CT technology are applied to coal rock fracture seepage research, and a coal rock simulation test piece containing a three-dimensional fracture cavity is reconstructed.
2) The micro particle tracing speed measurement technology is introduced into the coal rock fracture seepage research, so that the seepage characteristic of fluid in the coal rock fracture can be more accurately reflected, and theoretical guidance and technical prototype are provided for accurate gas extraction after mining influence.
3) Changing the reflection plane of the light rays emitted into the CCD camera by arranging M optical lenses with different focal lengths or different thicknesses; when the rotating disc rotates for one circle, the CCD camera can shoot images simulating the permeation state of the fluid in all fluid layers in the fracture cavity of the test piece in one period; the CCD camera shoots images of a plurality of periods, so that a three-dimensional flow field speed holographic image with high time resolution and time and space as functions is obtained, and basic data is provided for developing research on three-dimensional appearance of the interstitial cavity and influence of the three-dimensional appearance on seepage state and characteristics.
4) Irradiating a measured flow field area in the simulation test piece by using a pulse laser, shooting trace particle images exposed in a small area of a crack of the simulation test piece twice or for multiple times by using a CCD (charge coupled device) camera to form moving particle images, analyzing the images by using an image cross-correlation method, and obtaining the average displacement of the particle images in each small area so as to determine the fluid velocity of the whole area of the flow field.
5) A pulse laser is adopted to irradiate the simulation test piece, and a microscope objective and a CCD camera are combined to shoot images, so that the obtained images are clearer.
6) The distance between the upper clamp and the lower clamp for loading the simulation test piece can be adjusted, so that the simulation test piece and the light-transmitting coal rock clamp do not need to be replaced when the influence of the opening width of a crack of the simulation test piece on the permeation of fluid is researched, and the practicability is high and the operation is convenient.
7) The visible light is emitted into the simulation test piece, so that the damage of the visible light to a human body is small and the safety is high compared with invisible light or invisible rays; in the traditional test, invisible light or invisible rays are emitted into a test piece, so that the health of testers is harmed during the test; after the test, the residue is left in the test environment, which is not beneficial to the health of testers.
Additional features and advantages of the invention will be set forth in part in the detailed description which follows.
Drawings
FIG. 1 is a schematic structural diagram of a three-dimensional particle image velocimetry test system in a coal rock fracture cavity provided by the invention;
FIG. 2 is a schematic top view of the rotary disk of FIG. 1 according to the present invention;
FIG. 3 is a schematic diagram of the present invention using optical lenses with different thicknesses to capture images with different depth of field;
FIG. 4 is a schematic cross-sectional view of the light-transmitting coal rock clamp of FIG. 1, showing a minimal opening width of a simulated specimen fracture;
fig. 5 is a schematic sectional view of the light-transmitting coal rock clamp in fig. 1, wherein the opening width of the crack of the simulation test piece is increased.
In the figure, the position of the upper end of the main shaft,
1-rotating disk, 11-through hole, 12-driving mechanism, 2-optical lens, 21-thin planar lens, 22-thick planar lens, 3-visible light ray emitting device, 31-incident light ray, 32-reflected light ray, 33-first plane, 34-second plane, 35-third plane, 4-CCD camera, 41-microscope objective, 5-fluid box, 51-first valve, 52-first pressure sensor, 53-first flowmeter, 54-trace particle generator, 55-second pressure sensor, 56-second flowmeter, 57-second valve, 58-first pipe, 59-second pipe, 6-light-transmitting coal rock clamp, 61-upper clamp, 611-first lug, 62-lower clamp, 621-a second lug, 63-a stud, 64-an elastic element, 65-a nut, 66-an elastic membrane, 67-a fixed frame, 68-a ball joint, 7-a computer and 8-a synchronous controller.
Detailed Description
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "horizontal", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are only for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention.
In the description of the present invention, unless otherwise specified and limited, it is to be noted that the terms "mounted," "connected," and "connected" are to be interpreted broadly, and may be, for example, a mechanical connection or an electrical connection, a communication between two elements, a direct connection, or an indirect connection via an intermediate medium, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
In order to solve the problems in the prior art, as shown in fig. 1 to 5, the invention provides a method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity, and the method is used for acquiring a three-dimensional particle flow field velocity holographic image taking time and space as functions.
The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity comprises the following steps;
s1: and processing the coal rock into a coal rock test piece with a standard size. For example, a cylindrical coal rock test piece with the diameter of 50mm and the length of 100mm, and the diameter of the coal rock test piece is adapted to the sealed cavity of the light-transmitting coal rock clamp 6.
S2: and fracturing the coal rock test piece on a coal rock thermo-fluid-solid coupling CT experiment system through triaxial loading and unloading. For example, the coal rock test piece is fractured by a three-point bending resistance method on a CT experimental system.
S3: and scanning the fracture distribution condition of the coal rock test piece in the fracture through stage and positioning the radial position of the fracture by adopting a CT scanning system. And performing CT scanning on any time period in the process of fracturing the coal rock test piece through a CT scanning system, and observing and imaging the internal structure evolution of the coal rock test piece in real time.
S4: and splitting the coal rock test piece with the through crack into two parts along the crack.
S5: and scanning the formed plurality of gap surface walls one by using a three-dimensional scanner to form a gap surface three-dimensional point cloud model.
S6: and positioning the position relation of each pair of fracture surfaces in the post-peak strain stage on the computer 7 by utilizing the CT imaging fracture section diagram, and introducing the corresponding position relation of the point cloud model of the three-dimensional fracture surface into the computer 7 to form a post-peak fracture coal rock digital model for restoring the three-dimensional fracture appearance.
S7: the model is printed by a 3D printer, the printing material is made of a light-transmitting material, so that a light-transmitting test piece is printed, the light-transmitting material can be made of high-light-transmitting three-dimensional light curing molding resin, and the material can be used for producing colorless, light-transmitting and accurate functional parts. And printing the model by using an industrial-grade high-precision 3D printer, manufacturing a light-transmitting test piece with the same three-dimensional appearance as the fracture surface of the real rock, and reducing the post-peak fracture coal-rock entity reconstruction with the three-dimensional fracture appearance.
S8: and (3) testing the simulation test piece in a three-dimensional particle image velocity measurement test system in the coal rock fracture cavity to obtain a three-dimensional flow field velocity holographic image in the fracture cavity. Namely, the test is carried out in a three-dimensional particle image velocimetry test system in a coal rock fracture cavity.
The whole simulation test piece is a light-transmitting test piece, namely a full-light-transmitting test piece; or the upper part of the simulation test piece is the upper part of the light-transmitting test piece, and the lower part of the simulation test piece is the lower part of the coal rock test piece, namely the semi-light-transmitting test piece.
When the coal rock test piece is fractured along the diameter (namely, the fracture surface of the coal rock test piece is parallel to the axis of the coal rock test piece) in the step S2, the simulation test piece is transversely placed as shown in the figure 1 in the step S8; when the coal rock specimen fracture surface is not parallel to the coal rock specimen axis in step S2, the light-transmitting coal rock jig 6 may be rotated so that the incident light can be directed to the fracture surface in step S8.
As shown in fig. 1, in this embodiment, the three-dimensional particle image velocimetry test system used in the method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity includes a rotating disk 1, a driving mechanism 12 for driving the rotating disk 1 to rotate, a light-transmitting coal rock clamp 6, a fluid conveying device, and an image acquisition device. M optical lenses 2 with different focal lengths or different thicknesses are arranged on the rotating disc 1, wherein M is a positive integer larger than 1, and preferably M is larger than 10. As shown in fig. 2, the driving mechanism 12 for driving the rotating disc 1 to rotate includes a motor, an output shaft of the motor is coaxially and fixedly connected with the rotating disc 1 through a transmission shaft; the end face of the rotating disk 1 is circumferentially provided with N through holes 11, wherein the N is M or N is M +1, the M optical lenses 2 are arranged in the through holes 11 one by one and can rotate along with the rotating disk 1, and when the rotating disk 1 rotates, the simulation test piece can be positioned under one of the optical lenses 2 or the through hole 11 without the optical lens 2. In the present embodiment, as shown in fig. 2, sixteen through holes 11 are provided in the rotating disk 1, the number of the optical lenses 2 may be fifteen or sixteen, and when the number of the optical lenses 2 is fifteen, the optical lens 2 is not provided in one of the through holes 11. The light-transmitting coal rock jig 6 has a sealed cavity in which a simulation test piece is loaded. The output port of the fluid conveying device is connected with the inlet of the light-transmitting coal rock clamp 6, fluid enters the crack cavity of the simulation test piece from one end of the simulation test piece in the sealed cavity and then is discharged from the other end of the simulation test piece, and tracer particles are contained in the fluid passing through the crack cavity of the simulation test piece. The image acquisition device comprises a visible ray emission device 3 which is positioned above the optical lens 2 and corresponds to the position of the simulation test piece and a CCD camera 4 which is connected with a computer 7, light rays emitted by the visible ray emission device 3 irradiate the simulation test piece, and the light rays are reflected by the tracer particles, refracted by the optical lens 2 and then enter the CCD camera 4. In this embodiment, a synchronous controller 8 may be further provided, the synchronous controller 8 is respectively connected to the computer 7, the CCD camera 4 and the driving mechanism 12, the driving mechanism 12 of the rotating disk 1, the CCD camera 4 and the computer 7 are connected through the synchronous controller 8, so that the rotation of the rotating disk 1, the shooting by the CCD camera 4 and the data recording by the computer 7 can be synchronously performed, and the synchronous controller 8 adopts the prior art.
As shown in FIG. 1, the crack divides the simulation test piece into an upper part and a lower part; the upper part of the simulation test piece is made of a light-transmitting material, or the simulation test piece is made of a light-transmitting material, and the simulation test piece is positioned in the field range of the image acquisition device, so that visible light emitted by the visible light emitting device 3 can penetrate through the upper part of the simulation test piece and reach a crack cavity of the simulation test piece, and is reflected by the tracer particles and then enters the CCD camera 4, so that the CCD camera 4 can shoot the global condition of the flow of the tracer particles in the crack cavity of the simulation test piece, and the permeation condition of fluid in the crack cavity of the simulation test piece is indirectly reflected. In practice, the number of the optical lenses 2 may be adaptively changed according to the difference in height between the highest point and the lowest point of the simulated specimen fracture in the longitudinal direction.
The optical lenses 2 with different focal lengths or different thicknesses are arranged on the rotating disc 1, the driving mechanism 12 enables the rotating disc 1 to rotate rapidly, the M optical lenses 2 sequentially rotate to the position right above the simulation test piece, light rays emitted by the visible light emitting device 3 pass through the optical lenses 2 or the through holes 11 and then enter the simulation test piece, and the CCD camera 4 can shoot images of the simulation test piece at different depths of view (horizontal planes with different longitudinal heights in the figure 3). The rotating disc 1 rotates one circle rapidly, and the CCD camera 4 can shoot a plurality of images simulating the flow state of tracer particles in all fluid layers in the fracture cavity of the test piece, namely particle images taking space as a function are obtained; the rotating disc 1 rotates for a period, the rotating disc 1 rotates periodically to obtain particle images with time as a function, and the images on the time and the space are arranged to obtain three-dimensional particle flow field velocity holographic images with the time and the space as functions. Specifically, the CCD camera 4 is used for shooting trace particle images which are exposed in a small area of a test piece fracture for two or more times to form moving particle images, and then the images are analyzed by using an image cross-correlation method to obtain the average displacement of particles in each small area, so that the fluid speed of the whole area of a flow field is determined, and basic data are provided for developing research on the three-dimensional appearance of a cavity and the influence of the cavity on the seepage state and characteristics. In the present embodiment, the thicknesses of the M optical lenses 2 have the following characteristics: different incident light 31 is refracted through the optical lens 2 with corresponding thickness after being reflected by the tracer particles at different positions on the simulation test piece in the longitudinal direction, and emergent light can enter the CCD camera 4. For example, the M optical lenses 2 are M planar lenses with different thicknesses, and the M planar lenses are disposed in the through holes 11 one by one, for example, in the through holes 11 in an increasing or decreasing thickness relationship. The optical lens 2 with the corresponding thickness is an optical lens with different thicknesses preset and corresponding to the tracer particles at different positions in the longitudinal direction.
Through setting up the plane lens that M thickness is different, make the principle that CCD camera 4 shoots the image of different depth of field as shown in fig. 3, when there is not optical lens 2 in the through-hole 11 of rotary disk 1, incident ray 31 that the visible light emitter 3 above the simulation test piece sent is penetrated into the simulation test piece, by the tracer particle reflection of different positions on the simulation test piece longitudinal direction, but the most reflected ray 32 of tracer particle reflection in only first plane 33 can penetrate CCD camera 4, make CCD camera 4 shoot the state diagram of tracer particle in first plane 33. In the case where the optical lens 2 is not provided in the through hole 11, the thickness of the optical lens 2 may be zero. When the optical lens 2 is arranged in the through hole 11 of the rotating disc 1, light rays are emitted into the simulation test piece through the thin plane lens 21 and reflected by the tracer particles at different positions in the longitudinal direction of the simulation test piece, but only most of the light rays reflected by the tracer particles in the second plane 34 are reflected through the thin plane lens 21 and then emitted into the CCD camera 4, so that the CCD camera 4 shoots a state diagram of the tracer particles in the second plane 34. Similarly, light rays are emitted into the simulation test piece through the thick plane lens 22 and reflected by the tracer particles at different positions in the longitudinal direction of the simulation test piece, but only most of the light rays reflected by the tracer particles in the third plane 35 are refracted through the thick plane lens 22 and then emitted into the CCD camera 4, so that the CCD camera 4 shoots a state diagram of the tracer particles in the third plane 35. Because the position of the CCD camera 4 is fixed, after light passes through the optical lenses 2 with different thicknesses, the light is reflected and refracted by the corresponding optical lenses 2 and then enters the CCD camera 4, the longitudinal heights of the reflection planes are different, so that the second plane 34 is located above the third plane 35, and the first plane 33 is located above the second plane 34, so that the CCD camera 4 can shoot images in different depths of the scene.
Of course, the M optical lenses 2 may also be M optical lenses having different focal lengths and covering the simulation test piece in the longitudinal direction, such as M lenses having different focal lengths, and the M lenses are also disposed in the through holes 11 one by one, such as disposed in the through holes 11 in an increasing or decreasing relationship with the focal lengths; the lens is preferably a convex lens, and the zooming principle of convex lenses with different focal lengths is the prior art and is not described herein in detail.
As shown in fig. 1, the fluid conveying device comprises a fluid tank 5 and a trace particle generator 54, an outlet of the fluid tank 5 is communicated with a fluid inlet of the transparent coal rock clamp 6 through a first pipeline 58, a first valve 51 is arranged on the first pipeline 58, and a particle outlet of the trace particle generator 54 is communicated with the first pipeline 58; the fluid outlet of the light-transmitting coal rock clamp 6 is communicated with a second pipeline 59, a second valve 57 is arranged on the second pipeline 59, and the fluid discharged from the second pipeline 59 can be stored through another container. The fluid contained in the fluid tank 5 can be gas or liquid, and when the fluid is gas, the fluid tank 5 is a gas cylinder filled with a certain pressure; when the fluid is liquid, the liquid in the fluid tank 5 is delivered to the first conduit 58 by a pump. The tracer particles output by the tracer particle generator 54 enter the light-transmitting coal rock clamp 6 through the first pipeline 58, then enter the simulated test piece fracture cavity, flow together with the fluid in the fracture cavity, and indirectly reflect the permeation condition of the fluid in the simulated test piece fracture.
As shown in fig. 1, a first pressure sensor 52 is provided on the first pipe 58, and a second pressure sensor 55 is provided on the second pipe 59; and/or the first pipe 58 is provided with a first flow meter 53, and the second pipe 59 is provided with a second flow meter 56. The flow and pressure of the fluid entering the simulated test piece fracture are changed by adjusting the opening degree of the first valve 51, and the pressure sensor and the flow meter are used for detecting the pressure and the flow of the fluid in the first pipeline 58 and the second pipeline 59, so that the influence of the pressure and the flow of the fluid entering the simulated test piece fracture on the permeability characteristic of the fluid in the simulated test piece fracture is researched, and the fracture seepage basic theory is enriched.
As shown in fig. 1, the image capturing device further includes a microscope objective 41 located at the front end of the CCD camera 4. The microscope objective 41 plays a role in magnification, so that the image taken by the CCD camera 4 is clearer.
As shown in fig. 1, the visible ray emitting device 3 is a pulse laser. Compare natural light, the pulse laser that pulse laser sent in succession makes the light that the tracer particle reflected stronger, and the flowing condition of tracer particle in simulation test piece crack intracavity can be more clear demonstration tracer particle. The frequency of the pulse laser emitted by the pulse laser is the same as the switching frequency of the through hole 11 of the rotating disk 1 and the shooting frequency of the CCD camera 4.
As shown in fig. 1 and 3, the number of CCD cameras 4 is two, and the number of microscope objectives 41 is also two; the pulse laser is perpendicular to the optical lens 2, and the two CCD cameras 4 are symmetrically and obliquely arranged on two sides of the pulse laser. When a CCD camera 4 shoots a simulation test piece fracture intracavity permeability state diagram, the edge of a view field of an image acquisition device is relatively fuzzy, and the edge of the simulation test piece in the image is relatively fuzzy; the two CCD cameras 4 are arranged, so that the field range of the image acquisition device can be enlarged, the obtained edge of the simulation test piece is clearer, and the integral definition of the image is improved.
As shown in fig. 4, the transparent coal rock clamp 6 includes an upper clamp 61 and a lower clamp 62 forming a sealed cavity, the upper part of the simulation test piece is fixedly connected with the upper clamp 61, and the lower part of the simulation test piece is fixedly connected with the lower clamp 62, for example, by clamping or connecting through a transparent bolt; the upper clamp 61 and the lower clamp 62 are hermetically connected through an elastic membrane 66, but the upper clamp 61 and the lower clamp 62 can also be hermetically connected through a flexible membrane, such as a thin membrane; the distance between the upper clamp 61 and the lower clamp 62 is adjustable, so that the opening width of the simulated specimen slit is changed. In practice, in order to make the light penetrate through the light-transmitting coal rock clamp 6 and enter the fracture cavity of the simulation test piece, the upper clamp 61 may be made of a light-transmitting material, such as a high-light-transmitting three-dimensional light-curing molding resin, and the lower clamp 62 may be made of a light-transmitting material or a light-proof material, so that the light can enter the fracture cavity of the simulation test piece through the light-transmitting coal rock clamp 6.
The elastic membrane 66 is arranged to prevent the fluid and the trace particles in the fracture of the simulation test piece from leaking out from the space between the upper clamp 61 and the lower clamp 62; by changing the opening width of the crack of the simulation test piece, the permeability characteristics of the fluid under different crack widths can be researched, and the crack seepage basic theory is further enriched.
As shown in fig. 4, in the present embodiment, the lower clamp 62 is mounted on the fixing frame 67, the second support lugs 621 horizontally extend from two sides of the lower clamp 62, the studs 63 are fixedly connected to the two second support lugs 621, and the first support lug 611 horizontally extends from two sides of the upper clamp 61; an elastic element 64 sleeved outside the stud 63 is arranged between the first support lug 611 of the upper clamp 61 and the second support lug 621 of the lower clamp 62 in a pressing mode, the elastic element 64 can be a columnar compression spring or an elastic sleeve, the upper portion of the stud 63 penetrates through the first support lug 611 of the upper clamp 61 and is located above the upper clamp 61, and a nut 65 is connected to the upper portion of the stud 63 in a threaded mode.
When the opening width of the simulated specimen fracture needs to be increased, as shown in fig. 4 and 5, the nut 65 is unscrewed, the compressed elastic member 64 recovers deformation, the elastic member 64 moves the upper clamp 61 upward, and the upper clamp 61 moves the upper part of the simulated specimen upward, so that the opening width of the simulated specimen fracture is increased. Similarly, when the opening width of the simulated specimen fracture needs to be reduced, the nut 65 is screwed, the elastic piece 64 is compressed, the upper clamp 61 moves downwards, the upper part of the simulated specimen moves downwards along with the upper clamp 61, and therefore the opening width of the simulated specimen fracture is reduced.
Of course, in practice, the upper clamp 61 may be mounted on the fixing frame 67 so that the lower clamp 62 is close to or away from the upper clamp 61, so as to change the size of the opening width of the simulated specimen fracture.
As shown in fig. 4 and 5, the lower clamp 62 is hinged to the fixing frame 67 through the ball joint 68, so that the whole transparent coal rock clamp 6 can rotate relative to the fixing frame 67, when the crack surface of the simulation test piece is not parallel to the axis of the simulation test piece, the simulation test piece can be inclined by rotating the lower clamp 62, the incident light can be directly opposite to the crack surface, the height of the crack of the simulation test piece in the longitudinal direction is smaller, and the number of optical lenses 2 arranged on the rotating disk 1 can be reduced.
In this embodiment, the outer wall of the simulation test piece is connected with the inner wall of the seal cavity in a sealing manner, for example, a seal ring is arranged between the seal cavity and the two ends of the outer wall of the simulation test piece, so that the sealing performance around the simulation test piece is ensured, the fluid and the tracer particles can only permeate from the crack cavity of the simulation test piece, and the accuracy and the authenticity of the research on the crack permeability are ensured.
By using the method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity, the three-dimensional flow field velocity holographic image in the fracture cavity of the full-transmission test piece and the semi-transmission test piece can be acquired. Subsequently, the computer 7 is used for processing the three-dimensional flow field velocity holographic image in the full-light-transmission test piece fracture cavity to obtain a first permeability characteristic curve of fluid permeation in the full-light-transmission test piece fracture cavity; the computer 7 processes the three-dimensional flow field velocity holographic image in the semi-transparent test piece fracture cavity to obtain a second permeability characteristic curve of fluid permeation in the semi-transparent test piece fracture cavity; and calculating a third permeability characteristic curve when the whole simulation test piece is a coal rock test piece through the first permeability characteristic curve and the second permeability characteristic curve, thereby obtaining the truest and most accurate permeability characteristic of the fluid in the coal rock fracture and providing basic data for developing research on the three-dimensional appearance of the fracture cavity and the influence of the three-dimensional appearance on the seepage state and characteristics. The calculation method of the third permeability characteristic curve is not the point of the invention, and is not described in detail here.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.
Claims (8)
1. A method for acquiring a three-dimensional flow field velocity holographic image in a coal rock fracture cavity is characterized by comprising the following steps:
s1: processing the coal rock into a coal rock test piece with a standard size;
s2: on a coal rock thermo-fluid-solid coupling CT experiment system, fracturing the coal rock test piece through triaxial loading and unloading;
s3: scanning the fracture distribution condition of the coal rock test piece in the fracture penetration damage stage and positioning the radial position of the fracture by adopting a CT scanning system;
s4: splitting the coal rock test piece with the through fracture into two parts along the fracture;
s5: scanning the formed plurality of gap surface walls one by using a three-dimensional scanner to form a gap surface three-dimensional point cloud model;
s6: positioning the position relation of each pair of fracture surfaces in the post-peak strain stage on a computer by utilizing a CT imaging fracture section diagram, and introducing the corresponding position relation of the point cloud model of the three-dimensional fracture surface into the computer to form a post-peak fracture coal rock digital model for restoring the appearance of the three-dimensional fracture;
s7: printing the model by using a 3D printer, wherein the printing material is a light-transmitting material, so that a light-transmitting test piece is printed;
s8: testing a simulation test piece in a three-dimensional particle image velocity measurement test system in a coal rock fracture cavity to obtain a three-dimensional flow field velocity holographic image in the fracture cavity;
the three-dimensional particle image velocimetry test system in the coal rock fracture cavity comprises a rotating disk, a driving mechanism for driving the rotating disk to rotate, a light-transmitting coal rock clamp, a fluid conveying device and an image acquisition device;
the rotary disc is provided with M optical lenses with different focal lengths or different thicknesses, M is a positive integer larger than 1, the end face of the rotary disc is circumferentially provided with N through holes, N is M or N is M +1, the M optical lenses are arranged in the through holes one by one and can rotate along with the rotary disc, and the simulation test piece is positioned right below one of the optical lenses or the through hole when the rotary disc rotates; the driving mechanism enables the rotating disc to rotate rapidly, the M optical lenses are sequentially rotated to be right above the simulation test piece, so that light rays emitted by the visible light ray emitting device are emitted into the simulation test piece through the optical lenses or the through holes, and the CCD camera shoots images of the simulation test piece at different depths of view; the rotating disc rotates one circle rapidly, and the CCD camera shoots a plurality of images simulating the flow state of the tracer particles in all fluid layers in the fracture cavity of the test piece, namely particle images taking space as a function are obtained; the rotating disc rotates for a period, the rotating disc periodically rotates to obtain particle images taking time as a function, and the images on the time and the space are sorted to obtain three-dimensional particle flow field velocity holographic images taking the time and the space as functions;
the light-transmitting coal rock clamp is provided with a sealed cavity for loading a simulation test piece;
the output port of the fluid conveying device is connected with the inlet of the light-transmitting coal rock clamp, fluid enters the crack cavity of the simulation test piece from one end of the simulation test piece in the sealed cavity and then is discharged from the other end of the simulation test piece, and tracer particles are contained in the fluid passing through the crack cavity of the simulation test piece;
the image acquisition device comprises a visible ray emission device which is positioned above the optical lens and corresponds to the position of the simulation test piece and a CCD camera which is connected with the computer, and the light rays emitted by the visible ray emission device irradiate the simulation test piece, are reflected by the tracer particles and then are refracted by the optical lens and then enter the CCD camera;
the focal lengths of the M optical lenses are different, and the simulation test pieces are covered in the longitudinal direction;
or the thicknesses of the M optical lenses have the following characteristics: different incident rays are reflected by tracing particles at different positions in the longitudinal direction of the simulation test piece and then are refracted by an optical lens with corresponding thickness, and emergent rays can enter a CCD camera;
the whole simulation test piece is a light-transmitting test piece, namely a full-light-transmitting test piece; or the upper part of the simulation test piece is the upper part of the light-transmitting test piece, and the lower part of the simulation test piece is the lower part of the coal rock test piece, namely the semi-light-transmitting test piece.
2. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to claim 1, wherein the coal rock test piece is cylindrical, and the coal rock test piece is split into two semicylindrical shapes in step S4.
3. The method for acquiring the holographic image of the three-dimensional flow field velocity in the coal rock fracture cavity according to claim 1, wherein in the step S7, the light-transmitting material is a high-light-transmission three-dimensional light-curing molding resin.
4. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to claim 1, wherein the fluid conveying device comprises a fluid tank and a trace particle generator, an outlet of the fluid tank is communicated with a fluid inlet of the light-transmitting coal rock clamp through a first pipeline, a first valve is arranged on the first pipeline, and a particle outlet of the trace particle generator is communicated with the first pipeline; a fluid outlet of the light-transmitting coal rock clamp is communicated with a second pipeline, and a second valve is arranged on the second pipeline; a first pressure sensor is arranged on the first pipeline, and a second pressure sensor is arranged on the second pipeline; and/or a first flowmeter is arranged on the first pipeline, and a second flowmeter is arranged on the second pipeline.
5. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to claim 1, wherein the image acquisition device further comprises a microscope objective lens positioned at the front end of the CCD camera, and/or the visible ray emitting device is a pulse laser;
the simulation test piece is positioned in the field of view range of the image acquisition device.
6. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to claim 5, wherein the number of the CCD cameras is two, and the number of the microscope objective lenses is also two; the pulse laser is perpendicular to the optical lens, and the two CCD cameras are symmetrically and obliquely arranged on two sides of the pulse laser.
7. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to any one of claims 1 to 6, wherein the light-transmitting coal rock clamp comprises an upper clamp and a lower clamp which form the sealed cavity, the upper part of the simulation test piece is fixedly connected with the upper clamp, and the lower part of the simulation test piece is fixedly connected with the lower clamp; the upper clamp and the lower clamp are connected in a sealing way through a flexible film or an elastic film, and the outer wall of the simulation test piece is connected with the inner wall of the sealing cavity in a sealing way; the distance between the upper clamp and the lower clamp is adjustable, so that the opening width of the crack of the simulated test piece is changed.
8. The method for acquiring the three-dimensional flow field velocity holographic image in the coal rock fracture cavity according to claim 7, wherein the lower clamp is mounted on a fixed frame through a hinged joint, a stud is fixedly connected to the lower clamp, an elastic member sleeved outside the stud is arranged between the upper clamp and the lower clamp in a pressing mode, the upper portion of the stud penetrates through the upper clamp and is located above the upper clamp, and a nut is connected to the upper portion of the stud in a threaded mode.
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006058830A (en) * | 2004-07-20 | 2006-03-02 | Nagano Kogaku Kenkyusho:Kk | Optical unit of camera mounted on portable telephone |
| CN101169507A (en) * | 2006-10-27 | 2008-04-30 | 华晶科技股份有限公司 | Lens structure |
| CN103114848A (en) * | 2013-01-18 | 2013-05-22 | 西南石油大学 | Formation fracture space reconstruction method based on rock core measure |
| CN104980644A (en) * | 2014-04-14 | 2015-10-14 | 华为技术有限公司 | Shooting method and device |
| CN105158141A (en) * | 2015-09-08 | 2015-12-16 | 河海大学 | Recyclable coarse fracture high velocity seepage testing apparatus |
| CN109001237A (en) * | 2018-09-25 | 2018-12-14 | 长安大学 | A kind of rock mass internal structure production method based on CT scan and 3D printing |
| CN109444020A (en) * | 2018-12-17 | 2019-03-08 | 武汉理工大学 | A kind of rock mass fissure seepage flow microscopic feature observation device and observation method based on 3D printing technique |
| CN208670430U (en) * | 2018-09-01 | 2019-03-29 | 卜生 | A kind of gas pipeline leakage repairing clamp |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10571383B2 (en) * | 2017-12-11 | 2020-02-25 | James Joseph Spiegel | Concrete crack seal tester |
-
2019
- 2019-07-05 CN CN201910604533.3A patent/CN110320144B/en active Active
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2006058830A (en) * | 2004-07-20 | 2006-03-02 | Nagano Kogaku Kenkyusho:Kk | Optical unit of camera mounted on portable telephone |
| CN101169507A (en) * | 2006-10-27 | 2008-04-30 | 华晶科技股份有限公司 | Lens structure |
| CN103114848A (en) * | 2013-01-18 | 2013-05-22 | 西南石油大学 | Formation fracture space reconstruction method based on rock core measure |
| CN104980644A (en) * | 2014-04-14 | 2015-10-14 | 华为技术有限公司 | Shooting method and device |
| CN105158141A (en) * | 2015-09-08 | 2015-12-16 | 河海大学 | Recyclable coarse fracture high velocity seepage testing apparatus |
| CN208670430U (en) * | 2018-09-01 | 2019-03-29 | 卜生 | A kind of gas pipeline leakage repairing clamp |
| CN109001237A (en) * | 2018-09-25 | 2018-12-14 | 长安大学 | A kind of rock mass internal structure production method based on CT scan and 3D printing |
| CN109444020A (en) * | 2018-12-17 | 2019-03-08 | 武汉理工大学 | A kind of rock mass fissure seepage flow microscopic feature observation device and observation method based on 3D printing technique |
Non-Patent Citations (1)
| Title |
|---|
| 基于CT扫描与3D 打印技术的岩体三维重构及力学特性初探;田威 等;《岩土力学》;20170831;第38卷(第8期);第2297-2305页 * |
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