JP2858615B2 - Boiling observation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for observing a boiling state of a liquid in a microgravity environment, and more particularly to a temperature distribution of a boiling liquid in a container (chamber) such as a heat convection and a temperature gradient. The present invention relates to a boiling observation device that can observe with high accuracy.

[0002]

2. Description of the Related Art A boiling observation apparatus shown in FIG. 3 is conventionally used as a boiling observation apparatus for elucidating a boiling mechanism at the time of liquid boiling under zero gravity. This boiling observation device observes bubbles generated in the chamber by the Fizeau interferometer 46 and microlayers of boiling bubbles generated on the surface of the heating plate heater 37, and observes an observation window glass 39 installed on the side surface of the chamber 40. , 41,
The boiling state is observed by the CCD camera 42. Regarding the temperature distribution in the boiling liquid, the temperature measuring resistors 43, 44, 4 installed in the chamber 40 are used.
The temperature is measured with five or three tubes.

[0003] As described above, in elucidating the boiling mechanism of a liquid, (1) the state of micro-layers of bubbles during generation of boiling bubbles, (2) the observation of the boiling state of the liquid in the chamber, and (3) the state of the boiling in the chamber. It is necessary to obtain data on thermal convection and temperature distribution such as temperature gradient. However, in the conventional boiling observation apparatus, as described above, the temperature distribution in the liquid is measured by the three resistance temperature detectors installed in the chamber. Temperature can be measured, but the temperature distribution such as thermal convection and temperature gradient during that time can be estimated from the measured temperatures at three points, but for the part that is out of the position where the RTD is installed Is unclear, and further, it has been difficult to estimate the three-dimensional temperature distribution in the entire chamber. In order to solve these problems, it is conceivable to measure by placing a RTD in the whole chamber, but in such a case, the presence of the RTD disturbs the boiling state of the whole liquid. There are problems that arise.

Further, the measuring accuracy of the resistance temperature detector is ± 0.5 ° C.
However, there was a problem that a delicate temperature change could not be measured because it was only to the extent.

[0005]

SUMMARY OF THE INVENTION The present invention is capable of three-dimensionally measuring the temperature distribution of the entire liquid boiling in the chamber without affecting the boiling state of the entire liquid in the chamber. It is an object of the present invention to provide a boiling observation device capable of measuring minute temperature changes with increased accuracy.

[0006]

SUMMARY OF THE INVENTION A boiling observation apparatus according to the present invention uses a light from a light source of a Fizeau interferometer installed for observing bubbles generated in a chamber and micro layers generated on a heating plate heater surface. Is divided from the middle of the optical path set for the Fizeau interferometer, the observation light passing through the observation optical path set to pass through the chamber, and the reference light passing through the reference optical path set around the chamber. After passing through these separate optical paths, a Schlieren optical system that measures the temperature distribution of the cross section of the observation optical path in the chamber by observing the interference state of the light due to the phase difference generated when these lights are collected, Means were provided in two directions perpendicular to the chamber.

[0007]

According to the above means, the boiling observation apparatus of the present invention
Along with observing bubbles generated by boiling in the chamber and microlayers generated on the surface of the heating plate heater, it becomes possible to directly measure the temperature distribution of two orthogonal cross sections in the chamber. Also, since there is an optical measurement,
Unlike a resistance thermometer, it is possible to observe a three-dimensional temperature distribution in a liquid without disturbing the boiling phenomenon accompanying the temperature distribution measurement, and obtain data effective for elucidating the boiling mechanism. In addition, since the light from the light source of the Fizeau interferometer is used for the Schlieren optical system, the accuracy of temperature measurement is improved by about 5 times, which contributes to effective data acquisition. It can greatly contribute to the measurement of phenomena.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an embodiment of a boiling observation apparatus according to the present invention. The present embodiment is required to elucidate the boiling mechanism, (1) an apparatus using a Fizeau interferometer for observing a microlayer of bubbles during generation of boiling bubbles, and (2) an observation apparatus for observing a boiling state of the entire liquid in a chamber. And (3) One embodiment of the boiling observation apparatus of the present invention for observing the temperature distribution in the chamber will be described with reference to an apparatus integrally incorporated therein.

FIG. 1 is a plan view of an apparatus made so that an optical system can be easily understood. Reference numeral 20 surrounded by a dashed line indicates the Fizeau interferometer apparatus described in FIG. Reference numeral 19 surrounded by a dotted line indicates a boiling observation apparatus as one embodiment of the present invention. FIG. 2 further shows AA in FIG. 1,
1 shows an apparatus for observing the boiling state of the whole liquid.

In the boiling observation apparatus 19 using the schlieren optical system, the temperature distribution in the chamber 12 is three-dimensionally measured as described above. As shown in the figure, after the laser light output from the He-Ne laser oscillation tube 01 is expanded by the spatial filter 02, the direction of a part of the light is bent by the beam splitter 04. Using the bent light, the next beam splitter 05 separates the observation light 1 passing through the observation light path passing through the chamber 12 from the observation light 1 and the reference light. The reference light is further divided into two reference lights by the beam splitter 07. Here, the reference light bent in the right-angle direction by the beam splitter 07 is referred to as reference light 1, and the reference light that proceeds straight through the beam splitter 07 is referred to as reference light 2. The observation light 1 having passed through the chamber 12 crosses the reference light 1 again at the beam splitter 14, where a phase difference is generated.
By observing the interference state of light due to the phase difference with a CCD camera, the temperature distribution of the observation optical path cross section of the chamber 12 can be measured. Further, the observation light 2 that has traveled straight through the beam splitter 04 bends the direction of the light with the mirror 11 and passes through the observation light path provided in the lateral direction of the chamber 12 orthogonal to the observation light path through which the observation light 1 passes.

The observation light 2 travels straight through the beam splitter 07 by the beam splitter 22 and intersects with the reference light 2 which is bent and incident on the mirror 21 and generates a phase difference. To the CCD camera 24
By observing at, the temperature distribution in the cross section orthogonal to the cross section where the temperature distribution can be measured with the observation light 1 can be measured. As described above, according to the present embodiment, the temperature distribution of the two orthogonal cross sections of the chamber 12 can be measured. Thus, by combining and observing the temperature distribution, the three-dimensional temperature distribution in the chamber 12 can be observed.

In addition, the accuracy of temperature measurement also depends on the chamber 12.
When the thickness d of the observation fluid portion in the inside is about 10 cm and the observation is performed using a Ne—Ne laser having a wavelength λ of 632.8 mm as a light source, to observe one or more interference fringes, Δn = λ · N / d = 632.8 × 10 ^-9 · 1/10 × 10 ^-2 = 6.3
When water is used as the 28 × 10 ^-6 boiling liquid, the change in the refractive index per 1 ° C. is about 1 × 10 ^-4 / ° C. (at 20 to 30 ° C.), so that the measurement accuracy δ is δ = 6.328 × 10 6 ⁻⁶ / 1 × 10 ⁻¹⁴ = 0.063 ° C <0.1 ° C, and the measuring accuracy of the above-mentioned conventional RTD is ± 0.5.
It can be observed with an accuracy of 5 times or more of ° C.

Next, the Fizeau interferometer apparatus 20 for observing the state of the air bubbles generated in the chamber 12 and the state of the microlayer (liquid film) generated on the surface of the glass plate heater 09 will be described. The light source is the same He-Ne laser oscillation tube 0 as the schlieren optical system of the boiling observation device 19 described above.
1 is used, and the light that is expanded by the special filter 02 and transmitted straight through by the beam splitter 04 is used. After passing through the beam splitter 10, the light is collimated by the collimator lens 13 and directed to the glass plate heater 09.

At this time, a part of the light is reflected at the bottom of the glass plate heater 09 and is directed again toward the collimator lens 13. The transmitted light is partially reflected by the boiling bubbles generated on the surface of the glass plate heater 09, and proceeds toward the original optical path. The light that does not reflect at the bottom of the glass plate heater 09 and does not reflect even boiling bubbles and passes through the chamber 12 is used as the observation light 2 in the boiling observation device 19. The two reflected lights are bent by the beam splitter 10 and directed to the CCD camera 18. CC
In the D camera 18, the light enters from the mirror 11 and is generated between the light bent by the beam splitter and the two reflected lights.
By observing the interference state, the glass plate heater 0
Microlayers on nine surfaces and bubbles generated in the chamber 12 can be observed.

Further, the boiling state of the whole liquid in the chamber 12 can be observed by a CCD camera 26 installed on the upper part of the chamber 12, as shown in FIG. The light source is a light 28 provided at the lower part of the chamber 12, and the light illuminates bubbles inside the chamber 12. In FIG. 3 showing a conventional example, the apparatus for observing the boiling state of the whole liquid is observed in the same plane as the optical system of the Fizeau interferometer apparatus. In this way, planes perpendicular to these planes are observed. However, it observes the state of fluid boiling under microgravity where the influence of gravity is small, and this difference has no problem.

[0016]

As described above, according to the boiling observation apparatus of the present invention, it is possible to measure the temperature distribution in the boiling liquid three-dimensionally and extremely accurately, which has been a problem in the observation of the conventional apparatus. Will be able to Furthermore, since the measurement is performed using the same light source as the Fizeau interferometer, the measurement device is compact and lightweight, and it is easy to carry it under microgravity, that is, into a space or an aircraft capable of generating a microgravity environment. Furthermore, since the conventional apparatus can be used as it is or with a slight change in the arrangement, observation data necessary for elucidating the boiling mechanism can be acquired in more detail than before.

[Brief description of the drawings]

FIG. 1 is a plan view showing an embodiment of a boiling observation apparatus according to the present invention.

FIG. 2 is a front view taken on line AA of FIG. 1;

FIG. 3 is a plan view showing a conventional boiling observation device.

[Explanation of symbols]

01,31 He-Ne laser oscillation tube 02,33 Special filter (focus lens, pinhole) 03,32 Mirror 04 Beam splitter 05 Beam splitter 06 Collimator lens 07 Beam splitter 08 Collimator lens 09,37 Glass plate heater 10 Beam splitter 11 Mirror 12 chamber 13 collimator lens 14 beam splitter 15 mirror 16 collimator lens 17 CCD camera 18, 34 CCD camera 19 Schlieren optical system 20, 46 Fizeau interferometer 21 mirror 22 beam splitter 23 collimator lens 24 CCD camera 25 observation window glass 26, 42 CCD camera 27 observation window glass 28 illumination 29, 39, 41 observation window glass 35 beam splitter 36 collimation Tarens 38 Lighting 40 Chamber 43,44,45 Resistance thermometer

Claims (1)

(57) [Claims] An apparatus for observing a minute state of boiling of a heated liquid in a chamber, the apparatus comprising a Fizeau interferometer for observing bubbles of a boiling liquid and microlayers of the bubbles. Branching from the optical system of the Fizeau interferometer, the reference light passing through the observation optical path in the chamber and the reference light path bypassing the chamber, and passing these lights through the corresponding optical paths. A boiling observation apparatus characterized in that schlieren optical systems for measuring a temperature distribution in a chamber through which the observation light passes by the interference fringes generated at this time are provided in two directions orthogonal to the chamber.