KR101785896B1 - Method and system for simultaneous measurement of temperature, concentration, and velocity distribution of gas using 3d array of tdlas based laser beam - Google Patents

Abstract

A simultaneous measurement method and system of gas temperature, concentration and velocity distribution using a TDLAS-based laser beam three-dimensional array is presented. A method of measuring a gas using a TDLAS-based laser beam three-dimensional array according to an embodiment includes: passing laser beams arranged three-dimensionally in a measurement region where gas is generated in a measurement unit; And measuring a velocity distribution of the gas passing through the measurement region by detecting a correlation coefficient between the laser beams arranged in three dimensions.

Description

TECHNICAL FIELD The present invention relates to a method and system for simultaneously measuring temperature, concentration, and velocity distribution of a gas using a three-dimensional array of laser beams based on TDLAS,

The following embodiments relate to a method and system for simultaneously measuring temperature, concentration and velocity distributions of a gas using a TDLAS-based laser beam three-dimensional array.

Laser based optical component sensors have recently attracted attention in connection with extraction measurement technology. Laser-based measurement techniques have the advantage of being able to perform immediate field measurements and provide high-speed feedback suitable for dynamic process control. Tunable Diode Laser Absorption Spectroscopy (hereinafter referred to as TDLAS) is a very promising technique for measuring combustion parameters such as the composition of combustion gas and temperature.

TDLAS typically uses diode lasers that operate in the near-infrared and mid-infrared spectral regions. Suitable lasers have been extensively developed for use in the telecommunications industry. The lasers can therefore be used immediately for TDLAS applications. Since the invention of wavelength variable diode lasers, several TDLAS techniques have been developed for sensing and controlling the combustion process.

For example, wavelength modulation spectroscopy techniques, frequency modulation spectroscopy techniques, and direct absorption spectroscopy techniques are generally known. These techniques are based on the fact that the intensity of the laser light received by the detector is inversely proportional to the concentration of the gas when the laser light with wavelengths that can be absorbed by the gases in the combustion chamber is absorbed in the specific spectral band as it passes through the combustion chamber . The absorption spectrum received by the detector is used to determine the amount of gas component being analyzed in addition to the associated combustion parameters such as temperature.

For example, U.S. patent application 2002 / 0031737A1 (Von Drasek et al.) Describes a method and apparatus using a tunable diode laser for monitoring and / or controlling high temperature processes. This patent is characterized by the use of direct absorption spectroscopy techniques to determine the relative concentration, temperature and other parameters of a large number of combustion components.

Korean Patent Application No. 10-2016-0134624 discloses a technology for a method of automatically measuring a specific wavelength of a laser beam and a method and system for simultaneously measuring two-dimensional temperature and concentration distribution of a gas based on tomography technology.

However, the existing TDLAS-based temperature and concentration distribution measurement technique can not measure the velocity distribution.

Embodiments describe a method and system for simultaneous measurement of temperature, concentration and velocity distributions of a gas using a TDLAS-based laser beam three-dimensional array, more specifically, three-dimensional laser beams are arranged three-dimensionally, Dimensional velocity distribution of a cross-section from an optical signal obtained through a measurement region passing through the measurement region.

Embodiments use TDLAS to measure the velocity distribution of the gas passing through the measurement region by detecting the correlation amount between the three-dimensional laser beam signals by arranging the laser beam array three-dimensionally, and at the same time, TDLAS Concentration, and velocity distributions using a three-dimensional array of laser-based laser beams.

A method of measuring a gas using a TDLAS-based laser beam three-dimensional array according to an embodiment includes: passing laser beams arranged three-dimensionally in a measurement region where gas is generated in a measurement unit; And measuring a velocity distribution of the gas passing through the measurement region by detecting a correlation coefficient between the laser beams arranged in three dimensions, The step of detecting a coefficient of cross-correlation and measuring a velocity distribution of a gas passing through the measurement region may include measuring a velocity distribution of the laser beam in each layer of the measurement unit based on TDLAS (Tunable Diode Laser Absorption Spectroscopy) Acquiring a real-time absorption spectrum from an optical signal that has passed through the measurement region and calculating a correlation coefficient of absorption coefficients of each cell on each lattice formed by the laser beam in the measurement region -correlation) is calculated, it is determined that the same gas has passed through the region where the correlation coefficient has the largest value, It can be obtained a gas velocity profile by dividing the distance between the crossing points in the time difference eoteonaen through an absorption spectrum.

The step of passing three-dimensionally arranged laser beams through a measurement area where gas is generated in the measurement part includes: irradiating a tunable laser beam to the measurement area of the measurement part; Dividing the irradiated laser beam into a plurality of beams using a beam splitter; And passing the divided plurality of beams through the measurement area of the measurement area where the gas is generated using the light collecting part.

Wherein the step of measuring the correlation coefficient between the laser beams arranged in three dimensions and measuring the velocity distribution of the gas passing through the measurement area comprises the steps of: After passing through the measurement area, the two-dimensional velocity distribution of the cross-section can be measured from the obtained optical signal.

Wherein the step of measuring the correlation coefficient between the laser beams arranged in three dimensions and measuring the velocity distribution of the gas passing through the measurement region comprises the steps of: Obtaining an emerging optical signal; Calculating a coefficient of cross-correlation between the absorption coefficients on the respective gratings of the measurement region using the real-time absorption spectrum from the optical signal; And determining a velocity distribution by determining that the same gas has passed through a place where the correlation coefficient has the largest value and dividing the distance between points where the same gas passes through the time difference obtained through the absorption spectrum .

Calculating a theoretical temperature and concentration distribution of the gas by reconstructing an absorption characteristic at a specific wavelength at a point where the laser beam intersects the measurement region based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength; As shown in FIG.

Wherein calculating the theoretical temperature and concentration distribution of the gas comprises: sensing an absorption characteristic of the laser beam passing through the measurement area; And analyzing the optical signal of the laser beam that has passed through the measurement area and calculating a temperature and concentration distribution.

The step of calculating the theoretical temperature and concentration distribution of the gas may be reconstructed using a tomographic technique in an automatic fitting manner for the absorption spectrum at a specific wavelength of the laser beam.

Wherein calculating the theoretical temperature and concentration distribution of the gas comprises repeatedly comparing the theoretical and experimental waveforms by automatically broadening or narrowing the waveform at a specific wavelength using an absorption spectrum distribution at an arbitrary temperature of the gas To finally determine the resembling waveform and to calculate the theoretical temperature and concentration of the gas.

Wherein the step of calculating the theoretical temperature and concentration distribution of the gas comprises the steps of: selecting a plurality of specific wavelengths among the peak values using the absorption spectrum distribution; Repeatedly comparing the theoretical waveform and the experimental waveform by automatically widening or narrowing the waveform at the specific wavelength; Determining a final waveform within a predetermined error range; And calculating the theoretical temperature and concentration of the gas at a determined final waveform, wherein the experimental waveform is obtained in an experiment using a device for simultaneous measurement of two-dimensional temperature and concentration distribution of gas, have.

According to another embodiment of the present invention, there is provided a gas measurement system using a TDLAS-based laser beam three-dimensional array, comprising: a laser unit for passing laser beams arranged in three dimensions in a measurement region where gas is generated; And a gas measuring unit for measuring a coefficient of cross-correlation between the laser beams arranged in three dimensions and measuring a velocity distribution of the gas passing through the measuring region, wherein the gas measuring unit comprises a tunable diode (TDLAS) A laser beam is irradiated on each of the gratings formed by the laser beam in the measurement region to obtain a real-time absorption spectrum from an optical signal that passes through the measurement region in each layer of the measurement unit based on laser absorption spectroscopy A correlation coefficient between the absorption coefficients of each cell of the cell is calculated and then it is determined that the same gas has passed through the cell having the largest correlation coefficient, The velocity distribution can be obtained by dividing the distance between the passing points by the time difference obtained through the absorption spectrum.

Wherein the laser unit comprises: a laser for irradiating a tunable laser beam to the measurement area of the measurement unit; A beam splitter for dividing the laser beam irradiated by the laser into a plurality of beams; And a condensing unit for passing the plurality of beams divided by the beam splitter through the measurement area of the measurement unit where the gas is generated.

The gas measuring unit may measure the two-dimensional velocity distribution of the cross-section from the obtained optical signal after the laser beams arranged in three dimensions pass through the measurement region in each layer of the measurement unit.

Wherein the gas measuring unit comprises: a detecting unit that obtains an optical signal from each layer of the measuring unit, the optical signal coming after the laser beam passes through the measuring region; An analyzer for calculating a coefficient of cross-correlation between the absorption coefficients on the respective gratings of the measurement region using the real-time absorption spectrum from the optical signal; And a calculation unit that determines that the same gas has passed through the place where the correlation coefficient has the largest value and divides the distance between the points where the same gas passes through the time difference obtained through the absorption spectrum to obtain a velocity distribution .

The gas measuring unit reconstructs an absorption characteristic at a specific wavelength at a point where the laser beam intersects the measurement region based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength to determine a theoretical temperature and concentration The distribution can be calculated.

The gas measuring unit reconstructs the laser beam using a tomography technique in an automatic fitting manner for the absorption spectrum at a specific wavelength, and uses the absorption spectrum distribution at an arbitrary temperature of the gas to determine By repeating the theoretical waveform and the experimental waveform repeatedly by widening or narrowing the waveform automatically at the wavelength, the final resembling waveform can be determined and the theoretical temperature and concentration of the gas can be calculated.

According to embodiments, the velocity distribution of the gas passing through the measurement region is measured by detecting the correlation amount between the three-dimensional laser beam signals by arranging the laser beam array three-dimensionally using TDLAS, A method and system for simultaneously measuring the temperature, concentration, and velocity distribution of a gas using a TDLAS-based laser beam three-dimensional array can be provided.

1 is a block diagram illustrating a gas measurement system using a TDLAS-based laser beam three-dimensional array in accordance with one embodiment.
FIG. 2 is a view for explaining a configuration of a system for simultaneously measuring temperature, concentration, and velocity distribution using a TDLAS-based laser beam three-dimensional array according to an embodiment.
3 is a view showing a three-dimensional laser beam array sensor capable of measuring a velocity distribution of a gas according to an embodiment.
4 is a diagram for explaining the principle of obtaining a velocity according to an embodiment.
FIG. 5 is a flowchart illustrating a gas measurement method using a three-dimensional array of laser beams based on a TDLAS according to an embodiment.
6 is a diagram for explaining an arrangement of a general laser beam.
7 is a diagram showing absorption spectrum curves of six representative wavelengths.
Fig. 8 is a view showing the longevity curve according to the temperature of six (or N) representative wavelengths.

Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the embodiments described may be modified in various other forms, and the scope of the present invention is not limited by the embodiments described below. In addition, various embodiments are provided to more fully describe the present invention to those skilled in the art. The shape and size of elements in the drawings may be exaggerated for clarity.

The following embodiments relate to techniques for three-dimensionally arranging laser beams and measuring the two-dimensional velocity distribution of the cross-section from the optical signals obtained by passing these laser beams through a measurement area through which the gas passes. More specifically, by using a tunable diode laser absorption spectroscopy (TDLAS), a laser beam array is three-dimensionally arranged to detect a correlation amount between three-dimensional laser beam signals, And the simultaneous measurement of gas temperature, concentration, and velocity distribution using a TDLAS-based laser beam three-dimensional array.

1 is a block diagram illustrating a gas measurement system using a TDLAS-based laser beam three-dimensional array in accordance with one embodiment.

FIG. 1 illustrates a gas measurement system using a three-dimensional array of TDLAS-based laser beams according to an embodiment. The temperature, concentration, and velocity distributions of a gas can be simultaneously measured using a laser beam arranged in a three- have.

The gas measuring system 100 using the TDLAS-based laser beam three-dimensional array according to an embodiment may include a laser unit 110 and a gas measuring unit 120.

The laser unit 110 can pass laser beams arranged in three dimensions in a measurement region where gas is generated.

Here, the laser unit 110 may include a laser 111, a beam splitter 112, and a condenser 113.

The laser 111 can irradiate a tunable laser beam to the measurement area of the measurement part. Here, the measurement unit means the measurement object, and the measurement area can be a part of the measurement unit where the gas is generated. For example, the laser 111 uses a diode laser with a scanning range of 0.6 nm (NTT Electronics Co., NLKE5GAAA), and the laser scanning frequency can be set to 1 kz.

The beam splitter 112 can divide the laser beam irradiated by the laser 111 into a plurality of beams. For example, the laser beam can be split into 16 beams (or more). At this time, the laser beam can form a three-dimensional array.

The collimator 113 may pass the plurality of beams divided by the beam splitter 112 through a measurement area of the measurement part where the gas is generated.

The gas measuring unit 120 may measure the velocity distribution of the gas passing through the measurement region by detecting a coefficient of cross-correlation between three-dimensionally arranged laser beams.

The gas measuring unit 120 can measure the two-dimensional velocity distribution of the passage cross-section from the obtained optical signal after the laser beams arranged in three dimensions pass through the measuring region in each layer of the measuring unit.

Here, the gas measuring unit 120 may include a detecting unit 121, an analyzing unit 122, and a calculating unit 123.

The detector 121 can acquire an optical signal in which the laser beam passes through the measurement region in each layer of the measurement unit as the measurement target.

An analyzer 122 may analyze the optical signal of the laser that has passed through the measurement area.

More specifically, the analysis unit 122 calculates a coefficient of cross-correlation between the absorption coefficients on the respective gratings of the measurement region by tomography technique using the real-time absorption spectrum from the optical signal .

The calculation unit 123 can determine that the same gas has passed through the place where the correlation coefficient has the greatest value and can calculate the velocity distribution by dividing the distance between the points where the same gas has passed by the time difference obtained through the absorption spectrum.

Furthermore, the gas measuring unit 120 can calculate the temperature distribution and the concentration distribution as well as the velocity distribution. The gas measuring unit 120 described below may be the calculating unit 123 of the gas measuring unit 120.

The gas measuring unit 120 reconstructs the absorption characteristic at a specific wavelength at a point where the laser beam of the measurement region crosses, based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength, Can be calculated.

The gas measuring unit 120 reconstructs the laser beam using a tomography technique using an automatic fitting method for the absorption spectrum at a specific wavelength, By repeating the theoretical waveform and the experimental waveform repeatedly by widening or narrowing the waveform automatically at the wavelength, the final resembling waveform can be determined and the theoretical temperature and concentration of the gas can be calculated.

Furthermore, the gas measuring unit 120 selects the N specific wavelengths of the peak values using the absorption spectrum distribution, and calculates the error of the absorption coefficient in the theoretical waveform and the experimental waveform using the N-point algorithm The temperature and the concentration distribution can be reconstructed by repeatedly comparing until the temperature reaches the predetermined minimum value. For example, the N-points algorithm may be a six-point algorithm that is formed by selecting six specific wavelengths of peak values using an absorption spectrum distribution.

More specifically, the gas measurement unit 120 may include an initial value setting unit, a temperature and concentration reconstruction unit, and a minimum value determination unit.

The initial value setting unit can set the initial values of the temperature and the concentration. For example, the initial value setting unit can perform the reconstruction calculation by determining the initial absorption value using a multiply line of sight (MLOS) technique.

The temperature and concentration reconstruction section can reconstruct the absorption characteristics at a specific wavelength using the absorption spectrum distribution at the initial values of temperature and concentration. For example, the temperature and concentration reconstruction part can be reconstructed using the MART (Multiplicative algebraic reconstruction technique) method. This method can be repeatedly calculated so that the error of the absorption value obtained by summing up the given absorption value and the laser is minimized.

The minimum value determination unit can determine whether the difference between the theoretical signal of the reconstructed temperature and concentration and the absorption coefficient of the experimental signal is the minimum value. For example, the minimum value determination unit can use the MSE (Mean Squared Errors) method so that the final convergence of the reconstructed temperature can minimize the difference between the target amount of absorption and the calculated absorption amount.

The N-point algorithm including the initial value setting unit, the temperature and density reconstruction unit, and the minimum value determining unit is repeated until the difference between the theoretical signal and the experimental signal absorption coefficient becomes the minimum value Can be calculated.

According to the embodiments, the emission amount of the exhaust gas passing through the exhaust pipe having a large diameter can be measured by simultaneously calculating the temperature and the concentration distribution by combining the laser beam with the tomography technique by an automatic fitting method for the absorption spectrum at a specific wavelength It can be calculated accurately. Furthermore, the velocity distribution can be calculated simultaneously with temperature and concentration distributions.

This can be a theoretical method for calculating the theoretical temperature and concentration values of a gas for measuring gas emissions.

Next, a practical experimental method for measuring the gas emission amount will be described in detail.

FIG. 2 is a view for explaining a configuration of a system for simultaneously measuring temperature, concentration, and velocity distribution using a TDLAS-based laser beam three-dimensional array according to an embodiment. FIG. 2A shows a configuration of a system for simultaneously measuring the temperature, concentration, and velocity distribution of a gas using a TDLAS-based laser beam three-dimensional array, and FIG. 2B shows an example of a detailed view of the measuring unit.

Referring to Figures 2a and 2b, there is shown an example of an actual experiment for a combustion engine employing a plurality of laser beam paths to a combustion engine. Here, the path of the laser beam is arranged in three dimensions, and the path of the laser beam of 16 (or more) laser beams will be described below as an example.

In order to measure the 1388 nm absorption spectrum of the H ₂ O gas, the laser 210 uses a diode laser with a scanning range of 0.6 nm (NTT Electronics Co., NLKE5GAAA), and the laser scanning frequency can be set to 1 kz. The laser beam irradiated by the laser 210 can be divided into 16 beams by a beam splitter (OPNET CO., SMF-28e 1310 nm SWBC 1x6) 220. The laser signal is detected by a photodiode (Hamamatsu Photonics, G8370-01), and the detected signal can be stored in a data recorder (8861 Memory Highcoda HD Analog 16, HIOKI). And the measurement diameter of the cell 240 is 70 mm (or optionally adjustable).

The engine (FUJI HEAVY INDUSTRIES, Inc., EX13) 260 can be operated without load. The diameter of the exhaust pipe is 22 mm and the length is 160 mm. A thermocouple 230 with a 100 μm diameter (KMT-100-100-120) can be used for temperature measurement in the central region. A polynomial noise reduction technique can be used to remove the noise generated by beam steering, and all signals can be converted into absorption spectrum patterns.

In other words, for simultaneous measurement of the temperature and concentration distribution of the gas, the laser beam emitted from the tunable laser 210 of the laser part is divided into a plurality of beams by using the beam splitter 220, And can be passed through a gas generating portion such as an exhaust pipe connected to the engine 260. The analyzer 250 of the gas measuring unit can analyze the laser signal passing through the gas generating unit to check the gas emission amount.

At this time, the laser 210 is arranged three-dimensionally and can detect the velocity distribution of the gas passing through the measurement region by detecting the correlation amount between the three-dimensional laser beam signals.

3 is a view showing a three-dimensional laser beam array sensor capable of measuring a velocity distribution of a gas according to an embodiment.

3 shows an example of a three-dimensional laser beam array sensor 300 capable of measuring the velocity distribution of a gas according to an embodiment. The arrangement of the laser beams described in FIG. 6, which will be described later using TDLAS, The velocity distribution of the gas passing through the measurement region 330 can be measured by detecting the correlation amount (or correlation coefficient) between the three-dimensional laser beams 310 by arranging the three-dimensional laser beams 310 as shown in FIG.

That is, the two-dimensional velocity distribution of the cross-section can be measured from the optical signal obtained by passing the laser beam 310 arranged three-dimensionally through the measurement region 330 through which the gas passes. Here, reference numeral 320 denotes a sensor array, and reference numeral 340 denotes a window through which the laser beam passes.

As described above, the sensor measuring the TDLAS can shoot the laser beam 310, which is a wavelength variable diode laser, in the measurement region 330, and then measure the concentration of the gas through the amount of laser passing therethrough. At this time, the TDLAS can be measured not only by a fixed wavelength value but also by changing the shape of the TDLAS so that it can be absorbed.

Further, the velocity distribution of the gas passing through the measurement region 330 can be measured by arranging the arrangement of the laser beams 310 three-dimensionally and detecting the correlation amount between the three-dimensional laser beam 310 signals.

4 is a diagram for explaining the principle of obtaining a velocity according to an embodiment.

Referring to FIG. 4, a measurement region (measurement volume) 430 of the measurement section can pass through a laser beam arranged in three dimensions. At this time, the collimator 410 forms a three-dimensional array, and a plurality of beams divided by the beam splitter can pass through the measurement area 430 of the measurement part where the gas is generated. The detector 420 forms a three-dimensional array and can acquire an optical signal that passes through the measurement region 430 in each layer of the measurement region 430 of the measurement portion to be measured .

A laser beam is passed through the measurement region 430 at each layer of the measurement section based on TDLAS (Tunable Diode Laser Absorption Spectroscopy), and then a real-time absorption spectrum is obtained from the obtained optical signal, Correlation coefficients of the absorption coefficients of the respective cells on the lattice of each layer formed by the absorption coefficient of each layer can be calculated. It can be seen that the same gas passes through the lattice of each layer where the correlation coefficient has the largest value.

That is, the velocity distribution (u) can be obtained by dividing the distance dS between the points where the same gas passes through the time difference dt obtained the absorption spectrum. Here, the velocity distribution u can be obtained from the position where the correlation coefficient is the largest, and can be expressed as the following equation.

[Formula 1]

u = dS / dt

Therefore, real-time concentration distribution, temperature distribution, and velocity distribution can be obtained at the same time.

FIG. 5 is a flowchart illustrating a gas measurement method using a three-dimensional array of laser beams based on a TDLAS according to an embodiment.

Referring to FIG. 5, a method of measuring a gas using a TDLAS-based laser beam three-dimensional array according to an embodiment includes passing laser beams arranged in three dimensions in a measurement region where gas is generated in a measuring unit 510 ), And measuring a velocity distribution of the gas passing through the measurement region by detecting a correlation coefficient (coefficient of cross-correlation) between the three-dimensionally arranged laser beams.

And reconstructing the absorption characteristic at a specific wavelength at a point where the laser beam intersects the measurement region based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength to calculate the theoretical temperature and concentration distribution of the gas 530).

According to embodiments, the velocity distribution of the gas passing through the measurement region is measured by detecting the correlation amount between the three-dimensional laser beam signals by arranging the laser beam array three-dimensionally using TDLAS, can do.

Hereinafter, each step of the gas measurement method using the TDLAS-based laser beam three-dimensional array according to one embodiment will be described in more detail with an example.

The gas measurement method using the TDLAS-based laser beam three-dimensional array according to one embodiment can be more specifically explained using the gas measurement system using the TDLAS-based three-dimensional array of laser beams according to the embodiment described in FIG. The gas measurement system using the TDLAS-based laser beam three-dimensional array according to an exemplary embodiment may include a laser part and a gas measuring part.

In step 510, the laser part may pass laser beams arranged in three dimensions in a measurement area where gas is generated in the measurement part to be measured.

More specifically, the laser section can irradiate a tunable laser beam into the measurement region of the measurement section. Then, the irradiated laser beam is divided into a plurality of beams by using a beam splitter, and then, the plurality of divided beams are passed through a measurement region of a measurement region where a gas is generated by using a light collecting portion.

In step 520, the gas measuring part may measure the velocity distribution of the gas passing through the measurement area by detecting a coefficient of cross-correlation between three-dimensionally arranged laser beams. That is, the gas measuring unit can measure the two-dimensional velocity distribution of the passage cross-section from the obtained optical signal after the laser beams arranged in three dimensions pass through the measurement region in each layer of the measurement unit.
More specifically, the gas measuring unit acquires an optical signal from each layer of the measurement unit after passing through the measurement region based on TDLAS (Tunable Diode Laser Absorption Spectroscopy), acquires a real-time absorption spectrum from the optical signal , A coefficient of cross-correlation between the absorption coefficients of each cell on each lattice formed by the laser beam in the measurement region can be calculated. Thereafter, the gas measurement section determines that the same gas has passed through the lattice where the correlation coefficient is the largest, and the velocity distribution is obtained by dividing the distance between the points where the same gas passes through the time difference obtained through the absorption spectrum have. Meanwhile, the gas measuring unit can reconstruct the absorption characteristic using a tomography technique as an automatic fitting method for the absorption spectrum at a specific wavelength at a point where the laser beam intersects. In this case, when the absorption coefficient is estimated through the reconstructed absorption characteristic, the correlation coefficient can be obtained through these absorption coefficients. That is, the absorption coefficients of the respective cells on the respective gratings formed by the laser beam of the measurement region through the reconstructed absorption characteristic using the tomography technique as an automatic fitting method for the absorption spectrum at a specific wavelength Can be obtained.

delete

Then, in step 530, the gas measuring unit reconstructs the absorption characteristic at a specific wavelength at a point where the laser beam of the measurement region crosses, based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength, Temperature and concentration distributions can be calculated.

More specifically, the gas measuring unit can sense the absorption characteristic of the laser beam passing through the measurement region. Then, the optical signal of the laser beam passing through the measurement area can be analyzed and the temperature and concentration distribution can be calculated.

The gas measuring unit can reconstruct the laser beam using a tomograpping technique as an automatic fitting method for the absorption spectrum at a specific wavelength.

Such a gas measuring unit repeatedly compares the theoretical waveform with the experimental waveform by automatically broadening or narrowing the waveform at a specific wavelength using the absorption spectrum distribution at a certain temperature of the gas to finally determine a waveform that resembles the theoretical waveform, Can be calculated.

More specifically, the gas measuring unit can repeatedly compare the theoretical waveform with the experimental waveform by selecting a plurality of specific wavelengths among the peak values using the absorption spectrum distribution and automatically widening or narrowing the waveform at a specific wavelength. Then, the final waveform can be determined within a predetermined error range, and the theoretical temperature and concentration of the gas can be calculated in the final waveform determined.

Here, the experimental waveforms can be obtained from experiments using the apparatus for simultaneous measurement of the two-dimensional temperature and concentration distribution of the gas or given predetermined data.

6 is a diagram for explaining an arrangement of a general laser beam.

As shown in FIG. 6, the laser beams cross each other and can reconstruct an absorption characteristic at a specific wavelength at a crossing point of the laser beam by passing a tunable laser beam through the measurement cross section .

On the other hand, a theoretical method for automatically calculating the theoretical temperature and concentration values of gas by reconstructing the absorption characteristics at a specific wavelength at the intersection of the laser beam using the tomography technique, There is an actual experimental method for a combustion engine that employs a path of 16 laser beams (or more).

Below, a two-dimensional temperature and concentration distribution measurement technique of gas will be described in more detail with an example.

Tunable Diode Laser Absorption Spectroscopy (TDLAS) is used to measure the temperature and concentration of gas molecules. The basic principle can be explained by Beer-Lambert's law.

When the light passes through the absorption medium, the intensity of the light absorbed and transmitted is related to the concentration, which is the number of particles in the gas in the unit volume. The intensity ratio of the initial signal (incident light) to the transmitted signal (transmitted light) As shown in Fig.

[Formula 2]

은 투과된 빛의 강도를,

은 입사광의 초기강도를 나타내고,

는

파장을 가진 빛의 흡수량을 나타내며, 아래첨자 i, j,

는 각각 가스(기체)의 종(species), 레이저 경로(laser paths), 파장(wavelength)을 나타낸다.

는 온도함수인 선강도(line-strength),

는 선폭함수(broadening function)를 나타낸다. here,

The intensity of the transmitted light,

Represents the initial intensity of incident light,

The

Represents the amount of absorption of light with wavelength, subscript i , j ,

Respectively denote the species of gas (gas), laser paths, and wavelength.

Line-strength, which is a temperature function,

Represents a broadening function.

Line width expansion can take the form of a linear function that occurs due to the effects of temperature and pressure when a molecule absorbs light. And n _i is the number density of the gas and L is the absorption length. The line strength, which is a temperature function, can be expressed by the following equation.

[Formula 3]

는 표준온도(296K),

(lower state energy)는 저준위 에너지,

는 플랑크상수, k [J/K]는 볼츠만 상수, c [cm/s]는 빛의 속도, Q(T)는 분배함수(partition function)로서 분자의 에너지 상태량에 관계하는 4차식의 온도함수로 나타낼 수 있다. here,

(296K), < / RTI >

(lower state energy) is a low-level energy,

Is the Planck's constant, k [J / K] is the Boltzmann constant, c [cm / s] is the speed of light, and Q ( T ) is the partition function. .

Excluding wavelengths having a small line strength that can be ignored among a plurality of linearity values, a representative wavelength having a high line intensity can be selected. For example, six representative wavelengths having a high line intensity can be selected.

Table 1 shows the strength and low energy level of H ₂ O molecules at the selected representative wavelength provided by HITRAN2008 database.

[Table 1]

7 is a diagram showing absorption spectrum curves of six representative wavelengths.

7A and 7B are absorption spectrum curves generated by using six (or N) representative wavelengths indicated by # 1 to # 6 (#N), and absorption patterns of six (or N) It can be seen that they appear clearly different at different temperatures.

Fig. 8 is a view showing the longevity curve according to the temperature of six (or N) representative wavelengths.

As shown in Fig. 8, six (or N) representative wavelengths represented by six (or N) wavelengths represented by # 1 to # 6 (#N) And can show the line strength according to the temperature change.

The apparatus described above may be implemented as a hardware component, a software component, and / or a combination of hardware components and software components. For example, the apparatus and components described in the embodiments may be implemented within a computer system, such as, for example, a processor, controller, arithmetic logic unit (ALU), digital signal processor, microcomputer, field programmable array (FPA) A programmable logic unit (PLU), a microprocessor, or any other device capable of executing and responding to instructions. The processing device may execute an operating system (OS) and one or more software applications running on the operating system. The processing device may also access, store, manipulate, process, and generate data in response to execution of the software. For ease of understanding, the processing apparatus may be described as being used singly, but those skilled in the art will recognize that the processing apparatus may have a plurality of processing elements and / As shown in FIG. For example, the processing apparatus may comprise a plurality of processors or one processor and one controller. Other processing configurations are also possible, such as a parallel processor.

The software may include a computer program, code, instructions, or a combination of one or more of the foregoing, and may be configured to configure the processing device to operate as desired or to process it collectively or collectively Device can be commanded. The software and / or data may be in the form of any type of machine, component, physical device, virtual equipment, computer storage media, or device As shown in FIG. The software may be distributed over a networked computer system and stored or executed in a distributed manner. The software and data may be stored on one or more computer readable recording media.

The method according to an embodiment may be implemented in the form of a program command that can be executed through various computer means and recorded in a computer-readable medium. The computer-readable medium may include program instructions, data files, data structures, and the like, alone or in combination. The program instructions to be recorded on the medium may be those specially designed and configured for the embodiments or may be available to those skilled in the art of computer software. Examples of computer-readable media include magnetic media such as hard disks, floppy disks and magnetic tape; optical media such as CD-ROMs and DVDs; magnetic media such as floppy disks; Magneto-optical media, and hardware devices specifically configured to store and execute program instructions such as ROM, RAM, flash memory, and the like. Examples of program instructions include machine language code such as those produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter or the like.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. For example, it is to be understood that the techniques described may be performed in a different order than the described methods, and / or that components of the described systems, structures, devices, circuits, Lt; / RTI > or equivalents, even if it is replaced or replaced.

Therefore, other implementations, other embodiments, and equivalents to the claims are also within the scope of the following claims.

Claims (15)

In a gas measurement method using a TDLAS-based laser beam three-dimensional array,
Passing laser beams arranged in three dimensions in a measurement region where gas is generated in the measurement unit; And
Detecting a coefficient of cross-correlation between the laser beams arranged in three dimensions and measuring a velocity distribution of the gas passing through the measurement region
Lt; / RTI >
The step of measuring a velocity distribution of a gas passing through the measurement region by detecting a correlation coefficient of the three-dimensionally arranged laser beams,
A method of measuring a position of an object to be measured, the method comprising: obtaining a real-time absorption spectrum from an optical signal that passes through the measurement region in each layer of a measurement unit based on TDLAS (Tunable Diode Laser Absorption Spectroscopy) A coefficient of cross-correlation between the absorption coefficients of each cell on each lattice is calculated and then it is determined that the same gas has passed through the cell having the largest correlation coefficient, The velocity distribution is obtained by dividing the distance between the points where the same gas is passed by the time difference obtained through the absorption spectrum
A gas measuring method using a three dimensional array of laser beams based on TDLAS. The method according to claim 1,
The step of passing three-dimensionally arranged laser beams through a measurement region where gas is generated in the measurement unit,
Irradiating a tunable laser beam to the measurement area of the measurement unit;
Dividing the irradiated laser beam into a plurality of beams using a beam splitter; And
Passing the divided plurality of beams through the measurement area of the measurement area where the gas is generated using the light collecting part
A method of measuring gas using a three dimensional array of TDLAS based laser beams. The method according to claim 1,
Wherein the step of measuring the velocity distribution of the gas passing through the measurement region by detecting the correlation coefficient between the laser beams arranged in three dimensions comprises:
The three-dimensionally arranged laser beams pass through the measurement region in each layer of the measurement section and then measure the two-dimensional velocity distribution of the cross section from the obtained optical signal
A gas measuring method using a three dimensional array of laser beams based on TDLAS. The method according to claim 1,
Wherein the step of measuring the velocity distribution of the gas passing through the measurement region by detecting the correlation coefficient between the laser beams arranged in three dimensions comprises:
Acquiring an optical signal in each layer of the measurement section after the laser beam passes through the measurement region;
Calculating a coefficient of cross-correlation between the absorption coefficients on the respective gratings of the measurement region using the real-time absorption spectrum from the optical signal; And
Obtaining a velocity distribution by dividing the distance between the points where the same gas passes and the time difference obtained through the absorption spectrum by determining that the same gas has passed through where the correlation coefficient has the largest value,
A method of measuring gas using a three dimensional array of TDLAS based laser beams. The method according to claim 1,
Calculating a theoretical temperature and concentration distribution of the gas by reconstructing an absorption characteristic at a specific wavelength at a point where the laser beam intersects the measurement region based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength;
Further comprising:
And simultaneously measuring the temperature distribution, the concentration distribution, and the velocity distribution of the gas by passing the laser beam in the three-dimensional array through the measurement region
A gas measuring method using a three dimensional array of laser beams based on TDLAS. 6. The method of claim 5,
Wherein the step of calculating the theoretical temperature and concentration distribution of the gas comprises:
Sensing an absorption characteristic of the laser beam passing through the measurement area; And
Analyzing an optical signal of the laser beam that has passed through the measurement area and calculating a temperature and concentration distribution
A method of measuring gas using a three dimensional array of TDLAS based laser beams. 6. The method of claim 5,
Wherein the step of calculating the theoretical temperature and concentration distribution of the gas comprises:
Reconstruction using a tomography technique as an automatic fitting method for the absorption spectrum at a specific wavelength of the laser beam
A gas measuring method using a three dimensional array of laser beams based on TDLAS. 8. The method of claim 7,
Wherein the step of calculating the theoretical temperature and concentration distribution of the gas comprises:
By repeating the theoretical waveform and the experimental waveform repeatedly by widening or narrowing the waveform automatically at a specific wavelength by using the absorption spectrum distribution of the gas at an arbitrary temperature, the finally resembling waveform is determined, and the theoretical temperature of the gas and Calculating the concentration
A gas measuring method using a three dimensional array of laser beams based on TDLAS. 9. The method of claim 8,
Wherein the step of calculating the theoretical temperature and concentration distribution of the gas comprises:
Selecting a plurality of specific wavelengths among the peak values using the absorption spectrum distribution;
Repeatedly comparing the theoretical waveform and the experimental waveform by automatically widening or narrowing the waveform at the specific wavelength;
Determining a final waveform within a predetermined error range; And
Calculating the theoretical temperature and concentration of the gas in the final waveform to be determined
Lt; / RTI >
The experimental waveform is obtained by experiment using a device for simultaneous measurement of two-dimensional temperature and concentration distribution of gas or given by predetermined data
A gas measuring method using a three dimensional array of laser beams based on TDLAS. A gas measurement system using a TDLAS-based laser beam three-dimensional array,
A laser unit for passing laser beams arranged in three dimensions in a measurement region where gas is generated; And
A gas measurement unit for detecting a coefficient of cross-correlation between the laser beams arranged in three dimensions and measuring a velocity distribution of the gas passing through the measurement region,
Lt; / RTI >
Wherein the gas measuring unit comprises:
A method of measuring a position of an object to be measured, the method comprising: obtaining a real-time absorption spectrum from an optical signal that passes through the measurement region in each layer of a measurement unit based on TDLAS (Tunable Diode Laser Absorption Spectroscopy) A coefficient of cross-correlation between the absorption coefficients of each cell on each lattice is calculated and then it is determined that the same gas has passed through the cell having the largest correlation coefficient, The velocity distribution is obtained by dividing the distance between the points where the same gas is passed by the time difference obtained through the absorption spectrum
A gas measurement system using a TDLAS based laser beam three-dimensional array. 11. The method of claim 10,
The laser unit includes:
A laser for emitting a tunable laser beam to the measurement region of the measurement unit;
A beam splitter for dividing the laser beam irradiated by the laser into a plurality of beams; And
A beam splitter for splitting said plurality of beams into a plurality of beams,
A gas measurement system using a three dimensional array of TDLAS based laser beams. 11. The method of claim 10,
Wherein the gas measuring unit comprises:
The three-dimensionally arranged laser beams pass through the measurement region in each layer of the measurement section and then measure the two-dimensional velocity distribution of the cross section from the obtained optical signal
A gas measurement system using a TDLAS based laser beam three-dimensional array. 11. The method of claim 10,
Wherein the gas measuring unit comprises:
A detector for acquiring an optical signal from each layer of the measurement unit after the laser beam passes through the measurement area;
An analyzer for calculating a coefficient of cross-correlation between the absorption coefficients on the respective gratings of the measurement region using the real-time absorption spectrum from the optical signal; And
Calculating a velocity distribution by dividing the distance between the point where the same gas passes and the time difference obtained through the absorption spectrum,
A gas measurement system using a three dimensional array of TDLAS based laser beams. 11. The method of claim 10,
Wherein the gas measuring unit comprises:
Calculating a theoretical temperature and concentration distribution of the gas by reconstructing an absorption characteristic at a specific wavelength at a point where the laser beam intersects the measurement region based on the temperature and the absorption intensity characteristic of the laser at a specific wavelength, And simultaneously measuring the temperature distribution, the concentration distribution, and the velocity distribution of the gas by passing the laser beam in the three-dimensional array through the measurement region
A gas measurement system using a TDLAS based laser beam three-dimensional array. 15. The method of claim 14,
Wherein the gas measuring unit comprises:
Reconstructing the laser beam using a tomograpping technique in an automatic fitting manner for the absorption spectrum at a specific wavelength of the laser beam and automatically correcting the waveform at a specific wavelength using the absorption spectrum distribution at an arbitrary temperature of the gas. To repeatedly compare the theoretical waveform and the experimental waveform in such a way as to broaden or narrow the waveform to finally determine the waveform to resemble and to calculate the theoretical temperature and concentration of the gas
A gas measurement system using a TDLAS based laser beam three-dimensional array.

Images