• 한국연소학회:학술대회논문집
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• 2012.04a
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• pp.197-198
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• 2012

Efficient numerical analysis of combustion induced by premixed swirl multi-burners in a gas turbine combustor is conducted by adopting swirler model. By analyzing the internal recirculation zone, the inner and outer diameters of the swiler are determined to be 28 mm and 76mm to 28mm, respectively. Tangential velocity of 35m/s is determined from swirl and recirculation angles. With swirler model adopted, the predicted temperature of combustion gas agrees well with that from single-burner calculation without the model. But, NOx emission is underestimated by 60 %.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.2
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• pp.161-170
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• 2013

The flow and combustion characteristics in a premixed swirl combustor with a double cone burner are numerically analyzed to adopt a swirler model. The internal recirculation zone formed at the burner exit can be realized by a swirler with inner and outer diameters of 56 and 152 mm, respectively, and accordingly, the flow rate and radial velocity were determined. To select the tangential velocity, swirl and recirculation angles are introduced. A tangential velocity of 40 m/s produces an internal recirculation zone similar to that in a combustor. At the liner exit, the errors in temperature and velocity are 2.8% and 0%, respectively, and they are negligibly small. However, NOx emissions are underestimated by 67% in the numerical results obtained using the swirler model. Although considerable quantitative errors are induced by the swirler model, it can be useful numerical model for the EV burner because it can approximately simulate the essential flow and combustion characteristics in a premixed swirl combustor with a double cone burner and it is expected to make combustion analysis efficient in a gas turbine combustor with complex geometries.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.133-135
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• 2012

This study presents the prediction of NOx and mixing characteristics with several chemical reaction mechanisms of methane in EV burner of double cone. Experimental results are compared with numerical results for validation. Mixing characteristics are analyzed at monitoring points based on the modified unmixedness. The mixing characteristics were improved in a certain case, the lance injection case. In 1-step reaction case, inside of the cone, flame was formed and lots of NOx was generated because the fuel injected from the lance was overestimated. In 2-step reaction case, numerical results showed a good agreement with experimental results in a qualitative manner.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.36 no.1
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• pp.103-110
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• 2012

The flow field, fuel-air mixing, and behaviors of turbulent flames have been investigated using the large eddy simulation (LES) numerical technique in a premixed swirl combustor equipped with EV double cone burners. Recirculation zones are generated by the swirl burner, and lean premixed flames are formed within a distance of 0.2 m from the tip of the burner. NOx emission of 0.46 ppm is predicted at 1 atm and an air/fuel ratio of 38.7. However, most of the CO generated in a flame front continues to be oxidized as it moves toward the exit, and CO emission of 5.45 ppm is predicted at the exit. The NOx emission can be reduced by decreasing the pressure and air/fuel ratio. The characteristics of NOx emission have been investigated through RANS simulations for various fuel injection types, and it is found thereby that five-lance-hole injection produces the lowest NOx emission rate.

• Journal of the Korean Society of Combustion
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• v.19 no.3
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• pp.1-7
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• 2014

Experimental study has been carried out to understand combustion characteristics of a swirl-stabilized premixed gas turbine combustor for power generation. $NO_x$ and CO emissions, extinction limit, pressure loss, and temperature distribution were measured for various operating conditions. Results show that, with increasing inlet air temperature, $NO_x$ is increased due to a higher adiabatic flame temperature while CO is increased or decreased for low or high A/F ratio regime, respectively. depending on the flame location. With decreasing load from the design condition, $NO_x$ is decreased as thermal load is reduced. With further decreasing load, however, $NO_x$ is increased due to a longer residence time. CO is decreased and then increased with decreasing load. Flame extinction limit is extended with increasing inlet air temperature as the recirculation strength is enhanced.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.10
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• pp.911-918
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• 2013

The combustion characteristics of an EV (Environmental Vortex) burner (double-cone burner) adopted in a gas turbines are numerically investigated. The mixing of fuel and air is analyzed for reduction of NO emission. To predict the correlation between NO emission and fuel-air mixedness, 1-step and 2-step chemistry models are adopted. The results calculated by 1-step chemistry showed that NO emissions increased by 2% in the case of degraded mixedness and by 169% in the case of improved mixedness, where the temperature in the flame zone was overestimated upstream of the cone. However, the corresponding results calculated by 2-step chemistry showed that NO emission increased by 3% and decreased by 5%, where the flame zone was not formed inside the cone. The latter results agree well with the experimental ones indicating an increase of 63% and decrease of 11% in the respective cases. Despite quantitative errors, NO emissions can be predicted reasonably by the application of the 2-step chemistry model adopted here and design modification of burner for NO reduction can be proposed based on the numerical data.