JPH063250A - Surface tension measuring device - Google Patents

Abstract

PURPOSE:To measure the surface tension of a liquid by rotating and floating the rotating elliptic liquid ball of an object to be measured under nongravity or minute gravity, positioning it in a determined position by a supporting means of gas flow, and detecting its form and rotating speed by an optical means. CONSTITUTION:When a liquid 2 received in a liquid receiving vessel 1 is rotated at a determined rotating speed under ground gravity, and the whole device is laid in the state closer to nongravity, the liquid 2 becomes a rotating elliptic form and is rotated. A gas is blown out through a plurality of guiding nozzles 5, and the liquid ball 2A is floated from the vessel 1 and guided to the area of a light receiving element array 3 which is a measuring position. The liquid ball 2A is stabilized in the measuring position by the fine gas molecule flow from a holding nozzle 6. Thereafter, the longer diameter and shorter diameter of the liquid ball 2A are read from its profile projected to the array 3, and the rotating speed is detected from the periodic wave motion. These numerical values are substituted to a specified equation, whereby the precise surface tension of the liquid never influenced by gravity acceleration can be measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface tension measuring device, and more particularly, to the surface of a device in the process of developing a product using a new element or new material, manufacturing a metal and its alloy, or handling a liquid material in metallurgy. The present invention relates to a surface tension measuring device suitable for being applied to a field where precise numerical measurement of tension is required.

[0002]

2. Description of the Related Art An example of a classical surface tension measuring device which has been conventionally used in such a field will be described below.

(Part 1) Ring Pulling Method A basic configuration according to this example is shown in FIG. Here, 101 is a spring meter configured by using a coil spring 102, 103
Is a ring formed by a thin plate, which is hung at the lower end of the spring scale 101, 104 is placed below the ring 103, and a container (a liquid to be measured) 105 to be measured is stored in the container. Reference numeral 106 denotes a pedestal that allows the container 104 to move slightly up and down.

In the surface tension measuring device thus constructed, the lower surface of the circular ring 103 is kept in contact with the surface of the liquid 105, and then the container 1 is gradually moved together with the receiving table 106.
04 is lowered. With the lowering action,
At first, the surface tension of the liquid 105 overcomes, so the surface of the liquid 105 attached to the ring 103 extends and is pulled upward, but when the spring force of the coil spring 102 overcomes the surface tension. The liquid 105 is separated from the ring 103 at. Therefore, the surface tension can be read from the reading of the extension of the spring scale 101 at this moment. However, in this case, the liquid 1 attached and pulled up together with the ring 103
Since the weight of the attached portion of 05 is included, it is necessary to correct it as shown in the following formula (1). Note that FIG.
Indicates the state of specifications related to the above measurement.

[0005]

[Equation 1]

Here, r ₁ is the outer radius of the circular ring 103, r ₂ is the same inner radius, h is the height of the circular ring 103 pulled up to the time of measurement, σ is the surface tension, and ρ is the liquid density. , G is the acceleration of gravity, and f is the coefficient of friction.

(Part 2) Capillary Method In this example, as shown in FIG. 5, the capillarity by the capillary 201 is utilized. When a capillary with a small diameter is set up on the liquid surface 202, the liquid adhering to the inner wall is not wet. When it occurs, the liquid ascends in the capillary 201 to the equilibrium height due to the relationship between gravity and the liquid surface tension. Then, in such a case, a meniscus 203 is formed on the rising top of the liquid.
Therefore, when the height from the bottom surface of the meniscus 203 to the original liquid surface is h and the inner diameter of the capillary tube 201 is R, the surface tension σ can be calculated by the following equation (2).

[0008]

[Equation 2]

If the capillary 201 is extremely thin and the contact angle θ with the inner surface of the meniscus 203 is approximately 0,

[0010]

[Equation 3]

The above (1) and (2)
In addition to the method described in 1 above, although description is omitted, there are known methods such as a liquid drop method and a liquid drop method. However, in all of them, the measured value fluctuates depending on the contact state of the liquid with the vessel wall and the like. In addition, since g included in the measured value becomes a large element, it is difficult to accurately extract and calculate only the surface tension.

Further, recently, a method of measuring the surface tension of the liquid by using an approximate expression while vibrating the liquid droplet in a weightless state has been disclosed.

[0013]

However, in the conventional method for measuring the surface tension of the liquid under the gravity on the ground as described above, in the case of the (1) annular pulling method, There are variations in the material of the ring 103 itself and the adhesion of liquid, that is, the phenomenon of wetting, and the spring meter 10
There is a problem in that the accuracy of No. 1 cannot be improved, and sufficient measurement accuracy cannot be expected.

Further, even in the case of (2) the capillary system, the shape of the meniscus formed by wetting,
That is, the contact angle θ changes, and it is difficult to accurately capture the position. In any case, there is a problem that an extremely large volumetric force called gravity hinders the measurement of the surface tension, which is the binding force of the weak liquid molecules, and an accurate measurement cannot be obtained.

The object of the present invention is to pay attention to the problems of the conventional measurement method, and to maintain a non-contact state with respect to a liquid and weightlessness or close to weightlessness, and a precise method with a small error by a logical method. An object of the present invention is to provide a surface tension measuring device capable of obtaining a measured value of surface tension.

[0016]

In order to achieve such an object, the present invention provides a container capable of holding a spheroidal liquid droplet of a liquid to be measured which rotates under zero gravity or microgravity, and the container described above. A gas flow levitation means that acts to levitate the liquid ball to a predetermined measurement position, and also functions to support the liquid ball that has been levitated to the predetermined measurement position in that state and to reinforce the rotation of the liquid ball. And a detection means for optically detecting the spheroidal shape of the liquid ball supported at the predetermined measurement position and the rotation speed thereof, which are detected by the detection means. The surface tension of the liquid to be measured can be calculated based on the data.

[0017]

According to the present invention, the spheroidal liquid droplet of the liquid to be measured which is rotated under zero gravity or microgravity is floated from the container by the gas flow levitation means, and the floated liquid ball is supported by the gas flow. It is possible to measure the surface tension of the liquid to be measured by detecting the spheroidal shape of the liquid ball positioned by the optical detecting means and the rotational speed thereof by supporting and positioning the liquid ball at a predetermined measuring position by means of the means. .

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the present invention will be described in detail below with reference to the drawings, but prior to the description, the principle of application of the present invention will be described. That is, when the liquid is kept in a non-contact state close to zero gravity by levitating in the air,
Focusing on the fact that the item of gravitational acceleration can be eliminated from the calculation element, which enables highly accurate measurement and accurate calculation, the liquid surface caused by the adhesion between the liquid and the container and the influence of gravity It is possible to completely eliminate the cause of an error in calculation such as a change in shape.

In the measurement of the surface tension by the spinning drop method under the condition of weightlessness, the surface tension σ is expressed by the following equation (4) when the large centrifugal force acting on the rotating droplet and the surface tension are in equilibrium. ) Is what is required by.

[0020]

[Equation 4]

Here, e is the eccentricity, a is the major axis of the spheroid, b is the minor axis, and ω is the number of revolutions, the denominator is the surface area of the droplet, and the numerator is the moment of inertia.

That is, when the droplet is rotated in one direction around the polar axis in a state of almost zero gravity, the rotating droplet is subjected to the centrifugal force of the spin in order to stabilize it according to the principle of energy conservation. This means that the liquid surface near the equator expands and contracts in the polar direction so as to maintain a uniform short-axis spheroidal shape so as to be in equilibrium. However, if spin is applied too much, it goes without saying that the droplets will scatter and become a state like a miniature model of the galaxy nebula, and it is necessary to maintain a spin to such a degree that it does not occur.

Then, the measuring device and its operation for measuring the surface tension of the liquid by keeping the liquid in the state based on the above principle will be described with reference to FIG.

In FIG. 1, reference numeral 1 is a vessel for storing a liquid to be measured, which is a pot-shaped container in which at least the inner surface thereof is treated to prevent wetting, and 2 is a liquid which is contained in the container 1 and whose surface tension is to be measured. Is. Further, 3 is a light receiving element array which is arranged in a direction parallel to the paper surface and receives light emitted from a direction perpendicular to the paper surface, and which has an area sufficiently larger than the projected area of the liquid droplet 2A to be measured. It functions to keep and read the shape of the liquid droplet 2A. Reference numeral 4 denotes a photoelectric type position detection sensor which is disposed in the peripheral portion of the region of the light receiving element array 3 and monitors so that the peripheral portion of the measured liquid droplet 2A does not deviate from the region of the light receiving element array 3.

Further, 5 is a plurality of liquid droplet guiding nozzles arranged around the outer periphery of the light receiving element array 3, and 6 is an area of the light receiving element array 3, that is, liquid droplets that are measured symmetrically at a predetermined position in the measurement area. 2A is a positioning nozzle (hereinafter referred to as a holding nozzle) as a supporting unit that ejects gas while controlling gas, for example, air. In addition, here, a liquid (liquid ball) 2A that rotates from the inside of the rotary container 1 as described later.
Since a large amount of air flow is required to guide the light to the area of the light receiving element array 3, the guiding nozzle 5 has a larger discharge amount than the holding nozzle 6. Moreover, the plurality of guiding nozzles 5 are arranged in such a form that the liquid ball 2A can be easily guided to a predetermined position in the area after the liquid ball 2A is levitated from the rotary container 1.

Next, the measurement operation of the surface tension measuring device having such a configuration will be described. In the measurement, a means for measuring atmospheric conditions related to the surrounding environment such as temperature detecting means and pressure detecting means (not shown). Needless to say, is provided.

First, as a first step, the liquid 2 stored in the liquid storage container 1 under the condition of gravity on the ground is kept rotated by a rotating means (not shown) at a predetermined number of rotations, and the wetness is kept. The storage container 1 that has been subjected to the preventive treatment is guided together with the entire apparatus into a state of almost zero gravity. Then, the liquid 2 that has been given a rotation becomes a sphere (liquid ball) close to a spheroid with the short axis as the center of rotation. Then, next, a large amount of gas is ejected by a plurality of guide nozzles 5 to float a liquid ball 2A which is kept in an ellipsoidal shape that rotates and is floated from the inside of the storage container 1, and such a liquid ball 2A is a light receiving position which is a measurement position. It is led to the area of the element array 3. In addition, such levitation guidance is performed by controlling the gas blowing from the plurality of guidance nozzles 5 and detecting the liquid droplet 2A by the photoelectric position detection sensor.

Thus, if the liquid droplet 2A is guided to a predetermined measuring position within the above-mentioned region, then the holding nozzles 6 provided in the plurality of surroundings will not disturb the gravitational field of about 10 ^-6 g. The gas molecule flow is discharged from the four sides in such a manner as to wrap the liquid droplet 2A, and the liquid droplet 2A is stabilized at the measurement position.
Then, after that, the major axis a and the minor axis b of the liquid droplet 2A projected on the light receiving element array 3 are read and, for example, the periodic wave of the contour can be captured to detect the rotation speed ω. Thus, the gravitational acceleration g is calculated by substituting these measured values into the above-mentioned equation (4) and calculating.
It is possible to measure the accurate surface tension σ of the liquid that is not affected by The calculation is performed by a computer (not shown) having a CPU function (not shown), and data such as the rotation speed ω with respect to the ratio of the major axis a and the minor axis b of the spheroid are represented by the ambient temperature and the liquid temperature. It is stored in the storage means ROM on the basis of atmospheric pressure and the like, and is performed by looking up such a table each time measurement is performed.

As a simple means for reading a, b, and ω, a clear scale is placed instead of the light-receiving element array, and continuous shooting with a video camera is sufficient for rough measurement.

As described above, the method of guiding the liquid ball, which has been preliminarily rotated under ground power, to a predetermined detection position under microgravity has been described.

The reason for adopting this method is that it is possible that the liquid ball follows a stable floating course when it rotates. However, if we take the opposite idea, especially for liquid droplets with a large surface tension, after floating from a stationary container that has been processed or treated so that the surface is hard to get wet with a non-rotating sphere near a true sphere, After being guided to a predetermined position with the same mechanism as above, the outer wall of the cylinder is rotated for the first time to rotate the liquid ball with the viscosity of the air, and the above-mentioned holding nozzles are temporarily moved all at once in the ω direction around the assumed rotation axis. It may be possible to give the rotation later by tilting it so that the rotation is given. In any case, there is no change in using the basic concept of optically reading the shape of the spheroid and its rotation speed to know the value of the surface tension. Is it spinning before it becomes weightless,
It is the difference whether it is non-rotating until then.

FIG. 2 shows an example of the shape of the liquid storage container 1. In FIG. 2A, the inner surface has a spheroidal shape,
(B) shows a cylindrical shape, and (C) shows a spherical inner surface. However, the possible shape of this kind of container 1 is not limited to these, but a stable spheroidal liquid droplet is likely to be formed at least in a container that is not affected by wetting, and the liquid droplet is arbitrarily formed. Any shape may be used so long as it does not jump out of the container.

It is also conceivable to use laser light, sound pressure, or an electrostatic field as means for levitating the liquid droplets, but there still remains a problem to be solved regarding separation from the container and guidance to the measurement position. ing.

[0034]

As described above, according to the present invention, a container capable of holding a spheroidal liquid droplet of a liquid to be measured that rotates under zero gravity or microgravity, and the liquid droplet from the container. A gas flow levitation means that acts so as to float at a predetermined measurement position, and a gas flow that also functions to support the liquid ball floated at the predetermined measurement position in that state and to reinforce the rotation of the liquid ball. Supporting means and a detecting means for optically detecting the spheroidal shape of the liquid droplet supported at the predetermined measurement position and its rotation speed, and based on the data detected by the detecting means. Since it is possible to calculate the surface tension of the liquid to be measured, it is possible to solve the problem of gravitational acceleration, which has a large effect as a volume force as in the past, and the problem of measurement error due to wetting with equipment involved in measurement. And a little By using the energy balance condition between the centrifugal force and surface tension conditions and gravity,
It has become possible to carry out highly accurate measurements.

[Brief description of drawings]

FIG. 1 is an explanatory diagram schematically showing an example of the configuration of a surface tension measuring device of the present invention together with the operation.

FIG. 2 is a cross-sectional view showing examples of three forms of a liquid storage container according to the present invention by (A), (B), and (C).

FIG. 3 is an explanatory diagram showing a configuration example of a conventional ring pulling system.

FIG. 4 is an explanatory diagram of measurement specifications by an annular pulling method.

FIG. 5 is an explanatory diagram of measurement specifications in a conventional example using a capillary method.

[Explanation of symbols]

 1 Liquid Storage Container 2 Liquid 2A Liquid Ball 3 Photoreceptor Array 4 Photoelectric Position Detection Sensor 5 Guidance Nozzle 6 Holding Nozzle

Claims (3)

[Claims] 1. A container capable of holding a spheroidal liquid ball of a liquid to be measured which rotates under zero gravity or microgravity, and a gas flow which acts to float the liquid ball from the container to a predetermined measurement position. A floating means, a gas flow supporting means which also functions to reinforce the rotation of the liquid ball while supporting the liquid ball floated at the predetermined measurement position in that state, and supported at the predetermined measurement position. And a detection means for optically detecting the spheroidal shape of the liquid ball and its rotation speed, and the surface tension of the liquid to be measured can be calculated based on the data detected by the detection means. A surface tension measuring device characterized in that 2. The detecting means for optically detecting detects a major axis and a minor axis of a spheroid of the liquid ball and fluctuations of its periodic shape.
The surface tension measuring device according to. 3. The container according to claim 1, wherein at least an inner surface of the container for containing the liquid to be measured is anti-wetting, and has a floating port above which the liquid ball is floated. Surface tension measuring device.