JP3379352B2 - Method and apparatus for measuring two-dimensional temperature distribution of fluid - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a temperature measuring method or a temperature measuring apparatus capable of measuring the temperature distribution of a fluid in a two-dimensional region in a non-contact manner.

[0002]

2. Description of the Related Art The most common method for measuring the temperature of a fluid such as gas or liquid is to use a thermocouple. However, the method using a thermocouple requires contact with the fluid to be measured, and since one thermocouple measures the temperature at or near one point, the temperature distribution in the two-dimensional region can be continuous. It is impossible to measure it.

On the other hand, an optical measuring method is known as a method for measuring the temperature of a fluid to be measured in a non-contact manner. In the optical temperature measurement method, the infrared absorption / radiation method is a simple method (Charles A. Amann, SAEpap).
er 850395 (1985) etc.). However, with this method, it is difficult to obtain the temperature distribution in an arbitrary two-dimensional cross section on the optical axis, for example, because the measured value includes all information on the optical axis of the absorbed / emitted light.

Further, although CARS (Coherent Anti-Stokes Spectroscopy) and Raman spectroscopy are also known, this method is also a method of measuring temperature at a point, and it is difficult to obtain a temperature distribution in a two-dimensional region at the same time. (T. Michael Dayer, SAE paper
85036 (1985)).

The laser-induced fluorescence method is known as a powerful method for measuring a two-dimensional temperature distribution (A.
Arnold, et al. , Ber. Bunseng
es. Phys. Chem. Vol. 96, No10,
1388 (1992)). In this method, laser light of two different wavelengths is applied to the fluid to be measured, and a two-dimensional fluorescence image excited by the laser light is measured for each of the two laser lights. Then, the two-dimensional temperature distribution is measured from the intensity ratio of the fluorescence image and the Boltzmann distribution of the molecule or radical.

[0006]

However, since the laser-induced fluorescence method excites radicals such as OH, there is a problem that it is limited to a test fluid in which radicals exist, such as temperature measurement of a combustion field. is there. Further, there is a problem that the measurement requires a certain time, and the temperature distribution of the fluid to be measured cannot be measured instantaneously or in an extremely short time.
That is, since the wavelength bands of the respective fluorescence excited by the two laser beams are usually almost the same wavelength band,
The two fluorescent images need to be measured at intervals.

Therefore, when measuring the temperature of an unsteady field in which the temperature distribution changes with time, it is not possible to measure the instantaneous temperature distribution at a desired time. Therefore, for example, the temperature distribution in the cylinder of the operating engine cannot be measured. The present invention has been made in view of the above conventional problems, and provides a measuring method and a measuring apparatus capable of measuring the instantaneous temperature distribution of a two-dimensional region of a test fluid at a desired time without contact. It is the one we are trying to provide.

[0008]

A first invention of the present application is a temperature measuring method for measuring a temperature distribution in a two-dimensional region of a fluid in a non-contact manner,
First band light Δλ1 having a center wavelength λ1 different from the wavelength of the pumping light
And a second fluorescent substance that emits fluorescence of a second band light Δλ2 having a central wavelength λ2 different from λ1 with respect to the same excitation light.
Prepared is one in which the ratio of the fluorescence intensity I1 of λ1 and the intensity I2 of the second band light Δλ2 changes with temperature in a desired temperature region, and the test fluid is mixed with the first fluorescent substance and the second fluorescent substance, The test fluid is irradiated with the excitation light of the wavelength spread over the range of the two-dimensional region S (x, y) to be measured, and the first image for the first band light Δλ1 in the region S and the above The second band light Δ in the region S
The second image for λ2 is measured and the same coordinates (x,
The ratio R (x, y) between the measured intensity I1 (x, y) of the first image and the measured intensity I2 (x, y) of the second image in y).
Is calculated, the temperature T is calculated from the value of the ratio R, and the temperature distribution T (x, y) of the region S is determined.

In the present invention, the most remarkable thing is that
The fluorescence wavelength band Δλ1 of the first fluorescent substance and the fluorescence wavelength band Δλ2 of the second fluorescent substance with respect to the excitation light of the same wavelength are different from each other, and the fluorescence intensity I1 of the first band light Δλ1 and the intensity of the second band light Δλ2 The ratio with I2 changes with temperature in the desired temperature range. That is, for example, as shown in FIG. 6, when the wavelength of the excitation light is λo, between the wavelength of the first band light Δλ1 shown by the curve 61 and the wavelength of the second band light Δλ2 shown by the curve 62, for example, There is a difference that can be separated by an optical filter or the like.

There is a difference between the temperature characteristic of the fluorescence intensity I1 of the first fluorescent substance and the temperature characteristic of the fluorescence intensity I2 of the second fluorescent substance, and I1 / I2 (or I2 / I1) changes with the temperature T. To do. That is, for example, as shown in FIG. 7, there is a difference in temperature characteristics between the fluorescence intensity F1 of the first fluorescent substance per unit concentration and the fluorescence intensity F2 of the second fluorescent substance per unit concentration. As shown in 63, the ratio between the fluorescence intensities F1 and F2 changes with temperature.

The intensity of the excitation light is Io, the concentration of the first fluorescent substance in the test fluid is C1, the concentration of the second fluorescent substance in the test fluid is C2, and the concentration of the first fluorescent substance per unit concentration at temperature T is When the fluorescence intensity is F1 (T) and the fluorescence intensity per unit concentration at the temperature T of the second fluorescent substance is F2 (T), the fluorescence intensities I1 and I2 are as follows. I1 = K * Io * C1 * F1 (T) ・ ・ ・ (1) I2 = K * Io * C2 * F2 (T) ・ ・ ・ (2) However, in the above equation, K is a constant specific to the measuring device. Is.

The ratio R of the intensities I1 and I2 when the test fluid containing the first fluorescent substance having the concentration C1 and the second fluorescent substance having the concentration C2 is excited by the excitation light is given by the following equation. . R≡ (I1 / I2) = (C1 / C2) * {F1 (T) / F2 (T)} (3) Then, as described above, F1 (T) / F2 (T) is constant with respect to temperature. Not, it changes with temperature. Also, F
When 1 (T) / F2 (T) is replaced by the characteristic function F12 (T) defined by the following equation (4), the following is obtained.

F12 (T) ≡F1 (T) / F2 (T) ・ ・ ・ (4) R≡ (I1 / I2) = (C1 / C2) * F12 (T) ・ ・ ・ (5) F12 (T ) = (I1 / I2) * (C1 / C2) (6) Since (C1 / C2) is a constant, the measured value (I
1 / I2) and F12 (T) are in a proportional relationship,
If (T) (or, more directly, the relationship between the measured value (I1 / I2) and the temperature T) is known in advance, the measured value (I1
The temperature T can be obtained from / I2).

In the method of the present invention, the test fluid is irradiated with excitation light (for example, spread in a sheet shape in the region S) that spreads in the range of the two-dimensional region S (x, y) to be measured. . Then, the first image of the first band light Δλ1 in the area S and the second image of the second band light Δλ2 in the area S are measured. Then, a ratio R (x, y) between the measured intensity I1 (x, y) of the first image and the measured intensity I2 (x, y) of the second image at the same point (x, y) is calculated.
As a result, the value of F12 (T) at each position (x, y) is known from the above equation (5) or (6), and the distribution T (x, y) of the temperature T in the two-dimensional region S (x, y) is obtained. ) Can be determined.

In the measuring method of the present invention, the first band light Δλ1
And the second band light Δλ2 are different bands,
The fluorescence emitted from the test fluid can be separated into the first band light Δλ1 and the second band light Δλ2 by a band filter or the like, and the first image and the second image at the same time can be measured at the same time. Therefore, it is possible to measure a two-dimensional temperature distribution at a desired time (instantaneous or extremely short time).

That is, in the conventional laser-induced fluorescence method, since the wavelength bands of the respective fluorescence excited by the two laser beams are almost the same wavelength band, the two fluorescence images are separated by a certain time interval. The present invention can collect two pieces of image data at the same time, as opposed to being able to collect data separately, and as a result, can measure temperature instantaneously. As described above, according to the present invention, it is possible to provide a measuring method capable of measuring the instantaneous temperature distribution of a two-dimensional region of a fluid under test at a certain time without contact.

On the other hand, the second invention of the present application is a temperature measuring device for measuring the temperature distribution in a two-dimensional region of a fluid in a non-contact manner, and the first band light Δ having a central wavelength λ1 different from the wavelength of the excitation light.
A first fluorescent substance emitting fluorescence of λ1 and a second band light Δλ2 having a center wavelength λ2 different from λ1 with respect to the same excitation light.
And a second fluorescent substance that emits fluorescence of the first band light Δλ1 and the intensity I2 of the second band light Δλ2.
A fluorescent substance mixing means that mixes the first fluorescent substance and the second fluorescent substance with the fluid to be measured and a two-dimensional region S ( x, y) a light source for irradiating the fluid to be measured with the excitation light, a first image for the first band light Δλ1 in the region S, and a second image for the second band light Δλ2 in the region S Image measuring means for measuring the second image, and measurement intensity I1 (x, y) of the first image and second image at the same coordinates (x, y) upon receiving an output signal of the image measuring means. Intensity I2 (x,
y) and a ratio R (x, y) is calculated, and a temperature T is calculated from the value of the ratio R to determine a temperature distribution T (x, y) in the region S. Fluid 2
Dimensional temperature distribution measuring device.

A second invention is an apparatus for carrying out the method of the first invention, which comprises a fluorescent substance mixing means for mixing the first fluorescent substance and the second fluorescent substance, and a range of a two-dimensional region S (x, y). Light source for irradiating the fluid to be measured with excitation light that spreads to the fluid, image measuring means for measuring the first image and the second image, and an intensity I1 (x, y) upon receiving an output signal from the image measuring means. It has a calculation means for calculating the ratio R (x, y) with the intensity I2 (x, y) and determining the temperature distribution T (x, y) as described above. As a result, it is possible to provide a measuring device capable of measuring an instantaneous two-dimensional temperature distribution of a fluid to be measured at a certain time, without contact, as in the first aspect of the invention.

[0019]

DETAILED DESCRIPTION OF THE INVENTION

Embodiment Example 1 As shown in FIG. 1, this example is a temperature measuring device 1 that measures the two-dimensional temperature distribution of a fluid to be measured 81 in a heating constant volume container 80 in a non-contact manner. Then, the curves 611 to 614 of FIG.
As shown by 620, a first fluorescent substance that emits fluorescence of a first band light Δλ1 having a center wavelength λ1 different from the wavelength λo (not shown) of the excitation light and a center wavelength λ2 different from λ1 for the same excitation light. And a second fluorescent substance that emits fluorescence of the second band light Δλ2, and the first fluorescent substance and the second fluorescent substance are, as shown by a curve 630 in FIG. Intensity I1 of the second band and intensity I of the second band light Δλ2
It is assumed that the ratio with 2 changes with the temperature T in the desired temperature range.

Then, the first fluorescent substance and the second fluorescent substance are mixed in advance with the fluid to be measured at a predetermined concentration by a fluorescent substance mixing means (not shown), and the mixture is housed in the heating constant volume container 80. The temperature measuring device 1 comprises the above fluorescent substance mixing means,
, The two-dimensional area S (x,
y) The light source 11 for irradiating the fluid to be measured with sheet-shaped excitation light that spreads in the range of y), the first image for the first band light Δλ1 in the region S, and the second band light Δλ2 for the region S Image measurement means 15 for measuring the second image with respect to the first image and the measurement intensity I1 (x, y) of the first image and the second image at the same coordinates (x, y) in response to the output signals of the image measurement means 20. A calculation for calculating the ratio R (x, y) of the measured intensity I2 (x, y) and the temperature T from the magnitude of the ratio R to determine the temperature distribution T (x, y) in the region S. And means 40.

A supplementary explanation will be given below for each of them.
This example is an example of measuring the temperature of air as a fluid to be measured in the heating constant volume container 80. Inside the heating constant volume container 80, 0.31 mol / m ³ of toluene as the first fluorescent substance and diethyl ketone 2.3 as the second fluorescent substance are contained in the air.
It is filled with air mixed with 7 mol / m ³ .

The excitation light emitted from the light source 11 is YAG
It is the fourth harmonic of the laser (wavelength 266 nm). Then, the beam-shaped radiated light 31 is converted by the lenses 111 and 112 into parallel light 32 having a spread including a predetermined region S, enters the quartz window 801 of the heating constant volume container 80, and enters the container. Light is emitted from 802. An observation window 803 for transmitting light is provided at the bottom of the heating constant volume container 80, and a split mirror 12 including a half mirror or a dichroic mirror is provided below the observation window 803.

The observation light 35 incident on the split mirror 12 is
The light 351 split by the split mirror 12 and transmitted through the split mirror 12 passes through the first filter 211 and is captured by the first camera 221. On the other hand, the light 352 reflected by the split mirror 12 passes through the second filter 212,
The image is taken by the camera 222. The first filter 211 is a band filter that transmits the first band light Δλ1, and the second filter 212 is a band filter that transmits the second band light Δλ2.

Video outputs (first image and second image) I1 (x, y), I2 of the first and second cameras 221, 222
(X, y) is input to the calculating means 40. In the figure, reference numeral 41 is a display of the calculation means 40. FIG. 2 shows temperature characteristics 611 to 614 of fluorescence spectra when the excitation light is irradiated to a gas in which 0.31 mol / m ³ of toluene as a first fluorescent substance is mixed with air.
And diethylketone 2.3 as a second fluorescent substance in the air
The temperature characteristic 620 of the fluorescence spectrum when the gas mixed with 7 mol / m ³ is irradiated with the above excitation light is shown (the change in fluorescence intensity of diethyl ketone due to temperature is small, so that it is displayed collectively as a curve 620).

As can be seen from the figure, toluene emits fluorescence of the first band light Δλ1 having a wavelength of about 280 to 320 nm, and diethyl ketone has a second wavelength of about 340 to 500 nm.
The fluorescence of band light Δλ2 is emitted. The first and second filters 211 and 212 are band filters that transmit the first band light Δλ1 and the second band light Δλ2, respectively. Further, the temperature characteristics 611 to 614 and 620 of the fluorescence intensities I1 and I2 shown in the figure are significantly different, and the fluorescence intensity ratio I1 / I2 greatly changes depending on the temperature.

The calculating means 40 then calculates the ratio of both intensities from the image outputs I1 (x, y) and I2 (x, y) to the predetermined areas S (x, y) of the first and second cameras 221 and 222. Calculate R (x, y). A curve 630 in FIG. 3 is an example showing the relationship between the magnitude of the ratio R and the temperature T. Then, the arithmetic unit 40 determines the temperature T (x, y) in the region S from the relationship (curve 630) between the magnitude of the ratio R and the temperature T and R (x, y).

Then, the calculation means 40 displays the result on the display 41. As mentioned above, in this example,
The first image and the second image can be simultaneously measured by the first camera 221 and the second camera 222, and the two-dimensional temperature distribution can be measured instantaneously or in an extremely short time. In addition to the above-mentioned toluene, the first fluorescent substance is benzene,
A hydrocarbon having a benzene ring such as styrene can be used. In addition to the above-mentioned diethyl ketone, the second fluorescent substance includes ketones such as acetone and methyl ethyl ketone, and aldehydes.

As the light source of the excitation light, in addition to the fourth harmonic (266 nm) of the YAG laser, KrF excimer laser (248 nm), XeCl excimer laser (3
There is a light source that emits light in the absorption wavelength range of the first and second fluorescent substances, such as a dye laser (or a harmonic thereof).

Second Embodiment As shown in FIG. 4, this embodiment is different from the first embodiment in that a stereoscope 24 is used to measure the first image and the second image with one camera 23. It is one embodiment example. That is, the observation light 35 is the stereoscope 2
It directly enters the first filter 211 and the second filter 212 of No. 4 and is photographed by one camera 23 from the mirrors 241-244 through the lens 245.

The first image passing through the first filter 211 is detected in a half area of the detection surface of the camera 23, and the second image passing through the second filter 212 is detected by the camera 2.
It is detected in the remaining 1/2 area of the detection surface of No. 3. Then, the calculating means 40 calculates the intensity ratio between the same coordinates in the first image detected in the half area and the second image detected in the remaining half area, and calculates the two-dimensional temperature distribution. T
Find (x, y). Regarding the other points, the first embodiment
Is the same as.

Embodiment 3 This embodiment is another embodiment for measuring the two-dimensional temperature distribution in a cross section perpendicular to the axial center of the engine cylinder. As shown in FIG. 5, the engine cylinder 51 is provided with quartz glass windows 511 and 512 for transmitting the sheet-shaped excitation light 34 and an emission window 513 for the observation light 35, and a piston 52.
A transparent window 521 made of quartz glass that allows the observation light 35 to pass therethrough.
To provide. The observation light 35 transmitted through the window 521 is
The direction is changed by the mirror 531 and the light is emitted from the emission window 513.

The fluid to be tested is isooctane as a fuel, and benzene as the first fluorescent substance and acetone as the second fluorescent substance are mixed. The light source is a KrF excimer laser (wavelength 248 nm) (not shown), which forms the sheet-shaped excitation light 34, and the excitation light 34 is transmitted through the window 511 of the engine cylinder 51.
Incident from. The excitation light 34 passes through the engine cylinder 51, whereby the first fluorescent material and the second fluorescent material in the fuel are excited, and the first band light Δλ1 (wavelength approximately 280 nm to 3
20 nm) and the second band light Δλ2 (wavelength approximately 340 nm to 5)
00 nm).

The first band light Δλ1 and the second band light Δλ2
The observation light 35 including and passes through the window 521 of the piston 51, changes its direction by the mirror 531 and is emitted from the emission window 513. Then, the observation light 35 is split into two by the split mirror 12 as in FIG. 1, and the first filter 211,
The first image and the second image are captured by the first camera 221 and the second camera 222 through the second filter 212. And the outputs of the cameras 221 and 222 are
The temperature distribution T (x, y) in the cross section perpendicular to the axial center of the engine cylinder 51 is obtained by the same procedure as that of the first embodiment, which is input to the calculating means 40.

Then, in order to measure the instantaneous temperature distribution at the desired timing of the engine, the excitation light 34 is oscillated in a pulse form (light emission time of about 20 ns in this example).
Then, the shutters of the cameras 221 and 222 are set to the excitation light 3
It is operated at high speed in synchronization with the oscillation of 4 (1 in this example).
00ns or less). As a result, the instantaneous two-dimensional temperature distribution T in the engine cylinder 51 at the desired timing of the engine
(X, y) can be obtained. For others,
This is similar to the first embodiment.

[0035]

As described above, according to the present invention, it is possible to obtain a measuring method and a measuring device capable of measuring the temperature distribution of a two-dimensional region of a fluid under test at a constant time without contact. You can

[Brief description of drawings]

FIG. 1 is a system configuration diagram of a temperature measuring device according to a first embodiment.

FIG. 2 is a diagram showing the relationship between the fluorescence wavelength and the fluorescence intensity of the first fluorescent substance and the second fluorescent substance of Example 1 at different temperatures.

FIG. 3 is a diagram showing the relationship between the temperature and the ratio R of the intensity I1 of the first band light Δλ1 and the intensity I2 of the second band light Δλ2 in the first embodiment.

FIG. 4 is a system configuration diagram of a temperature measuring device according to a second embodiment.

FIG. 5 is a system configuration diagram of a temperature measuring device according to a third embodiment.

FIG. 6 is a diagram schematically showing the wavelength of excitation light of a first fluorescent substance and a second fluorescent substance, and the relationship between the fluorescent wavelength and the fluorescent intensity.

FIG. 7: Fluorescence intensity F1 per unit concentration of the first fluorescent substance
FIG. 6 is a diagram showing an example of the relationship between the fluorescence intensity F2 per unit concentration of the second fluorescent substance and temperature.

8 is a ratio F12 between F1 and F2 in FIG.
Fluorescence intensity I1 of the fluorescent substance and fluorescence intensity I2 of the second fluorescent substance
The figure which shows an example of the aspect of the change with respect to temperature of the ratio with.

[Explanation of symbols]

1. ． ． Temperature measuring device, 11. ． ． light source, 15. ． ． Image measurement means, 40. ． ． Computing means,

Continuation of the front page (56) Reference JP-A-7-198611 (JP, A) JP-A-64-9328 (JP, A) JP-A-8-110270 (JP, A) JP-A-7-43303 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01K 1/00-15/00 G01N 21/85

Claims (2)

(57) [Claims] 1. A temperature measuring method for contactlessly measuring a temperature distribution in a two-dimensional region of a fluid, the first fluorescent substance emitting fluorescence of a first band light Δλ1 having a center wavelength λ1 different from the wavelength of excitation light. And a second fluorescent substance that emits fluorescence of a second band light Δλ2 having a central wavelength λ2 different from λ1 with respect to the same excitation light, wherein the fluorescence intensity I1 of the first band light Δλ1 and the second band light Δλ2 Of the two-dimensional region S (x, x) to be measured by preparing a fluid whose ratio varies with the temperature in a desired temperature region and mixing the first fluorescent substance and the second fluorescent substance with the test fluid. y) Excitation light of the above wavelength spread over the range is radiated to the test fluid, and a first image for the first band light Δλ1 in the region S and a second image for the second band light Δλ2 in the region S are obtained. 2 images and the same coordinates (x, y ), The measured intensity I1 (x, y) of the first image and the measured intensity I2 of the second image in FIG.
A ratio R (x, y) with (x, y) is calculated, a temperature T is calculated from the value of the ratio R, and a temperature distribution T (x, y) in the region S is determined. Two-dimensional temperature distribution measurement method. 2. A temperature measuring device for contactlessly measuring a temperature distribution in a two-dimensional region of a fluid, the first fluorescent substance emitting fluorescence of a first band light Δλ1 having a central wavelength λ1 different from the wavelength of excitation light. And a second fluorescent substance that emits fluorescence of a second band light Δλ2 having a central wavelength λ2 different from λ1 with respect to the same excitation light, wherein the fluorescence intensity I1 of the first band light Δλ1 and the second band light Δλ2 Of which the ratio of the intensity I2 of the first fluorescent substance changes with the temperature in a desired temperature range is prepared, and a fluorescent substance mixing means for mixing the first fluorescent substance and the second fluorescent substance in the fluid to be measured, and a two-dimensional object to be measured A light source that irradiates the test fluid with the excitation light that spreads in the range of the region S (x, y), a first image of the first band light Δλ1 in the region S, and the second band in the region S Light Δλ
Image measuring means for measuring the second image for 2 and the same coordinate (x, y) upon receiving an output signal of the image measuring means.
And the measured intensity I1 (x, y) of the first image at
The ratio R (x, y) to the measured intensity I2 (x, y) of the image is calculated, and the temperature T is obtained from the value of the ratio R, and the region S
And a calculation means for determining the temperature distribution T (x, y) of the fluid.