• Journal of Advanced Marine Engineering and Technology
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• 제33권6호
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• pp.867-872
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• 2009

In centrifugal oil filters particles are forced to move toward the filter casing wall by centrifugal force in the rotating oil flow and the particles are trapped and removed on the filter paper installed at the wall. In the present study, flow field of oil and particle motion in a centrifugal oil filter has been numerically calculated in order to estimate the filtering efficiency for various operating conditions. Fluent code was used for the numerical calculations. Uncoupling the oil flow and the particle motion and the use of particle tracking trajectory enabled the estimation of filtering efficiency for various particle sizes, particle density and the filter rotational speed. Higher filtering efficiency was observed for heavier and larger particles as well as higher filter rotational speed. For the typical case of the particle density of $6000kg/m^3$ and the particle size of $10{\mu}m$ at 3500 RPM, the calculated filtering efficiency per passage was 0.31.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 춘계학술대회
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• pp.2017-2022
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• 2004

There are multistage preheaters in the power generation plan to improve the thermal efficiency of the plant and to prevent the components from the thermal shock. The energy source of these heaters comes from the extracted two phase fluid of working system. These two-phase fluid can cause the so-called Flow Accelerated Corrosion(FAC) in the extracting piping and the bubble plate of the heater for example, in case of point Beach Nuclear Power Plant and in the Wolsung Nuclear Power Plant. The FAC is due to the mass transport of the thin oxide layer by the convection. FAC is dependent on many parameters such as the operation temperature, void fraction, the fluid velocity and pH of fluid and so on. Therefore, in this paper velocity was calculated by FLUENT code in order to find out the root cause of the wall thinning of the feedwater heaters. It also includeed in the fluid mixing analysis model are around the number 5A feedwater heater shell including the extraction pipeline. To identify the relation between the local velocities and wall thinning, the local velocities according to the analysis results were compared with distribution of the shell wall thicknes by ultrasonic test.

• 설비공학논문집
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• 제22권8호
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• pp.562-566
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• 2010

Wind energy is one of the most general natural resources in the world. However, as of today, generating electricity out of wind energy is only available from big wind generator, Furthermore, an axial-flow turbine is the only way to produce electricity in the big wind generator. This paper is for the guidance of drawing impact fact about power turbine using cross-flow type transferring wind energy to electricity energy. It will find the ideal value which enables to make cross-flow power turbine(CPT) using computational fluid dynamics(CFD) code. This study tries to analyze the "Solidity" characteristics. We can find out turbine-blade number through CFD. CFD is using "Fluent_ver 6.3.16", and the data from its result will judge fan-blade performance through specific torque and specific power from each "Solidity" model. Based upon the above, we will make cross-flow power turbine of multi-blade centrifugal fan instead of axial-flow type.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.546-551
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• 2007

The present study numerically investigated the tube geometry and arrangement on the performance of a high temperature generator (HTG) of the double effect LiBr-water absorption system. FLUENT, as a commercial code, was used to estimate the thermal performance of the HTG. Key parameters were the spacing raito of circular and flattened tubes, the pitch ratio of the rib on the flattened tube, and total heat transfer area of the HTG. Temperature and velocity profiles around the tubes of the HTG were calculated to estimate the thermal performance of the HTG. When the spacing ratio of circular and flattened tube is 1.11 and 0.73, the exhaust gas temperature is $185^{\circ}C$ without rib. The exhaust gas temperature when applied the rib in flattened tubes was lower by $24^{\circ}C$ than that without the rib. Rib can reduce the HTG volume by 7%.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.552-557
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• 2007

Due to the recent improvement of living standard of residential buildings, the requirements of the thermal comfort and energy saving in heating system have been raised. The radiant floor heating system has been widely used as a residential heating method, which has been modernized to use hot water running into the tubes embedded in the floor structure. The uniform flow distribution is very important factor for a radiant floor heating system such as a blood vessel system in human body. Therefore, it is necessary to investigate the operating characteristics to develop an optimal radiant floor heating system. In this study, numerical analyses were carried out, using a commercial CFD code, FLUENT, to obtain the velocity distribution under steady, three-dimensional, standard k-$\varepsilon$ model and no-slip condition. Results are graphically depicted with various parameters.

• 설비공학논문집
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• 제19권9호
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• pp.662-668
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• 2007

In this study, jet fans are installed with 4 cases in the straight long tunnel; inlet-side setup, middle-side setup, outlet-side setup, and dispersion setup. A bus is selected as fired car, of which fire size is 20MW. And fired car locates at 100m, 700m, 1500m position from tunnel inlet, respectively. FLUENT, commercial finite-volume code, is used to analyze the performance. The velocity profile, $CO_2$ concentration, temperature distribution are examined for analysis. Performance of smoke control is compared by the backlayering length. Consequently, inlet-side setup of jet fans is a little more efficient than other cases considering the fire occurrence frequency in tunnel.

• 설비공학논문집
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• 제19권9호
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• pp.669-678
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• 2007

In this study, the ventilation characteristics is investigated numerically of the longitudinal ventilation method in the curved long road tunnel. Numerical work has been conducted for the jet fan location by utilizing the commercial finite-volume code, FLUENT. Configuration of the tunnel is three-lane, 1600 m long, $120m^2$ in area, 3000 m curvature radius. The velocity profile, distribution of mono-dioxide carbon and flow rate of air are examined in the tunnel. Through the analysis, it is found that the difference of ventilation flow rate Is a little by the jet fan location, but tunnel outlet setup (CASEIII) of jet fans is the most efficient concerned with CO concentration.

• 한국압력기기공학회 논문집
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• 제8권3호
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• pp.23-27
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• 2012

A seawater pumps in the nuclear power plant is responsible for providing cooling water to other components all the time. Because of the depreciation, the seawater pump with current impeller consumes too much power for maintaining the total head. Therefore the objective of this study is to reduce power with maintaining certain the total head by cutting the current impeller. By using a commercial CFD code, FLUENT, the overall performance of seawater pump with current and modified impeller was simulated. Also Affinity law was applied at pumps with various impeller diameter and evaluated the validity of the affinity law. The numerical results show that the pump efficiency is quite irrelevant to the diameters of the impellers and the pump efficiency becomes worse over the designed flow rate. And affinity law result and numerical one show good agreements at small change of impeller diameter. One of the impeller diameters was decided to modify and was applied to the nuclear power plant with the numerical study above.

• 한국자동차공학회논문집
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• 제23권1호
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• pp.74-87
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• 2015

A numerical parametric study has been accomplished to figure out the effect of grille shape built in a small passenger car on the aerodynamic performance such as drag and mass flow rate through CRFM(Condenser Radiator Fan Module). Three grille opening parameters and three grille mesh parameters are selected and adopted to a simple shape passenger car model. This research will provide a design guideline for grille opening geometry and mesh shape in the grille. FLUENT, which is very well known commercial code, hires k-${\epsilon}$ turbulence model at the driving speed of 110km/h with moving wall boundary condition. A porous media condition is prepared to estimate the pressure drop amount through CRFM parts.

• 한국군사과학기술학회지
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• 제22권6호
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• pp.773-783
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• 2019

A numerical analysis of a turbulent flow with a 'large-eddy breakup device(LEBU)' was performed to investigate the influence of the device on the drag of underwater vehicle using commercial CFD code, FLUENT. In the present study, the vehicle drag was decomposed to skin-friction coefficient(C_f) and pressure coefficient(C_p). The variation of the vehicle C_f and C_p were observed with changing location of the device and Reynolds number. As a result, the device decreased the vehicle C_f because it suppressed the turbulent characteristics behind the device. The larger Reynolds number, the higher reduction effect when the device was placed in front part of, and near the vehicle. On the other hand, the device increased/decreased the vehicle C_p with increasing/decreasing turbulent kinetic energy at recirculating flow region behind the vehicle. The total drag change by the device was caused by C_p rather than C_f.