SU1509807A1 - Method of determining swirl field - Google Patents

Abstract

The invention is intended to study the physical processes in liquids under laboratory conditions. The purpose of the invention is to make it possible to determine the vorticity field in real time with high accuracy. The method is that linearly polarized light is passed through the liquid. Then, in the light passing through the liquid, a component is isolated with a polarization, perpendicular polarization of the light incident on the liquid, and a phase that coincides with the phase of the transmitted light component with a polarization parallel to the polarization of the incident light. The selected light component is used to visualize the field of vorticity, and the field of vorticity is measured from the distribution of the light intensity in a plane perpendicular to the direction of its propagation. 3 il.

Description

The invention relates to the field of studying physical processes in liquids in laboratory experiments.

The aim of the invention is to improve the accuracy and ensure the determination of the field of vorticity in real time.

On the firm, 1 and 2, diagrams of douh devices are presented, variously implementing this method in Fig. 3, a diagram explaining the operation of a resonant amplifier in the device shown in Fig. 2.

The device shown in Fig. 1 contains a light source 1, optically coupled through a polarizer 2, arranged in series with an expanding telescope 3, a cuvette 4 with the liquid under study, a rotator 5 of the polarization plane and a reflecting mirror 6 optically coupled through a polarizer 2 with a cuvette; 4 consecutively located extending telescope 7, lens B and photo indicator 9.

As a source of light 1, you can use any standard illuminator that forms a parallel beam of light at the exit, for example, an industrial gas heater LG-79-1. As a polarizer 2, a Glan prism can be used or

SP

with

sc

31509807

anisotropic wedge with optical axis,

ten

15

20

parallel or perpendicular to the forming dihedral angle at the top of U1nna.

To create vorticity, you can pump the fluid through a stationary cuvette or rotate a hermetically sealed cuvette with a liquid around a certain axis (for example, for a cylindrical cuvette - around the longitudinal axis).

Expanding telescopes 3 and 7 may be absent if the light source forms a light beam with an aperture comparable to the aperture of the entrance window of the cuvette.

As a rotator 5 of the polarization plane, the Farade cell can be used.

As a photo indicator of 1tor, a screen, a camera, an electro-optical converter (EOC), a photomatrix, etc. can be used.

For research, almost any liquid can be taken, transparent in the wavelength range used.

The device shown in Fig. 25 has a higher sensitivity and contains successively located source 10 of monochromatic light, an expanding telescope 11, a cuvette 12 with the liquid under study, a narrowing telescope 13, a polarizer-modulator 14, an amplifier 15 optically coupled with element 16 connections with successively located resonant amplifier 17, filter 18, expanding telescope 19, and PHOTOJQ light.

As the active medium of a resonant amplifier, one can {- use dyes, vapors of alkali metals, etc.

The cuvette and photo light are similar to those described in figure 1.

The method of determining the vorticity field consists in injection into the fluid passing through the moving fluid with those components proportional to the vorticity. The distribution of the intensity of light, caused by this component in the plane perpendicular to the direction of its propagation, repeats the distribution of the vorticity of the fluid through which this light passed.

The dielectric constant tensor of a two-fluid liquid contains a term proportional to the vorticity of the liquid.

25

| K with + / 1,0

+ i-Ы

Uk

, Eh; DV,

+)

9HK

)

thirty

35

By the indicator 20, the source 21 of monochromatic light, optically connected by the same communication element 16 with the elements 17,18,19 and 20.

As a source of 10 monochromatic light, you can use a solid-state or gaseous laser, for example a laser of the LPIS type.

As a polarizer-modulator 14, polarizers can be used.

Eh; EHK

The first term is about the dielectric constant of a stationary liquid, the second and third terms arise due to the movement of a liquid, causing a change in the polarization of the transmitted light (the dynamo-optical effect), and the second term

h (: g-- + -} proportional to ten

Cr X i Eh

deformation of the fluid and lead to elliptical polarization of the linear flow through the fluid

and elements of tenz

) ra

i (

avK

the third is weak

swag, rot v

45

. - EU; Eh; EHK

proportional to the component, t, e, components of the vorticity vector. This term determines the rotation of the polarization of the linearly polarized light passing through the liquid, while the nature of the polarization does not change.

When falling linearly polarized-SG t ilCl, U, C; n-riJ: l Jinns-rinVJ iiWJl l j: ju.l

modulators operating on the basis of the effect of light on a layer of a moving liquid Farad.

As amplifier 15, it is possible to use an amplifier with an active element similar to that used in source 10.

As the communication element 16, a plane-parallel plate can be used.

55

bones of thickness L the vector E of the amplitude of the electric field of a light wave in the transmitted light has the form

i / l (k L (

E

Bbll

 EU-2 EU

l - ,

gk L

five.

rot V

one,

(2)

0

five

0

As the active medium of a resonant amplifier, you can {- use dyes, alkali metal vapors, etc.

The cuvette and photo light box are similar to those described in figure 1.

The method for determining the vorticity field is to detect the light transmitted through the moving fluid by a component proportional to the vorticity. The distribution of the intensity of light caused by this component in the plane perpendicular to the direction of its propagation repeats the distribution of the vorticity of the fluid through which this light has passed.

The dielectric constant tensor of a two-fluid liquid contains a term proportional to the vorticity of the liquid.

Q of light.

five

| K with + / 1,0

+ i-Ы

Uk

, Eh; DV,

+)

9HK

)

0

five

Eh; EHK

The first term is about the dielectric constant of a stationary liquid, the second and third terms arise due to the movement of the liquid and cause a change in the polarization of the transmitted light (the dynamo-optical effect), and the second term

h (: g-- + -} in proportion to tens X i Eh

deformation of the fluid and leads to elliptical polarization of the linear

and elements of tenzo) pa

i (

avK

third term, rot v

five

. - EU; Eh; EHK

proportional to the components, t, e, components of the vorticity vector. This term determines the rotation of the polarization of the linearly polarized light passing through the liquid, while the nature of the polarization does not change.

When falling linearly polarized, t ilCl, U, C; n-riJ: l Jinns-rinVJ iiWJl l j: ju.l

 light on a moving liquid layer

bones of thickness L the vector E of the amplitude of the electric field of a light wave in the transmitted light is

i / l (k L (

E

Bbll

 EU-2 EU

l - ,

five.

rot V

one,

(2)

where is her

k l Gf

tensor

amplitude vector of wave incident on the medium; wave number;

(EUT + 9vi h. Xi Eh / I, -2 coescentors. When choosing the Z axis in the direction of light propagation, the x axis in the direction of polarization of the incident light in the light passing through the moving fluid along with the light component

Si

(Bx)

polarized along the x axis the light component appears

with polarization, perpendicular polarization of the incident light, i.e. by (). This

l rizovanna along the axis y

in the first approach

component E (

consists of two terms, one from which is proportional to the deformation medium, and the other - to the vorticity.

/ Ilk L

. 6Y

 EI

p1 E ,, Ehh

 8y

+ 1) Eh

 J

(3)

where A is the axial component (z-component) of the vorticity vector, Ji (rot v) ij. The first term in this expression, proportional to the deformation, has a phase that is perpendicular to the phase of the E component, i.e. shakes "bch" c in quadrature with the field of wave E,

and the second term, proportional to the vorticity, has a phase that coincides

with a phase of component E, i.e. , you are t

spu

in-phase with E,

Thus, in the elliptic-polarized light transmitted through the moving fluid, there is a proportional to the fluid vorticity of the component with polarization, the perpendicular polarization of the incident linearly polarized light, and phase E, 50

It is rational of the vorticity of the fluid. This component, proportional to the vorticity of the liquid, can be separated from the component E J by passing it through a polarizer. The distribution of the intensity of light due to this component in the plane, the perpendicular direction of its propagation, repeats the distribution of the vorticity of the liquid through which this light has passed. The field of vorticity can be visualized by a picture of the distribution of the intensity of light caused by this component on the photo indicator mounted in a plane perpendicular to the direction of its propagation. The measurement of the vorticity field is carried out by photometric this pattern.

The operation of the device shown in FIG. 2 is also based on

that kogshonenta floor E,

in the formula

(3) is proportional to the vorticity.

I

ten

5098076

in formula (3), mutually, and the rotation i is polarized due to the vorticity of the medium (the second term in g formula (3J) is non-reciprocal (Faradean type. Therefore, if after passing; auger-polarized light through the driving fluid into the In the opposite direction, passing light through the liquid in the opposite direction along the same path, having previously turned its polarization 1 пол by 90, the polarization change caused by the deformation of the medium is compensated, and the polarization rotation caused by the vorticity of the liquid doubled.

Consequently, in the double past (forward and backward) through the moving fluid, the light along with the component of light polarized along the x axis

15

20

x „6Ы1 h

(, B,), will only be present that KONmoHeHTa of light, polarized

25 along the axis y

(kg)

which is proportional

in phase with, and the component of the floor E,

It is rational of the vorticity of the fluid. This component, proportional to the vorticity of a liquid, can be separated from the component E J by transmitting light through a polarizer. The distribution of the intensity of light due to this component in the plane, the perpendicular direction of its propagation, repeats the distribution of the vorticity of the liquid through which this light has passed. The vorticity field can be visualized by the pattern of the distribution of light intensity due to this component on the photo indicator mounted in a plane perpendicular to the direction of its propagation. The measurement of the vorticity field is carried out by photometric this pattern.

The operation of the device shown in FIG. 2 is also based on that.

in phase with, and the component of the floor E,

that kogshonenta floor E,

in the formula

in phase with, and the component of the floor E,

(3) is proportional to the vorticity.

I

the phase of the transmitted light component with the polarization of the parallel polarization of the incident light.

The basis of the operation of the device for implementing the method j shown in Fig. 1 is the property that the change in the psrnstr condition due to the deformation of the medium {. The first term

55

proportional to deformation, oscillating in quadrature with the wave field

„Calc

(

A monochromatic linearly polarized light along the X axis, a frequency light formed by the source, a passage through the cell with the liquid under study, with

 15

acquires elliptical polarization at the exit from the cuvette, and the resulting deformation of the liquid leads to the ellipticity of the transmitted light, and the resulting vorticity causes the major axis of the ellipse to rotate relative to the x axis, leaving the character of polarization unchanged. In order to select a light component proportional to the vorticity, the light is first passed through a polarizer-modulator 14, in which the angle of inclination 8 is polarized and the light passing through it to the y axis is modulated with a frequency D chosen by

 c (t is the relaxation time of the population of the active medium of the amplifier. 17) and, It is advisable to choose the amplitude of the modulation of this angle so that the output of the polarizer-modulator. 14 light components

out

sin 0, (E h +

E5

Cos

were

J u O-it u H-LJ h

one order of magnitude (the amplitude E of the light at the output of the polarizer-modulator 14 is equal to the sum of these components — the law of Malus).

This linearly polarized and modulated light with frequency L is used as a backlight in the resonant amplifier 17, to which the light of a7iiWo frequency (fig. 3) from the source 21 is simultaneously directed. As a result, at the output of the amplifier 17 the field contains is proportional to E I CWf), where E (is the frequency field amplified in it with “E (.

Due to the fact that the angle 0. is modulated in time with the frequency-and: Wo j, the backlight contains various low-frequency harmonics A, and the field at

50

The output of amplifier 17, among other distri- bution metrics, intensifies the harmonic of the OR. + A, the amplitude of the bones of the light.

The method is carried out as follows.

At the initial time, the cuvette 4 is at rest. Turn on laser 1 and calibrate the entire system. It is as follows. The generated light source 1 parallel beam of light is directed to the polarizer 2 - the Glan prism. Since laser 1 forms linearly polarized radiation, polarizer 2 is tuned to the maximum transmission of light incident on it.

the second is proportional to Е Е (,

those. proportional to vorticity.

The selection of this harmonic can be accomplished using a filter 18, which, however, it is advisable to constructively combine with an amplifier 17, collecting the latter in a regenerative circuit with a single-mode resonator at a frequency of 05, + L, while it is better to use an active medium that has one of the levels split with a splitting frequency equal to / v i 55

eight

0

five

0

five

0

five

0

Example. The method is carried out at the facility assembled according to the scheme shown in FIG. As the source of light 1 use gas laser LG-79-1. Polarizer 2 shown in the form of a Glan prism. The field of vorticity is created in a cylindrical cell 4 filled with distilled water. Cuvette length d 300 mm. The cuvette windows with a diameter of 100 mm are made of K-8 optical glass and reinforced with rubber gaskets with cap nuts. In the cuvette, a hole is closed, closed with a screw cap, for pouring the cuvette into a closed cell. The cuvette 4 rotates on two ball bearings, the inner rings of which are pressed into the body of the cuvette, and the outer ones are pressed into the supports fixed to the massive base. The rotation of the cuvette 4 is carried out from a 600 W three-phase electric motor using a belt drive. The pulley on the cuvette 4 is placed in the middle of its length and is performed as 1: 1, 1: 1/2, 1: 1/4, respectively. The electric motor is fastened through a rubber gasket on the same basis as the cuvette. The system contains a tension adjustment device for the drive belt. The speed of rotation of the cuvette can be adjusted from zero to 3600 rpm.

As mirror 6, I use a dielectric mirror with a reflection coefficient on L 63 µm 1 99% with a diameter of 100 mm.

As a non-reciprocal. Elemen: Fresnel rhombus is used.

As a photo indicator 9, a screen is used, the image of which is taken on a photographic film for a photo camera.

9150

The linearly polarized radiation received at the output of the polarizer 2, through the expanding telescope 3, is directed into the cuvette 4 with the investigated area. From the code of the cuvette 4, the light beam is directed onto the rotator 5 of the polarization plane, which turns the polarization on.

Then the light beam is directed to the reflecting mirror 6. The light beam reflected by the mirror 6 again passes through the rotator of the polarization plane and experiences a rotation of the polarization plane by another 1G / 4. Next, the beam is successively passed through the cuvette. 4 and the telescope 3 in the opposite direction and directed to polarization 2. In this case, the screen 9 installed behind the expanding telescope 7 and the lens 8 must have a dark field, because due to reciprocity, the rotation of the field is compensated for by the backward passage of the light beam through the system transformations due to random anisotropy of optical elements.

ten

A cuvette is then rotated up to a speed of 3600 rpm, and a vorticity field is observed on screen 9, and a vorticity field is measured by photometry of the intensity distribution of the light field on the screen.

Claims (1)

Invention Formula The method of determining the vorticity field, characterized in that, in order to increase the accuracy and ensure the measurement of the field of vorticity in a real time scale, linearly polarized light is passed through the liquid, the spatial amplitude distribution of the components with polarization, perpendicular polarization, passes through the light liquid light incident on the medium, and a phase that coincides with the phase of the transmitted light component with a polarization parallel to the polarization of the incident light, and the amplitude distribution is enhanced The hry components are judged on the vorticity field. Fiel fi) eleven ff / ti Phie.g Fia.