• Korean Chemical Engineering Research
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• v.54 no.4
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• pp.527-532
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• 2016

The effects of gas velocity and solid circulation rate on the axial solid holdup distribution have been determined in a 10 mm-I.D. ${\times}$ 800 mm-high circulating fluidized bed plasma reactor under reduced pressure (1torr). Polystyrene polymer powder and nitrogen gas are used as solid and gas materials respectively. The change of solid circulation rate by a large gas flow rate of the riser (40~80 sccm) is also possible by a relatively small gas flow rate of the solid recirculation part (6.6~9.9 sccm). The solid circulation rate in the reactor under reduced pressure increases with increasing aeration velocity in the solid recirculation part. The axial solid holdup in the riser decreases from the dense at the bottom to the dilute phase at the top section of the riser. Solid holdups at the axial positions in the riser increase linearly with increasing solid circulating velocity. From these results, we could determine the position of plasma load for good plasma ignition, maintain and plasma reaction.

• Journal of the Korean Society of Propulsion Engineers
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• v.17 no.5
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• pp.70-79
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• 2013

The isothermal flow structure and mixing characteristics of a hybrid/dual swirl jet combustor for micro-gas turbine (MGT) were numerically investigated. Location of pilot burner, swirl angle and direction were varied as main parameters with the identical thermal load. As a result, the variations in location of pilot nozzle, swirl angle and direction resulted in the significant change in turbulent flow field near burner exit, in particular, center toroidal recirculation zone (CTRZ) as well as turbulent intensity, and thus the flame stability and emission performance might be significantly changed. With the comparison of experimental results, the case of swirl angle $45^{\circ}$ and co-swirl flow including optimum location of pilot burner were chosen in terms of the flame stability and emissions for the development of hybrid/dual swirl jet combustor.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.430-435
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• 2001

This paper introduces a pressure correction method for microflow computation. Conventional CFD methods with no slip boundary condition fail to predict the rarefaction effect of the wall when simulating gas microflows in the slip-flow regime. Pressure correction method with an appropriate slip boundary condition is an efficient tool in analyzing microscale flows. The present unstructured SIMPLE algorithm adopts both the classical Maxwell boundary condition and Langmuir boundary condition proposed by Myong. The simulation results of microchannel flows show that the proposed method has an effective predictive capability for microscale flows.

• Proceedings of the KSME Conference
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• 2001.06e
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• pp.643-648
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• 2001

The direct simulation Monte Carlo(DSMC) method is applied to investigate steady and unsteady flow fields of a single-stage disk-type drag pump. Two different kinds of pumps are considered: the first one is a rotor-rotor combination, and the second one is a rotor-stator combination. The pumping channels are cut on a rotor and stator. The rotor and stator have 10 Archimedes' spiral blades, respectively. In the present DSMC method, the variable hard sphere model is used as a molecular model, and the no time counter method is employed as a collision sampling technique. For simulation of diatomic gas flows, the Borgnakke-Larsen phenomenological model is adopted to redistribute the translational and internal energies. The DSMC results are in good agreement with the experimental data.

• Journal of the korean Society of Automotive Engineers
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• v.14 no.3
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• pp.80-89
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• 1992

An experimental study of in-cylinder of flow and combustion characteristics in two gasoline engines of different intake ports which are denoted as original port and masked shroud head (MSH) ports is presented. The flows generated by the MSH and the original port are invest- igated by laser Doppler velocimeter(LDV) under steady flow and motoring (non-firing) condit -ions. Combustion characteristics with different swirl levels produced by two intake ports are analyzed by combustion pressure measurement and statistical calculation. The swirl inside the cylinder of the MSH port engine is found to be much higher than the original port, and the MSH has a large eddy motion of cylinder diameter size. Using ensemble average method to valuate engine turbulence under motoring condition, the MSH port engine is shown to have h -igher turbulence intensity than the original port, so that the effect of the MSH port on fast burn is shown. Also the cyclic variations of peak pressure and the reaching time in the MSH port are apparently reduced.

• Journal of the Korean Society of Combustion
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• v.23 no.1
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• pp.21-27
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• 2018

The effect of swirl flow structures on combustion dynamics of two interacting, lean-premixed flames was experimentally investigated, with a particular emphasis on swirl numbers and swirl rotational directions. Our results show that the amplitude of limit cycle oscillations is very sensitive to the combination of swirl numbers and rotational directions, while the instability frequency remains nearly unchanged. The counter-rotating cases show significantly lower pressure perturbations, and this behavior appears to be related to the formation of compact interacting zone with higher heat release rate, indicating the presence of increased flame surface wrinkling caused by intense turbulence.

• 유체기계공업학회:학술대회논문집
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• 2000.12a
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• pp.82-87
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• 2000

The direct simulation Monte Carlo (DSMC) method is applied to investigate the flow field of a disk-type drag pump. The pumping channels are cut on both sides of a rotating disk. The rotor has 10 Archimedes' spiral blades. In the present DSMC method, the variable hard sphere model is used as a molecular model, and the no time counter method is employed as a collision sampling technique. For simulation of diatomic gas flows, the Larsen-Borgnakke phenomenological model is adopted to redistribute the translational and internal energies.

• 한국전산유체공학회:학술대회논문집
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• 1998.11a
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• pp.71-77
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• 1998

In this study we calculated the flowfields around the axisymmetric bodies in the rarefied gas regime by using the DSMC. A flat-ended cylinder was selected as a representative axisymmetric body and the gas used for all calculations was nitrogen. With zero angle of attack, an increasingly rapid rise in density and the effect of shock waves near the flat-ended face were examined. And on the cylinder surface velocity slips and boundary layers could be observed in the results. Larsen-Borgnakke model was used for the energy redistribution in inelastic collisions. And by considering all internal energy modes, the distributions of translational, rotational and vibrational temperatures were plotted. The calculations were peformed for various Knudsen numbers, Especially the rotational temperatures calculated for a case were compared with the experimental results. And the simulation results show good agreements with the experimental ones.

• 한국전산유체공학회:학술대회논문집
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• 2007.04a
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• pp.79-82
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• 2007

The aerodynamic coefficients of Apollo capsule are calculated using a DSMC solver, SMILE, and the results agree very well with the data predicted by NASA. The aerodynamic characteristics of an orbital block which operates at high altitudes in the free molecule regime are also predicted. For the nominal flow conditions, the predicted aerodynamic force is very small since the dynamic pressure is extremely low. And the additional aerodynamic coefficients for the analysis of the attitude control are presented as the angle of attack and the side slip angle vary from $+45^{\circ}\;to\;-45^{\circ}$ of the nominal angle.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.847-852
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• 2000

Three dimensional CFD investigations are carried out to understand the complex flow field in a gas turbine combustor with multi-element fuel injectors. The gas turbine considered here is the GE7FA model which has aye fuel injectors in each combustor can and utilizes lean-premixed combustion to meet nitric oxide emission requirements. Detailed three-dimensional flow characteristics and fuel-air mixture formation process inside the fuel nozzle and gas turbine combustor including five swirl nozzle tips are analyzed using commercial FLUENT code.