• Journal of the Korean Society of Propulsion Engineers
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• v.22 no.1
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• pp.72-79
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• 2018

An experimental study was performed to investigate the chemiluminescence characteristics in the spray combustion of ultransonically atomized kerosene. The radical intensity of the spray flame was measured using an ICCD camera and the amount of fuel consumed was obtained by a precise flow-rate measurement technique during combustion. Fuel consumption increased linearly with the increase in carrier-gas flow rate, and typical group combustion, which is a characteristic of spray combustion, was observed. It was found from the analysis of chemiluminescence that the maximum emission intensities of OH and CH radicals decrease, and they move downstream resulting in the increase in a vivid reaction zone as the spray flow rate increases.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.6
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• pp.485-496
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• 2015

The present study presents experimental results on the characteristics of emission spectra of kerosene/air swirl flames. The aviation fuel Jet A-1, which is used for the liquid rocket engines of the Korea Space Launch Vehicle, is used with three different swirlers to investigate the swirl strength effects. The emission spectra from the flames are measured with a spectrometer as the swirl strength and combustion air temperature are varied. Chemiluminescence intensities of $OH^*$, $CH^*$ and $C_2{^*}$ are identified from the spectra. The chemiluminescence intensities from the kerosene flames show sensitivity to the swirl strength and are affected by changes in the combustion air temperature. Among the three radicals of interest, $C_2{^*}$ show the most significant changes in chemiluminescence intensity with the swirl strength and equivalence ratio. The intensity ratios $I_{OH^*}/I_{CH^*}$ and $I_{C_2{^*}}/I_{CH^*}$ are adequate for indicating changes in the equivalence ratio with the air and fuel mass flow rates, respectively.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.5
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• pp.10-19
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• 2012

To eliminate the onset of combustion instabilities and develop effective approaches for control, flame structure is very important. In this study, we conducted experiments under various operating conditions with a model gas turbine combustor to examine the relation of combustion instability and flame structure by OH chemiluminescence and laser diagnostics of He-Ne laser absorbtion system. The swirling LNG($CH_4$)/air flame was investigated with overall equivalence ratio of 1.2 and dump plane fuel-air mixture velocity 25 ~ 70 m/s. We founded that the combustion instability phenomenon occurs at lower mixing velocity and higher mixing velocity conditions. We also concluded that fluid dynamical vortex frequency has major effects on the combustion instability characteristics at lower mixing velocity condition.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.367-376
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• 2012

To eliminate the onset of combustion instabilities and develop effective approaches for control, flame structure is very important. In this study, we conducted experiments under various operating conditions with a model gas turbine combustor to examine the relation of combustion instability and flame structure by OH chemiluminescence and laser diagnostics of He-Ne laser absorbtion system. The swirling LNG(CH4)/air flame was investigated with overall equivalence ratio of 1.2 and dump plane fuel-air mixture velocity 25 ~ 70 m/s. We founded that the combustion instability phenomenon occurs at lower mixing velocity and higher mixing velocity conditions. We also concluded that fluid dynamical vortex frequency has major effects on the combustion instability characteristics at lower mixing velocity condition.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1146-1151
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel de-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented for typical locations.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.227-231
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• 2014

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.320-327
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• 2005

An experimental study was performed to investigate the effects of partially premixing, varying the equivalence ratios from $1.36{\sim}{\infty}$, and swirlers with swirl numbers of 0, 0.28, 0.64, and 1.32, on the characteristic of radical ($OH^{\ast}$, $CH^{\ast}$, and $C_2^{\ast}$) and pollutant emission in partially premixed swirling flames. The signal from the electronically excited state of $OH^{\ast}$, $CH^{\ast}$, and $C_2^{\ast}$ was detected through a band pass filter with a photo multiplier tube, and flow fields images were detected through a schlieren system. The results demonstrated that the flame height decreases and jet spreading angle increase with increasing a swirl number. The more momentum ratio and swirl number increase, the more decrease flame height, and the generation of sooting flame is promoted.

• Journal of Energy Engineering
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• v.13 no.3
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• pp.205-213
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• 2004

Usefulness of an optical fiber was demonstrated by detecting the generation of self-excited combustion oscillations. OH chemiluminescence intensity detected by the optical fiber showed mostly excellent agreement with those obtained by high speed CCD camera measurements when combustion oscillations were strong. Symptoms of self-excited combustion oscillation were also studied in order to predict the onset of combustion oscillation before it proceeded to a catastrophic failure. For the purpose, we have found and proposed unique measures to tell the onset of self-excited combustion oscillations based on the careful statistics of fluctuating properties in flames, such as pressure or omission of OH radicals.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.1
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• pp.1-8
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• 2019

To analyze the dynamic behavior and the structure of the gaseous methane-gaseous oxygen diffusion flame formed by a swirl/shear-coaxial injector, combustion experiments were carried out under different propellant injection conditions. As a result, the OH radical emission intensity of the diffusion flame visualized through chemiluminescence was observed to increase as the propellant mass flow and the momentum flux ratio increased. And flames with swirl showed a more high radical emission intensity than those without swirl.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.28 no.11
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• pp.1368-1375
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• 2004

Measurements of OH chemiluminescence in an atmospheric pressure, laboratory-scale dump combustor at equivalence ratios ranging from 0.63 to 0.89 were reported. The signal from the first electronically excited state of OH to ground state was detected through a band-pass filter with an ICCD. The objectives of this study are two: One is to see the effects of equivalence ratio on global heat release rate and local Rayleigh index distribution. To get the local Rayleigh index distribution, the line-of-sight images were inverted by tomographic method, such as Abel do-convolution. Another aim is to investigate the validity of using OH chemiluminescence acquired with an ICCD as a qualitative measure of local heat release. For constant inlet velocity and temperature, the overall intensities of OH emission acquired at different equivalence ratio showed periodic and higher value at high equivalence ratio. OH intensity averaged over one period of pressure increased exponentially with equivalence ratio. Local Rayleigh index distribution clearly showed the region of amplifying or damping the combustion instability as equivalence ratio increased. It could provide an information/insights on active control such as secondary fuel injection. Finally, local heat release rate derived from reconstructed OH images were presented fur typical locations.