Laser Induced Florescence (LIF) Technique and ItsApplication for Flow Visualization and Scalar Field

(Temperature or Concentration ) Measurement

Hui HU, Toshio KOBAYASHI,Tetsuo SAGA and Nubuyuki TANIGUCHI

Institute of Industrial Science, University of Tokyo,Roppongi 7-22-1, Tokyo 106-8558, Japan

Laser Induced Florescence (LIF) Technique

Energy level

E1

E2

photon

Absorb energyfrom laser light

LIF emission

Spectrum of fluorescent dye (Rhohdamine B)

Hf ( x0,y0) : measured fluorescence intensity A: the fraction of the fluorescence light collected by camera. quantum efficiency, L: the length of the sampling volume along the path of excitation beam molar absorptivity C(x0,y0): the molar concentration of the fluorescent dye. I(x0,y0): the intensity of excitation light beam at the point (x0,y0 )

The intensity of the LIF light at point (x0,y0)

),()(),(),( 000000 yxLCTAyxIyxH f εΦ=

:Φ

:ε

lceIyxI ε−= 000 ),(

Point (x0,y0)

camera

Laser I0

LIF Technique for fluorescent dye concentration measurement

),()(),(),( 000000 yxLCTAyxIyxH f εΦ=

),(),( 0000 yxCyxH f ∝

Keep flow temperature and measurementsystem parameters in constant

Calibration profile for concentration measurement

0

0.2

0.4

0.6

0.8

1

0 0.2 0.4 0.6 0.8 1

C/C0 , C0=0.3mg/l

(I-I

b)/(

I0-I

b)

Laser power=highLaser power=middleLaser power=lowTheory Value

(Hu et al. 1998)

Concentration measurement results

Circular jet flow(Hu et al. 1998)

Concentration measurement results

Lobed jet mixing flow(Hu et al. 1998)

Lobe trough sliceLobe peak slice

LIF Technique for flow temperature field measurement

),()(),(),( 000000 yxLCTAyxIyxH f εΦ=

)(),( 00 TyxH f ε∝

Keep fluorescent dye concentration andmeasurement system parameters in constant

Calibration profile for temperature measurement

The shortages for single emission LIF technique

s Complex calibration• uniformity of laser sheet• the laser power changing between the calibration

test and experiment• absorption effect of the fluorescent dye• etc.

),()(),(),( 000000 yxLCTAyxIyxH f εΦ=

lceIyxI ε−= 000 ),(

The attenuation effect of laser light

laser power 2.5w

0

0 .2

0 .4

0 .6

0 .8

1

1 .2

0 50 100 150 200 250L length (mm)

H(X

)/H

(0)

c0:1g;1250l

c0:1g:100l

Point (x0,y0)

camera

Laser I0

lceIyxI ε−= 000 ),(

(Hu et al. 1998)

),(),(),(),( 0011100001 yxLCTAyxIyxH f λεΦ=

Dual emission LIF technique:

222

111

2

1 )(),(

),(

ΦΦ

∝c

cTyxH

yxH

f

f

εε

),()(),(),( 0022200002 yxLCAyxIyxH f λεΦ=

the measurement results from a singleemission and dual emission LIF technique

Dual emission LIF technique

(Sakakibara et al. 1999)

PIV-PLIF System for velocity and temperature orspice simultaneous measurement

velocity vectors from PIV and temperature distribution (background) form PLIF )(Hart et al. 1999)