• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.6
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• pp.15-25
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• 2011

One dimensional combustion modeling of aluminum combustion behavior is proposed. Combustion model is assumed that region consists as follows ; preheat, reaction, post reaction region. Flame speed as a function of particle size, equivalence ratio for unitary particles and fraction ratio of micro to nano particle size for binary particles were investigated for lean burn condition at 1 atm. Results were compared with experimental data. For unitary particles, flame speed increase as particle size decreases, but opposite trend with equivalence ratio. For binary particles, flame speed increases proportionally as nano particle fraction increases. For flame structure, separated or overlapping flames are observed, depending on the fraction of nano sized particles.

• Clean Technology
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• v.10 no.2
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• pp.89-100
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• 2004

The optimization for the water bath design and the skimmer installation are conducted to separate floated-sludge from the waste water in a water bath of a painting booth. VOF(volume of fluid) model is used to analyze the flow pattern of sludge-water-air mixture in a water bath. From the results of numerical analysis, the design criteria of the skimmer, the separation plate and the sludge inlet port of a water bath are obtained for effective sludge separation from water in bath. Furthermore, the installation condition of the skimmer immersed in water is optimized to minimize entrained air and pressure loss.

• Journal of the Korean Society of Propulsion Engineers
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• v.4 no.1
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• pp.93-101
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• 2000

In a gas-turbine engine, fan blades in flow path are confronted with many kinds of loading. The study of the excited force by the wake of struts has proposed and the possibility of fatigue failure about rotating fan blades by the excited force at the steady state is evaluated. Equations of the excited force of wakes has been derived at the steady state and the maximum pressure distributions measured at the transient state are proposed. Dynamic characteristics and the fatigue strength of fan blades by experimental test were obtained. To evaluate HCF(High Cycle Fatigue) damage of fan blades, FEM analysis was performed with a steady state harmonic response, which was followed by high cycle fatigue damage factor from goodman diagram.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.457-462
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• 2011

This paper presents a numerical investigation of deflagration to detonation transition (DDT) induced by shock wave and flame interaction in ethylene-air mixtures. Also shows the change of DDT triggering time by wall cooling effect. A model is consisted of the compressible reactive Navier-Stokes equations. And the effect of viscosity, thermal conduction, molecular diffusion, chemical reaction and wall effect are included. Using this model, the generation of hot spot by repeated shock and flame interaction, occurrence of detonation, and wall cooling effect of detonation confining boundaries are studied.

• Fire Science and Engineering
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• v.27 no.4
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• pp.1-6
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• 2013

When the pressurization system that uses difference of pressure for smoke control is designed, the factors influencing on the pressure field in building should be applied to design process and the stack effect is one of the main factors. Numerical analysis based on network model in 20-story building is carried out to analyze the pressurization system of smoke control in consideration of stack effect. Calculations are conducted for three conditions, that is, stack effect only, pressurization only and stack effect plus pressurization. Results including the detailed pressure field and flow rate at each floor are represented and the stack effect are effectively visualized. Meanwhile, the pressure of stairwell is increased as much as the summation of the stack effect and pressurization, and the problem induced by rise of pressure is pointed out.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.6
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• pp.178-186
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• 2002

3-D numerical studies are performed to investigate the effect of the trunk height and approaching air velocities on the pressure distribution of notchback road vehicle. For this purpose, the models of test vehicle with four different trunk heights are introduced and PHOENICS, a commercial CFD code, is used to simulate the flow phenomena and to estimate the values of pressure coefficients along the surface of vehicle. The standard k-$\xi$ model is adopted for the simulation of turbulence. The numerical results say that the height variation of trunk makes almost no influence on the distribution of the value of pressure coefficient along upper surface but makes very strong effects on the rear surface. That is, the value of pressure coefficient becomes smaller as the height is increased along the rear surface and the bottom surface. Approaching air velocity make no differences on pressure coefficients. Through the analysis of pressure coefficient on the vehicle surfaces one tried to assess aerodynamic drag and lift of vehicle. The pressure distribution on the rear surface affected more on drag and lift than pressure distribution on the front surface of the vehicle does. The increase of trunk height makes positive effects on the lift decrease but negative effects on drag reduction.

• Explosives and Blasting
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• v.36 no.4
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• pp.1-8
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• 2018

This numerical study was intended to evaluate the applicability of the half charge blasting to mining and tunnelling. The half charge blasting is a method that two separate rounds are sequentially blasted for the rock burdens in which long blast holes have already been drilled at one operation. The aim of the method is to decrease the construction cost and period in mining and tunnelling projects as well as to increase the blasting efficiency. Several numerical analyses were conducted by using the Euler-Lagrange solver on ANSYS AUTODYN to identify the effects of the suggested method on the blasting results in underground excavations. The overall performance of the suggested method was also compared to an ordinary blasting method. The analysis model was comprised of the Eulerian parts (explosive, air, and stemming materials) and the Lagrangian parts (rock material). As a result, it was found that, owing to the air decks formed in the bottom parts of the long blast holes, the first round of the suggested method presented a higher shock pressure and particle velocities in the vicinity of the blast holes compared to the ordinary blasting method.

• Journal of the Korean Society of Marine Environment & Safety
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• v.27 no.5
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• pp.683-690
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• 2021

The ventilation system of the engine room of a ship is generally installed to supply the combustion air necessary for the internal combustion engine and to remove the heat source generated in the engine room, and it must satisfy the international standard (ISO 8861) for the design conditions and calculation standards for the ventilation of the ship engine room. The response delay of the ventilation system including the fire detector is affected by the airflow formed inside the area and the location of the fire detector. In this study, to improve the initial fire detection response speed of a fire detector installed on a fishing vessel and to maintain the sensitivity of the installed detector, the smoke behavior was simulated using the air flow field inside the engine room, the amount of combustion air in the internal combustion engine, and the internal pressure of the engine room as variables. Analysis of the simulation results showed that reducing the flow rate in the air flow field and increasing the vortex by reducing the internal pressure of the engine room and installing a smoke curtain would accelerate the rise of the ceiling of the smoke component and improve the smoke detector response speed and ventilation system.

• KSBB Journal
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• v.4 no.2
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• pp.150-156
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• 1989

The chaacterisitics of a commercial membrance-coverd electrode in air-saturated saline solution were investigated in terms of a steadystate one-dimensional model. The electrode system miiersed in an aqueous medium consists of three layers: an external concentration boundary layer, a membrance, and an inner electrolyte layer. The membrance can be permeabld to the water and impermeable to the ionic species. In stationary midium, the water migrates from the external medium to the inner electrolyte layer until a thermodynamic equilibrium is reached. In a following midium, however, there is a reverse direction of water movement due to the hyrodynamic pressure differential until both thickness of the electrolyte layer and the membrance are equal.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.6
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• pp.456-467
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• 2002

The objective of this study is to analyze and evaluate the impact of the stack effect in high-rise buildings for solving the various problems resulting from it. For the evaluation of the impact of the stack effect, computer program simulations based on the network model were performed for a typical high-rise office building. The results of the simulations show that the impact caused by the stack effect is mainly dependent on building envelope air-tightness and internal airflow resistance, so the problems due to the stack effect may be solved to some extent by installing vestibules around entrance doors and doors serving elevators, and by zoning the elevators.