JPH09113531A - Device and method for measuring flow velocity distribution - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow velocity distribution measuring device for measuring the distribution of flow velocity of a flow passage to be measured without changing the constitution of an object to be tested, in which the fluid is circulated. SOLUTION: Fluid, which flows in a fluid cell 4 forming a flow passage to be measured and which includes a color element for absorbing the laser beam, is irradiated with the pulse laser beam by a second harmonic generator 28 of a pulse YGA laser from a direction crossing the flowing direction. Similarly, the fluid is irradiated with the probe laser beam to be transmitted through the fluid by a CW color element laser generating unit 21 from a direction crossing the flowing direction of the fluid and crossing the pulse laser beam so as to change refractive index of the fluid, and the distribution of refractive index is photographed as a change of the intensity of the probe laser beam by a streak camera 27 so as to obtain the distribution of flow velocity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow velocity distribution measuring device and method capable of measuring the flow velocity distribution of an object to be measured in a flow path under measurement with high resolution spatially and temporally.

[0002]

2. Description of the Related Art FIG. 9 shows the structure of a conventional flow velocity distribution measuring device described in, for example, "Laser Handbook (1982, published by Ohmsha)". In FIG. 9, 100 is a flow velocity distribution measuring device, 1 is an N ₂ pulse laser generator, 2
Is a lens for condensing the N ₂ pulse laser generator 1, 3 is a slit for determining the irradiation position of the N ₂ pulse laser generator 1 on the fluid cell 4, and 4 is a flow to be measured in which a fluid mixed with luminescent particles flows. A fluid cell forming a passage.

Reference numeral 5 is a night-vision scope for amplifying the emission of luminescent particles in the fluid excited by the N ₂ pulse laser generator 1, and 6 and 7 are images of the night-vision scope 5 transferred to a television camera 8 Reference numeral 9 is a video tape recorder for recording an image of the television camera 8, and 10 is a monitor television for observing the image of the television camera 8.

Reference numeral 11 is a photo interrupter for generating a trigger signal corresponding to the position of a hole (not shown) formed in the rotary plate 12, 12 is a rotary plate, and 13 is a photo interrupter 11 and N ₂ pulse laser generation. A laser trigger device for synchronizing with the device 1, 14 is a photo interrupter power supply of the photo interrupter 11, 15 is a motor for rotating the rotary plate 12, and 16 is a controller of the motor 15.

Next, the operation will be described. When the position of the hole of the rotary plate 12 matches the position of the photo interrupter 11,
A trigger signal is generated from the photo interrupter 11, and the laser trigger device 13 operates to operate the N ₂ pulse laser generator 1.
Oscillates. The N ₂ pulsed laser light (excitation light) is condensed by the lens 2 and irradiated on the fluid cell 4. In the fluid cell 4, a fluid in which luminescence particles are mixed as a tracer flows in a direction perpendicular to the paper surface. The luminescent particles have the property of emitting light when excited by excitation light.

Luminescent particles in the fluid are excited by excitation light at the position of the slit 3, and the position of the hole of the rotary plate 12 moves from the photointerrupter 11 to the position between the fluid cell 4 and the night-vision scope 5. The light emission pattern after the time Δt is amplified by the night-vision scope 5, transferred by the lenses 6 and 7, and photographed by the television camera 8. The captured images are recorded by the video tape recorder 9 and the monitor TV 1
Observe at 0. The distance traveled by the luminescent particles is measured at Δt time from the photographed image, and the flow velocity is determined accordingly.

[0007]

In the conventional flow velocity distribution measuring device configured as described above, it is necessary to mix luminescence particles having a particle diameter of several tens of μm as a tracer into the fluid, and therefore the fluid to be evaluated. The composition of the flow is changed, the characteristics of the flow are changed, the capillaries are clogged with particles, the filter attached to the test object needs to be removed, and the circulation attached to the test object is changed. There was a problem that the pump was damaged by particles.

The present invention has been made in order to solve the above problems, and it is easy to maintain the flow velocity distribution in the flow path under measurement without changing the constituent elements of the test object for circulating the fluid. An object of the present invention is to provide a flow velocity distribution measuring apparatus and method capable of measuring the flow velocity.

[0009]

In view of the above-mentioned object, the first invention of the present invention provides a fluid containing a dye that absorbs laser light flowing in a flow path to be measured of an object to be measured and a direction of the flow of the fluid. Irradiating pulsed laser light from the intersecting direction, irradiating probe laser light that is transmitted to the fluid from a direction that also intersects with the flow direction of the fluid and also intersects with the pulsed laser light. There is provided a flow velocity distribution measuring device characterized in that the flow velocity distribution of the flow path to be measured is measured by changing the refractive index of the fluid and measuring the refractive index distribution by the fluid from the probe laser light that has passed through the fluid. .

In a second aspect of the present invention, the refractive index distribution due to the change in the refractive index generated in the fluid irradiated with the pulsed laser light is measured by a streak camera as the temporal change in the intensity of the probe laser light. The flow velocity distribution measuring apparatus according to claim 1, wherein the flow velocity distribution is obtained by performing the above.

According to a third aspect of the present invention, an interference fringe formed by the probe laser beam and the probe laser beam transmitted through the fluid in which the refractive index is changed by the pulse laser beam is obtained by a Mach-Zehnder interferometer, The flow velocity distribution measuring device according to claim 1, wherein the flow velocity distribution is obtained by measuring the refractive index distribution as a temporal change of the interference fringes with an ICCD camera with a high speed gate.

A fourth aspect of the present invention is directed to a fluid cell which forms the flow path to be measured and through which the fluid flows, and a direction in which the probe laser light is generated and which intersects with the flow direction of the fluid in the fluid cell. A probe laser light generating means for irradiating a probe laser light, and a pulse laser which generates the pulse laser light and transmits the pulse laser light to the fluid from a direction intersecting with the flow direction of the fluid in the fluid cell and also intersecting with the pulse laser light. Light generating means, probe laser light photographing means including the streak camera for photographing the time change of the probe laser light transmitted through the fluid, which has a change in refractive index due to the influence of the pulsed laser light, and the pulse laser light generation Means for controlling the streak camera according to the timing of the pulsed laser light of the means, and the probe laser light imaging First measurement processing means for performing image processing of the image obtained by the means to obtain a flow velocity distribution from the temporal change of the intensity of the probe laser light; and first monitoring means for monitoring the image of the streak camera. The flow velocity distribution measuring device according to claim 2, further comprising:

A fifth aspect of the present invention is directed to a fluid cell which forms the flow path to be measured and through which the fluid flows, and a direction in which the probe laser beam is generated and which intersects the fluid flow direction of the fluid cell. A probe laser light generating means for irradiating a probe laser light, and a pulse laser which generates the pulse laser light and transmits the pulse laser light to the fluid from a direction intersecting with the flow direction of the fluid in the fluid cell and also intersecting with the pulse laser light. Light generating means, a probe laser light having a change in refractive index due to the influence of the pulsed laser light, which has passed through the fluid, and a probe in which the probe laser light from the pulsed laser light generating means is partially branched directly. Interference fringe forming means including the Mach-Zehnder interferometer for obtaining interference fringes with the laser light, and time of the interference fringes from the Mach-Zehnder interferometer I with the high-speed gate to shoot the change
Interference fringe photographing means including a CCD camera, second photographing control means for controlling the high speed gated ICCD camera according to the timing of the pulsed laser light of the pulsed laser light generation means, and images of the high speed gated ICCD camera are stored. Memory means for performing image processing of the image obtained by the interference fringe photographing means, and second measurement processing means for obtaining a flow velocity distribution from the temporal change of the interference fringes, and the measurement processing means. Second monitor means for monitoring the image,
The flow velocity distribution measuring device according to claim 3, further comprising:

According to a sixth aspect of the present invention, the probe laser light generating means and the pulse laser light generating means branch laser light from one laser generator by laser light branching means, and The flow velocity distribution measuring device according to any one of claims 1 to 5, wherein the pulsed laser light is obtained by pulsing with a chopper means.

In a seventh aspect of the present invention, the pulsed laser light is the second harmonic of a YAG laser having a short pulse width,
The flow velocity distribution measuring device according to any one of claims 1 to 5, wherein either excimer laser light or copper vapor laser light is used.

An eighth invention of the present invention is that, as the probe laser light, a continuous wave dye laser light, an Ar laser light,
The flow velocity distribution measuring apparatus according to any one of claims 1 to 5, wherein either He-Ne laser light or the second harmonic of a continuous wave YAG laser is used.

According to a ninth aspect of the present invention, a dye that absorbs laser light is added to a fluid flowing through a flow path to be measured of an object to be measured, and a pulse laser is added to the fluid from a direction intersecting the direction of the flow. Irradiating light, irradiating with probe laser light which is transmitted to the fluid from a direction that also intersects the flow direction of the fluid and also intersects with the pulsed laser light, and changes the refractive index of the fluid by the pulsed laser light. Change
The flow velocity distribution measuring method is characterized in that the flow velocity distribution in the flow path to be measured is measured by measuring the refractive index distribution thereby obtained from the probe laser light that has passed through the fluid.

In a tenth aspect of the present invention, the refractive index distribution due to the change in the refractive index generated in the fluid irradiated with the pulsed laser light is defined as the temporal change in the intensity of the probe laser light transmitted through the fluid. The flow velocity distribution measuring method according to claim 9, wherein the flow velocity distribution is obtained by measuring.

An eleventh invention of the present invention obtains an interference fringe by the probe laser light and the probe laser light transmitted through the fluid in which the refractive index is changed by the pulse laser light and obtains a refractive index distribution. The flow velocity distribution measuring method according to claim 9, wherein the flow velocity distribution is obtained by measuring the change in the interference fringes with time.

A twelfth aspect of the present invention is characterized in that the laser light from one laser generator is branched and the probe laser light and the laser light are pulsed to obtain the pulsed laser light. Item 9 is the flow velocity distribution measuring method according to any one of items 9 to 11.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The embodiments will be described below. Embodiment 1 FIG. 1A and 1B are diagrams showing a configuration of a flow velocity distribution measuring device according to Embodiment 1 of the present invention, wherein FIG. 1A is a plan view and FIG. 1B is a side view. In the figure, 100a is a flow velocity distribution measuring device, 21 is a CW dye laser generator for generating continuous wave (CW) dye laser light used for probe laser light, 22 is a beam expander for expanding the probe laser light, and 23 is Slits 4 for shaping the probe laser light are fluid cells forming a flow path to be measured. In the fluid cell 4, a fluid containing a pigment dye that absorbs laser light, which will be described later, flows in a direction perpendicular to the paper surface.

Reference numeral 24 is a diaphragm for the amount of probe laser light, and 25
Is an image relay optical system for image-relaying the image of the fluid cell 4, 26 is an optical filter that transmits only the probe laser light, and 27 is a streak camera (for example, manufactured by Hamamatsu Photonics) that captures a high-speed temporal change of the incident image. c2830 type).

28 is a second harmonic generator of a short pulse width YAG laser beam used as an excitation light source (pulse laser light source), 29
Is a transmission optical system for pumping light (pulse laser light), and 30 is a delay circuit for setting the operation timing of the streak camera 27.

Reference numeral 31 is a camera controller of the streak camera 27 (for example, using C-CCD / IL manufactured by Hamamatsu Photonics), 32 is an image processing unit composed of a personal computer for processing the image of the streak camera 27, and 10 is a monitor television.

The CW dye laser generator 21, the beam expander 22 and the slit 23 constitute a probe laser beam generating means, and the second harmonic wave generator 28 and the transmission optical system 2 are provided.
Reference numeral 9 constitutes a pulsed laser light generating means, and a light quantity diaphragm 24,
The image relay optical system 25, the optical filter 26, and the streak camera 27 constitute a probe laser light photographing means,
The delay circuit 30 and the camera controller 31 constitute a first photographing control means, the image processing section 32 constitutes a first measurement processing means, and the monitor television 10 constitutes a monitor means.

Next, the operation will be described. Pulse YAG
The transmission optical system 29 irradiates the fluid cell 4 with excitation light composed of pulsed laser light emitted from the second harmonic generator 28 of the laser light. On the other hand, the probe laser light emitted from the CW dye laser generator 21 is emitted by the beam expander 22.
After being enlarged by, it is shaped by the slit 23 and passes through the fluid cell 4. Then, the probe laser light transmitted through the fluid in the fluid cell 4 is photographed by the streak camera 27 as an image of the fluid in the fluid cell 4 by the image relay optical system 25 through the light quantity diaphragm 24.

The streak camera 27 starts its operation immediately before the excitation light is incident on the fluid cell 4, and the delay circuit 30 is operated by the signal from the second harmonic generator 28 in accordance with the timing of the pulsed laser light as the excitation light. And the camera controller 31.

The fluid flowing in the fluid cell 4 needs to contain a dye that absorbs the laser light that is the excitation light, and if it is not contained in the original fluid, it is added. Here, ethyl alcohol was used as the fluid, and Rh6G as a dye dye was added to absorb the excitation light. The dye concentration is 0.
The excitation light is absorbed almost uniformly for a fluid width of 3 mm in the excitation light traveling direction as 005 mmol / L (mmol / liter). The refractive index distribution generated at this time forms a thermal lens (concave lens) for the probe laser beam.

FIG. 2 shows the concave lens and the streak camera 2.
7 shows an image of temporal intensity change of the probe laser beam P incident on the beam No. 7, and FIG. 3 shows a graph thereof. In both figures, (a) is before the excitation light is incident (t0),
(b) is when the excitation light is incident (t1), (c) is after the excitation light is incident for n seconds
The state of (t2) is shown.

The concave lens enlarges the probe laser light P (see FIG. 2B) and attenuates the amount of light transmitted through the slit 24. However, since this concave lens moves downstream with the flow of the fluid containing the pigment, the amount of probe laser light that passes through the slit 24 returns with time before the excitation light is incident. An image captured by the streak camera 27 for the above-described change in the amount of probe laser light is read into the image processing unit 32.

FIG. 4A shows an image of image data taken by the streak camera 27 (distribution above a certain intensity), FIG. 4B shows a processing example of the image data, and FIG. 4C shows the obtained fluid distribution. Here is an example: The distance from the wall shown in the figure is Xa, X
From the image data corresponding to b, Xc (see (a)), the times ta, tb, and tc (see (b)) from the incidence of the excitation light to the minimum probe laser light amount (intensity) are read. (c)
Represents the flow velocity distribution in the figure in which the maximum flow velocity is plotted as 1, since the reciprocal of these times is the velocity.

In this measurement example, 3 mm of the width of the fluid cell 4 was image-relayed to 300 pixels of the streak camera 27, so one pixel is 10 μm, but the spatial resolution is determined by the image relay optical system 25 and the streak. It is determined by the larger of the pixel size of the camera 27, 13 μm. In addition, in this embodiment, the average flow velocity was measured at 15 m / s or less, so the sweep time of the streak camera 27 was set to 600 μs. Should be raised.

In the first embodiment, the pigment dye is R
Although h6G was used, a Rhodamine-based Rh101, which is a pigment dye that attracts the second harmonic of the YAG laser light,
The same effect can be obtained by using either Rh19 or RhB.

In the first embodiment, the pumping light (pulse laser light) is required to have pulse oscillation and high directivity and high brightness. Therefore, the second harmonic generator 29 of the YAG laser light having a short pulse width is used. However, even if copper vapor laser light having an oscillation wavelength of 20 nm is used, the same effect can be obtained by doubling the dye concentration of the fluid according to the absorptivity of the dye.
Also, excimer laser light can be used, but in this case, COU is used as a dye that absorbs the excimer laser light.
MARUIN-based CUUMARIN 102 and CUUMAR
The same effect can be obtained by using IN152.

Further, in the first embodiment, the probe laser light is CW oscillation and high directivity is required.
(Continuous oscillation) The dye laser generator 21 was used, but He-Ne laser light, Ar laser light, C
The same effect can be obtained by using the second harmonic of the W YAG laser light.

Embodiment 2 5 is a diagram showing a configuration of a flow velocity distribution measuring device according to a second embodiment of the present invention,
(a) shows a plan view and (b) shows a side view. In the figure, 10
0b is a flow velocity distribution measuring device, 40 is CW (continuous oscillation)
An Ar laser generator, 41 is a beam splitter that splits CWAr laser light into probe laser light and excitation light (pulse laser light), and 42 is a mirror that changes the optical path of the excitation light.
Reference numeral 43 is a chopper for pulsing the CWAr laser light branched for the excitation light, and 44 is a chopper controller for controlling the chopper 43. The other components are the same as those in the first embodiment.

The beam splitter 41 and the mirror 42 form a laser beam splitting means, and the chopper 43 and the chopper controller 44 form a chopper means.

Next, the operation will be described. The laser light emitted from the CWAr laser generator 40 is used as a probe laser light and an excitation light at a ratio of 1:99 by the beam splitter 41.
(Pulsed laser light). After the optical path of the excitation light is changed by the mirror 42, it is converted into pulsed light having a short pulse width by the chopper 43. The streak camera 27 is controlled by the delay circuit 30 and the camera controller 31 by a signal from the chopper controller 44 of the chopper 43 so that the streak camera 27 starts its operation immediately before the excitation light enters the fluid cell 4. Other operations are the same as those in the first embodiment. As a result, it can be realized with one laser generator.

Although the CWAr laser generator 40 is used in the second embodiment, the same effect can be obtained by using the second harmonic of the CW YAG laser.

Embodiment 3 FIG. 6 is a diagram showing the structure of a flow velocity distribution measuring device according to the third embodiment of the present invention.
In the figure, 100c is a flow velocity distribution measuring device, and 50
Is a Mach-Zehnder interferometer with two half mirrors 50a,
50d, two total reflection mirrors 50b and 50e, and a compensator 50c that corrects the optical path length.
Further, 51 is an optical filter that transmits only the probe laser light of the WC dye laser generator 21, and 52 is an ICC with a high-speed gate that captures an image of the fluid in the fluid cell 4 as interference fringes.
It is a D camera (for example, C4346 manufactured by Hamamatsu Photonics is used).

Reference numeral 53 denotes a camera controller of the ICCD camera 52 with a high speed gate (for example, C292 manufactured by Hamamatsu Photonics).
5 use), 54 is a memory for storing the image of the ICCD camera 52 with a high speed gate (for example, KKT manufactured by Microtechnica)
IF-66A is used), 55 is an image processing unit (for example, PIAS)
LA-525 manufactured by the company is used), and 29a is a slit for shaping the excitation light into a rectangular shape. It should be noted that the other parts denoted by the same reference numerals as those in the above-mentioned embodiment indicate the same or corresponding parts.

The CW dye laser generator 21 and the beam expander 22 compose probe laser light generating means, and the second harmonic generator 28, the transmission optical system 29, and the slit 29a compose pulse laser light generating means. , The Mach-Zehnder interferometer 50 constitutes the interference fringe forming means, and the image relay optical system 25, the optical filter 51, and the high speed gated I
The CCD camera 52 constitutes the interference fringe photographing means, the delay circuit 30 and the camera controller 53 constitute the second photographing control means, the memory 54 constitutes the memory means, and the image processing section 55 constitutes the second measurement processing means. And the monitor television 10 constitutes a second monitor means.

Next, the operation will be described. The excitation light (pulse laser light) emitted from the second harmonic generator 28 of the YAG laser having a short pulse width passes through the transmission optical system 29, the intensity distribution is shaped by the slit 29a, and then the fluid in the fluid cell 4 Is irradiated.

On the other hand, after the probe laser light emitted from the CW dye laser generator 21 is expanded by the beam expander 22, it passes through the fluid cell 4 via the half mirror 50a which constitutes the Mach-Zehnder interferometer 50, and then the whole. After passing through an optical path (test optical path) reflected by the reflection mirror 50e and after being reflected by the half mirror 50a, a total reflection mirror 50b,
Interference occurs when the light is split into an optical path (reference optical path) passing through the compensator 50c and is coupled again by the half mirror 50d.

By adjusting the inclinations of the total reflection mirrors 50b and 50e and the half mirrors 50a and 50d, the interval and the direction of the interference fringes can be arbitrarily adjusted. Here, as shown in FIG. The interference fringes are adjusted so as to be parallel to the fluid flow so that the time change of the interference fringes can be easily seen.

A probe laser beam from the image relay optical system 25 is taken as an interference fringe of the fluid in the fluid cell 4 by an ICCD camera 52 with a high speed gate through an optical filter 51. The timing of photographing with the ICCD camera 52 with a high-speed gate is the second harmonic generator 2 of the pulse YAG laser.
The delay circuit 30 and the camera controller 5 according to the timing of the pulsed laser light, which is the exciting light, by the signal from 8
Control with 3.

Similar to the above-mentioned embodiment, here, ethyl alcohol is used as the fluid, and Rh6G, which is a pigment dye, is added in order to absorb the excitation light. Dye density is 0.005m
As the mol / L, the excitation light was absorbed almost uniformly with respect to the fluid width of 3 mm in the excitation light traveling direction. As a result, a refractive index distribution is generated in the fluid, and the optical path difference between the reference optical path and the test optical path can be observed as changes in interference fringes.

An image of interference fringes when the excitation light is incident is taken by the ICCD camera 52 with a high speed gate and stored in the memory 54. Next, the delay time is set by the delay circuit 30, and the interference fringes after Δt time (delay time) from the excitation light incidence are similarly stored in the memory 54. 7A shows the interference fringes when there is no excitation light, FIG. 7B shows the change of the interference fringes when the excitation light is incident, that is, when the delay time is 0, and FIG. 7C shows the interference fringes at the delay time Δt. Show changes.

The flow velocity Vn can be obtained by measuring the distance 1n at which the interference fringes at the distance Xn from the wall surface move with the delay time Δt from the two images in the image processing unit 55. The flow velocity Vn is calculated by the following equation.

Vn = 1n / Δt [m / s] (1)

From the above, the flow velocity distribution can be obtained as shown in FIG. 7 (d). The third embodiment
Then, Rh6G was used as the pigment dye, but as in the first embodiment, the Rhodamine-based Rh101, Rh was used as the pigment dye for attracting the second harmonic of the YAG laser light.
The same effect can be obtained by using either h19 or RhB.

In the third embodiment, the pumping light (pulse laser light) is required to have pulse oscillation, high directivity and high brightness. Therefore, the second harmonic generator 29 of the YAG laser light having a short pulse width is used. However, copper vapor laser light or ximer laser light can also be used as in the first embodiment.

Further, in the above-mentioned third embodiment, the probe laser light is CW oscillation and high directivity is required.
(Continuous oscillation) The dye laser generator 21 was used, but similarly to the first embodiment, the second harmonic of the He-Ne laser light, the Ar laser light, and the CW YAG laser light, which are easy to obtain and handle, is used. May be.

Embodiment 4 FIG. 8 is a diagram showing the configuration of a flow velocity distribution measuring device according to the fourth embodiment of the present invention.
In the figure, 100d is a flow velocity distribution measuring device,
CW (continuous wave) Ar laser generator, 41 CWAr laser light for probe laser light and excitation light (pulse laser light)
A beam splitter 42 for splitting the light is used as a beam splitter, and 42 is a mirror for changing the optical path of the excitation light.

Reference numeral 43 is a chopper for pulsating the CWAr laser light branched for the excitation light, and 44 is a chopper controller for controlling the chopper 43. The other components are the same as those in the third embodiment. That is, the fourth embodiment is
The same modification as the second embodiment is applied to the third embodiment.

The beam splitter 41 and the mirror 42 form a laser beam splitting means, and the chopper 43 and the chopper controller 44 form a chopper means.

Next, the operation will be described. The laser light emitted from the CWAr laser generator 40 is used as a probe laser light and an excitation light at a ratio of 1:99 by the beam splitter 41.
(Pulsed laser light). After the optical path of the excitation light is changed by the mirror 42, the chopper 43 converts the excitation light into pulsed light having a short pulse width. ICCD camera 52 with high speed gate
Is operated by the signal from the chopper controller 44 of the chopper 43 and the delay circuit 30 and the camera controller 53.
Control with and. Other operations are the same as those in the third embodiment.
As a result, the flow velocity distribution measuring device of the present invention can be realized with one laser generator.

Although the CWAr laser generator 40 is used in the fourth embodiment, the same effect can be obtained by using the second harmonic of the CW YAG laser.

[0059]

As described above, the first to fifth aspects of the present invention are as follows.
In the invention, the pulsed laser light is applied to the fluid containing the dye that absorbs the laser light flowing in the measurement target flow path of the measurement object from the direction intersecting the flow direction of the fluid, and the flow direction of the fluid is similarly changed. The probe laser light that is transmitted through the fluid is irradiated from a direction that intersects and also intersects with the pulse laser light, the refractive index of the fluid is changed by the pulse laser light, and the refractive index distribution thereby is transmitted through the fluid. Since the flow velocity distribution of the measurement target flow channel is measured by measuring from the probe laser beam, the flow velocity distribution of the measurement target flow channel of the measurement target is non-contact, without removing a filter or the like from the measurement target. As it is and without using a solid tracer as in the past, it can be performed without damaging the measuring object or affecting the characteristics of the fluid. Effects such that can provide velocity distribution measuring apparatus capable of performing accurate measurement conforming to the present state is obtained.

In the sixth aspect of the present invention, the laser light from one laser generator is branched by the laser light branching means and pulsed by the probe laser light and the chopper means to obtain pulsed laser light respectively. Therefore, it is possible to realize a single laser generator and to provide an inexpensive flow velocity distribution measuring device.

Further, in the seventh and eighth aspects of the present invention, since the light sources of the pulsed laser light and the probe laser light can be selected respectively, it is possible to provide a flow velocity distribution measuring device which is easier to implement and has more flexibility. And so on.

According to the ninth to eleventh aspects of the present invention, a dye that absorbs laser light is added to the fluid flowing through the flow path to be measured of the object to be measured, and the fluid intersects with the direction of flow of the dye. From the pulsed laser light, similarly irradiating a probe laser light that is transmitted to the fluid from a direction that intersects the flow direction of the fluid and also intersects the pulsed laser light, Since the refractive index is changed and the resulting refractive index distribution is measured from the probe laser beam that has passed through the fluid to measure the flow velocity distribution in the measured flow path, the flow velocity distribution in the measured flow path of the measurement target object is measured. Is non-contact, without removing the filter etc. from the object to be measured, and because a solid tracer is not used as in the past, damage to the object to be measured or fluid Practicable without affecting the properties, effects such as capable of providing the flow velocity distribution measuring method capable of performing accurate measurement reliability conforming to high and current is obtained.

In the twelfth aspect of the present invention, since the laser light from one laser generator is branched and the probe laser light and the laser light are pulsed to obtain the pulsed laser light, the laser generation is performed. It is possible to realize with a single device, and it is possible to provide an effect that a flow velocity distribution measuring method that can be more easily executed can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a flow velocity distribution measuring device according to a first embodiment of the present invention, in which (a) is a plan view and (b) is a side view.

FIG. 2 is a diagram showing an image of temporal intensity change of probe laser light incident on a concave lens and a streak camera according to the first embodiment of the present invention.

3 is a graph showing a temporal intensity change of the probe laser light of FIG.

FIG. 4 is a diagram showing image data of a streak camera, an image processing method, and an example of a flow velocity distribution measured in the first embodiment of the present invention.

5A and 5B are diagrams showing a configuration of a flow velocity distribution measuring device according to a second embodiment of the present invention, in which FIG. 5A is a plan view and FIG. 5B is a side view.

FIG. 6 is a diagram showing a configuration of a flow velocity distribution measuring device according to a third embodiment of the present invention.

FIG. 7 is a diagram showing a time change of interference fringes measured in a third embodiment of the present invention and a result of processing into a flow velocity distribution.

FIG. 8 is a diagram showing a configuration of a flow velocity distribution measuring device according to a fourth embodiment of the present invention.

FIG. 9 is a diagram showing a configuration of a conventional flow velocity distribution measuring device.

[Explanation of symbols]

4 fluid cell, 10 monitor TV, 21 CW dye laser generator, 27 streak camera, 28 pulse Y
Second harmonic generator of MG laser, 32, 55 image processing unit, 40 CWAr laser generator, 41 beam splitter, 42 mirror, 43 chopper, 50 Mach-Zehnder interferometer, 52 ICCD camera with high speed gate, 5
4 memory, 100a-100d Flow velocity distribution measurement measurement.

Claims (12)

[Claims] 1. A pulsed laser beam is applied to a fluid containing a dye that absorbs a laser beam flowing through a flow path to be measured of an object to be measured, in a direction intersecting with the flow direction of the fluid, and the flow direction of the fluid is similarly measured. The probe laser light that is transmitted through the fluid is irradiated from a direction that intersects with the pulse laser light, and the pulse laser light changes the refractive index of the fluid. A flow velocity distribution measuring device, characterized in that the flow velocity distribution in the flow path to be measured is measured by measuring from the probe laser beam. 2. The flow velocity distribution is obtained by measuring the refractive index distribution due to the change in the refractive index generated in the fluid irradiated with the pulsed laser light as a temporal change in the intensity of the probe laser light with a streak camera. The flow velocity distribution measuring device according to claim 1, characterized in that. 3. The Mach-Zehnder interferometer is used to obtain interference fringes formed by the probe laser beam and the probe laser beam transmitted through the fluid in which the refractive index has changed due to the pulsed laser beam, and the refractive index distribution is provided with a high-speed gate. The flow velocity distribution measuring device according to claim 1, wherein the flow velocity distribution is obtained by measuring the change in the interference fringes with time with an ICCD camera. 4. A fluid cell which forms the flow path to be measured and through which the fluid flows, and a probe which emits the probe laser light and irradiates the probe laser light in a direction intersecting the direction of the fluid flow of the fluid cell. Laser light generating means, pulsed laser light generating means for generating the pulsed laser light, and transmitting the pulsed laser light to the fluid from a direction that intersects with the flow direction of the fluid in the fluid cell and also intersects with the pulsed laser light; A probe laser light photographing means including the streak camera for photographing the time change of the probe laser light transmitted through the fluid, which has a change in the refractive index due to the influence of the laser light, and the timing of the pulse laser light of the pulse laser light generating means. A first photographing control means for controlling the streak camera according to the above, and an image obtained by the probe laser light photographing means. A first measurement processing unit that performs image processing to obtain a flow velocity distribution from a temporal change in the intensity of the probe laser beam; and a first monitoring unit that monitors the image of the streak camera. The flow velocity distribution measuring device according to claim 2. 5. A fluid cell that forms the flow path to be measured and through which the fluid flows, and a probe that emits the probe laser light and irradiates the probe laser light in a direction intersecting the direction of the fluid flow of the fluid cell. Laser light generating means, pulsed laser light generating means for generating the pulsed laser light, and transmitting the pulsed laser light to the fluid from a direction that intersects with the flow direction of the fluid in the fluid cell and also intersects with the pulsed laser light; Interference fringes due to the probe laser light that has a change in the refractive index due to the influence of the laser light and has passed through the fluid, and the probe laser light that has been obtained by directly branching the probe laser light from the pulse laser light generation means. Interference fringe forming means including the Mach-Zehnder interferometer to be obtained, and photographing the temporal change of the interference fringe from the Mach-Zehnder interferometer An interference fringe photographing means including an ICCD camera with a high speed gate; a second photographing control means for controlling the ICCD camera with a high speed gate in accordance with the timing of the pulsed laser light of the pulsed laser light generating means; and an ICCD camera with a high speed gate. A memory means for storing an image, and image processing of the image obtained by the interference fringe photographing means to obtain a flow velocity distribution from a temporal change of the interference fringe.
4. The flow velocity distribution measuring device according to claim 3, further comprising: a measurement processing unit of 1. and a second monitor unit that monitors an image processed by the measurement processing unit. 6. The probe laser light generating means and the pulse laser light generating means branch laser light from one laser generator by laser light branching means and pulse it by the probe laser light and chopper means. 6. The pulsed laser light is obtained, and the pulsed laser light is obtained.
The flow velocity distribution measuring device according to any one of 1. 7. The pulse laser light is any one of the second harmonic of YAG laser light having a short pulse width, excimer laser light, and copper vapor laser light. The flow velocity distribution measuring device according to Crab. 8. The probe laser light is any one of continuous wave dye laser light, Ar laser light, He—Ne laser light, and second harmonic of continuous wave YAG laser. 6. The flow velocity distribution measuring device according to any one of 1 to 5. 9. A dye that absorbs laser light is added to a fluid flowing through a flow path to be measured of an object to be measured, and the fluid is irradiated with pulsed laser light from a direction intersecting with the flow direction of the fluid. A probe laser beam that is transmitted through the fluid is irradiated from a direction that intersects with the flow direction of the fluid and also intersects with the pulse laser beam, and the pulse laser beam changes the refractive index of the fluid. A flow velocity distribution measuring method, characterized in that the flow velocity distribution in the flow path to be measured is measured by measuring the distribution from probe laser light that has passed through the fluid. 10. A flow velocity distribution is obtained by measuring a refractive index distribution due to a change in the refractive index generated in the fluid irradiated with the pulsed laser light as a temporal change in the intensity of the probe laser light transmitted through the fluid. The flow velocity distribution measuring method according to claim 9, which is obtained. 11. An interference fringe formed by the probe laser beam and the probe laser beam transmitted through the fluid in which a change in the refractive index due to the pulsed laser beam is generated, and a refractive index distribution is temporally changed in the interference fringe. The flow velocity distribution measuring method according to claim 9, wherein the flow velocity distribution is obtained by measuring as. 12. The pulsed laser light is obtained by branching laser light from one laser generator and pulsating the probe laser light and the laser light. The method for measuring the flow velocity distribution described in.