Aerosol lidar optical layout 1- telescope, 2, 6 - photodetectors, 3 - - PowerPoint PPT Presentation

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Laser sensing of aerosol flows

Valery G. Shemanin.

Novorossiysk Polytechnic Institute, Kuban State Technological University Novorossiysk, 353900 Russia vshemanin@mail.ru

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Abstract

The main points of this work:

• lidar signal for the aerosol particles,
• the laser radiation spectral transmittance signal
• Mie scattering indicatrix for the aerosol particles in

the air flows at the various wavelengths experimental studies for

• this particles concentration level and
• its size distribution function measurements

in our experimental conditions. All of these results show that the aerosol lidar can serve as the powerful instrument solid particles pollution monitoring in the atmospheric border layer under the city area

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Aerosol lidar optical layout

1- telescope, 2, 6 - photodetectors, 3 – 532 nm wavelength interference filter, 4 – lens objective, 5 – mirror R~1, 7 – glass filter, 8 – prism, 9 – laser

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Aerosol lidar equation

P(λ, R) = PL(λ)K1A0ΔRT2(λ, R)σ(λ, R) /R2,

(1) (2)

P(λ, R) - the back scattered emission power at the wavelength λ at the ranging distance R from the distance interval ΔR ; PL(λ) - the laser radiation pulse power; K1- the lidar calibration constant; A0 - the cross section of the receiving telescope aperture T(λ, R) = exp[ −∫α(λ, R) dR] - the transmittance or transparency at the wavelength λ from the lidar up to the studied volume at distance R; α (λ, R) – the extinction coefficient; σ(λ, R) = [dσ(λ, R)/dn] n(R)] -Mie back scattering coefficient; n(R) – the number concentration

(3)

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Laser Doppler anemometer optical layout

1- RF spectrum analyzer, 2- HF filter, 3- amplifier, 4- LF filter, 5 – counter, 6- photo detector, 7- diaphragm, 8- objective, 9- focusing lens, 10- laser beam splitter, 11- laser

n N V S

D

 

    sin 2 m m f T V

D D D

      

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The plot of the LDA velocity values versus MNN velocity dependence

vD- LDA, vM- MMN-240 – at the number concentration of 473 1/cm3

y = 1,0197x + 0,2419 R2 = 0,9898 2 4 6 8 10 2 4 6 8 10 12 vM, m/s vD, m/s

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The plot of the gravimetric data versus the LDA number concentration dependence

C- gravimetric data, n – LDA number concentration at the aerosol flow velocity of 4.6 m/s

y = 4E-06x2 + 0,0087x + 0,0573 R2 = 0,9999 1 2 3 4 5 6 100 200 300 400 500 n, 1/cm3 C, g/m3

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The cement particles size distribution histogram

0,1 0,2 0,3 0,4 0,5 0,6 n/n0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 2r, 10 mkm S LDA

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The plot of the cement particles Mie back scattering coefficient values versus LDA number concentration

y = 0,0047x + 0,6455 R2 = 0,989 1 2 3 4 100 200 300 400 500 n, 1/cm3 σ10e+4, 1/m

σ- lidar Mie back scattering coefficient in 10e-4 1/m, n- LDA number concentration, (dσ(λ, R)/dn)= (3.2±0.5)10e-10 cm2 , (2.1±0.6) – calc., at 532 nm laser wavelength

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The closed gas pipe layout

1- electric motor, 2- fan, 3 – heater, 4- control system, 5-directing wings, 6- optical layout, 7- windows, 8, 9- photodetectors, 10- glass filters, 11,13- mechanical devices, 12- pinhole for gravimetric test, 14 – base construction, 15- tachometer

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The plot of the cement particles mass concentration logarithm dynamics in the gas pipe

The gas pipe cross section is 400x400 mm, the air flow velocity is about 15 m/s and C- the gravimetric data in mg/m3

y = -0,0018x + 3,3104 R2 = 0,8197 0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00 200 400 600 800 1000 1200 t, s lgC

The plot of the cement particles mass concentration dynamics in the gas pipe

The air flow velocity is about 15 m/s

y = 639,5e-0,0025x R2 = 0,8348 100 200 300 400 500 600 700 800 200 400 600 800 1000 1200 t, s C, mg/m3

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Some formulas for the cement particles air flow spectral transmittance and Mie scattering indicatrix

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) exp( ) exp( l K I D I I

 

    n m Q d n K     ) , ( 4

2

  



) /( 3

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 l C D

m



 

 

 

3 2

) ( ) ( 3 dd d f d dd d f d C K

m



 

 



3 2 3 2

) ( ) ( ) , , , ( 4 3 ) ( dd d f d dd d f m d I VC I R I

m ð

     







   

4

) ( ) ( ) ( d I I I

р р

The optical layout of the cement particles Mie scattering indicatrix and spectral transmittance values measuring instrument

1- laser, 2- glass filters, 3, 4 - mirror 5, 9, 11- photo detectors, 7- air pipe, 8- aerosol flow, 10- directing mechanical device, 12- the recording and control system

) ( ) , , ( ) , , ( ] ) 1 ( ) ( ) ( ) 1 ( ln[

32 01 1 32 32 1

        

 

F n Q n Q ref U ref U ex U ex U D D    

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The plot of the cement particles scattering indicatrix in the angle range of 5 – 170 degrees

y = 0,0001x2 - 0,0356x + 3,314 R2 = 0,9767 0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 30 60 90 120 150 180 Teta, degrees Ix, arb.u.

The flow velocity is 15 m/s, 650 nm laser radiation wavelength

The plot of the cement particles scattering signal dynamics at the angle of 70 degrees

y = 8,0558e-0,0023x R2 = 0,9593 0,00 2,00 4,00 6,00 8,00 10,00 12,00 14,00 200 400 600 800 1000 1200 t, s Ufs, V

The flow velocity is 15 m/s, 650 nm laser radiation wavelength

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The plot of the cement particles air flow

• ptical density signal dynamics at the optical

length of 40 cm and 650 nm wavelength

y = 0,2143e-0,0023x R2 = 0,9372 0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 200 400 600 800 1000 1200 t, s D

The optical length is 40 cm, 650 nm wavelength

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The plot of the cement particles air flow

• ptical density signal logarithm dynamics

y = -0,001x - 0,669 R2 = 0,9372

• 2,500
• 2,000
• 1,500
• 1,000
• 0,500

0,000 200 400 600 800 1000 1200 t, s lgD

The optical length is 40 cm, 650 nm wavelength

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The plot of the cement particles scattering signal values at the 70 degrees versus mass concentration dependence

y = 0,0063x + 1,1554 R2 = 0,9272 1 2 3 4 5 6 7 8 9 200 400 600 800 1000 C, mg/m3 Ufs, V

The flow velocity is 15 m/s, 650 nm laser radiation wavelength

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The plot of the cement particles air flow

• ptical density values versus mass

concentration dependence

y = 4E-05x + 0,0768 R2 = 0,9255 0,00 0,05 0,10 0,15 0,20 0,25 0,30 0,35 0,40 0,45 0,50 2000 4000 6000 8000 10000 C, mg/m3 D

The optical length is 40 cm, 650 nm wavelength

The plot of the cement particles extinction efficiency average values ratio versus its average volume-square sizes

δ32 – the volume-square middle size in mkm; Q(650)/Q(532) and Q(650)Q(405) - extinction efficiency average values ratio at the pair of laser radiation wavelengths

y = -0,878x2 + 1,578x + 0,3131 R2 = 0,9982 y = -1,4885x2 + 2,865x - 0,2261 R2 = 0,9974 0,2 0,4 0,6 0,8 1 1,2 1,4 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1 d32 Q Q(650)/Q(532) Q(650)Q(405)

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The plot of the cement particles optical density D(650)/D(405) ratio and extinction efficiency average values ratio Q(650)Q(405) dynamics

– Q(650)Q(405) calc., D(650)/D(405) – exp.

y = -0,3716Ln(x) + 3,1983 R2 = 0,9831 y = -0,3139Ln(x) + 2,8072 R2 = 0,938 0,2 0,4 0,6 0,8 1 1,2 500 1000 1500 2000 2500 t,s Q1/Q2 D1/D2

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The plot of the logarithm normal distribution function maximum versus d32 dependence

R0 and d - in mkm; 120 probes

y = 0,8564x + 0,0786 R2 = 0,986 0,2 0,3 0,4 0,5 0,2 0,3 0,4 0,5 d32, mkm ro, mkm

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The plot of the cement particles logarithm normal distribution function half width versus d32 dependence

Sigma and d32 - in mkm; 120 probes

y = -1,4037x + 0,8996 R2 = 0,8503 0,1 0,2 0,3 0,4 0,5 0,6 0,2 0,3 0,4 0,5 d32, mkm Sigma

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The plot of the cement particles size logarithm normal distribution function and real distribution function

d - in mkm; Probe No.7

0,5 1 1,5 2 2,5 3 0,2 0,4 0,6 0,8 1 1,2 1,4 d, mkm A, arb.u. LNL No.7

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The plot of the cement particles size distribution dynamics in air flow

• 0,2

0,2 0,4 0,6 0,8 1 1,2

• 1,5
• 1
• 0,5

0,5 1 1,5 2 2,5 lgd A, arb.u. 10 20 50

d - in mkm; 0, 10, 20 and 50 s – the time moment from the aerosol injection

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The plot of the cement particles size distribution function in air pipe

• 0,2

0,2 0,4 0,6 0,8 1 1,2 1,4

• 1,5
• 1
• 0,5

0,5 1 1,5 lgd A, arb.u. F-exp F-100

d - in mkm; F-100 s – the time moment from the aerosol injection, F-ext – at the enter of the filter

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The plot of the cement particles size distribution dynamics in air pipe

• 0,5

0,5 1 1,5 2 2,5 3

• 1
• 0,8
• 0,6
• 0,4
• 0,2

0,2 0,4 lgd A, arb.u. F-3600 F-exp

d - in mkm; F-3600 s – the time moment from the aerosol injection, F-ext – at the exit of the filter

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Conclusion



This linear dependence between Mie back scattering coefficient and the number concentration of the cement aerosol particles makes a possibility to measure this concentration by such an aerosol lidar.



The experimental setup was created for the laser radiation spectral transmittance and Mie scattering indicatrix measurements and these data were recorded with the cement particles probes concentration measurements by gravimetric method.



All of the experimental results give us the possibility to reconstruct the real particles size distribution function.



Therefore it is possible to determine the laser radiation spectral transmittance signal, Mie scattering indicatrix and the lidar signal for the aerosol particles in the air flows at the various wavelengths and to get this particles concentration level and particles size distribution function.



All of these results give the enough data about the aerosol flows in our approach.

Our works



V.E. Privalov, A.E. Fotiadi, V.G. Shemanin, “Lasers and Atmospheric Environmental Monitoring”, St.-Pb.: Lan, 2013, 288 p.



S.V. Polovchenko, V.E. Privalov, P.V.Chartiy, V.G. Shemanin, “Particles Size Distribution Function Reconstruction on the Basis of Multiwaves Laser Sensing Data”, J. Opt. Technology, 2016, Vol.83, No.5, pp.43-49



V.E. Privalov, E.I. Voronina, V.G. Shemanin, “Air quality controlling system for industrial region”, Proc. SPIE, 2001, Vol. 4680, pp. 122 - 128



V.E. Privalov, V.G. Shemanin, Lidar Parameters for the Gaseous Molecules and Aerosol Remote Sensing in Atmosphere. S.-Pb.: Baltic STU, 2001, 56 pp.



V.E. Privalov, V.G. Shemanin, P.V. Charty, “Polydisperse Aerosol in air Flow Mi Scattering Indicatrix Experimental Studies”, Proc. SPIE, 2004 ,

• Vol. 5447, pp. 242-250,



V.E. Privalov, V.G. Shemanin, P.V. Charty, “Nano- and Micropowder Laser Multywavelengths Sensing and Aerodynamics Classifications”, Key Engineering Materials, 2010 , Vol. 437, pp. 571-574,

Thanks for Your attention!

Схема пылевого стенда



1 – электродвигатель, 2 – вентилятор,



3 – нагревательные элементы, 4 – блок управления оптикой,

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5 – направляющие лопатки, 6 – оптическая часть измерителя, 7 – смотровые окна, 8 – фотоприемник ММСП, 9 – фотоприёмник МИСР, 10 – сфетофильтр, 11 – противовес, 12 – отверстие в крышке штуцера, 13 – механизм поворота фотоприёмника МИСР, 14 – постамент,

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15 – электронный тахометр

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