• Journal of the Korean Society of Combustion
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• v.8 no.2
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• pp.7-16
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• 2003

The transfer of air pollutants between passenger room and service room in train are investigated by the computational analysis. The effects of service room temperature, inlet velocity, initial concentration and heating are studied. The flow induced by the difference of density between two rooms is found to take the major role in transfer of polluted air. Low temperature of service room enhances the polluted air flow into passenger room along the floor. Exhaust fan above the door between two rooms is not effective for this case. Strong inlet flow is found to suppress polluted air flow from service room. The heating of passenger room can promote air pollution.

• 한국연소학회:학술대회논문집
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• 2002.06a
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• pp.11-15
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• 2002

Experimental studies on effects of the interaction of duplex swirl injector and the liquid temperature on the spray characteristics were conducted. Water and fuel were used as a test fluid for the experiments. The drop size distributions of the liquid spray were measured with Malvern particle sizer. The liquid temperature and distance of injectors were adopted as the operating parameter. The results show that SMD decrease as the increases of fuel temperature and pressure. The spray angle increase as fluid temperature increases. For fuel spray, SMD of impacting surface increase as the distance of injectors is lengthened.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.75-81
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• 2001

MCVD(modified chemical vapor deposition) used in making optical-fiber currently utilizes the hydrogen-oxygen burner as a energy supply source. To improve the productivity and to reduce the manufacturing cost of optical-fiber, a natural gas-oxygen burner has been developed. The manufacturing processes of optical-fiber consist of vapor deposition, collapse and drawing processes. Among these processes, the vapor deposition and the collapse processes are important in terms of improving the productivity and saving the production cost. The vapor deposition and collapse processes are performed by combustion heat and flame force supplied by a burner. So the flame force of the burner used in these processes is required to have an optimal and consistent value in order to allow uniform heating and collapse of quartz tube. In this regard, the momentum ratio of natural gas and oxygen has been optimally determined by modification of a burner and the inlet flow pass also has been modified.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.156-162
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• 2001

The effects of co-flow and the variation of the equivalence ratio on NOx emission were investigated experimentally for unconfined and confined partially premixed flames. The shape, length, temperature of flames and the concentration of burnt gas were measured. Two types of co-flow (parallel and swirling co-flow) were considered. For unconfined flames, flame with parallel co-flow is the longest and the next is flame without co-flow. Flame with swirl is the shortest. The length of swirling flame increases suddenly under certain value of equivalence ratio. EINOx is diminished by the decrease of equivalence ratio. It is found that the unconfining of flame enhances the emission of NOx. The EINOx of unconfined flame with parallel co-flow is less than that of flame without co-flow.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.53-59
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• 2001

Experimental measurements are conducted to investigate the structure of flat $CH_4/O_2/N_2$ premixed flames. The flames are simulated using a detailed chemical kinetic mechanism. Four flames established at equivalence ratio = 0.55 are studied with the different $O_2$ enrichment level, ${\Omega}$ = 0.21, 0.25, 0.30, and 0.35. The measured flame speed and species composition profiles are compared with the calculations. Whereas there is overall good agreement between the measurements and predictions, it appears that as the $O_2$ enrichment level is increased the position of the flame is moved toward the exit of the burner and the rapid temperature rise happens near the exit of the burner, and some areas of further refinement in the kinetic mechanism are identified.

• 한국연소학회:학술대회논문집
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• 2001.06a
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• pp.90-98
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• 2001

Characteristics of high temperature rocket nozzle flow is discussed along with the aspects of computational analysis. Three methods of nozzle flow analysis, frozen-equilibrium, shifting-equilibrium and non-equilibrium approaches, were discussed, those were coupled with the methods of computational fluid dynamics code. A chemical equilibrium code developed for the analysis of general hydrocarbon fuel was coupled with three approaches of nozzle flow analysis. The approaches were used for the performance prediction of KSR-III Rocket, and compared with the theoretical results from NASA CEA (Chemical Equilibrium with Applications) code.

• 한국연소학회:학술대회논문집
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• 1999.10a
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• pp.219-230
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• 1999

The Equations of Chemical kinetics are very stiff, which forces the use of an implicit scheme. The problem of implicit scheme, however, is that the jacobian must be solved at each time step. In this paper, we examined the methodology that can be stable without full chemical jacobian, This method is derived by applying the different time steps to the chemical source term. And the lower triangular chemical jacobian is derived. This is called the preconditioned time differencing method and represents partial implicit method. We show that this method is more stable in chemical kinetics than the full implicit method and that this is more efficient in supersonic combustion problem than the full jacobian method with same accuracy.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.85-92
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• 2000

End-gas temperatures were measured using CARS technique in a conventional DOHC spark-ignition engine fueled with PRF80. The measured pressure data were analyzed using band pass filter method. The measured CARS temperatures were compared with adiabatic core temperatures calculated from measured pressure. Significant heating by pre-flame reaction in the end gas was observed in the late part of compression stroke under both knocking and non-knocking condition. CARS temperatures measured at 10 crank angle degree before knock occurrence was higher than adiabatic core temperatures. These results indicate that there exist some exothermic reactions in low pressure and temperature region. CARS temperatures began to be higher than the adiabatic core temperature when the end-gas temperatures reached 700 K. The temperature elevation due to the pre-flame reaction correlated better with CARS temperature than with cylinder pressure.

• 한국연소학회:학술대회논문집
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• 2005.10a
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• pp.15-19
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• 2005

Three-dimensional structures of unsteady detonation wave propagating through a square-shaped tube is studied using computational method and parallel processing. Inviscid fluid dynamics equations coupled with variable-${\gamma}$ formulation and simplified one-step Arrhenius chemical reaction model were analysed by a MUSCL-type TVD scheme and four stage Runge-Kutta time integration. Results in three dimension show the two unsteady detonation wave propagating mode, the Rectangular and diagonal mode of detonation wave instabilities. Two different modes of instability showed the same cell length but different cell width and the geometric similarities in smoked-foil record.

• 한국연소학회:학술대회논문집
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• 2007.05a
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• pp.27-30
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• 2007

We have been setting up experiments on propagation of shock waves generated by the pulsed laser ablation. One side of a thin metal foil is subjected to laser ablation as a shock wave is generated from a localized spot of high intensity energy source. The resulting reactive shock wave, which penetrates through the foil is reflected by an acoustic impedance which causes the metal foil to high-strain rate deform. This short time physics is captured on an ICCD camera. The focus of our research is generating reactive shock wave and high strain rate deforming of thin metal foil for accelerating micro-particles to a very high speed on the orders of several thousand meter per second. Somce innovative applications of this device will be discussed.