CN106197302A - The measurement apparatus of a kind of Venturi tube aeration bubbles micron order diameter and measuring method - Google Patents

Abstract

The invention discloses a measuring device and method for measuring the micron diameter of air-entrained bubbles in a Venturi tube, including a box body, a light source, a computer and a high-speed camera. The box body is provided with a water pump and a bubble breaker. One end of the bubble breaker is connected, the center of the bubble breaker is connected with the air intake pipe, the air intake pipe is provided with a regulating valve, the light source is set outside the box, the high-speed camera is set outside the box, and is aligned with the port at the other end of the bubble breaker. The camera is connected to the computer. The invention has a simple structure and principle, and is easy to operate. It can measure bubbles in the micron level. Compared with other measurement methods, firstly, because the measuring equipment is placed outside the flow field, it will not interfere with the flow field. Secondly, This method can simultaneously obtain the sizes of all the bubbles in the target section in a certain instant.

Description

A kind of measuring device and measuring method of micron-scale diameter of air-entrained bubbles in Venturi tube

technical field

The invention relates to the technical field of micron-scale bubble measurement, in particular to a measuring device and method for measuring the micron-scale diameter of air-entrained bubbles in a Venturi tube.

Background technique

With the development of measurement technology, experimenters have developed many methods of measuring bubble size. According to the location relationship between the measured equipment and the system under test, the measurement methods can be divided into two categories, built-in method and external method. Specific methods include: conductivity probe method, optical fiber method, photoelectric capillary method, acoustic method, and high-speed camera method. The probe of the conductivity probe method must pierce the bubble to obtain the signal, so this method is only applicable when measuring the bubble with a large diameter, and because the probe head is placed inside the flow field, it will have a negative impact on The flow field produces some disturbance. The photoelectric capillary method can only be used to measure the number of particles and cannot be used to measure the phase boundary area. Because the mechanical form of the fluid will be destroyed when the probe is placed in the flow field, thus changing the size and shape of the bubbles. The acoustic method mainly utilizes that the bubbles will emit certain vibrations when they flow, so the sound pressure generated is relatively high, and its frequency is determined by the diameter of the bubbles, so the relationship between the diameter of the bubbles and the sound frequency can be obtained. This method cannot be applied in jet aeration, mainly because a water pump is required for jet aeration, and the vibration of the water pump during operation will interfere with the vibration of the air bubbles. First of all, the high-speed camera method is to measure outside the flow field without disturbing the flow field. This method can intuitively show the movement status and various characteristic parameters of the bubbles, so this method has been widely used. Compared with the probe method Smaller bubbles can be measured than the camera method.

Contents of the invention

The object of the present invention is to provide a measuring device and measuring method for the micron-scale diameter of aerated bubbles in a Venturi tube, so as to solve the problems raised in the above-mentioned background technology.

In order to achieve the above object, the present invention provides the following technical solutions: a device for measuring the micron-scale diameter of air-entrained bubbles in a Venturi tube, including a box, a light source, a computer and a high-speed camera, and the box is equipped with a water pump and a bubble crushing device. The water pump is connected to one end of the bubble breaker, the center of the bubble breaker is connected to the air intake pipe, the air intake pipe is provided with a regulating valve, the light source is set outside the box, and the high-speed camera is set on the The outside of the box is aligned with the port at the other end of the bubble breaker, and the high-speed camera is connected to the computer.

Preferably, the bubble breaker includes a tube body, one end of the tube body is a fluid inlet port, and the other end is a fluid outlet port, the center of the tube body is provided with a gas suction port, and the inner cavity of the tube body is formed by a constricted section , a throat, an expansion section and an annular cavity, the contraction section is arranged at the fluid inlet end, the expansion section is arranged at the fluid outlet end, the throat is arranged between the contraction section and the expansion section, and the ring The lumen is located at the lower end of the larynx.

Preferably, the computer is provided with an image signal conditioning module, the image signal conditioning module includes an operational amplifier, a two-stage field-effect broadband amplifier and a choke coil, and one input end of the operational amplifier is connected to one end of the resistor B and the capacitor respectively. One end of B, the other end of capacitor B is grounded, the other end of resistor B is connected to one end of resistor A and one end of capacitor A, the other end of capacitor A is connected to the output end of the operational amplifier, and the other input end of the operational amplifier is respectively connected to one end of resistor C and one end of resistor D , the other end of the resistor C is grounded, and the other end of the resistor D is connected to the output end of the operational amplifier; the first end of the two-stage field effect broadband amplifier is connected to one end of the capacitor E, the other end of the capacitor E is connected to one end of the resistor F, and the other end of the resistor F is connected to the operational amplifier. The output terminal of the amplifier and the second terminal of the two-stage field effect broadband amplifier are respectively connected to one terminal of the capacitor F, one terminal of the capacitor G and one terminal of the capacitor H through a choke coil, and the other terminal of the capacitor F, the other terminal of the capacitor G, and the other terminal of the capacitor H are all grounded , the third terminal of the two-stage field effect broadband amplifier is connected to the output terminal of the operational amplifier through a capacitor D and a resistor E, and the fourth terminal of the two-stage field effect broadband amplifier is grounded.

Preferably, its measurement method comprises the following steps:

A. Turn on the water pump and the regulating valve of the intake pipe. After the fluid enters the constriction section from the fluid inlet port, the pressure decreases and the flow velocity increases. At the same time, the air enters from the gas suction port, and the flow velocity reaches the maximum value at the throat. Finally, the pressure gradually recovers through the expansion section. The flow rate decreases and the fluid flows out from the fluid outlet port;

B. The high-speed camera captures the image of the fluid flowing out of the fluid outlet, and sends it to the control module in the computer after being processed by the image signal conditioning module in the computer;

C. The control module performs grayscale, histogram equalization, background uniformization, threshold segmentation and edge extraction operations on the collected images;

D. Finally, compare it with the calibration object of known size under the same shooting conditions with the high-speed camera to obtain the actual size of the bubbles in the fluid.

Compared with prior art, the beneficial effect of the present invention is:

(1) The structure and principle of the present invention are simple, easy to operate, and can measure bubbles in the micron level. Compared with other measurement methods, firstly, because the measuring equipment is placed outside the flow field, it will not interfere with the flow field. Secondly, this method The size of all bubbles in the target cross-section can be obtained at the same time.

(2) The image signal conditioning module adopted in the present invention has strong anti-interference ability, can amplify the collected image signal, and has low distortion, which improves the image collection efficiency and quality.

Description of drawings

Fig. 1 is the overall structure schematic diagram of the present invention;

Fig. 2 is a schematic structural view of the bubble breaker of the present invention;

Fig. 3 is the schematic diagram of the image signal conditioning module of the present invention;

In the figure: 1. Cabinet; 2. Light source; 3. Computer; 4. High-speed camera; 5. Water pump; 6. Bubble breaker; 7. Air intake pipe; 8. Regulating valve; 9. Pipe body; 10. Fluid Inlet port; 11. Fluid outlet port; 12. Gas suction port; 13. Contraction section; 14. Throat; 15. Expansion section; 16. Ring cavity; 17. Operational amplifier; 18. Two-stage field effect broadband amplifier; 19 , choke coil; 181, first end; 182, second end; 183, third end; 184, fourth end; 1a, resistance A; 2a, resistance B; 3a, resistance C; 4a, resistance D; 5a , resistance E; 6a, resistance F; 1b, capacitance A; 2b, capacitance B; 3b, capacitance C; 4b, capacitance D; 5b, capacitance E; 6b, capacitance F; 7b, capacitance G; 8b, capacitance H.

detailed description

The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, not all, embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

Please refer to Figures 1-3, the present invention provides a technical solution: a device for measuring the micron-scale diameter of air-entrained bubbles in a Venturi tube, including a cabinet 1, a light source 2, a computer 3 and a high-speed camera 4, and the cabinet 1 is equipped with There is a water pump 5 and a bubble breaker 6, the water pump 5 is connected to one end of the bubble breaker 6, the center of the bubble breaker 6 is connected to the air inlet pipe 7, the air inlet pipe 7 is provided with a regulating valve 8, and the light source 2 is set in the box 1 On the outside, the position of the light source can be adjusted according to the position of the camera. The high-speed camera 4 is arranged on the outside of the box body 1, and is aimed at the other end port of the bubble breaker 6. The high-speed camera 4 is connected to the computer 3, and the high-speed camera adopts the FASTCAMSA5 type of Photron Company. speed camera.

In this embodiment, the bubble breaker 6 includes a tube body 9, one end of the tube body 9 is a fluid inlet port 10, the other end is a fluid outlet port 11, the center of the tube body 9 is provided with a gas suction port 12, and the inner cavity of the tube body 9 is It consists of constriction section 13, throat 14, expansion section 15 and annular cavity 16. Constriction section 13 is arranged at fluid inlet end 10, expansion section 15 is arranged at fluid outlet end 11, throat 14 is arranged at constriction section 13 and expansion Between the segments 15 , an annular cavity 16 is provided at the lower end of the throat 14 .

In the present embodiment, the computer 3 is provided with an image signal conditioning module, and the image signal conditioning module includes an operational amplifier 17, a two-stage field effect broadband amplifier 18 and a choke coil 19, and one input end of the operational amplifier 17 is connected to one end of the resistor B 2a respectively And one end of capacitor B 2b, the other end of capacitor B 2b is grounded, the other end of resistor B 2a is connected to one end of resistor A 1a and one end of capacitor A 1b respectively, the other end of capacitor A 1b is connected to the output end of operational amplifier 17, and the other input of operational amplifier 17 Terminals are respectively connected to one end of resistor C3a and one end of resistor D4a, the other end of resistor C3a is grounded, and the other end of resistor D4a is connected to the output end of operational amplifier 17; the first end 181 of the two-stage field effect broadband amplifier 18 is connected to capacitor E One end of 5b, the other end of capacitor E 5b is connected to one end of resistor F6a, the other end of resistor F6a is connected to the output end of operational amplifier 17, and the second end 182 of the two-stage field effect broadband amplifier 18 is connected to one end of capacitor F6b through choke coil 19 respectively , one end of capacitor G 7b, one end of capacitor H 8b, and the other end of capacitor F 6b, the other end of capacitor G 7b, and the other end of capacitor H 8b are all grounded, and the third end 183 of the two-stage field effect broadband amplifier 18 passes through capacitor D 4b, resistor E 5a is connected to the output terminal of the operational amplifier 17, and the fourth terminal 184 of the two-stage field effect broadband amplifier 18 is grounded. The operational amplifier 17 processes the signal to ensure the quality of the transmitted signal, and amplifies the signal information by 2 times through the feedback principle, and then passes it to the back two-stage field effect broadband amplifier 18 to amplify the signal again, and finally the signal Output, the image signal conditioning module adopted in the present invention has strong anti-interference ability, can amplify the collected image signal, and has low distortion, which improves the image collection efficiency and quality.

Measurement method of the present invention comprises the following steps:

A. Turn on the water pump 5 and the air intake pipe regulating valve 8. After the fluid enters the constriction section 13 from the fluid inlet port 10, the pressure decreases and the flow rate increases. The pressure in the expansion section 15 gradually recovers, the flow rate decreases, and the fluid flows out from the fluid outlet port 11;

B. The high-speed camera 4 captures the image of the fluid flowing out of the fluid outlet port 11, and sends it to the control module in the computer 3 after being processed by the image signal conditioning module in the computer 3;

C. The control module performs grayscale, histogram equalization, background uniformization, threshold segmentation and edge extraction operations on the collected images;

D. Finally, compare with the high-speed camera 4 under the same shooting conditions to carry out a calibration object of known size to obtain the actual size of the air bubbles in the fluid.

Among them, grayscale can simplify the image information without affecting the outline of the image, which is convenient for the next step of processing. Histogram equalization can make the image clearer and more details can be seen. Background homogenization is to reduce the interference of the background on the image. Threshold segmentation divides the image into two regions, the target image and the background image. Edge extraction can extract the outline of bubbles. Since the image processing can only obtain the pixel size of the bubble, it is necessary to shoot the calibration object with the same size under the same shooting conditions before shooting the bubble, so as to obtain the actual size represented by the unit pixel. Through the above-mentioned process, you can Obtain the number of pixels of the long and short diameter of the bubble and the number of pixels contained in each bubble. Since the bubble is not a standard circle, the long and short diameters obtained can only be used as a reference. The size of the bubble is the diameter of a standard circle with the same measurement area.

The invention is simple in structure and principle, easy to operate, and can measure bubbles in the micron level. Compared with other measurement methods, firstly, because the measuring equipment is placed outside the flow field, it will not interfere with the flow field; secondly, this method can simultaneously obtain The size of all bubbles in the target cross-section at a certain moment.

Although the embodiments of the present invention have been shown and described, those skilled in the art can understand that various changes, modifications and substitutions can be made to these embodiments without departing from the principle and spirit of the present invention. and modifications, the scope of the invention is defined by the appended claims and their equivalents.

Claims (4)

1. a measurement apparatus for Venturi tube aeration bubbles micron order diameter, including casing (1), light source (2), computer (3) With high speed camera (4), it is characterised in that: it is provided with water pump (5) and bubble fragmentation device (6), described water pump (5) in described casing (1) Being connected with bubble fragmentation device (6) one end, described bubble fragmentation device (6) center is connected with air inlet pipe (7), in described air inlet pipe (7) Being provided with regulation valve (8), described light source (2) is arranged on casing (1) outside, and described high speed camera (4) is arranged on casing (1) outside, And alignment bubble fragmentation device (6) other end port, described high speed camera (4) is connected with computer (3).

The measurement apparatus of a kind of Venturi tube aeration bubbles micron order diameter the most according to claim 1, it is characterised in that: Described bubble fragmentation device (6) includes that body (9), described body (9) one end are fluid inlet end (10), and the other end is fluid issuing End (11), the center of described body (9) has gas suction inlet (12), and described body (9) inner chamber is by contraction section (13), throat (14), expansion segment (15) and ring cavity (16) composition, described contraction section (13) is arranged on fluid inlet end (10) place, described expansion segment (15) being arranged on fluid outlet (11) place, described throat (14) is arranged between contraction section (13) and expansion segment (15), described Ring cavity (16) is arranged on throat (14) lower end.

The measurement apparatus of a kind of Venturi tube aeration bubbles micron order diameter the most according to claim 1, it is characterised in that: Be provided with picture signal conditioning module in described computer (3), described picture signal conditioning module include operational amplifier (17), two Level field effect broadband amplifier (18) and choking-winding (19), an input of described operational amplifier (17) connects respectively Resistance B(2a) one end and electric capacity B(2b) one end, electric capacity B(2b) other end ground connection, resistance B(2a) other end connects resistance A respectively (1a) one end and electric capacity A(1b) one end, electric capacity A(1b) outfan of other end concatenation operation amplifier (17), operational amplifier (17) another input connects resistance C(3a respectively) one end and resistance D(4a) one end, resistance C(3a) other end ground connection, resistance D(4a) outfan of other end concatenation operation amplifier (18)；First end of described two-stage field effect broadband amplifier (18) (181) electric capacity E(5b is connected) one end, electric capacity E(5b) other end connection resistance F(6a) one end, resistance F(6a) other end connection fortune Calculating the outfan of amplifier (17), second end (182) of two-stage field effect broadband amplifier (18) is by choking-winding (19) point Lian Jie electric capacity F(6b) one end, electric capacity G(7b) one end, electric capacity H(8b) one end, and electric capacity F(6b) other end, electric capacity G(7b) another One end, electric capacity H(8b) the equal ground connection of the other end, the 3rd end (183) of two-stage field effect broadband amplifier (18) passes through electric capacity D (4b), resistance E(5a) outfan of concatenation operation amplifier (17), two-stage field effect broadband amplifier (18) the 4th end (184) Ground connection.

4. realize the measuring method of the measurement apparatus of a kind of Venturi tube aeration bubbles micron order diameter described in claim 1, It is characterized in that: its measuring method comprises the following steps:

A, unlatching water pump (5) and air inlet pipe regulation valve (8), fluid enters contraction section (13) pressure afterwards from fluid inlet end (10) and subtracts Little, flow velocity increases, and air enters from gas suction inlet (12) simultaneously, reaches maximum at throat (14) flow velocity, the most stretched Section (15) pressure gradually recovers, and flow velocity reduces, and fluid flows out from fluid outlet (11)；

B, high speed camera (4) shooting fluid outlet (11) flow out the image of fluid, and are adjusted by picture signal in computer (3) Send to computer (3) interior control module after reason resume module；

C, control module carry out gray processing, histogram equalization, background uniformity, Threshold segmentation and edge to the image gathered and carry Extract operation；

D, the demarcation thing finally carrying out known dimensions with high speed camera (4) under equal shooting condition compare, and obtain fluid The actual size of middle bubble.