• Journal of computational fluids engineering
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• v.20 no.2
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• pp.46-51
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• 2015

In this paper, we have developed numerical model for particulated flow through narrow slit using Eulerian-Granular method. Commercial software (FLUENT) was utilized as simulation tool and main focus was to identify the effect from various numerical options for modeling of solid particles as continuos phase in granular flow. Gidaspow model was chosen as basic model for solid viscosity and drag model. And lun-et-al model was used as solid pressure and radial distribution model, respectively. Several other model options in FLUENT were tested considering the cross related effect. Mass flow rate of the particulate through the slit was measured to compare. Due to the high volume density of the stacked particulates above the slit, effect from various numerical options were not significant. The numerical results from basic model were also compared with experimental results and showed very good agreement. The effects from the characteristics of particles such as diameter, angle of internal friction, and collision coefficient were also analyzed for future design of velocity resistance layer in solar thermal absorber. Angle of internal friction was found to be the dominat variable for the particle mass flow rate considerably. More defined 3D model along with energy equation for complete solar thermal absorber design is currently underway.

• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.703-710
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• 2010

Recently, small hydropower attracts attention because of its clean, renewable and abundant energy resources to develop. However, suitable turbine type is not determined yet in the range of small hydropower and it is necessary to study for the effective turbine type. Therefore, a 80kW-Class cross-flow turbine is adopted in this study because of its simple structure and high possibility of applying to small hydropower. The result shows that as effective head increases, tangential and radial flow velocities increase and thus, the increased tangential velocity contributes to the increase of angular momentum and output torque.

• The Journal of Korean Medicine
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• v.18 no.1
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• pp.456-469
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• 1997

The cerebral infarction arised from occulsion of cerebral artery has a high mortality rate and fatal sequelae. Sohabhyangwon(蘇合香元) is generally regarded to have a effect of walking up the patient from unconsiousness and promoting the flow of Qj(氣) by warming channel. METHOD The purpose of this study is to find out the effections of Sohabhyangwon(蘇合香元) on regional cerebral blood flow and relative cerebral infarction area in the experimentally induced infartion in rats In this experiment, 12 Spraque-Dawley rats weighting 280-350g were used. Cerebral ischemia induced by intraluminal suture technique of Kozumi's and Zea-Longer's method. $Co_{2},\;O_2$, pH, arterial blood pressure in rats were checked by Blood Gas Analyzer every 30 minutes for 2 hours. And regional cerebral blood flow were checking by hydrogen clearance technique, cerebral infarcted area was megsured by Image Analysis System. RESULTS 1. During the experiment, $CO_{2},\;O_2$, pH, arterial blood pressure in rats had no change in both sample group and control group. 2. Cortical cerebral blood flow decreased at same rate in both sample group and control group after inducing cerebral infarction. 3. On comparison of relative cerebral infarcted area, Sohabhyangwon(蘇合香元) perfused group showed a significant decrease. CONCLUSION According to the result above, Sohabhyangwon has a protection effect on cranial nerve and-has no effect on cerebral blood flow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.12
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• pp.1061-1069
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• 2010

In this study, a simplified axisymmetric model is proposed for the problem of compressible internal flow past a microgap. Using numerical and experimental methods, the phenomena of choked flows are observed; these flows are induced by the acceleration of subsonic flows past the narrow cross-section of an annular shape made by a microgap. The relation between mass flow rate and differential pressure is obtained, and by comparing the result with experimental results, the reliability of the numerical results is discussed. The generation of a supersonic jet flow and its diffraction are visualized by performing the numerical analysis of axisymmetric compressible Navier-Stokes equations. This investigation greatly extends the physical understanding of the axisymmetric compressible flow, which has a wide range of engineering applications, e.g., in the case of valves in automotive power systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.1
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• pp.1-7
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• 2005

The heat transfer characteristics of an internal heat exchanger for $CO_2$ refrigeration cycle are numerically investigated. The numerical model is verified using the published experimental results for the concentric tube type internal heat exchanger. The Hardy-Cross Method gives very good agreement between the calculation and experimental results on the heat transfer rates and exit temperatures. Also, appropriate combination of heat transfer correlations is found. The operating parameters of the heat exchanger are calculated at transcritical region of $CO_2.$ The heat transfer rate of the counter flow type heat exchanger shows the $32\%$ greater than that of the parallel flow type heat exchanger. The increase of heat exchanger length enhances the heat transfer rate. The thermodynamic characteristics and heat transfer coefficient of $CO_2$ in the internal heat exchanger are estimated.

• Transactions of the Korean Society of Automotive Engineers
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• v.21 no.1
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• pp.36-42
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• 2013

Recently, the automobile of the future will be able to substitute an electric vehicle for an internal combustion engine, so the following research is actively in the process of advancing. A traction motor is one of the core parts which compose the electric vehicle. Especially, it is difficult to connect cooling water piping to an in-wheel motor because the in-wheel motor is located within the wheel structure. This structure has disadvantage for closed type and air cooling, so the cooling design of motor housing and internal in-wheel motor is important. In this study, thermo-flow analysis of the in-wheel motor for vehicles was performed in consideration of ram air effect. In order to improve cooling efficiency of the motor, we variously changed geometries of housing and internal shape. As a result, we found that the cooling efficiency was most excellent, in case the cooling groove direction was same with air flow direction and arranged densely. Furthermore, we investigated the cooling performance enhancement with respect to variable geometries of internal in-wheel motor.

• The KSFM Journal of Fluid Machinery
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• v.16 no.2
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• pp.10-14
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• 2013

The present study conducts CFD analyses on the internal flow fields of roots type vacuum pumps of semiconductor fabrication facility, and the computed CFD results for internal pressure and temperature distributions are applied to structural analyses of the pumps. The coupled analysis results between flow and structure show that the deformation of pump structure is mainly resulted from the thermal expansion of gas in pump, and the deformed impeller and housing produce their severe contact and impact phenomena causing mechanical damage and fracture.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.1361-1366
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• 2009

This study is to see the internal flow for the plasma cutting fume collector. Plasma cutters are widely used in the canning industry and Fume cause the device because it will affect the performance of the design of dust collector. Therefore, to determine the distribution of the internal flow using CFD and Solver was used for calculated with commercial CFD code STAR-CCM+. The results show that design of chamber was incorrect after passed the filter for exhaust to the fan. And the location of the duct to the influx of dust collector and the design was incorrect. In addition, an array of filter was also inappropriate. As a result, present fume collector need to improvement.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.5
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• pp.422-429
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• 2011

The critical fluid velocity of cantilevered cylindrical shells subjected to internal fluid flow is investigated in this study. The fluid-structure interaction is considered in the analysis. The cantilevered cylindrical shell is supported intermediately at an arbitrary axial position. The intermediate support is simulated by two types of artificial springs: translational and rotational spring. It is assumed that the artificial springs are placed continuously and uniformly on the middle surface of an intermediate support along the circumferential direction. The steady flow of fluid is described by the classical potential flow theory. The motion of shell is represented by the first order shear deformation theory (FSDT) to account for rotary inertia and transverse shear strains. The effect of internal fluid can be considered by imposing a relation between the fluid pressure and the radial displacement of the structure at the interface. Numerical examples are presented and compared with existing results.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.2
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• pp.111-120
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• 2012

In this study, to present the data in the internal thermal condition of Double skin facade were measured internal temperature and inlet and outlet openings wind speed of double skin facade. Measurements were similar to temperatures in the upper double skin facade. Especially in summer, temperature stratification is through to be unfulfilled seamlessly despite inlet and outlet openings open. Double skin facade inlet and outlet openings of the air flow rate was slower outlet openings of the air flow rate than inlet openings of the air flow rate.