ch double-pulsed plif measurement in turbulent premixed...

13th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 26-29 June, 2006

- 1 -

CH Double-Pulsed PLIF Measurement in Turbulent Premixed Flame

Mamoru Tanahashi, Shohei Taka, Toshio Miyauchi

Dept. of Mechanical and Aerospace Engineering, Tokyo Institute of Technology, Japan, [email protected]

Abstract The flame displacement speeds in turbulent premixed flames have been measured directly by the CH double-pulsed planar laser-induced fluorescence (PLIF). The CH double-pulsed PLIF system consists of two independent conventional CH PLIF measurement systems, and laser beams from each laser system are lead to same optical pass using the difference of polarization. The highly time-resolved measurements are conducted in relatively high Reynolds number turbulent premixed flames on a swirl-stabilized combustor. Since the time interval of the successive CH PLIF can be selected to any optimum value for the purpose intended, both of the large scale dynamics and local displacement of the flame front can be discussed. By selecting an appropriate time interval (100µs~200µs), deformations of the flame front are captured clearly. Successive CH fluorescence images reveal the burning/generating process of the unburned mixtures or the handgrip structures in the burnt gas, which have been predicted by three-dimensional direct numerical simulations of turbulent premixed flames. To evaluate the local flame displacement speed directly from the successive CH images, a flame front identification and displacement vector evaluation schemes are developed. Direct measurements of the flame displacement speed are conducted by selecting a minute time interval (≈30µs) for different Reynolds number (Reλ = 63.1~115.0). Local flame displacement speeds coincide well for different Reynolds number cases, which suggests the correctness of the flamelet concept. Furthermore, comparisons of the mean flame displacement speed and the mean fluid velocity show that the convection in the turbulent flames will affect the flame displacement speed for high Reynolds number flames. 1. Introduction The description of dynamics of flame front has been one of the most important subjects in the turbulent combustion research since that is the basis of turbulent combustion models in the flamelet concept (Clavin 1985, Williams 1985, Pope 1988, Peters 2000, Law 2000, Williams 2000). In the concept of the flame stretch, increasing rate of the flame area is expressed by flame displacement speed, flame curvature and strain rate at the flame front (Pope 1988, Candel et al. 1990). The effects of the strain rate have been discussed based on the Markstein number (Peters 2000, Clavin 2000). In previous studies (Poinsot et al. 1992, Sinibaldi et al. 2003), the curvature and strain rate effects have been investigated in the steady or unsteady laminar flames because the flame elements in turbulent flames are assumed to be laminar flame under weak stretch with small curvature. To confirm the theory of the flame stretch experimentally, measurements of the flame displacement speed are required. In general, shadowgraph or laser tomography has been adopted to estimate flame displacement (Sinibaldi et al. 2003, Kido et al. 2003). However, in these techniques, flame propagation normal to the flame front is assumed. In turbulent flames, the flame elements do not always move into the flame normal direction due to strong convection effects of turbulence. In the numerical investigations by direct numerical simulations (DNS) (Haworth and Poinsot 1992, Baum et al. 1994, Echekki and Chen 1996, Tanahashi et al. 2000, Oijen et al. 2005), consumption speed and local heat release rate are commonly used to represent characteristics of flamelets instead of the flame displacement speed, and effects of the curvature and stretching rate have been discussed. In experiments, measurements of the local consumption speed or heat release rate are quite difficult even by CH planer laser-induced fluorescence (PLIF) due to severe calibration problem. To investigate turbulent flame structures experimentally, PLIF (Dyer and Crosley 1984, Hanson


- 2 -

1986) of molecules and radicals produced in chemical reactions, such as OH (Smooke et al. 1992), CO (Seitzman et al. 1987), CH (Allen et al. 1986, Carter et al. 1998, Mansour et al. 1998) and CH2O (Böckle et al. 2000), are commonly used. Since CH radicals are promoted at the flame front and have narrow width enough to represent the reaction zones, CH PLIF measurements have been used to visualize instantaneous flame structures. Although conventional PLIF measurements have been a very powerful tool to obtain instantaneous local flame structures, investigation of dynamics of flame structures in turbulence has been difficult due to the limitation of time resolution. The time resolution of conventional PLIF measurement is of the order of Hz, which is limited by experimental instruments, in most cases by camera and laser power. Recently, several time resolved PLIF measurement have been reported (Kychakoff et al. 1987, Seitzman et al. 1994, Schefer et al. 1994, Kaminski et al. 1999, Nygren et al. 2001, Watson et al. 2002, Hult et al. 2005). To investigate mechanism of flame stabilization of the turbulent jet diffusion flames, double-pulsed CH PLIF and CH4 Raman scattering technique has been reported by Schefer et al. (1994) and simultaneous CH double-pulsed PLIF and particle image velocimetry (PIV) has been conducted by Watson et al. (2002). By using 4 head YAG laser cluster, Kaminski et al. (1999), Nygren et al. (2001) and Hult et al. (2005) have investigated dynamics of the flame front from time resolved OH PLIF. In this study, CH double-pulsed PLIF measurement is adopted to evaluate flame displacement speed in turbulent premixed flames. The developed time resolved CH PLIF system is applied to relatively high Reynolds number turbulent premixed flames on a swirl-stabilized combustor, and dynamics of local flame structures are discussed. To evaluate the flame displacement speed directly from successive CH images, a flame front identification and displacement vector evaluation schemes are developed. 2. Experimental Setup and Apparatus 2.1 CH Double-Pulsed PLIF Measurement System The schematic diagram of the experimental setup for CH double-pulsed PLIF measurement is shown in Fig.1. By combining two independent CH PLIF systems, the time-resolved PLIF system is comprised. For CH-PLIF measurement, the Q1(7,5) transition of the B2Σ--X2Π(0,0) band at 390.30nm is excited and fluorescence from the A-X(1,1), (0,0) and B-X(0,1) bands between 420 and 440nm is detected. CH radical is excited by two laser systems. First dye laser (Lambda Physik, Scanmate2) is pumped by a XeCl excimer laser (Lambda Physik, LPX 110I, 308nm, 200mJ/pulse) with BiBuQ dye in p-dioxane solvent and second dye laser (Sirah Precisionscan) is pumped by a Nd:YAG laser (Spectra-Physics, Quanta Ray PRO-190, 355nm, 300mJ/pulse) with Exalite389 dye in p-dioxane solvent. These laser systems generate laser pulses of about 18-20mJ/pulse and about 20-22mJ/pulse, respectively. Laser beams from each laser systems are polarized in vertical and horizontal direction and are lead to same optical pass by a polarizing beam splitter. The combined beams are expanded into laser sheets by laser sheet forming optics. Fluorescence from excited CH radicals are detected by two intensified CCD cameras (Andor Technology, iStar DH734-25U-03, 1024 × 1024pixels) fitted with 105mm f2.8 lens (Nikon, Micro-nikkor) and optical filter (SCHOTT, KV418). These cameras are located on the opposite side of the burner, and optical axes are set to be perpendicular to the laser sheets. Timing control of these laser systems and cameras are conducted by a delay/pulse generator (SRS, DG535) and internal delay generator of each camera. Therefore, time interval ∆t of successive PLIF could be selected unrestrainedly. In this study, ∆t is set to the range of 30 to 200µs. The laser beam is shaped into 200µm thickness vertical sheet with 30mm height. The thickness of the laser sheet is measured by


- 3 -

Fig. 1. Schematic diagram of the CH double-pulsed PLIF measurement.

Table 1. Experimental conditions.

Q[l/m] Rel Reλ u′rms[m/s] l [mm] λ[mm] η[mm] l/δF u′rms/SL 200 265.8 63.1 1.24 3.42 0.812 0.0575 82.9 3.20 250 602.0 95.0 1.59 6.02 0.950 0.0548 146.0 4.12 300 881.0 115.0 1.92 7.27 0.949 0.0498 176.6 4.99

a photodiode scanning. Each camera affords a view of 30mm×30mm. Therefore, spatial resolution of PLIF is 30µm×30µm×200µm. To optimize signal-to-noise ratio, image intensifier gate time is set to 30ns; this value is given from preliminary experiments conducted on a steady laminar flame in the slot burner with different gate time. 2.2 Experimental Apparatus Figure 2 shows schematics of the swirl-stabilized combustor (Tanahashi et al. 2005) and a direct photograph of methane-air turbulent premixed flame at stoichiometric condition with flow rate Q = 300L/min. This combustion rig consists of contraction section, swirl injection section and combustion chamber. The inner diameter of 120mm in the contraction section is reduced to 40mm diameter in the swirl injection section. The inner-cross section of combustion chamber is 120mm ×120mm, and the length of the chamber is 550mm. On each side of the combustion chamber, a silica glass plate of 120mm×170mm and 5mm thickness is installed to allow optical access. The swirl nozzle has swirl vanes of 14mm inner diameter and 40mm outer diameter with inclination of 45 degree from the nozzle axis. Although a secondary fuel nozzle is mounted at center of the swirl vanes, this nozzle is not used in the present study. In this experiment, vertical and horizontal directions of the laser sheet is defined as the x and y axis, respectively. The z axis is selected to be normal to the laser sheet. In this study, CH double-pulsed PLIF measurements are conducted for three different flow rates; Q = 200, 250 and 300L/min, at stoichiometric condition. To investigate turbulence characteristics of the unburned mixture, hot-wire measurements are conducted in inert flows (Tanahashi et al. 2005). The CH double-pulsed PLIF measurement is conducted in a cross-section with the maximum u'rms, where u'rms indicates turbulence intensity. A white box in the direct photograph denotes the measurement region of PLIF. Turbulence characteristics obtained by the hot-wire measurement are shown in Table 1. Here, l is integral length scale, Rel is Reynolds number based on integral length scale and u'rms, Reλ is Reynolds number based on Taylor micro scale (λ) and u'rms, δF is a


- 4 -

Fig. 2. Schematic of a swirl combustor (left) and a direct photograph of turbulent premixed flame for Q = 300L/min (right). laminar flame thickness and SL is laminar burning velocity. With the increase of the flow rate, Reλ changes from 63.1 to 115.0. These conditions are the same with those in our previous study for simultaneous CH-OH PLIF and stereoscopic PIV (Tanahashi et al. 2005) and classified into the corrugated flamelets regime in the turbulent combustion diagram by Peters (1999). 3. Dynamics of Flame Front in Turbulence Typical successive CH fluorescence images for Reλ = 63.1 (Q = 200L/min) are shown in Fig. 3 for three different realizations. Time interval of successive CH PLIF are 100µs for Fig. 3 (a) and (b), and 200µs for (c), and each image shows 30mm×30mm regions. In these figures, black line represents the integral length scale of turbulence. Flame front represented by high concentration CH layer shows very complicated distribution and have several sizes of wrinkling; large-scale more than integral length scale to small-scale less than Taylor micro scale (Tanahashi et al. 2005). In addition to these instantaneous features of flame front, dynamics of flame front can be discussed from the successive flame front images. As shown in Fig. 3, ring-like flame fronts are found in the first images (see circle A). The size of these flame fronts is diminished or they disappear in the second images. Isolating process of the unburned mixture from main flame front is also observed as denoted by a circle B in Fig. 3. These deformations of flame front might represent the burning and generating process of the unburned mixture in the burnt gas or the handgrip structure which has been shown by three-dimensional direct numerical simulation (DNS) of turbulent premixed flames (Nada et al. 2004). 4. Direct Measurement of Flame Displacement Speed 4.1 Evaluation of Flame Displacement Speed In this study, from successive CH fluorescence images, flame displacement speed is evaluated by the following procedures:


- 5 -

(a)

(b)

(c)

Fig. 3. CH double-pulsed fluorescence images of CH4-air turbulent premixed flames ( φ = 1.0, Reλ = 63.1, (a) and (b): ∆t = 100µs, (c): ∆t = 200µs ).

(1) Set interrogation region just like an analysis technique for the conventional PIV. (2) Define the flame front from the mean intensity of CH fluorescence in each interrogation

regions. (3) Evaluate flame displacement speed using the cross-correlation method.

Here, optimizations of the size of interrogation region and the magnitude of the flame displacement are required to evaluate the displacement speed by the cross-correlation method. Time interval of successive CH PLIF and interrogation region size are set to 30µs and 48 × 48pixels, respectively. These conditions were determined from preliminary experiments with different time interval. Note that thickness of clearly captured flame front is not more than 15pixels. The cross-correlation algorithm based on fast Fourier transformation is used to calculate the local flame displacement speed in two-dimensional cross section. This code is mainly constructed based on the high resolution PIV algorithm (Tanahashi et al. 2002). To detect the flame front precisely, interrogation regions are 50% overlapped. To evaluate the displacement within sub-pixel accuracy, 3-point Gaussian fitting is applied. In the process of flame displacement speed evaluation, detection of the flame front is most important. Figure 4 (a) shows probability density functions of mean fluorescence intensity in interrogation regions. The mean fluorescence intensity is normalized by the maximum fluorescence intensity of each image. Note that it is impossible to conform the photographic


- 6 -

(a)

(b)

Fig. 4. Probability density functions of mean CH signal in the interrogation regions (a), and the maximum of correlation function in the interrogation regions (b).

(a)

(b)

(c)

Fig. 5. Successive CH fluorescence images (a) and (b), and detected flame front (c) (Reλ = 63.1, ∆t = 30µs). sensitivity of two ICCD cameras and pulse energy of successive laser beams. Therefore, signal-to-noise ratios of the successive CH fluorescence images are different. If the same threshold was selected for the mean fluorescence intensity, flame front that does not exist in fact might be detected incorrectly. As for the case with the independent threshold for each image, it is difficult to remove the influence of accidental shot noises. In these situations, the threshold for flame front detection should be selected based on the geometrical average of fluorescence intensities in the corresponding interrogation regions. In Fig. 4 (a), probability density function of the geometrical average is also plotted. This result suggests that 0.3 of the normalized geometrical average is suitable for the threshold to detect the flame front correctly. In the cross-correlation method, displacements of flame front in interrogation regions are evaluated from the location with the maximum of correlation function. Figure 4 (b) shows probability density functions of the maximum of correlation functions. Since low correlation gives spurious displacement speeds, threshold of the maximum correlation coefficient is set to be 0.35. Furthermore, due to 50% overlap of interrogation regions, several adjacent interrogation regions might be detected as flame front. To eliminate the region in which flame front is NOT included completely, fluorescence intensity in central area of interrogation regions is compared with mean intensity. If the intensity in central area is stronger than the mean one, that region is treated as flame front. This discrimination is effective to reduce the spurious vectors. Figure 5 shows the successive CH fluorescence images and detected flame front from corresponding images. Detected flame front coincide very well with the location where CH intensity is high. Figure 6 shows vector map of flame displacement speed for three different Reynolds number with successive CH fluorescence images. In these figures, red and blue color represents 1st and 2nd CH


- 7 -

(a)

(b)

(c)

Fig. 6. Successive CH fluorescence images and vector maps of flame displacement speed (red: 1st image, blue: 2nd image, (a): Reλ = 63.1, (b): Reλ = 95.0, (c): Reλ = 115.0). (a)

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 5 10 15 20

Reλ = 63.1Reλ = 95.0Reλ = 115.0

P

Sd [ m/s ]

(b)

10-3

10-2

10-1

100

-20 -15 -10 -5 0 5 10 15 20

Reλ = 63.1Reλ = 95.0Reλ = 115.0

Sd,u [ m/s ]

(c)

10-3

10-2

10-1

100

-20 -15 -10 -5 0 5 10 15 20

Reλ = 63.1Reλ = 95.0Reλ = 115.0

Sd,v [ m/s ]

Fig. 7. Probability density functions of flame displacement speed (a), and x: (b) and y: (c) component. fluorescence image, respectively. White vectors represent the local flame displacement speed evaluated by the above-mentioned method. Directions of the flame displacement vectors coincide very well with observations from the successive CH fluorescence images. 4.2 Flame Displacement Speed of Turbulent Premixed Flame In Fig. 7 (a), probability density functions of local flame displacement speed Sd are presented. To obtain these results, 120 sets of successive CH images and more than 5000 displacement vectors are used for each condition. The probability for high displacement speed is a little bit high for high Reynolds number case. Mean fluid velocity in the measurement region has been measured by stereoscopic PIV (Tanahashi et al. 2005). The mean velocity and turbulence intensity increase for high Reynolds number. Typical values are about 5.0m/s to 8.9m/s for mean streamwise velocity and about 2.5m/s to 3.6m/s for turbulence intensity. Although the velocity field depends on Reynolds number significantly, the flame displacement speed is slightly affected by Reynolds number. These results reflect the correctness of the flamelet concept, because the turbulent burning velocity increase due to the increase of flame surface area and the flame displacement speed is not modified significantly. Figure 7 (b) and (c) show probability density functions of x and y component of the flame displacement speed. The probability density functions of each component are independent on Reynolds number and coincide very well. The different Reynolds number effect in Sd and in Sd,u and Sd,v is caused by the correlation between Sd,u and Sd,v, and closely related to hydrodynamical structure as described below. It should be noted that probability density functions in Fig. 7 (b) and


- 8 -

(a)

(b) (c)

Fig. 8. Vector maps of mean flame displacement speed and distributions of the number density of detected flame front, (a): Reλ = 63.1, (b): Reλ = 95.0, (c): Reλ = 115.0.

(a)

(b)

(c)

Fig. 9. Vector maps of mean flame displacement speed (white arrows) and mean fluid velocity (black arrows), (a): Reλ = 63.1, (b): Reλ = 95.0, (c): Reλ = 115.0. (c) show large peaks at 0m/s. This might be caused by several possible reasons. One is existence of the re-circulation zone in the swirl-stabilized combustor. As the re-circulation zone play an important role for flame stabilization, stationary flame with Sd ≈ 0 has high possibility even for the turbulent state. Another is three-dimensionality of turbulent flames. Since the present measurement is conducted in two-dimensional cross section in highly turbulent swirling flow, flame fronts which propagate into out-of-plane can not be measured. Such flame elements are detected as stationary flame with Sd ≈ 0. Figure 8 shows mean flame displacement vector maps and distributions of number density of detected flame front. As the present measurements were conducted in the swirl-stabilized combustor, isolated flame islands which are shown in Fig. 3 move into the upper-left side in the measurement region. With the increase of flow rate (or Reynolds number), the isolated unburned mixture in the burned gas increases as shown in Fig. 6 and in our previous study (Tanahashi et al. 2005), which results in the increase of turbulent burning velocity in the flamelet regions. Therefore, the magnitude of the mean flame displacement speed is larger for high Reynolds number case. In our previous study (Tanahashi et al. 2005), simultaneous CH-OH PLIF and stereoscopic PIV measurements have been conducted in the same plane. In Fig. 9, mean flame displacement vectors are compared with the mean velocity vectors obtained from previous PIV measurements. The mean velocity distributions are evaluated from more than 130 realizations, and the compared region are denoted by a box with dotted lines in Fig. 8. With the increase of Reynolds number, the mean flame displacement vectors tend to align with the mean velocity vectors. These results suggest that effects of convection become strong for high Reynolds number case. Even for the


- 9 -

highest Reynolds number case, misalignment still remains, which might be caused by the sampling number for the present displacement speed measurement. However, this misalignment will be explained from the simultaneous CH double-pulsed PLIF and stereoscopic PIV, which gives flame displacement speed, flame curvature and the strain rare simultaneously, in the near future. 5. Summary In this study, CH double-pulsed PLIF measurement has been developed to measure the local flame displacement speed directly. The developed measurement system was applied for relatively high Reynolds number methane-air turbulent premixed flames stabilized on a swirl combustor. By selecting an appropriate time interval of successive CH PLIF, modifications of the flame front are captured clearly. From the successive CH fluorescence images, the burning and generating process of the unburned mixture in the burnt gas or the handgrip structure which have shown by DNS can be observed. To evaluate the local flame displacement speed directly from the successive CH images, a flame front identification and displacement vector evaluation schemes are developed. Local flame displacement speeds coincide well for different Reynolds number cases, which represent the correctness of the flamelet concept. Furthermore, comparison of mean flame displacement speed and mean fluid velocity shows that convection in the turbulent flames will affect the flame displacement speed. Direct measurement of local flame displacement speed described in this paper can be conducted with stereoscopic PIV measurement simultaneously. The simultaneous CH double-pulsed PLIF and stereoscopic PIV measurements will provide detail information about important factors such as flame displacement speed, flame curvature and strain rate to describe the dynamics of flame surface in turbulence. Acknowledgments This work is partially supported by Grant-in-Aid for Scientific Research (A) (No.15206023) of Japan Society for the Promotion of Science. References Allen MG, Howe RD, Hanson RK (1986) Digital imaging of reaction zones in hydrocarbon-air

flames using planar laser-induced fluorescence of CH and C2. Opt. Lett. 11: 126-128 Baum M, Poinsot TJ, Haworth DC, Darabiha N (1994) Direct numerical simulation of H2/O2/N2

flames with complex chemistry in two-dimensional turbulent flows. J. Fluid Mech. 281: 1-32 Böckle S, Kazenwadel J, Kunzelmann T, Shin D -I, Schulz C, Wolfrum J (2000) Simultaneous

single-shot laser-based imaging of formaldehyde, OH and temperature in turbulent flames. Proc. Combust. Inst. 28: 279-286

Candel SM, Poinsot TJ (1990) Flame stretch and the balance equation for the flame area. Combust. Sci. and Tech. 70: 1-15

Carter CD, Donbar JM, Driscoll JF (1998) Simultaneous CH planar laser-induced fluorescence and


- 10 -

particle imaging velocimetry in turbulent nonpremixed flames. Appl. Phys. B 66: 129-132 Clavin P (1985) Dynamic behavior of premixed flame fronts in laminar and turbulent flows. Prog.

Energy Combust. Sci. 11: 1-59 Clavin P (2000) Dynamics of combustion fronts in premixed gases: from flames to detonations.

Proc. Combust. Inst. 28: 569-585 Dyer MJ, Crosley DR (1984) Rapidly sequenced pair of two-dimensional images of OH laser-

induced fluorescence in a flame. Proc. Int. Conf. Laser 84: 211-218 Echekki T, Chen JH (1996) Unsteady strain rate and curvature effects in turbulent premixed

methane-air flames. Combust. Flame 106: 184-202 Hanson RK (1986) Combustion diagnostics: planar imaging techniques. Proc. Combust. Inst. 21:

1677-1691 Haworth DC, Poinsot TJ (1992) Numerical simulations of Lewis number effects in turbulent

premixed flames. J. Fluid Mech. 244: 405-436 Hult J, Meier U, Meier W, Harvey A, Kaminski CF (2005) Experimental analysis of local flame

extinction in a turbulent jet diffusion flame by high repetition 2-D laser techniques and multi-scalar measurements. Proc. Combust. Inst. 30: 701-709

Kaminski CF, Hult J, Alden M (1999) High repetition rate planar laser induced fluorescence of OH in a turbulent non-premixed flame. Appl. Phys. B 68: 757-760

Kido H, Nakahara M, Nakashima K, Hashimoto J (2003) Influence of local flame displacement velocity on turbulent burning velocity. Proc. Combust. Inst. 29: 1855-1861

Kychakoff G, Paul PH, van Cruyningen I, Hanson RK (1987) Movies and 3-D Images of Flowfields Using Planar Laser-Induced Fluorescence. Appl. Opt. 26: 2498-2500

Law CK, Sung CJ (2000) Structure, aerodynamics, and geometry of premixed flamelets. Prog. Energy Combust. Sci. 26: 459-505

Mansour MS, Peters N, Chen YC (1998) Investigation of scalar mixing in the thin reaction zones regime using a simultaneous CH-LIF/Rayleigh laser technique. Proc. Combust. Inst. 27: 767-773

Nada Y, Tanahashi M, Miyauchi T (2003) Effect of turbulence characteristics on local flame structure of H2-air premixed flames. J. Turbulence 5: pn.16

Nygren J, Richter M, Hult J, Kaminski CF, Alden M (2001) Temporally resolved single-cycle measurements of fuel- and OH-distributions in a spark ignition engine using high speed laser spectroscopy. Fifth Intl. Symp. on Diagnostics and Modeling of Combustion in Internal Combustion Engines 572-580

Peters N (1999) The turbulent burning velocity for large-scale and small-scale turbulence. J. Fluid Mech. 384: 107-132

Peters N (2000) Turbulent Combustion. Cambridge Press. Poinsot TJ, Echekki T, Mungal MG (1992) A study of the laminar flame tip and implications for

premixed turbulent combustion. Combust. Sci. and Tech. 81: 45-73 Pope SB (1988) The evolution of surfaces in turbulence. Intl. J. Engng. Sci. 26: 445-469 Schefer RW, Namazian M, Filtopoulos EEJ, Kelly J (1994) Temporal evolution of

turbulence/chemistry interactions in lifted, turbulent-jet flames. Proc. Combust. Inst. 25: 1223-1231

Seitzman JM, Haumann J, Hanson RK (1987) Quantitative two-photon LIF imaging of carbon monoxide in combustion gases. Appl. Opt. 26: 2892-2899

Seitzman JM, Miller MF, Island TC, Hanson RK (1994) Double-pulsed imaging using simultaneous OH/acetone PLIF for studying the evolution of high-speed, reacting mixing layers. Proc. Combust. Inst. 25: 1743-1750

Sinibaldi JO, Driscoll JF, Mueller CJ, Donbar JM, Carter CD (2003) Propagation speeds and stretch rates measured along wrinkled flames to assess the theory of flame stretch. Combust. Flame 133: 323-334


- 11 -

Smooke MD, Xu Y, Zurn RM, Lin P, Frank JH, Long MB (1992) Computational and experimental study of OH and CH radicals in axisymmetric laminar diffusion flames. Proc. Combust. Inst. 24: 813-821

Tanahashi M, Fujimura M, Miyauchi T (2000) Coherent fine-scale eddies in turbulent premixed flames. Proc. Combust. Inst. 28: 529-535

Tanahashi M, Murakami S, Choi GM, Fukuchi Y, Miyauchi T (2005) Simultaneous CH-OH PLIF and stereoscopic PIV measurements of turbulent premixed flames. Proc. Combust. Inst. 30: 1665-1672

Tanahashi M, Ootsu M, Fukushima M, Miyauchi T (2002) Measurement of coherent fine scale eddies in turbulent mixing layer by DPIV. Engineering Turbulence Modeling and Measurements 5: 525-534

van Oijen JA, Groot GRA, Bastiaans RJM, de Goey LPH (2005) A flamelet analysis of the burning velocity of premixed turbulent expanding flames. Proc. Combust. Inst. 30: 657-664

Watson KA, Lyons KM, Carter CD, Donbar JM (2002) Simultaneous two-shot CH planar laser-induced fluorescence and particle image velocimetry measurements in lifted CH4/air diffusion flames. Proc. Combust. Inst. 29: 1905-1912

Williams FA (1985) Combustion Theory. Benjamin Cummings Williams FA (2000) Progress in knowledge of flamelet structure and extinction. Prog. Energy

Combust. Sci. 26: 657-682

ch double-pulsed plif measurement in turbulent premixed...

Documents