CN104677426B - Mixed gas temperature field concentration field measurement method and device based on acousto-optic fusion - Google Patents

Abstract

The invention belongs to acoustooptical measuring field, more particularly to a kind of mixed gas temperature field concentration field measurement method and device based on acousto-optic fusion.Some sound wave lines and fixed wave length laser optical path that the method is obtained according to survey calculation pass through the velocity of sound and spectrum integral absorptivity of measured zone, association index SVD inversion algorithms determine the velocity of sound and the spectral absorptance distribution in gas 2 dimensional region, using the velocity of sound and spectral absorptance and mixed gas temperature and the functional relation of concentration, mixed gas are rebuild simultaneously in the temperature field of measured zone and concentration field, the device utilizes two frequency of sound wave of narrow bandwidth, measure the phase difference of receiving and transmitting signal, realize the measurement of accurate acoustic transit time, the ratio between laser intensity and collimater incident laser intensity for being received using detector are fixed spectrum integral absorptivity.Present invention can apply to the multiple fields in industrial production and life, the particularly monitoring and control of boiler combustion process.

Description

Mixed gas temperature field concentration field measurement method and device based on acousto-optic fusion

Technical field

It is dense the invention belongs to acoustooptical measuring field, more particularly to a kind of mixed gas temperature field based on acousto-optic fusion Degree field measurement method and device.

Background technology

With industrialized fast development, gas temperature and concentration of component have become chemical industry toxic gas detection, Indispensable monitoring object in the fields such as bioengineering, combustion diagnosis.Especially for large-scale thermal power boiler and industry Combustion process in stove, due to the reflection combustion process parameter that temperature and concentration are always coupled, if it can accurately be measured simultaneously Temperature field and concentration field, will be significant to control operating condition.

In terms of acoustic method thermometric, early in 1873, Mayler was just proposed and successfully using acoustic method gas is determined first Thermal condition under body environment, but until or so eighties in 20th century, acoustic method thermometry is just as a kind of emerging section Technology is formally proposed and paid close attention to by scholars and engineers and technicians, but can be measured using the method thermometric The influence of gas concentration change, and be earliest the relaxation studied by Zener, Landau, Teller in terms of acoustic method surveys concentration Attenuation theory is used for the measurement of diatomic gas, and Schwarz, Kneser propose that SSH is theoretical, with gas molecule sound wave shadow Collided under sound caused by intramolecule microscopic vibration free energy, rotatably mounted energy and macro molecules translation free energy it Between the mutual metastasis model of energy explain gas relaxation acoustic attenuation, then, it is many that SSH theories are successfully applied to analysis by Tanczos Atomic gas.The beginning of this century, Northwestern Univ USA Dain, Lueptow etc. have developed SSH theories, and the D-L theories of proposition can be used In three kinds of measurements of polyatomic gas composition, but due to high temperature rotational relaxation and the complexity of vibration relaxation vibration mechanism, should Theory is still in conceptual phase.

And in terms of optical method, twentieth century middle period, Schawlow and Townes proposes the principle of design laser, with The development of semiconductor laser with tunable manufacturing technology, tunable semiconductor laser light is utilized to nineteen sixties Source becomes possibility obtaining high-resolution absorption spectrum.Goulard etc. first proposed in the eighties and be rebuild using optics Technology carries out the research of non-reacting fluid, and subsequent foreign study scholar is in the gas reconstruction side based on laser absorption spectroscopy Face has carried out substantial amounts of algorithm research and experimental analysis.Tunable absorption spectroscopy techniques have high sensitivity and accuracy, but Tunable equipment is expensive in itself, is unfavorable for application, and due to the complexity of functional relation, for its temperature field concentration Rebuild while field and be algorithmically only capable of the iterative algorithms such as selection genetic simulated annealing, the real-time of reconstruction cannot be guaranteed.

The content of the invention

A kind of mixed gas temperature field concentration field measurement method based on acousto-optic fusion, including：

The spectrum integral absorptivity of step 1, the velocity of sound that measurement is propagated in tested region and fixed wave length laser；

Step 2, set up respectively and combined sound speed, the spectrum integral absorptivity of fixed wave length laser and mixed gas concentration, Relational model between temperature, it is proposed that merged based on acousto-optic and determine mixed gas temperature, concentration coupling model simultaneously；

Step 3, in 2 dimensional region, the spectrum integral absorptivity for obtaining the velocity of sound and fixed wave length laser using step 1 is believed Breath, based on index SVD solution of inverse problems algorithms, is calculated the spectrum of the velocity of sound that 2 dimensional region do not exist together and fixed wave length laser Integration absorptivity；The coupling model that recycle step 2 is set up, realizes the reconstruction meter to being tested 2 dimensional region temperature field and concentration field Calculate.

The measuring method of the velocity of sound in the step 1 is：Using two frequency of sound wave of narrow bandwidth, T-R signal is measured Phase difference, realize the measurement in accurate propagation time；Installation site according to acoustic sensor calculate correspondence Acoustic Wave Propagation away from From the velocity of sound is the business of Acoustic Wave Propagation distance and corresponding acoustic transit time.

The information of the spectrum integral absorptivity of the fixed laser in the step 1 is strong by laser detector reception signal Degree is obtained with corresponding collimater lasing intensity.

In described step 2, the velocity of sound is expressed as follows with mixed gas temperature, concentration relationship：

Wherein, c is the velocity of sound, γ_mixIt is mixed gas level pressure thermal capacitance with to determine the ratio between volumetric heat capacity, R be gas constant, T is cigarette Temperature degree, M_mixIt is mixed gas average molecular mass；γ_mixAnd M_mixIt is relevant with gas constituent concentration and temperature.

In described step 2, the spectrum integral absorptivity of fixed wave length laser is with the pass between mixed gas temperature, concentration It is that formula is expressed as follows：

Wherein, A is the spectrum integral absorptivity of fixed wave length laser, I₀It is incident intensity, I_tIt is projection light intensity, ν is laser Frequency, P is the pressure of measuring environment, and to absorb light path, X is absorbent components concentration, α to L_vIt is absorption coefficient, S_v(T) it is measurement institute With intensity of the spectral line under temperature T；I₀With I_tThe Beer-Lambert laws and S for meeting_v(T) expression formula is as follows：

Wherein,It is linear function, meetsQ (T) is segmentation function, and its usable temp T's is multinomial Formula is fitted, and h is Planck's constant, and c is the light velocity in vacuum, and E is low-level energy, k_BIt is Boltzmann constant, T is measurement temperature Degree, T₀It is reference temperature, S_v(T₀) it is reference temperature T₀Under the intensity of spectral line.

In described step 3, rebuild with following simultaneously to being tested the do not exist together temperature and concentration of mixed gas of two-dimensional space Two formulas are described：

Wherein, L_ABRepresent at A to the sound wave path at B, L_CDRepresent at C to the sound wave path at D, t_ABIt is sound wave from A Propagation time to B, c (x, y) is the velocity of sound at coordinate (x, y) place, A_CDFor laser from C to the integration absorptivity at D, α (x, Y) it is the absorption coefficient at coordinate (x, y) place.

A kind of mixed gas temperature field concentration field measurement device based on acousto-optic fusion, including：Acoustic sensor, laser quasi Straight device, laser detector, single-chip microcomputer, the first amplifier, two-way switch, acoustic emission end variable connector, acoustic receiver end multichannel Switch, the second amplifier, phase detecting module, laser controller, LASER Light Source and pedestal, laser chopper, laser shunt, Optical fiber, lock-in amplifier, data collecting card, computer；

Wherein, multiple acoustic sensors and corresponding laser aligner and laser detector are arranged around tested region； Acoustic sensor connects acoustic emission end variable connector and sound wave receiving terminal variable connector, acoustic emission end variable connector point respectively Not Lian Jie two-way switch, phase detecting module, the first amplifier, single-chip microcomputer, acoustic receiver end variable connector connects second respectively Amplifier, two-way switch, phase detecting module, computer are connected with phase detecting module and single-chip microcomputer again；Multiple laser quasis Straight device is connected with laser shunt by optical fiber, laser shunt, laser chopper, LASER Light Source and pedestal, laser controller Be sequentially connected, light source power by laser controller control, laser detector, lock-in amplifier, data collecting card, computer is successively It is connected.

The acoustic sensor is transceiver, and each acoustic sensor is connected to variable connector chip by holding wire, is surpassed Acoustic emissions signal is provided by single-chip microcomputer, while single-chip microcomputer provides the control signal of two-way switch and variable connector, two-way switch It is responsible for selection acoustic sensor and completes transmitting or receive capabilities, and variable connector control signal is responsible for the choosing of acoustic measurement passage Select.

The computer sends the enable signal instruction of acoustic measurement, and each measurement result is passed by USB interface data wire Defeated time computer.

The laser aligner sends laser, the laser that laser controller control light source sends by after chopper modulation by Laser shunt is divided into some Shu Jiguang by Optical Fiber Transmission to laser aligner, and the laser after laser detector receiving attenuation is simultaneously Voltage signal is converted into, the amplifying circuit carried by inside is exported to lock-in amplifier after being amplified, and lock-in amplifier is defeated The signal for going out passes through the incoming computer of data collecting card.

The invention provides a kind of new method and device for rebuilding mixed gas temperature field and concentration field, with following beneficial Effect：(1) measuring method proposes that principle is simple, has gathered acoustics and optical measurement advantage, and precision is higher first.(2) due to The LASER Light Source cost of fixed wave length is relatively low, and increased acoustic equipment price is relatively low honest and clean, therefore whole system cost is more tunable Laser detection system is much lower.(3) reconstruction of temperature field and concentration field can be simultaneously completed, with larger engineering significance.

Brief description of the drawings

Fig. 1 is the temperature field based on acousto-optic fusion method, concentration field measurement apparatus structure schematic diagram.

Fig. 2 (a)-(c) is for while rebuild temperature field, concentration field method schematic diagram.

Fig. 3 (a)-(b) is measured data of experiment figure.

Fig. 4 (a)-(b) is the temperature field and concentration field figure for rebuilding.

Wherein, 1- acoustic sensors, 2- laser aligners, 3- laser detectors, 4- tested regions, 5- single-chip microcomputers, 6- One amplifier, 7- two-way switch, 8- acoustic emissions end variable connector, 9- acoustic receivers end variable connector, the amplifiers of 10- second, 11- phase detecting modules, 12- laser controllers, 13- LASER Light Sources and pedestal, 14- laser chopper, 15- laser shunt, 16- optical fiber, 17- lock-in amplifiers, 18- data collecting cards, 19- computers.

Specific embodiment

The present invention provides a kind of temperature field concentration field measurement method and device based on acousto-optic fusion.Below in conjunction with the accompanying drawings, Preferred embodiment is elaborated.

Fig. 1 show the temperature field based on acousto-optic fusion method, concentration field measurement apparatus structure schematic diagram.In figure, tested The surrounding of region 4 arranges some acoustic sensors 1 and correspondence laser aligner 2 and laser detector 3.Acoustic module part, acoustics Sensor 1 connects acoustic emission end variable connector 8 and sound wave receiving terminal variable connector 9,8 points of acoustic emission end variable connector respectively Not Lian Jie two-way switch 7, phase detecting module 11, the first amplifier 6, single-chip microcomputer 5, acoustic receiver end variable connector 9 connects respectively Connect the second amplifier 10, two-way switch 7, phase detecting module 11, computer 19 again with phase detecting module 11 and the phase of single-chip microcomputer 5 Connection.Optical module part, several laser aligners 2 are connected with laser shunt 15 by optical fiber 16, laser shunt 15 It is connected with laser chopper 14, LASER Light Source and pedestal 13, light source power is controlled by laser controller 12, several laser acquisitions Device 3 is connected with lock-in amplifier 17, data collecting card 18 and computer machine 19 successively, and computer machine 19 receives data collecting card 18 data signal.

Each acoustic transceiver is transceiver, and it not only can be as acoustic emission end but also can be as acoustic receiver End, the process of the whole some sound wave time measurements of acoustic module is as follows：The control single chip computer 5 of computer 19 sends and sonic sensor 1 rated operation frequency identical square-wave signal, amplifies signal by the first amplifier 6, and by phase detecting module 110 The phase of now signal is taken, the transmitting of the control signal of two-way switch 7 is some by variable connector 8,9 switch chip antenna array controls The transmitting-receiving of acoustic sensor 1, the signal for receiving is amplified by the second amplifier 10, the reception of 7 control signals of double choosing switches, phase Position detection module 11 picks up the phase for receiving signal again, and contrast obtains phase information and feeds back to computer 19.Whole optics The measurement process of some fixed spectrum integration absorptivities of module is that external high frequency sinusoidal modulation signal is input into laser controller 12, laser controller 12 is opened, LASER Light Source and pedestal 13 send laser under the control of laser controller 12, by optical chopper If the laser of 14 modulation is divided into the main line of phase co-wavelength by laser shunt 15, corresponding collimater is transferred to by optical fiber 16 2, laser is interacted with gas in tested region 4, and the laser after decay is received by laser detector 3 and is converted into voltage letter Number, and export to lock-in amplifier 17 after the amplifying circuit carried by inside is amplified, lock-in amplifier 17 is exported Signal passes through the incoming computer 19 of data collecting card 18.Computer 19 is by processing phase detecting module 8 and data collecting card 18 Derived measurement data, temperature field and the concentration field of tested region 4 are obtained using the acousto-optic blending theory for proposing.

Embodiment

Burnt the CO for obtaining completely in atmosphere with methane₂-H₂O-N₂-O₂As a example by mixed gas, it is shown as with Fig. 2：Set up Two relational models：The velocity of sound relies on mixed gas temperature, the threedimensional model of concentration, and fixed wave length laser absorption coefficient relies on mixing The threedimensional model of gas temperature, concentration.

Such as Fig. 2 (a), if measuring spread speed of the sound wave in mixed gas for c₀, then a water can be just done in figure Side grain, a line is met at model, similarly, is integrated absorptivity by the fixed spectrum that measures and is absorbed coefficient divided by distance α₀, can also make an intersection, such as Fig. 2 (b).This two intersections are projected on temperature-concentration coordinate again, two projection intersection points are The corresponding temperature of mixed gas and concentration such as Fig. 2 (c).Comprise the following steps that：

Step 1：According to the acousto-optic fusion measurement temperature, the new method of concentration that are proposed, for specific tested gas, meter Calculation obtains the velocity of sound and fixed wave length absorption coefficient model shown in Fig. 2 (a) (b)；

Step 2：The acoustic part measuring system proposed using this patent, the sound wave of CF is sent by Single-chip Controlling By controlling acoustic emission sequentially by variable connector after amplification, receiving terminal is received signal simultaneously, is carried out successively；

Step 3：The opticator measuring system proposed using this patent, is divided the laser of fixed wave length by laser shunt If into main line, being received by corresponding laser detector by tested region by being sent by collimater after fiber optic conduction；

Step 4：By the contrast of phase detecting module and reception laser intensity and former laser intensity, by host computer terminal The treatment of acoustic intelligence and optical information is carried out, acoustic signals and laser signal is extracted in the time diagram 3 (a) of tested region and decay Result figure 3 (b), then by inversion algorithm, the velocity of sound and absorption coefficient of pixel in 2 dimensional region are obtained, finally by step 1 The computation model for obtaining, the reconstruction for realizing temperature field and concentration field is calculated.

Step 5：Reconstructed results are carried out with temperature field Fig. 4 (a), concentration field Fig. 4 (b) image to show, tested region temperature is exported Degree and concentration information.

The above, the only present invention preferably specific embodiment, but protection scope of the present invention is not limited thereto, Any one skilled in the art the invention discloses technical scope in, the change or replacement that can be readily occurred in, Should all be included within the scope of the present invention.Therefore, protection scope of the present invention should be with scope of the claims It is defined.

Claims (2)

1. it is a kind of based on acousto-optic fusion mixed gas temperature field concentration field measurement method, it is characterised in that including：

The spectrum integral absorptivity of step 1, the velocity of sound that measurement is propagated in tested region and fixed wave length laser；

Step 2, respectively foundation and combined sound speed, the spectrum integral absorptivity and mixed gas concentration, temperature of fixed wave length laser Between relational model, it is proposed that merged based on acousto-optic and determine mixed gas temperature, concentration coupling model simultaneously；

Step 3, in 2 dimensional region, the spectrum integral absorptivity information of the velocity of sound and fixed wave length laser, base are obtained using step 1 In index SVD solution of inverse problems algorithms, the spectrum integral of the velocity of sound that 2 dimensional region do not exist together and fixed wave length laser is calculated Absorptivity；The coupling model that recycle step 2 is set up, realizes calculating the reconstruction for being tested 2 dimensional region temperature field and concentration field；

In described step 3, the temperature and concentration of the mixed gas that do not existed together to tested two-dimensional space are rebuild with following two formula simultaneously It is described：

$t_{AB}={\∫}_{L_{AB}}\frac{ds}{c(x,y)}$

$A_{CD}={\∫}_{L_{CD}}\mathrm{\α}(x,y)ds$

Wherein, L_ABRepresent at A to the sound wave path at B, L_CDRepresent at C to the sound wave path at D, t_ABFor sound wave from A to B The propagation time at place, c (x, y) is the velocity of sound at coordinate (x, y) place, A_CDFor laser from C to the integration absorptivity at D, α (x, y) It is the absorption coefficient at coordinate (x, y) place；

The measuring method of the velocity of sound in the step 1 is：Using two frequency of sound wave of narrow bandwidth, the phase of T-R signal is measured Potential difference, realizes the measurement in accurate propagation time；Installation site according to acoustic sensor calculates correspondence Acoustic Wave Propagation distance, sound Speed is the business of Acoustic Wave Propagation distance and corresponding acoustic transit time；

The information of the spectrum integral absorptivity of the fixed laser in the step 1 be by laser detector received signal strength with Collimater lasing intensity is corresponded to obtain；

In described step 2, the velocity of sound is expressed as follows with mixed gas temperature, concentration relationship：

$c=\sqrt{\frac{{\mathrm{\γ}}_{mix}RT}{M_{mix}}}$

Wherein, c is the velocity of sound, γ_mixFor mixed gas level pressure thermal capacitance with determine the ratio between volumetric heat capacity, R is gas constant, and T is flue gas temperature Degree, M_mixIt is mixed gas average molecular mass；γ_mixAnd M_mixIt is relevant with gas constituent concentration and temperature；

In described step 2, the spectrum integral absorptivity of fixed wave length laser is with the relational expression between mixed gas temperature, concentration It is expressed as follows：

$A={\∫}_{-\mathrm{\∞}}^{+\mathrm{\∞}}-ln\left(\frac{I_t}{I_0}\right)dv={\mathrm{PLXS}}_v\left(T\right)={\mathrm{\α}}_{v}L$

Wherein, A is the spectrum integral absorptivity of fixed wave length laser, I₀It is incident intensity, I_tBe projection light intensity, ν be laser frequently Rate, P is the pressure of measuring environment, and to absorb light path, X is absorbent components concentration, α to L_vIt is absorption coefficient, S_v(T) for measurement is used Intensity of the spectral line under temperature T；I₀With I_tThe Beer-Lambert laws and S for meeting_v(T) expression formula is as follows：

$S_v\left(T\right)=S_v\left(T_0\right)\frac{Q\left(T_0\right)}{Q\left(T\right)}\exp \[-\frac{hcE}{k_B}(\frac{1}{T}-\frac{1}{T_0})\]\×\[\frac{1-\exp (hcE/k_{B}T)}{1-\exp (hcE/k_B{T}_0)}\]$

Wherein,It is linear function, meetsQ (T) is segmentation function, and the multinomial of its usable temp T is intended Close, h is Planck's constant, c is the light velocity in vacuum, and E is low-level energy, k_BIt is Boltzmann constant, T is measurement temperature, T₀ It is reference temperature, S_v(T₀) it is reference temperature T₀Under the intensity of spectral line.

2. it is a kind of based on acousto-optic fusion mixed gas temperature field concentration field measurement device, it is characterised in that including：Acoustics sensor Device, laser aligner, laser detector, single-chip microcomputer, the first amplifier, two-way switch, acoustic emission end variable connector, sound wave connect Receiving end variable connector, the second amplifier, phase detecting module, laser controller, LASER Light Source and pedestal, laser chopper, swash Optical branching device, optical fiber, lock-in amplifier, data collecting card, computer；

Wherein, multiple acoustic sensors and corresponding laser aligner and laser detector are arranged around tested region；Acoustics Sensor connects acoustic emission end variable connector and sound wave receiving terminal variable connector respectively, and acoustic emission end variable connector connects respectively Two-way switch, phase detecting module, the first amplifier, single-chip microcomputer are connect, acoustic receiver end variable connector connects the second amplification respectively Device, two-way switch, phase detecting module, computer are connected with phase detecting module and single-chip microcomputer again；Multiple laser aligners It is connected by optical fiber with laser shunt, laser shunt, laser chopper, LASER Light Source and pedestal, laser controller are successively Connection, light source power by laser controller control, laser detector, lock-in amplifier, data collecting card, computer phase successively Even；

The acoustic sensor is transceiver, and each acoustic sensor is connected to variable connector chip, ultrasonic wave by holding wire Transmission signal is provided by single-chip microcomputer, while single-chip microcomputer provides the control signal of two-way switch and variable connector, two-way switch is responsible for Selection acoustic sensor completes transmitting or receive capabilities, and variable connector control signal is responsible for the selection of acoustic measurement passage；

The computer sends the enable signal instruction of acoustic measurement, and each measurement result is returned by USB interface data line transfer Computer；

The laser aligner sends laser, and the laser that laser controller control light source sends is after chopper is modulated by laser Shunt is divided into some Shu Jiguang by Optical Fiber Transmission to laser aligner, and the laser after laser detector receiving attenuation is simultaneously converted It is voltage signal, the amplifying circuit carried by inside is exported to lock-in amplifier after being amplified, lock-in amplifier output Signal passes through the incoming computer of data collecting card.