• 한국자동차공학회논문집
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• 제9권5호
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• pp.148-156
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• 2001

Computational Fluid Dynamics (CFD) analysis was carried out to investigate exhaust gas flow and acoustic characteristics in the exhaust system of a passenger car. Transient 3-dimensional flow field in the front and rear mufflers was simulated by CFD and far-field sound pressure was modeled by a simple monopole source method. Engine performance simulation was also performed to obtain the boundary condition of instantaneous fluid flow variation at the inlet of the exhaust system. Detailed exhaust gas flow characteristics such as velocity and pressure distribution inside the mufflers were presented and the pulsating pressure amplitude was compared at several positions in the exhaust system to deduce sound pressure level. The present method of the acoustic analysis coupled with CFD techniques would be very effective for the prediction of sound noise from vehicle exhaust systems although the effects of the inlet boundary condition and heat transfer on the accuracy of the prediction have to be validated through further studies.

• 한국산업보건학회지
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• 제8권2호
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• pp.163-177
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• 1998

Computational Fluid Dynamics(CFD) was applied to predict air flow around the hoods : circular hoods, square hoods, and push-pull hoods. A commercially available CFD software, CFD-ACE(Ver. 4.0), was tested, which is based on the finite volume method using the ${\kappa}-{\varepsilon}$ turbulence model. Numerical results were compared with the experimental, analytical and numerical results from other studies. CFD solutions showed an excellent agreement with the previous experimental and numerical results. It is promising that CFD techniques could be applied on the variety of complex problems in the industrial ventilation engineering.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.67-70
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• 2012

Many computational fluid dynamic (CFD) simulations have treated the coal kinetics poorly due to large physical domain sizes and high computational complexity, particularly for the recent oxy-coal boilers. Furthermore, some modelers' lack of understanding of the kinetic rate model seems to worsen the simulation accuracy. This study is to suggest the importance of proper use of single-film global kinetic model generally used in CFD code to describe the oxy-fuel combustion of coal char through simple char burnout calculation.

• 상하수도학회지
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• 제23권1호
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• pp.107-112
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• 2009

This study was conducted for verification and systematization of estimation method about the headloss using CFD(Computational Fluid Dynamics). Head loss which happens between the inlet and outlet of in-line mixer can be a major factor for the design and construction. Also, this Case studies about the sensitivity related to the velocity in the piping system. As result, program's default calculation function was used to get each side's total pressure and the differential of each total pressure could be defined as head loss from in-line mixer. In the case of adopting pipe surface friction factor and geometry loss, Calculation residual can be much more reduced. It was found that residual of value between CFD method and field test ranged about 3 through 18 precent.

• 한국철도학회논문집
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• 제9권5호
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• pp.511-516
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• 2006

A standard framework of CFD(Computational Fluid dynamics) analysis for railway system has been developed to evaluate the overall aerodynamic performance of railway system and has been adopted to numerical simulation of the pressure field around KTX train. The framework is composed of standard aerodynamic model and standard aerodynamic performance to customize the general CFD solution process reflecting the characteristics of railway system such as various operation mode and performance factors. The results show that the standard framework of CFD analysis for railway system can provide objectivity and consistency to the CFD analysis for railway system and the pressure field around KTX train has been successively solved.

• 한국자동차공학회논문집
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• 제7권5호
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• pp.22-30
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• 1999

Optimization of in-cylinder flow is regarded as one of the most important factors to realize stable stratified charge combustion in a Spark-ignited Direct Injection(SDI) engine. Therefore, Computational Fluid Dynamic(CFD) simulation technique were used to clarify the characteristics of in-cylinder flow of a SDI engine with top entry intake port. Also, CFD results were compared to experimental results using Laser Doppler Velocimetry(LDV), Particle Image Velocimetry(PIV) and good validations were met. As the results reverse tumble flow generated during intake process was preserved by configuration of curved piston while base and reverse tumbles were diminished at the end of compression stroke in case of flat top piston. In addition, it will be needed to optimize the fuel mixture distribution based on these results.

• 항공우주시스템공학회지
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• 제2권2호
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• pp.46-50
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• 2008

Aerodynamic characteristics, such as drag and lift, play an important role in automobile design under certain speed conditions. Such characteristics are essential to design an automobile since they are directly related to automobile's performance such as passenger safety and fuel consumption. There is a huge demand for the automobile to have safe performance at high speed. Reduction in drag is also important and it could lead to the solution of air flow induced noise and dust problems. The objective of this research is to find out the aerodynamic differences between conventional side mirror and a modified one using CFD. Although drag generated around a side mirror is only about 7% of the total drag when a car runs, it is very closely related to driver's field of vision and noise generation. CFD simulation of the flowfield around a car side-view mirror was performed using a commercial code; Gambit and FLUENT.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2008년도 하계학술발표대회 논문집
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• pp.1184-1189
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• 2008

This paper is a study about characteristics of the SSC-1 nozzle, which is used in a fire extinguishing system in a ship. Through this paper, we can find that the traces and elements’ distributions obtained from experiments are as the same as the simulation analysis results of CFD program. At the point of 100mm, the $\alpha$ is 34.9 in the CFD analysis, and it is 32.5 in the experiment. This shows that there is no big different between the CFD analysis and the experiment result. And the average elements velocity is similar to the SMD.

• 한국유체기계학회 논문집
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• 제18권1호
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• pp.44-50
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• 2015

Labyrinth seals are commonly used in various kinds of turbomachinery to reduce leakage flow. In the present 3D CFD analysis of see-through-type labyrinth air seal, the methodology of determining leakage and rotordynamic coefficients is suggested with the relative coordinate system for steady-state simulation. The leakage flow and rotordynamic forces predicted by using different solvers and turbulent models of FLUENT are compared with the results of the existing bulk-flow analysis code LABYSEAL.FOR and experiment. The present CFD result of direct stiffness(K) shows only improvement in prediction. The results of leakage and rotordynamic coefficients as well as computing time are sensitive against the used solver and turbulent model.

• International Journal of Automotive Technology
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• 제8권5호
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• pp.615-622
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• 2007

In this study, a Coupled Computational Fluid Dynamics(CFD) and Finite Element Analysis(FEA) method are used to predict and evaluate the performance of an automotive shock absorber. Averaged Navier-Stokes equations are solved by the SIMPLE method and the RNG $k-\varepsilon$ is used to model turbulence. CFD analysis is carried out for different intake valve deflections and piston velocities. The force exerted on the valve in each valve deflection is obtained. The valve deflection-force relationship is investigated by the FEA method. The force exerted on the valve in each piston velocity is obtained with a combination of CFD and FEA results. Numerical results are compared with the experimental data and have shown agreement. Dependence of valve deflection as a function of piston velocity is investigated. Effects of hydraulic oil temperature change on valve behavior are also studied.