• Transactions of the Korean Society of Mechanical Engineers
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• v.16 no.3
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• pp.578-588
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• 1992

In order to predict the effect of swirl on the structure of concentric laminar jet diffusion flame, present study examined the effect of swirl on the flame characteristics by numerical numerical analysis through theoretical model. The theoretical model has been developed for the co-axial laminar jet flame such that the fuel and air are supplying with swirl through inner and outer co-axial tube respectively. For the parametric study, swirl number, Reynolds number of fuel and air and directions of swirl are chosen as important parametes. The results of study show that the flame with width and shorter length is formed by larger swirl number. The important factor of the flame shape is the recirculating zone formed around jet axis near the exit of nozzle. In case of weak swirl, the effect of directions of swirl is not appeared. However, for the strong swirl, the flame with shorter length are appeared in case of counter-swirl compared with the case of co-swirl.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.7
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• pp.79-88
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• 2006

In the present paper, the swirl flow structure and flame characteristics of turbulent premixed combustion in a model gas turbine combustor are investigated using large eddy simulation(LES). A G-equation flamelet model is employed to simulate the unsteady flame behavior. When inlet swirl number is increased, the distinct flow structures, such as the shapes of corner recirculation and center toroidal recirculation zone, are observed and the flame length is shorted gradually. Also, the phenomena of flashback are identified at strong swirl intensity. In order to get the accurate description of unsteady flame behavior, the predictive ability of the acoustic wave in a combustor is primarily evaluated. It is found that the vortex generated near the edge of step plays an important role in the flame fluctuation. Finally it is examined systematically that the flame and heat release fluctuation are coupled strongly to the vortex shedding generated by swirl flow and acoustic wave propagation from the analysis of flame-vortex interaction.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.6
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• pp.788-794
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• 1999

The swirl flame is mostly used to stabilize the flame on the burner nozzle in the industrial combustor. In the case of the weak swirl flame(S<0.4), the recirculation zone could not be formed, but in the strong swirl(S>0.6) flame, it could be formed in the center of the swirl flame. In this study, the measurement and analysis of emission species, temperature, radicals of premixed swirl flame in the combustor were performed to understand the NO formation and emission characteristics of the swirl flame of natural gas. The result of NO emission in the swirl flame is that the amount of NO emission in the strong swirl flame decreased about 60% compared with that of the weak swirl flame. The main region of NO formation of the weak swirl flame is positioned in the down stream(z=100~200mm) of the flame, but that of the strong swirl flame is positioned in the up stream(z=40mm) where the recirculation zone seems to be formed. It is supposed that the increase of flame surface and the formation of inversed flame cause the reduction of the high temperature region on the production of NO in the strong swirl flame. The result of NO-temperature relation revealed that the factor of NO formation is not only temperature but also another parameters in the weak swirl flame, but in the strong swirl flame, NO is proportional to the temperature of higher than 1200K.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.2
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• pp.12-23
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• 2021

In this study, the combustion instability characteristics of low-swirl injector and high-swirl injector is compared by model gas turbine combustor. To compare of unstable behavior in high-swirl injector and low-swirl injector, we performed lots of measurement of combustion instability, with variable of equivalence ratio, combustor length and injector type. The results shown that longitudinal instability occur dominantly in model gas turbine combustor. In addition, it was found that high-swirl injector has more wide range of unstable regime than low-swirl injector. The blockage ratio what one of a parameter in low-swirl injector has not much effected in aspects of overall combustor behavior. Also, revealed that combustion instability occurred in the same combustor length has same properties, regardless of the injector type.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.20 no.7
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• pp.2326-2336
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• 1996

So most practical combustor is considered to the swirl flame, it is very important to examinate swirl flame structure and combustion characteristics. Recently, attention has been paid to the flame diagnostic by radical luminous intensity. For swirl flame structure and combustion characteristic, reverse flow boundary, temperature, ion current and radical luminous intensity were measured in the double-coaxial swirl combustor which was used principle of multi-annular combustor. This study had three experimental condition, S-type, C-type, SC-type. S-type and C-type flames were formed recirculation zone, but SC-type flame wasn't formed. C-type flame had two recirculation zone. The position with maximum value of ion current and CH-radical, temperature and OH-radical had similarity distribution almost. Therefore, it is possible that the macro structure of flame was measured by radical luminous intensity in the high intensity of turbulent combustion field which was formed by swirl.