JP2008064679A - Method and device for visualizing air current - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily and precisely visualize a turbulence in an air current flowing at a slow wind velocity, and to easily and precisely visualize the turbulence in the air current (turbulence in a boundary layer) generated in the vicinity of an applied film face, even when the wind velocity of drying air is low, for example, as in a drying process for an applied film. <P>SOLUTION: This method of visualizing the turbulence in the air current is provided with the first process for evaporating a solvent in an upstream of the air current to contain solvent vapor in the air current, and the second process for visualizing optically a concentration distribution of the solvent vapor in the air current, in a downstream of the air current, and the turbulence of the air current is visualized as the concentration distribution of the solvent vapor. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an airflow visualization method and apparatus, and more particularly to an airflow visualization method and apparatus for visualizing turbulence of an airflow generated in the vicinity of a coating film in a coating film drying process.

  In the drying process of the coating film, turbulence of the air flow in the drying device, especially in the vicinity of the coating film (dry air, solvent vapor evaporated from the coating film, etc.) causes drying unevenness (specifically, streaky unevenness) on the coating film surface. This refers to strip-shaped uneven surface stripes formed along the flow direction of dry air, called flow unevenness, mottle, spots, etc., and hereinafter collectively referred to as “streaked surface unevenness”) It has been known.

  Conventionally, wall trace method, tuft method, tracer method, optical method, etc. have been put to practical use as methods for grasping the fluid behavior of such a boundary layer (reference: fluid experiment handbook, Asakura Shoten).

For example, the PIV method (for example, Patent Document 1) that accurately grasps the flow behavior by simultaneously visualizing the flow pattern and traces of tracer particles, and forming an oil film in which pigment is dispersed on the surface of the object to be examined. Wall surface tracing method for visualizing oil flow by flowing oil over the surface of the oil film (for example, Patent Document 2), applying a shear stress liquid crystal whose hue changes depending on the magnitude and direction of the shear stress to the surface of the object to be examined. A method of visualizing the magnitude and direction of a shearing force by flowing a fluid over the surface and measuring a change in hue has been proposed (for example, Patent Document 3).
JP-A-8-211087 JP 58-182513 A JP 2003-28730 A

  However, the turbulence of the air flow that causes streaky surface unevenness on the coating film surface is mainly a boundary layer having a thickness of several millimeters or less in the air flow in the vicinity of the coating film surface. The problem with accurate measurement is that it involves extremely complicated work.

  Further, in the methods of Patent Documents 2 and 3, since the shearing force of the airflow is small, it could not be visualized unless the wind speed was 30 m / second or more. For this reason, there has not yet been proposed a method capable of easily visualizing the air flow even when the wind speed is as low as about 1 m / sec as in the coating film drying step.

  The present invention has been made in view of such circumstances, and since it is possible to visualize the turbulence of the airflow flowing at a low wind speed easily and with high accuracy, the wind speed of the dry wind is, for example, as in the coating film drying process. An object of the present invention is to provide an airflow visualization method and apparatus capable of easily and accurately visualizing airflow turbulence (boundary layer turbulence) generated in the vicinity of a coating film surface even when the coating film surface is small.

  Claim 1 of the present invention is a method for visualizing turbulence of an air flow in order to achieve the above object, wherein the solvent is evaporated on the upstream side of the air flow, and the solvent vapor is included in the air flow. And a second step of optically visualizing the concentration distribution of the solvent vapor in the air stream on the downstream side of the air stream, wherein the turbulence of the air stream is visualized as the concentration distribution of the solvent vapor. A method for visualizing airflow is provided.

  According to the first aspect, when the turbulent air stream is passed through the surface of the solvent, the evaporation rate is uneven due to the turbulence of the air stream, and the concentration distribution of the solvent vapor is present in the air stream passing through the surface of the solvent. appear. By visualizing this concentration distribution by an optical method, turbulence of the air current can be visualized as a concentration distribution of the solvent vapor. In addition, if the change in the concentration distribution is visualized over time, the change over time in the turbulence of the airflow can be grasped.

  A second aspect of the present invention is characterized in that, in the first aspect, the air stream containing the solvent vapor is formed by passing the air stream through a liquid solvent surface.

  Since the evaporation rate of the liquid solvent varies due to the turbulence of the passing air stream, a concentration distribution of the solvent vapor is generated in the air stream, and the turbulence of the air stream can be visualized optically.

  A third aspect is characterized in that, in the first or second aspect, the visualization is performed by a Schlieren method.

  The schlieren method is a method of visualization using a known schlieren optical system. The visualization mechanism of the schlieren optical system is not particularly limited, but a mechanism including a light source, a pinhole, a schlieren lens, a knife edge, a CCD camera, and a screen is preferable.

  A fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the solvent is an organic solvent having a boiling point of 100 ° C. or less.

  According to the fourth aspect, since the volatility of the solvent is high, a high-concentration solvent can be included in the air stream, and the visualization accuracy can be improved.

  A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the air velocity of the airflow is set to 10 m / second or less.

  If the wind speed is too high, the solvent is easily volatilized immediately, and the solvent vapor is easily diluted with a large amount of air, which is not preferable because the concentration distribution of the solvent vapor in the airflow cannot be measured accurately. According to the fifth aspect, the concentration distribution of the solvent vapor in the airflow can be clearly visualized.

  A sixth aspect of the present invention is the method according to any one of the first to fifth aspects, wherein, in the first step, the solvent is evaporated by passing an air stream through the solvent on the planar member, The turbulence of the air current in the boundary layer in the vicinity of the planar member is visualized.

  According to the sixth aspect, when the airflow flowing on the surface of the planar member is disturbed, unevenness occurs in the evaporation rate of the solvent on the planar member. This unevenness in the evaporation rate appears as a concentration distribution of the solvent vapor in the air stream. By visualizing this concentration distribution by an optical method, it is possible to visualize the turbulence of the air current in the vicinity of the planar member (the turbulence of the boundary layer).

  A seventh aspect of the present invention according to the sixth aspect is characterized in that the surface of the planar member is a coating film surface in which a coating film is coated on a belt-like support.

  According to the seventh aspect, even when the wind speed of the drying air is low as in the coating film drying step, the turbulence of the air current (disturbance of the boundary layer) generated near the coating film surface can be visualized easily and with high accuracy.

  Claim 8 of the present invention is a visualization device for visualizing the turbulence of the air flow in order to achieve the above object, and is arranged on the upstream side of the air flow to evaporate the solvent in the air flow passing through the air flow. A solvent evaporating part that contains solvent vapor therein, an optical visualization part that is disposed downstream of the air stream and optically visualizes the concentration distribution of the solvent vapor in the air stream after passing through the solvent evaporating part; The airflow visualization device is characterized in that the airflow turbulence is visualized as a concentration distribution of the solvent vapor.

  In the eighth aspect of the present invention, the present invention is configured as an apparatus. In the solvent evaporation section, the solvent is evaporated in the passing air stream, and the solvent vapor is included in the air stream. If the airflow is disturbed in the process of evaporating the solvent, the evaporation rate becomes uneven and appears as a concentration distribution of the solvent vapor in the airflow. By visualizing this concentration distribution by the optical visualization unit, the turbulence of the air current can be visualized as the concentration distribution of the solvent vapor. Further, if the change in the concentration distribution is visualized over time, the change over time in the turbulence of the air current can be grasped, so that the turbulence in the air current can be continuously measured online.

  A ninth aspect of the present invention according to the eighth aspect is characterized in that the optical visualization unit is a Schlieren optical device.

  A tenth aspect of the present invention is the visualization device according to the eighth or ninth aspect, wherein the visualization device includes a flat plate member through which the airflow flows, and a porous body is flush with a concave portion of the solvent evaporation portion formed on the upstream side of the flat plate member. And a transparent measurement window of the optical visualization unit is formed on the downstream side of the flat plate member.

  According to the tenth aspect, since the airflow flows along the flat plate member, it is possible to reach the measurement window while maintaining the concentration distribution of the solvent vapor generated in the solvent evaporation section. In this case, the solvent evaporating part is embedded in the recess of the flat member and is flush with the flat plate member, and the turbulence of the air flow by the solvent evaporating part is not generated, so that the visualization accuracy can be improved. In addition, since a transparent measurement window of the optical visualization unit is formed on the downstream side of the flat plate member and visualization is performed through the measurement window, disturbance during visualization can be eliminated.

  Further, since the porous body is housed in the concave portion of the solvent evaporation section, it is possible to suppress the solvent in the solvent evaporation section from flowing out even if the flat plate member is inclined at an arbitrary angle with respect to the horizontal.

  An eleventh aspect of the present invention is the method according to the tenth aspect, wherein the flat plate members are arranged so as to face each other as an upper plate and a lower plate, respectively, and the measurement parts formed respectively on the upper plate and the lower plate are mutually It is characterized by facing.

  According to the eleventh aspect, it is possible to measure the concentration distribution of the solvent vapor caused by the airflow in the vicinity of the flat plate member, particularly the convection.

  A twelfth aspect is characterized in that, in the tenth or eleventh aspect, the flat plate member is provided with a heating means for heating the solvent evaporation section.

  As a result, the evaporation rate can be increased even with a low-volatile solvent, and precise control can be performed.

  A thirteenth aspect of the present invention is the method according to any one of the ninth to twelfth aspects, wherein a schlieren lens and a mirror are provided on an optical path formed between a light source in the schlieren optical device and an airflow after passing through the solvent evaporation section. The surface accuracy of the schlieren lens and the mirror is one wavelength or less.

  According to the thirteenth aspect, it is possible to reduce the influence of disturbance caused by the mirror and the schlieren lens, and it is possible to obtain a clear observation image. Here, one wavelength is 550 nm.

  According to the present invention, the turbulence of the airflow flowing at a low wind speed can be visualized easily and with high accuracy. Therefore, even in the case where the wind speed of the drying air is low, for example, in the coating film drying process, Can be visualized easily and with high accuracy.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an airflow visualization method and apparatus according to the present invention will be described below with reference to the accompanying drawings.

  A first embodiment of the present invention will be described.

  FIG. 1 is a schematic diagram showing a schematic configuration of a visualization device 10 according to the first embodiment of the present invention. This embodiment is a method of visualizing turbulence of airflow (disturbance of the boundary layer) in the vicinity of the surface of the measurement plate by flowing gas over the measurement plate.

  As shown in FIG. 1, the visualization apparatus 10 mainly includes a measurement plate 12 in which an air stream containing a solvent flows along the surface, and a concentration distribution of the solvent vapor in the airflow formed on the measurement plate 12. And a Schlieren optical device 14 for optical visualization. In addition, there is no limitation in particular as a method of supplying gas on the measurement board 12, For example, a nozzle and an air blower can be used. Although it depends on other conditions, the wind speed is preferably 10 m / second or less, more preferably 5 m / second or less. In addition, when using the visualization apparatus 10 in the apparatus which the airflow (drying air) generate | occur | produces, for example like a drying apparatus, the means to supply gas is not required.

  First, the configuration of the measurement plate 12 will be described with reference to FIG.

  2 is a schematic diagram showing the configuration of the measurement plate 12 of FIG. 1, in which FIG. 2 (a) is a perspective view showing the configuration of the measurement plate 12, and FIG. 2 (b) is FIG. 2 (a). It is an AA sectional view taken on the line. FIG. 3 is an enlarged cross-sectional view showing the vicinity of the recess in FIG.

  As shown in FIG. 2, the measurement plate 12 is fitted into a flat plate 12a that is a frame-shaped member having a rectangular hole, a solvent evaporation section 16 formed on the surface of the flat plate 12a, and a rectangular hole of the flat plate 12a. And a combined transparent measuring window 18.

  As shown in FIG. 3, the solvent evaporating section 16 is configured by accommodating a porous body 24 and a solvent (reference numeral 26 in the figure) in a recess 16a formed on the surface of the flat plate 12a. The porous body 24 sucks and evaporates the solvent by a capillary phenomenon. Thereby, even if the angle of the measuring plate 12 is arbitrarily changed with respect to the horizontal, it is possible to prevent the solvent from dripping or flowing out from the solvent evaporation section 16. In addition, when arrange | positioning horizontally with the surface (surface in which the solvent evaporation part 16 was formed) facing upwards, you may only fill a solvent in the recessed part 16a. Moreover, piping can be connected to the recessed part 16a and a solvent can always be supplied using pumps, such as a syringe pump. Thereby, the turbulence of the airflow can be continuously observed.

  The porous body 24 is preferably stored so as to be flush with the surface of the flat plate 12a. Thereby, the flatness of the whole measuring plate 12 can be maintained, and it can suppress that unnecessary disturbance arises in airflow.

  Although there is no limitation in particular as the porous body 24, a sintered metal, sponge, a woven fabric, a filler of beads, etc. can be used preferably. As the sintered metal, for example, a disc-like or sheet-like bronze sintered body (porosity 25 to 43%), a stainless sintered body (porosity 36 to 48%) manufactured by SMC Corporation can be preferably used. .

  The volume of the recess 16a formed on the surface of the flat plate 12a is appropriately determined according to the amount of solvent used. The cross-sectional shape of the recess 16a is not particularly limited, and various shapes such as a rectangle (square, rectangle), a trapezoid, a V shape, and a semicircle can be employed. Moreover, the solvent evaporation part 16 does not need to be a member fixed to the flat plate 12a as described above, even in a state where a web coated with a coating liquid containing an organic solvent is transported flush with the measurement plate. good.

  The transparent measurement window 18 fitted in the rectangular hole of the flat plate 12a can receive measurement light emitted from the schlieren optical device 14.

  Note that, as in the present embodiment, the measurement window 18 is not limited to be configured to fit into the rectangular hole of the flat plate 12a. For example, the entire flat plate 12a may be a transparent plate having a uniform refractive index, or a transparent plate may be formed. Alternatively, the measurement air may be directly irradiated with the measurement light.

  The material of the measurement window 18 is not particularly limited, but a glass material, a resin material described later, and the like can be preferably used. The planar shape of the measurement window 18 is not particularly limited, and may be other than a rectangle such as a circle.

  If the distance (D1) from the solvent evaporation section 16 to the measurement window 18 is too long, relaxation due to diffusion of the solvent vapor easily occurs, and the contrast when imaged is reduced. For this reason, it is preferable that the distance (D1) from the solvent evaporation part 16 to the measurement window 18 is set to an appropriate distance according to the wind speed. For example, if the wind speed is about 0.1 m / second, the distance (D1) from the solvent evaporation section 16 to the measurement window 18 is preferably 200 mm or less, and more preferably 150 mm or less.

  Further, a heating means (not shown) may be provided around the solvent evaporation section 16 (particularly, on the back surface of the measurement plate 12 corresponding to the recess 16a). As a result, precise control is possible, for example, the evaporation rate can be increased even with a low-volatile solvent. Such heating means is not particularly limited, and various heaters, heat exchangers, and the like can be used.

  The planar size of the flat plate 12a is not particularly limited, but can be set to, for example, 300 × 500 mm because of a configuration that allows simple testing. Although the thickness of the flat plate 12a is not particularly limited, it can be set to, for example, about 5 mm from the viewpoint of strength, economy, and the like. In this case, the planar size of the measurement window 18 is not particularly limited, but is preferably about 200 to 500 mm square larger than the Schlieren lens.

  The material of the flat plate 12a is not particularly limited, but is preferably excellent in workability, and specifically, metal materials such as aluminum and aluminum alloys, polydimethyl sulfoxide (PDMS), polymethyl methacrylate. Resin materials such as (PMMA), polyvinyl chloride (PVC), ultraviolet curable resin, and polycarbonate (PC) can be preferably used.

  In addition, it is preferable that the surface (surface in which the solvent evaporation part 16 is formed) and the back surface of the measurement plate 12 have ensured sufficient flatness.

  Next, the schlieren optical device 14 will be described with reference to FIGS. 1 and 4.

  FIG. 4 is a schematic diagram for explaining a part of the internal configuration of the schlieren optical device 14, in which FIG. 4A is a mechanism for emitting measurement light to the measurement window 18, and FIG. In this mechanism, the measurement light after passing through the measurement window 18 is incident. In the figure, a dotted arrow indicates the direction of measurement light.

  As shown in FIGS. 4A and 4B, the schlieren optical device 14 in this embodiment includes a light source 28, a pinhole 30, schlieren lenses 32 and 34, a knife edge 36, a CCD camera 38, and a screen 40. I have.

  The light emitted from the light source 28 is formed into parallel light by the pinhole 30 and the schlieren lens 32 and is emitted to the outside of the schlieren optical device 14 (see FIG. 4A). The measurement light emitted from the schlieren optical device 14 passes through the measurement window 18 and the flat plate 12a via the mirror 20 in FIG. 1 and then is reflected by the mirror 22, and again on the measurement plate 12, the measurement window 18, and the mirror 20 And is incident on the schlieren optical device 14. The incident measurement light is imaged by the schlieren lens 34 and the knife edge 36, and is imaged on the screen 40 by the CCD camera 38 (see FIG. 4B).

  In the optical mechanism described above, when the concentration distribution of the solvent vapor is generated in the airflow in the vicinity of the measurement window 18, the measurement light is refracted at a refractive index corresponding to the concentration distribution of the solvent vapor. The vapor concentration distribution is imaged. Here, in order to improve the accuracy of visualization, the surface accuracy of the schlieren lenses 32 and 34 and the mirrors 20 and 22 is preferably 1 wavelength or less (1 wavelength λ = 550 nm), and is 1/2 wavelength or less. More preferably.

  Note that the optical mechanism of the schlieren optical device 14 is not limited to the above-described embodiment, and any optical mechanism may be used as long as it has an equivalent function. Further, when measuring the concentration distribution of the solvent vapor in the airflow as in the present embodiment, since the light source using a high voltage and the combustible gas coexist, as shown in FIG. It is preferable to perform casing and to pressurize the inside of the casing more than the surroundings. Thereby, the user can observe and measure airflow more safely.

  The solvent used in the present embodiment can be variously selected according to the purpose of measurement, but is preferably highly volatile from the viewpoint of measurement accuracy, and more preferably an organic solvent having a boiling point of 100 ° C. or lower.

  Next, the operation of the visualization device 10 in the present embodiment will be described with reference to FIG.

  First, a predetermined amount of the solvent 26 is supplied to the concave portion 16a of the measuring plate 12 using a dropper or the like. Next, air having a wind speed of about 1 m / second starts to flow on the measurement plate 12 (arrow F in the figure). Thereby, the solvent 26 filled in the recess 16a evaporates through the porous body 24, and flows downstream along with air (first step).

  Further, the measurement light emitted from the schlieren optical device 14 passes through the measurement window 18 via the mirror 20, is reflected by the mirrors 22 and 20, and is incident on the schlieren optical device 14 again. The incident measurement light is imaged in the schlieren optical device 14 (second step).

  This makes it possible to visualize the concentration distribution of the solvent vapor caused by the airflow near the surface of the measurement window 18, particularly the disturbance of the boundary layer. Therefore, the disturbance of the boundary layer can be visualized as a concentration distribution of the solvent vapor.

  Next, a second embodiment of the present invention will be described. This embodiment is a method of visualizing the influence of airflow, particularly convection, in the vicinity of a wall surface in a rectangular parallelepiped case by flowing gas into a rectangular parallelepiped case having both ends opened. Hereinafter, the same members or functions as those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 5 is a schematic diagram showing a schematic configuration of the visualization apparatus 10 ′ according to the present invention. FIG. 6 is a perspective view showing a configuration of the rectangular parallelepiped case 42 of FIG.

  As shown in FIG. 5, the visualization device 10 ′ of the present embodiment is the same except that the rectangular parallelepiped case 42 is used instead of the measurement plate 12 in the visualization device 10 of the first embodiment (FIG. 1). It is configured.

  As shown in FIG. 6, the rectangular parallelepiped case 42 is configured in a cylindrical shape in which four surfaces are covered and both ends are opened. Similarly to the measurement plate 12 in the first embodiment, a concave portion 16a and a transparent measurement window 18 are respectively formed on the upper plate 42a and the lower plate 42b facing each other, and are arranged facing each other. (See FIG. 5).

  About the material of the rectangular parallelepiped case 42, the thing similar to 1st Embodiment can be used.

  Next, the operation of the visualization device 10 ′ in this embodiment will be described with reference to FIG. 5.

  First, a predetermined amount of solvent is supplied to each of the recesses 16a and 16a formed on the upper plate 42a and the lower plate 42b with a dropper or the like. Next, air having a wind speed of about 1 m / sec starts to flow into the rectangular parallelepiped case 42 (arrow F in the figure). As a result, the solvent filled in the recesses 16a and 16a evaporates through the porous bodies 24 and 24, and flows downstream along with the air.

  The measurement light emitted from the schlieren optical device 14 passes through the measurement windows 18 and 18 via the mirror 20, is then reflected by the mirrors 22 and 20, and is incident on the schlieren optical device 14 again. The incident measurement light is imaged in the schlieren optical device 14.

  Thereby, the concentration distribution of the solvent vapor caused by the airflow passing between the measurement windows 18 and 18, particularly the convection can be visualized. Therefore, the turbulence of the airflow (particularly the convection state) can be visualized as the concentration distribution of the solvent vapor.

  According to the visualization devices 10 and 10 ′ described above, by visualizing the concentration distribution of the solvent vapor in the airflow near the wall surface, the turbulence of the airflow generated near the coating film surface in the coating film drying process (disturbance of the boundary layer) ) In a pseudo manner. Therefore, by optimizing the drying conditions based on the above results, it is possible to suppress the occurrence of streaky surface unevenness on the coating film surface.

  As mentioned above, although embodiment of the visualization method and apparatus of the airflow concerning this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in each of the above embodiments, the measurement plate 12 having the solvent evaporation section 16 and the measurement window 18 is used, but the measurement window 18 is not necessarily required. That is, the concentration distribution of the solvent vapor is also measured by directing measurement air to the airflow downstream of the solvent evaporation section 16 after passing the airflow on a flat plate on which only the solvent evaporation section 16 is formed. it can. Moreover, as the solvent evaporation part 16, other than the structure which provided the recessed part 16a on the flat plate, the opening container filled only with the solvent may be sufficient.

  In each of the above embodiments, an example using a dropper or the like has been shown as a method of supplying the solvent to the solvent evaporation section 16, but the present invention is not limited to this, and a flow path or a pipe communicating with the bottom of the recess 16a is formed. It can also be configured to be supplied by a pump or the like.

  In each of the above embodiments, an example in which a schlieren optical device is used as the optical visualization device has been described. However, the optical system device is not particularly limited as long as the optical system device has a mechanism similar to the schlieren optical device.

  Further, in each of the above embodiments, the reflective schlieren method in which two mirrors (planar mirrors) 20 and 22 are installed through the measurement window 18 and the screen 40 is disposed on the same side as the light source 28 is employed. It is not limited to. That is, the installation state of the mirror is determined by the installation location and layout of the schlieren optical device 14 with respect to the measurement window 18, and the number of mirrors may be only one, or may be three or more.

  However, if the optical path length of the parallel light is too long, the solvent gas flows into the optical path or a temperature distribution is generated, which is not preferable because the measurement light is affected by disturbance. For this reason, it is preferable to set the optical path length of parallel light to be 1 m or less.

  Moreover, it is preferable to casing the entire optical path (including the mirrors 20 and 22 in FIGS. 1 and 5) in the schlieren optical system so that disturbances such as a solvent concentration difference and a temperature difference do not enter the optical path.

  The present invention is not limited to the above-described embodiment, and can be widely applied when the concentration distribution of solvent vapor is visualized continuously over time. In particular, when the organic solvent is evaporated (dried), the airflow is disturbed in the vicinity of the wall surface or the like, which is effective for visualization and observation of the airflow turbulence when evaporation unevenness (drying unevenness) occurs. Note that the vicinity of the wall surface refers to the vicinity of the viscous bottom layer in the turbulent boundary layer, although it depends on the wind speed, specifically, an area within about 1 mm from the wall surface.

  A test for visualizing the concentration distribution of the solvent vapor in the airflow was performed using the visualization apparatus 10 'of FIG.

  As the schlieren optical device 14, a schlieren compact SLC-100 (manufactured by Mizojiri Optical Industry) was used.

<Overview of Schlieren Compact SLC-100>
Light source 28: Xe lamp (75W)
Knife edge 36: Fine adjustment of single edge, rotation around optical axis TV camera: CCD monochrome camera TV monitor: 9 inch monochrome monitor Focal length: 1m
Measurement area: 100 mm square Aluminum mirrors TFA-100C15-4 (manufactured by Sigma Koki Co., Ltd.) were used as the mirrors 20 and 22.

  The upper plate 42a and the lower plate 42b constituting the rectangular parallelepiped case 42 have a plane size of 300 × 500 mm, the recess 16a has a plane size of 200 × 50 mm, and the measurement window 18 has a plane size of 200 × 200 mm. As the solvent, methyl ethyl ketone (MEK, boiling point 78 ° C.) or anone (boiling point 155.6 ° C.) was used. A sintered metal element ESS-50-200-5-2-M (manufactured by SMC) was filled as the porous body 24 into the recess 16a of the lower plate 42b.

  And the turbulence of the airflow when changing experimental conditions as follows was measured and observed.

  First, tests 1 to 3 and 6 to 7 are cases in which the air wind speed is changed in a range of 0.5 to 20 m / sec. At this time, the distance D1 between the solvent evaporation section 16 and the measurement window 18 was constant at 50 mm, and MEK was used as the solvent.

  Tests 3 and 8 are cases in which the type of solvent was changed. At this time, the air velocity was set to 2 m / second, and the distance D1 between the solvent evaporation section 16 and the measurement window 18 was set to be constant at 50 mm.

  These results are shown in Table 1. FIG. 7 shows a photograph of a schlieren image (φ100 mm) obtained when the wind speed is changed.

  As shown in Table 1, when the wind speed was 0.5 to 2 m / sec under the conditions of this example, a streak-like structure was relatively clearly seen (tests 1 to 3 and photograph (b) of FIG. )reference). On the other hand, when the wind speed was 10 m / sec, the streak-like structure was thin and unclear (test 5), and when the wind speed was 20 m / sec, the streak-like structure was hardly seen (photo of test 6 and FIG. 7). c)). In addition, when the wind speed was 0.1 m / sec, no streak-like structure was observed, but this is presumably because the wind speed was sufficiently slow and laminar (see Test 4, Fig. 7 (a)). .

  Further, when MEK having a boiling point lower than 100 ° C. was used as a solvent, a streak-like structure was relatively clearly seen (Test 3), but when an anone having a boiling point higher than 100 ° C. was used, a streak-like structure was observed. The structure was thin and unclear (Test 7). This is presumably because the highly volatile solvent contains the solvent in a high concentration in the air stream.

  Next, an obstacle is placed on the upstream side of the solvent evaporation section 16 formed on the lower plate 42b to form a turbulent air flow, and the distance D1 between the solvent evaporation section 16 and the measurement window 18 is changed for measurement and measurement. An observation experiment was conducted. At this time, the air velocity was kept constant at 0.1 m / second, and MEK was used as the solvent.

  As shown in Table 2, when the distance D1 between the solvent evaporation section 16 and the measurement window 18 was 150 mm or less, the turbulence of the air flow was clearly seen (Tests 8 to 10). In particular, when the distance D1 is 50 mm or less, the turbulence of the air flow is more clearly seen. On the other hand, when the distance D1 was increased to 200 mm, the turbulence of the air current could not be clearly observed (Test 11). This is presumed to be because if the distance D1 from the solvent evaporation section 16 to the measurement window 18 is too long, the solvent vapor diffuses and the contrast when imaged decreases.

  Note that the difference between the observation results in Test 4 and Test 8 was that in Test 4 the airflow was not disturbed by the laminar flow as described above, whereas in Test 8 the airflow was disturbed by the obstacle. It is presumed to be due to

  From the above, it was found that the turbulence of the air current can be observed relatively clearly under the conditions of this example if the wind speed is 10 m / sec or less. It was also found that the use of a highly volatile solvent (specifically, a solvent with a boiling point of 100 ° C. or less) and a small distance from the solvent evaporation section to the measurement window improve the visualization accuracy and contrast. It was.

  From the above results, it was confirmed that by applying the present invention, the turbulence of the air current can be clearly visualized even when the wind speed is as low as 1 m / sec.

It is a mimetic diagram showing a schematic structure of visualization apparatus 10 in a 1st embodiment concerning the present invention. It is a schematic diagram which shows the structure of the measuring plate of FIG. It is an expanded sectional view which shows the inside of the recessed part of FIG. It is a schematic diagram explaining a part of internal structure of the schlieren optical apparatus of FIG. It is a schematic diagram which shows schematic structure of the visualization apparatus 10 'in 2nd Embodiment which concerns on this invention. It is a schematic diagram which shows the structure of the rectangular parallelepiped case of FIG. It is a photograph figure which shows the observation result of a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10, 10 '... Visualization device, 12 ... Measuring plate, 42 ... Rectangular case, 12a ... Flat plate, 42a ... Upper plate, 42b ... Lower plate, 14 ... Schlieren optical device, 16 ... Solvent evaporation part, 16a ... Recessed part, 18 ... Measurement window 20, 22 ... mirror, 24 ... porous body, 26 ... solvent, 28 ... light source, 30 ... pinhole, 32, 34 ... Schlieren lens, 36 ... knife edge, 38 ... CCD camera, 40 ... screen

Claims (13)

A method for visualizing turbulence in airflow,
A first step of evaporating the solvent upstream of the air stream and including solvent vapor in the air stream;
A second step of optically visualizing the concentration distribution of the solvent vapor in the air stream on the downstream side of the air stream,
A method for visualizing an air current, wherein the turbulence of the air current is visualized as a concentration distribution of the solvent vapor.   The method of visualizing an airflow according to claim 1, wherein the airflow containing the solvent vapor is formed by passing the airflow through a liquid solvent surface.   The air flow visualization method according to claim 1 or 2, wherein the visualization is performed by a schlieren method.   The method for visualizing an airflow according to any one of claims 1 to 3, wherein the solvent is an organic solvent having a boiling point of 100 ° C or lower.   The air flow visualization method according to any one of claims 1 to 4, wherein a wind speed of the air flow is set to 10 m / second or less.   In the first step, the turbulence of the air current in the boundary layer in the vicinity of the planar member is visualized in the second step by allowing the airflow to pass through the solvent on the planar member and evaporating the solvent. The air flow visualization method according to any one of claims 1 to 5.   The airflow visualization method according to claim 6, wherein the surface of the planar member is a coating film surface in which a coating film is coated on a belt-like support. A visualization device for visualizing turbulence in an air current,
A solvent evaporating unit that is disposed on the upstream side of the air stream, evaporates the solvent in the passing air stream, and includes the solvent vapor in the air stream;
An optical visualization unit that is disposed on the downstream side of the air stream and optically visualizes the concentration distribution of the solvent vapor in the air stream after passing through the solvent evaporation unit;
An airflow visualization device that visualizes the turbulence of the airflow as a concentration distribution of the solvent vapor.   The air flow visualization device according to claim 8, wherein the optical visualization unit is a Schlieren optical device. The visualization device includes a flat plate member along which the airflow flows,
A porous body is embedded flush with the concave portion of the solvent evaporation section formed on the upstream side of the flat plate member, and a transparent measurement window of the optical visualization section is formed on the downstream side of the flat plate member. The airflow visualization device according to claim 8 or 9, characterized in that   The flat plate members are arranged so as to face each other as an upper plate and a lower plate, respectively, and the measurement windows respectively formed on the upper plate and the lower plate face each other. The air flow visualization device according to claim 10.   The air flow visualization device according to claim 10 or 11, wherein the flat plate member is provided with heating means for heating the solvent evaporation section. A schlieren lens and a mirror are arranged on an optical path formed between a light source in the schlieren optical device and an airflow after passing through the solvent evaporation section,
The airflow visualization device according to any one of claims 9 to 12, wherein surface accuracy of the schlieren lens and the mirror is one wavelength or less.

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