JPH0337699B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an apparatus for visualizing fluid concentration in a flow field in a water flow model.

(Conventional technology) Conventionally, methods for measuring concentration in water flow models include sampling methods that extract part of the fluid, and methods that create a flow field using an electrolyte solution in the fluid and measuring changes in concentration by electrical conduction. There is an electrical measurement method that measures the change in degree.

By the way, in order to make quantitative information easier to see, a technique is known in which the state is displayed using a pseudo-color image, such as a temperature distribution or a satellite photograph.

To give an overview of this technology, an analog image signal inputted by a TV camera is converted into a digital image signal using a sampling circuit according to a certain sampling mode, which is then temporarily stored in a computer's memory and then read out. The image is then displayed as a pseudo-color image on a display that has been subjected to color designation processing in stages according to the intensity of brightness. Here, the intensity of brightness of each pixel is classified according to the number of memory bits. For example, in the case of 4 bits, it is divided into 2 ⁴ =16 steps. Therefore, the color of the image signal/luminance signal converted into a digital signal can be specified according to the number of steps. for example,
Colors are specified such as red if the brightness is within a certain range, blue if the brightness is lower, and green if the brightness is higher.

(Problem to be Solved by the Invention) However, the concentration measurement methods in the water flow model described above all measure the concentration of the fluid absolutely through a measuring device, and the flow field itself is visually observed at an arbitrary cross section. Therefore, it is not a method in which information regarding concentration and mixing, that is, quantitative information can be obtained relatively. Therefore, the concentration distribution and changes in the flow field, especially
It is not useful for researching or understanding the phenomenon of turbulent mixing. Furthermore, since all of these concentration measurement methods are contact-type methods that require the installation of an extraction tube or sensor within the flow field, there is a problem in that the flow of the fluid may be changed to something different from the actual flow. Note that the bubble tracer method, which uses air bubbles as tracers, has been used for a long time as a visualization method that allows trends in the entire flow area to be observed at a glance, but this method cannot be used for quantitative analysis because it has large errors due to differences in specific gravity. .

On the other hand, in the above-mentioned technology that displays the state using pseudo-color images, changes in brightness are simply expressed by differences in color, and are not displayed with brightness, such as bright red or dark red. do not have.
That is, even if the colors are displayed in the same color, they include brightness with a certain width and cannot accurately represent concentration changes in the flow field.
In addition, the pseudo-colorization method in the above technology samples an analog image signal in a certain mode, temporarily stores it in a computer as a digital image signal, and then performs color specification processing when reading it out and displays it as a color image on a display. It is a thing,
This is a so-called still image communication method that requires processing time. Therefore, although it can be used for static images such as satellite photographs, it is insufficient for observing concentration changes in the flow field of a fluid water flow model.
In other words, sampling is generally performed on one scan line.
126 to 512 points are taken, but if you try to reduce the number of sampling points to shorten the image reception processing time and get closer to a moving image, the image will become rough and lack precision.
On the other hand, if accuracy is increased by increasing the number of samplings, even if a high-speed and large-capacity computer is used to speed up processing, it will take several seconds to several minutes to even obtain a still image, resulting in continuous processing. It is not possible to perform pseudo-colorization processing for videos. Therefore, it cannot be used for the above-mentioned density visualization that requires precise pseudo-color display of moving body images.

As described above, although there has been a desire for a pseudo-colorization method that converts an input image into an arbitrary color image in real time, there has been no technology to achieve this.

Therefore, as a result of intensive research to solve the problems associated with the above-mentioned prior art, the present inventors found that if a fluid contains fine and homogeneous bubbles densely, when light is applied, the light hits the bubbles. It is thought that the intensity of the scattered light is proportional to the number of bubbles in a unit volume, and that the intensity of the brightness of the scattered light and the concentration level are proportional to each other. I came to know something.

The present invention is a device for visualizing the concentration of a fluid forming a flow field of a water flow model, and the present invention is a device for visualizing the concentration of a fluid forming a flow field of a water flow model, and the concentration in the water flow model is such that the flow field is converted into an arbitrary color image corresponding to the intensity of scattered light in real time. The purpose is to provide a visualization device.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides a system in which at least one small hole with a diameter of 3 mm or less is bored in a pipe line connecting a model water tank and a pressure water supply source. A large amount of fine and homogeneous air bubbles are created in the water flow by the deaeration phenomenon caused by the local pressure drop when passing through the orifice, and the water flow densely containing these fine and homogeneous air bubbles is used to create a water flow inside the aquarium. A visualization device that reproduces a flow field, shines slit light on this flow field, and visualizes the flow in an arbitrary cross section by diffused reflection from bubbles, and a TV camera that photographs the scattered light and uses the camera to measure the brightness of the flow field. The luminance signal output according to
This signal is introduced into an RGB separate circuit and converted into R, G, and B signals of the same level.
Pseudo-color that cuts off one, two, or all of the RGB signals at different signal voltage levels and outputs them to a color display device to display the concentration distribution of fluid in the flow field using colors and their brightness differences. This is a concentration visualization device for a water flow model, characterized by comprising an image device.

(Function) With this configuration, a large amount of fine and homogeneous air bubbles appear in the water flow due to the degassing phenomenon of the orifice, and a flow field is reproduced in the model aquarium by the water flow densely containing these air bubbles. When slit light is applied to this flow field, the slit light is diffusely reflected by the bubbles, making it possible to visualize the flow in any cross section.

Then, this flow field is inputted as an image as a luminance signal corresponding to the brightness, and then is once divided into RGB signals of the same level, and any one, two, or all of these RGB signals have different signal voltages. It is converted into an artificial color image signal that is cut off at the level and distributed into different brightness levels and reproduced on a color display device as a pseudocolor image.

In this way, since the flow field of the water flow model is converted into a color image using an arbitrary color scheme corresponding to the intensity of scattered light, the concentration of the fluid forming the flow field of the water flow model can be easily visualized.

(Example) The configuration of the present invention will be described in detail below based on an example shown in the drawings.

The concentration visualization device according to the present invention includes a visualization device A that reproduces a flow field with a fluid containing a large amount of fine and homogeneous air bubbles, and a pseudo color visualization device that photographs the flow field and reproduces the image in different colors for each predetermined concentration range. image system B.

FIG. 1 schematically shows a water flow model visualization device that implements the method of the present invention. This visualization device includes a model water tank (hereinafter abbreviated as water tank) 1 that reproduces a flow field to be visualized, a fluid supply unit 2 that supplies fluid/water mixed with air bubbles 4 to the water tank 1 from, for example, the bottom surface; It mainly consists of a slit light source 3 that irradiates a slit light 5 onto the flow field within the water tank 1. In this visualization device, fluid flowing in from the bottom of the water tank 1 reproduces a flow field within the water tank 1 and is then drained from the drain port 6 above the water tank 1 through a water pipe (not shown). The wastewater does not contain any foreign matter other than air bubbles, and the air bubbles, except for some, dissolve into the water again, so it may be drained as is without any treatment, or it may be reused as is. is also possible. Note that the fluid may be introduced from above the water tank 1 and drained from the bottom, or may be introduced from the side wall.

Here, the fluid supply unit 2 that supplies fluid/water to the water tank 1 has an orifice 9 provided in the middle of a pipe line 8 connecting a pressure water supply source (not shown) and the fluid spout 7 of the water tank 1. , the air solidly dissolved in the pumped fluid is caused to appear in the fluid as bubbles 4 by the deaeration phenomenon accompanying the local depressurization action in the orifice 9, and is supplied as a fluid containing a large amount of bubbles 4. It is something to do.

The orifice 9 has at least one small hole with a diameter of 3 mm or less. There is a close relationship between the diameter of the small hole of the orifice 9 and the diameter and homogeneity of the generated bubbles 4. If the small hole diameter exceeds 3 mm, the generated bubbles 4 will be extremely heterogeneous, making it difficult to measure accurately or quantitatively. become unsuitable. Generally, when bubbles are used as tracers, taking into consideration errors due to poor flow tracking and errors due to buoyancy, the optimal bubble diameter based on visualization is preferably in the range of 0.06 to 0.2 mm. The most preferable value is around 0.1 mm in view of the conditions that prevent premature melting. Therefore, according to the experimental results of the present inventors (Fig. 3), which determined the relationship between the diameter of the orifice 9 and the particle size ratio of the generated bubbles 4, an orifice 9 with a diameter of 3 mm has a diameter of 0.2 mm or less, which is optimal for visualization. The bubbles 4 account for about 70% and have an average diameter of 0.113 mm, which is generally homogeneous; however, when the orifice 9 has a diameter of 4 mm, the bubbles with a diameter of 0.2 mm or less account for about 30%, which becomes heterogeneous. From this experimental result, the preferred orifice diameter is 1.5 mm or less, most preferably 0.8 mm or more and 0.5 mm or more. Diameter 0.5mm
The reason for excluding the orifice 9 below is that the fluid can become clogged with dust, making bubble generation unstable.If an effective filter can be installed upstream to completely remove dust, A diameter of less than 0.5 mm is also acceptable. According to the experimental results shown in Figure 3, when a pressure of 9 kg/cm ² is applied to an orifice diameter of 0.8 mm, the diameter
It was confirmed by measuring the enlarged photograph with a microscope that bubbles 4 in the range of 0.0781 to 0.2106 mm were generated. The average diameter of the bubbles at that time is approximately 0.1 mm, which can be said to be the most preferable bubble diameter within the visualization area. Here, when increasing the flow rate, by increasing the number of small holes in the orifice 9 to increase the amount of bubbles generated, the content rate of bubbles contained in the fluid can be kept constant.

In this embodiment, the water tank 1 is made of a translucent material such as acrylic resin or glass and has a rectangular cylindrical shape with a square cross section. has. This water tank 1 is only a container for forming a flow field in the case of a water flow model such as a nozzle or burner, but it is used as a part of the model when visualizing the flow of fluid in a furnace. used. Therefore, aquarium 1
The shape is not limited to that shown in the drawings, and can take various shapes depending on needs, such as a cylinder or an elbow shape. Further, as shown in FIG. 4, a model for reproducing the flow field to be observed, such as a nozzle model or a burner model 10, is generally attached to the water jet outlet 7 at the bottom of the water tank. However, there are cases where the model is placed in the aquarium 1 away from the water jet outlet 7 and no change is made to the flow at the water jet outlet 7. In the case of this example, burner nozzle model 10
A burner tile model 11 was installed to measure the mixing state of fuel and air, its ratio, etc.
The burner nozzle model 10 ejects fluid mixed with air bubbles 4 (corresponding to fuel), and from around it, fluid without air bubbles (corresponding to secondary air) is ejected, and the burner tile model 11 It is provided so that the two can be mixed inside. Of course, the number and position of the water jet ports 7 are not limited to those shown. For example, when a water flow model is used when a plurality of burners are installed in a furnace, the influence of the burner placement position on heat distribution may be observed using the water flow model. In addition, since the entire peripheral wall of the aquarium 1 of this embodiment is formed of a translucent material, the surface facing the observer or observation equipment corresponds to the observation window, and the surface facing the slit light source 3 corresponds to the incident light source. Corresponds to a light window. However, the water tank 1 does not need to be formed of a transparent material on its entire circumference, and it is sufficient if at least the observation window and the incident light window are made of a transparent material. The observation window and the incident light window can be positioned at an angle of 90 to 145 degrees from the direction of incidence of the slit light 5, since optimal diffused reflection can be obtained, and the water tank 1 should be formed into a cylindrical shape. In this case, the peripheral wall can be replaced by forming the 90 to 145 degree range of a perforated material. Note that if the other peripheral wall surfaces (including the bottom surface) other than the observation window and the incident light window are made of a light absorber, observation will be easier because only the bubbles will stand out due to the scattered light without turning off the lighting in the observation room. be. Here, the light absorber may be one in which only the inner surface of the aquarium 1 is colored black. Furthermore, when observing the state of the flow field in a plane perpendicular to the flow direction, that is, in slices, a slit light 5 that crosses the flow field is used.
The range of 90 to 145 degrees is the ceiling and upper part of the aquarium 1. Therefore, in this case, an observer or observation equipment is installed above the aquarium 1.

Furthermore, the slit light source 3 for irradiating the slit light 5 into the aquarium 1 may be any known means. For example, a plate with slits may be inserted into a slide projector to obtain slit light. In this case, by preparing several slit plates with different cutting directions of the slits, it is possible to obtain the slit light 5 that passes through any cross section of the flow. The slit light 5 hits the bubble 4 and is diffusely reflected, but the scattered light has a characteristic that it is best detected in the range of 90 to 145 degrees from the direction in which the light is incident. Furthermore, if the diameter of the bubbles 4 is sufficiently fine and uniform, the intensity of the scattered light is considered to be proportional to the number of bubbles in a unit volume, that is, the bubble number density, which means that the intensity of the brightness of the scattered light is proportional to the concentration level. means proportional to.

First, when the fluid is pumped from the pressure water supply source to the water tank 1, we visualize the air that is solidly dissolved in the fluid due to the degassing phenomenon caused by the local depressurization effect in the orifice 9. Optimal fine and homogeneous bubbles are created densely in the fluid. Then, a desired flow field is reproduced in the water tank 1 using the fluid densely containing fine and homogeneous air bubbles. When the slit light 5 is irradiated there, the slit light 5 causes bubbles 4.
Since the bubbles 4 are diffusely reflected and scattered by the water, the presence of bubbles 4 in the water flow becomes clearly visible like sparks as shown in FIG. 4, making the flow visible. At this time, the intensity of the scattered light is considered to be proportional to the number of bubbles in a unit volume, or the density of bubbles, which means that the intensity of the scattered light is proportional to the concentration. can be visually observed from the perspective of the intensity of scattered light.

Further, the flow in the aquarium 1 is displayed in color in a pseudo-color image system B as shown in FIG. 2 with colors and brightness corresponding to the density.

The aforementioned pseudo-colorized imaging system B, one embodiment of which is shown in block diagram form in FIG.
It is based on baseband transmission using a TV camera 21 for shooting, an amplification circuit 23 that amplifies weak image signals and brightness signals, a pseudo colorization circuit 24 that converts the brightness signals into color signals, and a color display. It consists of at least a device 25. Of course, it is also possible to use modulated transmission, but in this case it goes without saying that an amplitude modulation circuit, a demodulation circuit, etc. are required.

As the TV camera 21, an industrial black and white TV camera is used because a luminance signal is used in the pseudo camera integrated image system B of the present invention. Although it is possible to use a color television camera by extracting only the luminance signal, it is expensive and impractical.

The pseudo coloring circuit 24 illustrated in FIG. 5 converts the luminance signals into R color signals (hereinafter referred to as R
signal), G color signal (hereinafter referred to as G signal)
and a color signal circuit between the RGB separate circuit 26 and the color display device 25, which cuts off color signals below a predetermined voltage level that is different from each other. It consists of a low cut-off circuit 27 that converts the brightness signal level into a color image. The low cut-off circuit 27 consists of a transistor 28 whose base receives a color signal, a variable resistor 29 inserted between the emitter of the transistor 28 and the ground, and a bias circuit. The operating point of the transistor 28 is set by the resistance value, and the transistor 28 is driven only when the color signal input to the base is at a level higher than the voltage level determined based on the operating point. It is a circuit.
That is, between the emitter of the transistor 28 and the ground, there is a series body of the variable resistor 29 and the resistor 31 inserted between the reference power supply 20 and the ground.
Transistor 2 with the resistance value between this emitter and ground
8 emitter side voltage levels are set. Therefore, the low cut-off circuit 27
The transistor 28 is operated only when the voltage level of the color signal higher than the emitter side voltage level set by 9 is input to the base, and by changing the resistance value of the variable resistor 29, The low level region of the corresponding color signal will be cut out and not output. Further, the collector of the transistor 28 is connected to the drive transistor 32.
It is directly connected to the emitter of the cut-off color signal and is provided so as to amplify the color signal after being cut off and then output it to the color display device 25. A bias circuit consisting of a capacitor 33 and a resistor 34 is connected to the emitter side of the transistor 28, and a diode 3 is connected to the base side of the drive transistor 32.
5 and a resistor 36 in parallel, it is connected to the reference power supply 20 together with the bias circuit.

The low cut-off circuit 27 is provided in each color signal circuit between the RGB separate circuit 26 and the color display device 25, and is connected to the variable resistor 2.
Each operation of 9 has a different operating point. Therefore, the color signal passing through this low cut-off circuit 27 is amplified and sent to the color display device 25.
When the RGB signals are input to the RGB signal, the cutoff areas are different, so that all of the RGB signals, a combination of any two signals, one signal, or no signal is generated depending on the brightness level, thereby creating a color image.
The most practical color display device 25 is a plum tube, and various types of known types can be used. For example, the cathode ray tube of a color television may be used as is.

Therefore, in the pseudo-color image device configured as described above, an image of an object is input as a luminance signal corresponding to its brightness, and then it is decomposed into RGB signals of the same level, and any color signal is By cutting off at the level, a color signal is artificially generated according to the additive color mixing method, and a color image is displayed on the color display device 25.
will be reproduced in In other words, depending on the brightness of the subject
The brightness signals output from the TV camera 21 are sent to the RGB separate circuit 26 so that they are at the same level.
signal, G signal, and B signal. Next, for each color signal, an arbitrary cutoff level is set in a low cutoff circuit 27 provided in each color signal circuit, and signals in a region below this level are cut off.

For example, while the R signal is outputted to the color picture tube 5 after amplification with the cutoff amount set to 0,
For the G signal, the low cut-off level is set to 1/2 of the maximum brightness level, and for the B signal, the low cut-off level is set to about 4/5 of the brightness level, and the G signal exceeds that level.
By outputting the signal and the B signal, the image on the color display device 25 is displayed in pseudo color in three colors, red, yellow, and white, depending on the brightness level, as shown in FIG. Moreover, each color has a brightness corresponding to a brightness level. For example, taking red as an example, even in the red region there are bright red, dark red, and colors intermediate between these, and if the brightness level becomes extremely low, red appears black. Therefore, this pseudo-color image appears to the human eye as black, dark red, red,
It appears to have five colors: yellow and white. In addition, in order to clearly distinguish between black parts and dark red, the low cut-off level of the R signal should be set to about 1/5 or less of the maximum brightness level to suppress color signal output in low brightness areas. There is also.

In addition, as shown in FIG. 7, the pseudo coloring circuit 24 includes a high cutoff circuit 37 in addition to the low cutoff circuit 27, and high cutoff is performed not only in the low brightness area of each color signal but also in the high brightness area at mutually different levels. However, the R signal, G signal, and B signal may be distributed to different brightness regions.

Here, the high cut-off circuit 37 cuts off color signals above a certain voltage level and passes only color signals below the cut-off level. An example of the high cut-off circuit 37 is one that inputs a color signal to the variable resistor 39, which is the base bias of the transistor 38, and the collector, and connects the color signal above a certain level to ground, and connects the RGB separate circuit 26 and the low cut-off circuit. 27 and a resistor 40 between them. That is, the RGB separate circuit 26 side of the resistor 40 is grounded through the series body of the resistor 41 and the variable resistor 39, and the low cut-off circuit 27 side is grounded to the collector of the transistor 38. Further, the transistor 38 has an emitter side and a base side connected to a variable resistor 39. Therefore, by changing the resistance value of the variable resistor 39 and setting it to a certain value, the drive level between the best-emitters is determined based on this value, so that when the color signal reaches a voltage level higher than this drive level, the transistor 38 is driven and the color signal is grounded.
As a result, the high level of the color signal based on the setting value of the variable resistor 39 is cut off.
Note that this high cut-off circuit 37 is provided in each color signal circuit, and different drive levels, that is, high cut-off levels are set respectively.

Therefore, when the color signals that have passed through the high cut-off circuit 37 and the low cut-off circuit 27 are amplified and input to the color display device 25, the cut-off regions are different, so that the color signals are divided into different regions (edges) depending on the brightness level. (including cases where they overlap), creating a color image. In other words, the image of the subject is input as a luminance signal corresponding to its brightness, and then decomposed into RGB signals of the same level, which are then cut off at different high cut-off levels and low cut-off levels, thereby eliminating artifacts. The color image signal generated in the above is reproduced as a color image on the color display device 25. here,
For color specification, for example, to set the high brightness band to green, set the high cutoff level to the maximum brightness level, raise the low cutoff level to the high brightness side, and set the medium brightness band to blue. To set the high cutoff level to about 2/3 of the maximum brightness level, raise the low cutoff level to medium brightness, and to set the low brightness band to red, set the high cutoff level to 1/2 of the maximum brightness level. If the low cutoff level is set to approximately /3 and the low cutoff level is set to the lowest brightness level, the image on the color display device 25 will be displayed in pseudo color in three colors: red, blue, and green. At this time, if the low cutoff level is set slightly below the high cutoff level of the lower region, no signal areas, ie, black areas, will not occur at the color boundary, which is suitable for observing luminance changes. In this case, as shown in Figure 8, red, purple, blue,
Displayed in pseudocolor in five colors: cream and green. Moreover, each color has a brightness corresponding to a brightness level. For example, taking red as an example, even in the red area there are bright red, dark red, and colors intermediate between these, and if the brightness level becomes extremely low, red appears black. Therefore, this pseudo-color image appears to the human eye as six colors: black, dark red, purple, blue, cream, and green. Note that, in order to clearly distinguish between black parts and dark red, the low cutoff level of the R signal may be set slightly higher than the lowest brightness level to suppress the color signal output in the low brightness area.

Furthermore, as shown in FIG.
4 is provided with a variable gain amplifier circuit 42 in addition to the low cut-off circuit 27 and the high cut-off circuit 37,
In addition to distributing the R signal, G signal, and B signal to different brightness regions, any color signal may be amplified with a relatively higher gain than other color signals to increase the brightness of any color. . Here, as an example of the variable gain amplifier circuit 42, a complementary Darlington circuit is provided with a variable resistor 43 on the input base side, and by changing the resistance value of the variable resistor 43 in each color signal circuit, the input Some signal voltages can be varied to amplify any color signal with a resulting higher gain than other color signals.

According to this pseudo-coloring circuit 24, the image displayed on the color display device 25 has color signals distributed to different brightness levels through the high cut-off circuit 37 and low cut-off circuit 27, and only arbitrary color signals are divided into other colors. Since it is amplified to a higher gain than the signal and output,
To create a color image in which a subject is displayed in different colors for each brightness level in a predetermined range and colors representing arbitrary brightness levels are emphasized.

As shown in Fig. 10, the color image corresponding to the brightness is divided into black, dark red, purple, blue, and black, with green in the high brightness band, blue in the medium brightness band, and red in the low brightness band.
Even if it is displayed in 6 colors of cream and green,
In a low brightness level area, there is a problem in that it becomes difficult to observe changes in brightness due to the decrease in brightness. Therefore, the variable resistor 4 in the variable gain amplifier circuit 42 of the R signal circuit
By lowering the resistance value of No. 3, the input signal voltage can be increased to amplify it more than other color signals, thereby brightly emphasizing the colors in the low luminance band. For example, in a combustion water flow model where a fluid containing dense bubbles is treated as fuel, areas where the combustion air is much larger than the fuel and the number of bubbles per unit volume is small, the brightness is low and it is not easy to observe as it is. However, if the R signal is amplified to brighten and emphasize the low luminance component, that part will emerge as a contour, making it easier to observe.

As mentioned above, pseudo-colorized image system B
The pseudo-coloring circuit 24 is configured as shown in FIGS. 5, 7, and 9, and by this pseudo-coloring image system B, a fluid containing a large amount of fine and homogeneous bubbles is reproduced in the visualization device A. When reproducing a flow field as a color image, the concentration distribution of the fluid in the flow field is determined for each brightness level in a predetermined range based on the similarity between the number of bubbles in a unit volume, that is, the concentration, and the intensity of scattered light. The images are displayed using different colors and their brightness, making it possible to visualize the concentration distribution.

Furthermore, since the pseudo-color image system B can convert an analog image signal into a color image signal with an arbitrary color scheme without converting it into a digital image signal,
Compared to conventional pseudo-colorization, which can only display still images in color even when using a high-speed, large-capacity computer, input images can be converted into any color image in real time, allowing accurate pseudo-coloring of moving images. The display becomes suitable for visualization of the required concentration.

Moreover, since a computer or the like is not used, pseudo-coloring suitable for density visualization can be achieved at an extremely low cost.

The flame formed in a combustion burner reaches its maximum temperature when the fuel and combustion air are near the stoichiometric mixing ratio and becomes incandescent; however, in the water flow model mentioned above, which assumes a fluid containing bubbles as fuel, this region is This is different from the highest brightness level region because the number of bubbles is small. Rather, the region with the highest brightness level, that is, the region where many bubbles exist, has a temperature lower than the outer peripheral temperature of the flame and approaches a dark red color because there is no combustion air in an actual burner flame. Therefore, in the pseudo coloring circuit shown in FIG.
4 For example, by inserting an inverter circuit as shown in Figure 11, a signal in the brightness region (generally a low brightness region) corresponding to the theoretical mixing ratio is converted into a signal with a high voltage level, while the signal in the original high brightness region is By lowering the signal level, a color image can be created in which the area near the outer periphery of the flame becomes white.

[Effects of the Invention] As is clear from the above explanation, the concentration visualization device of the present invention reproduces a flow field with a water flow that densely contains fine and homogeneous bubbles, and diffusely reflects it by shining slit light on it. While visualizing the flow in an arbitrary cross section, the scattered light is photographed with a TV camera, and the brightness signal output from the TV camera is converted into R signal, G signal, The concentration of fluid in the flow field can be determined by converting the RGB signals into B signals, cutting off one, two, or all of these RGB signals at different voltage levels, and outputting them to a color display device to construct a color image. The distribution is displayed using different colors and differences in brightness for each luminance level in a predetermined range based on the proportional relationship between the number of bubbles in a unit volume, that is, the concentration, and the intensity of the brightness of scattered light. Therefore, it becomes possible to visualize the concentration distribution.

Furthermore, since the analog image signal is converted to a color image signal with an arbitrary color scheme without converting it to a digital image signal, the input image can be converted into pseudocolor in real time, which eliminates the need for precise pseudocolor display of moving object images. Pseudo-coloring suitable for density visualization can be achieved. Moreover, since a computer or the like is not used, pseudo-coloring suitable for density visualization can be achieved at an extremely low cost, which is a great practical effect.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a flow field visualization device that constitutes a concentration visualization device in a water flow model according to the present invention, and FIG. 2 is a schematic diagram of the same pseudo-color image device.
Figure 3 is a graph showing the experimental results of the relationship between orifice diameter and bubble diameter ratio, Figure 4 is an explanatory diagram showing a visualized flow field, and Figure 5 is an example of a pseudo-coloring circuit. 6 is an explanatory diagram showing pseudo colorization, FIG. 7 is a circuit diagram showing another embodiment of the pseudo colorization circuit, FIG. 8 is an explanatory diagram showing pseudo colorization, and FIG. 9 is an explanatory diagram showing pseudo colorization. FIG. 10 is a circuit diagram showing still another embodiment of the pseudo coloring circuit, FIG. 10 is an explanatory diagram showing pseudo coloring, and FIG. 11 is a circuit diagram showing an inverter circuit inserted into the pseudo coloring circuit. 1... Water tank, 3... Slit light source, 4... Bubbles, 5... Slit light, 8... Piping, 9... Orifice, 21... TV camera, 24... Pseudo coloring circuit, 25... Color display device, 2
7...Low cut-off circuit, 37...High cut-off circuit, 42...Variable gain amplification circuit, A...Visualization device, B...Pseudo-color image system (pseudo-color image device).

Claims (1)

[Claims] 1 An orifice with at least one small hole with a diameter of 3 mm or less is installed in the pipe connecting the model water tank and the pressure water supply source, and the degassing phenomenon caused by the local pressure drop when passing through the orifice creates fine and homogeneous water. A large amount of air bubbles appear in the water flow, and the water flow densely containing these fine and homogeneous air bubbles reproduces the flow field in the aquarium.
A visualization device that illuminates this flow field with slit light and visualizes the flow in an arbitrary cross section by diffuse reflection from bubbles, and a TV camera that photographs the scattered light and outputs a brightness from the camera according to the brightness of the flow field. The signals are introduced into an RGB separate circuit and converted into R, G, and B signals of the same level, and after cutting off any one, two, or all of these RGB signals at different signal voltage levels, a color display is produced. output to the device,
A concentration visualization device for a water flow model, comprising a pseudo-color image device that displays the concentration distribution of a fluid in a flow field using colors and differences in brightness.