• 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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• 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.

• Journal of Environmental Science International
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• v.14 no.1
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• pp.15-22
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• 2005

Natural gas possesses several characteristics that make it desirable as an engine fuel; 1)lower production cost, 2)abundant commodity and 3)cleaner energy source than gasoline. Due to the physics characteristics of natural gas, the volumetric efficiency and flame speed of a natural gas engine are lower than those of a gasoline engine, which results in a power loss of $10-20{\%}$ when compared to a normal gasoline engine. This paper describes the results of a research to improve the performance of a natural gas engine through the modification and controls of compression ratio, air/fuel ratio, spark advance and supercharging and method of measuring flame propagation velocity. It emphasizes how to improve the power characteristics of a natural gas engine. Combustion characteristics are also studied using an ion probe. The ion probe is applied to measure flame speed of gasoline and methane fuels to confirm the performance improvement of natural gas engine combustion characteristics.

• 한국연소학회:학술대회논문집
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• 2003.12a
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• pp.49-56
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• 2003

Mathematical formulation of the zone conditional two-fluid model is established to consider flame-generated turbulence in premixed turbulent combustion. The conditional statistics of major flow variables are investigated to understand the mechanism of flame generated turbulence. The flow field in burned zone shows substantially increased turbulent kinetic energy, which is highly anisotropic due to reaction kinematics across thin flamelets. The transverse component of rms velocities in burned zone become larger than axial component in the core of turbulent flame brush. The major source or sink terms of turbulent kinetic energy are the interfacial transfer by the mean reaction rate and the work terms by fluctuating pressure and velocity on a flame surface.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.25-31
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• 2002

For the better understanding of the stability of turbulent combustion, more researches on extinction and re-ignition are needed. Flame interactions in non-premixed flame have also not been greatly researched. We made a hybrid twin jet flame, the combinations of diffusion flame and partially-premixed diffusion flame, in a twin jet counterflow configuration. The extinction limits of a crossed twin jet counterflow have been extended in comparison with those of a one-dimensional counterflow because of flame interactions through heat transfer and joint ownership of various radicals. Besides, we have obtain ignition $Damk\"{o}hler$ number by experimental method without external ignition source using the extinction characteristic in a crossed twin jet counterflow flame. From results, we can identify the hysteresis between extinction and ignition $Damk\"{o}hler$ number in S-curve.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.6
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• pp.76-81
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• 2011

Fossil fuel, the energy source of internal combustion engine automobiles, is limited in resource and has caused environmental issues for decades. Accordingly, automobile manufacturers from many countries around the world are developing or producing eco-friendly vehicles that utilize alternative sources of energy. These vehicles are equipped with many electronic and electrical components which operate on high voltage and/or large current that were not used in conventional combustion engine automobiles. In this paper, in order to analyze the electro-magnetic interference noise, electric vehicles and fuel cell electric vehicles are tested under the guidelines of KMVSS (Korean Motor Vehicle Safety Standards) as well as under test modes that are not stipulated under the guidelines.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.653-663
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• 2000

A lot of hazardous wastes are discharged as by-products of working process by industrial development. Hazardous wastes is physical characteristics of difficult destruction at hight temperature. Numerical simulation and combustion experiment performed of dump incinerator for hazardous waste incineration. For the numerical simulation, the SIMPLEST algorithm was used to ensure rapid converge A K-$\varepsilon$ model was incorporate for the enclosure of turbulence flow. Combustion model was used by ESCRS (extended simple chemically reacting system) model available of CHEMKIN thermodynamic data for the source term of species conservation equation or energy equation. Radiation model is used by six flux model. A parametric screening studies was carried out through numerical simulation and experiment. Residence time and concentration in the incinerator was strongly dependent on the parameters of mixture velocity, mixture equilibrium ratio, surrogate velocity and surrogate equilibrium ratio.

• Proceedings of the KIEE Conference
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• 1999.07e
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• pp.2308-2310
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• 1999

The effect of magnetic field on NOx removal characteristics from a combustion flue gas has been experimentally investigated for a DC corona discharge reactor with a multipoint plate geometry in our Lab. Combustion flue gas removal efficiency of this type was much higher than that of the other types. In this paper, needle-plate geometry discharge system with applied magnetic field at a right angle to the electric field was made. Input power source was used negative DC. The corona discharge characteristics for this system was investigated and compared with the corona characteristics for the corona discharge system without magnetic field.

• Journal of Advanced Marine Engineering and Technology
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• v.23 no.4
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• pp.543-551
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• 1999

Diesel engine is a major source of the air pollution. In general the concentrations of these pollu-tants in diesel engine exhaust differ from values calculated assuming chemical equibrium. Thus the detailed chemical mechanisms by which these pollutions form and the kinetic of these process-es are important in determining emission levels. In this study the computer program has been developed to calculate the required thermodynam-ic properties of combustion products(10 spacies) for both equilibrium and non-equilibrium in cylin-der for diesel engines. Nitric oxide emissions are calculated by using the extended Zeldovich Kinet-ic mechanism with a steady state assumption for the N concentration and equilibrium values used for H, O, $O_2$ and OH concentrations. By the results it is confirmed that developed simulations program with the NO prediction model is validated against residual mass fraction combustion index of Wiebe's functions pre-mixed com-bustion ration fuel injection timing.

• Journal of the Korean Society of Safety
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• v.6 no.1
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• pp.14-25
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• 1991

The smouldering combustibility of cellulose insulation treated with boric acid-borax-alum as combustion retardants are examined by cigarette ignition method and electrical cardrige heater method. The alum to be required at an add on level of at least 12% by weight of cellulose treated with boric acid-borax-alum=2 ： 1 ： 2 fomulatlon if resistance to smouldering combustion by cigarette ignition is to be achived. The optimum electrical ignition source employed by electrical cartidge heater method was 23.2 watts(80V) power level The effectiveness of Alum as a third combstion retardant are acceptable both smouldering resistance and flame resistance at 18% level of all examined formulation.