48 144 2006 206-213 Journal of the Combustion Society of Japan Vol. 48 No. 144 (2006) 206-213 ORGNAL PAPER * * An Approach to Combustion Diagnostics of Premixed Flame by Chemiluminescence of OH * and CH * 1 * 1 1 1 SEO, Takehiko 1 *, AKAMATSU, Fumiteru 1, SHBAHARA, Masahiko 1, KATSUK, Masashi 1 1 565-0871 2-1 Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan 2005 10 29 ; 2006 3 23 Received 29 October, 2005; Accepted 23 March, 2006 Abstract : Combinations of optical interference band-pass filter and photomultiplier are often used for detecting OH* and CH* chemiluminescences in examining the correlation between chemiluminescent intensities and the combustion quantities, such as equivalence ratio and temperature. Since we consider that the influence of continuous background emission on chemiluminescent emission intensities should not be ignored, we propose a technique for removing those influences on OH* and CH* chemiluminescent emission intensities measured by the combination of optical band-pass filters and photomultipliers. Moreover, the correlation between the actual chemiluminescent emission intensities without the influence of continuous background emission and the physical quantities has been investigated in the present study. By separating chemiluminescent emission intensities of OH* and CH* from continuous background emission intensities, it becomes possible to measure equivalence ratio using chemiluminescent emission intensities at any positions of a flame. This technique holds wider applicability than the conventional methods. Key Words : Combustion, Spectroscopic measurements, Chemiluminescence, Temperature measurements, Rayleigh scattering, Continuous background emission OH* CH* C 2* [1-3] [4,5] [6] [7] [1,2,4,5] [8] * Corresponding author. E-mail: seo@combu.mech.eng.osaka-u.ac.jp Fig.1 Example of emission spectrum of laminar premixed flame. 1 OH* CH* OH* CH* 1 (48)
207 250 450 nm CHO (Vaidya Band) 350 500 nm CO O OH* CH* 2 ( 40 mm 8 mm) 1.0 1.2 Dibble Fuel[9] ( CH 4 : H 2 = 37.9 : 62.1) ( 23.3 %) ( MCRO ) [10,11]MCRO MCRO MCRO ( ST-U200D-SY NA = 0.2 200 µm) (OREL MS257) Fig.2 Experimental system with spectroscope. CCD (ANDOR DH520-18F - 04) PC 300 Line / mm 0.32 nm 21 ms 300 CCD 0 x y z x 10 µm 20 µm 1 µm (Mitsutoyo 2119F) MCRO SN 1.0 1.4 (49)
208 48 144 2006 CH* 1.2 20 mm 71 CCD 50 W (1) Fig.3 Calibration factor in functions of wavelength. flame abs flame ( ) = measured( ) light abs light measured ( ) ( ) (1) flame abs ( ) flame measured ( ) light abs ( ) light measured ( ) (1) 3 387 nm 300 nm SN CCD CCD 260 nm 485 nm 0 293 nm 0 CCD (a) OH* Band Fig.4 X-axis profile of chemiluminescent emission intensities measured by spectroscope. (a) OH* Band Fig.5 X-axis profile of c / d ratio. (b) CH* Band (b) CH* Band (50)
209 [3] OH*(0,0)R OH*(0,0)Q OH*(1,1)R OH*(1,1)Q 303.7 nm 335.3 nm OH* CH*(0,0) 416.6 nm 442 nm CH* 1 2 OH* 335.3 nm 344.8 nm OH* CH* 412 nm 416.6 nm 442 nm 446.6 nm 4 d c s x S d() S c() S s() (2) d (OH*) d c s = = = 2 d = 1 2 c = 1 2 s = 1 S ( ) S ( ) S ( ) S d() = S c() S s() d c s (3) d = c + s MCRO d (OH*) x = 0 x = 0 d (OH*) 1/2 x 4(a) c (OH*) x = 0 4(b) d (CH*) c (CH*) d (CH*) d (CH*) CH* (2) (3) Fig.6 Experimental system with D.M. and B.P.F. Table 1 Characteristics of D.M. and B.P.F. 5 c d x 5(a) OH* c / d OH* 5(b) CH* c / d 1.0 CH* 20 % ( ) (51)
210 48 144 2006 (a) OH* B.P.F. (b) CH* B.P.F. Fig.7 Profile of transmit rate of B.P.F. OH* CH* (488 nm) (D.M.) (B.P.F.) 1 C.W. FWHM OH* CH* 7 (counts) OH* (0,0)R (0,0)Q (1,1)R CH* (0,0) /V 100 Hz A/D (NEC DL2300) 12 bit FFT 1.0 mm/s x x ( ) 10 µm 3 (3 ch 488.0 nm) (a) OH* emission intensity (b) CH* emission intensity Fig.8 X-axis profile of chemiluminescent emission intensities measured by B.P.F and the spectroscope. [9] 488 nm (Spectra Physics BeamLok2080 8 W) SN 6 OH* CH* 7 nm S d() T() ( 7 ) db S d() T() (4) l db = Sd ( ) T( ) s { } s 0 l 8 (a) OH* (b) CH* x ( ) OH* CH* (4) (52)
211 (a) OH* Band (b) CH* Band Fig.9 X-axis profile of cb/ db ratio. OH* CH* x 9 ( db ) ( cb ) cb / db x db (OH*) OH* c / d OH* x cb / db ( c / d) CH* c / d CH* OH* OH* 9 OH* CH* cb / db x OH* CH* x = -200 µm x = 200 µm cb / db Fig.10 X-axis profile of chemiluminescent emission intensities and temperature in case of different equivalence ratio. 10 (a) (c) OH* CH* (b) (d) OH* CH* (e) x ( ) (x = 0) OH* x OH* (x = 0) OH* x = 0 CH* x = 60 µm CH* 1.2 (53)
212 48 144 2006 CH* CH* [4,5] 9(a) OH* cb / db (5) Fig.11 Correlation between normalized OH* and CH* emission intensities. cb db ( OH*). = 14. 6e 984 4 ( OH*) E x (5) x OH* x 9(b) CH* cb / db x 1.0 1.2 (5) (5) x 11 OH* CH* (a) (b) Fig.12 Correlation between temperature and normalized emission intensity ratio OH* / CH*. CH* 11 OH* CH* OH* CH* 12 OH* CH* 11 (a) (b) 2 A B (b) A (54)
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