• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.1
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• pp.591-596
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• 2016

Numerical analyses were performed on the heat flow characteristics of a heat transfer plate with six different shapes (basic, rectangle, triangle, wave type) to reduce the level of white smoke at a stack. In this study, to examine the heat transfer performance (heat transfer capacity, pressure drop, turbulence kinetic energy, heat transfer coefficient) on the heat transfer plates, simulations were conducted using the commercial computational fluid dynamics software, ANSYS CFX Ver.14 under uniform flow conditions. The thermal flow phenomenon in a channel with six heat transfer plates could be predicted adequately under uniform flow conditions. The heat transfer capacity, pressure drop, turbulence kinetic energy, and heat transfer coefficient were affected by the flow rate, aspect ratio and plate shape. These results provide guidelines to design an effective heat exchanger with the wave type to reduce white smoke.

• Journal of Mechanical Science and Technology
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• v.20 no.8
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• pp.1302-1308
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• 2006

The unsteady Hartmann flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer taking the Hall effect into consideration. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to an exponential decaying pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the ion slip and the uniform suction and injection on both the velocity and temperature distributions is examined.

• The KSFM Journal of Fluid Machinery
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• v.13 no.4
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• pp.45-50
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• 2010

The goal of paper is to investigate the flow and scalar distribution through the HP Nozzle Guide Vane (NGV) passage. Flow and scalar distribution measurement are conducted by using 5-hole pressure probe and $CO_2$ tracing technique, respectively. Three different experimental cases are considered depending on cooling flow condition. The result shows that the vortical secondary flow patterns are observed clearly and these flow characteristics maintain through the NGV passage regardless of cooling flow injection. Compared to center region, the high axial velocity flow is observed near wall region due to cooling flow injection. Without cooling flow, the $CO_2$ (scalar) distribution becomes to be uniform quickly due to the strong flow mixing phenomenon. However, in cases of cooling flow, scalar distribution is significantly non-uniform.

• 한국전산유체공학회:학술대회논문집
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• 2007.10a
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• pp.39-44
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• 2007

A similarity solution of the Navier-Stokes equation for the axisymmetric stagnation flow near a plane wall coated with a magnetic fluid of uniform thickness is constructed. The shape functions representing the flow in two (magnetic and normal) fluid layer are determined from a third order boundary value problem, which is solved by the Runge-Kutta method with two shooting parameters. Features of the flow including streamline pattern and interface velocity are investigated for the varying values of density ratio, viscosity ratio, and Reynolds number. The results for the interface and wall shear stress, boundary layer and displacement thickness are also presented.

• Journal of Mechanical Science and Technology
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• v.19 no.11
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• pp.2053-2060
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• 2005

The unsteady Couette flow of an electrically conducting, V1SCOUS, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer taking the Hall effect into consideration. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to an exponential decaying pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of the ion slip and the uniform suction and injection on both the velocity and temperature distributions is examined.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.7
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• pp.1799-1807
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• 1994

Natural convection from a slightly inclined circular cylinders immersed in quiescent cold pure water was studied experimentally. The experiment was carried out for circular cylinders with uniform heat flux ranging from $100W/m^{2} to 800 W/m^{2}$ and inclined angle ranging from horizontal $({\phi}=0^{\circ}) to 15^{\circ}$. The flow fields around cylinder were visualized and heat transfer characteristics investigated by measuring the surface temperatures for each case. As the results, it is shown that flow patterns are changed consecutively through the sequence of steady state downflow, unsteady state flow and steady state upflow with increasing heat flux. At the same inclined angle, as heat flux increases, the average Nusselt number decreases and then increases. At the same heat flux, as inclined angle increases, the average Nusselt number decreases.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05b
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• pp.663-668
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• 1996

A two-dimensional continuum model for the prediction of the hydrogen mixing phenomena in the containment compartment under the severe accident conditions is developed. The model could predict well the distribution of time-dependent hydrogen concentration for selected HEDL Experiment. For a simulation of these experiments, the hydrogen is mixed uniform over the test compartment. To predict the extent of non-uniform distribution, the dominant factors such as the geometrical shape of obstacle and velocity of source injection in mixing phenomena are investigated. If the obstacle disturbing the flow of gas mixture exists in the compartment, the uniform distribution of hydrogen may be not guaranteed. The convective circulation of gas flow is separately formed up and down of the obstacle position, which makes a difference of hydrogen concentration between the upper and lower region of the compartment. The recirculation flow must have a considerable mass flow rate relative to velocity of the source injection to sustain the well-mixed conditions of hydrogen.

• Journal of Ocean Engineering and Technology
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• v.15 no.2
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• pp.39-45
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• 2001

With uniform heat generation from the inner surface of the cylindrical heater placed in a cross flow boundary condition, heat flow that is conducted along the wall of the heater creates a non-isothermal surface temperature and non-uniform heat flux distribution. In the present investigation, the effects of circumferential wall heat conduction on convection heat transfer is investigated for the case of forced convection around horizontal circular tube in cross flow of air. The wall conduction number which can be deduced from the governing energy equation should be used to express the effect of circumferential wall heat conduction. It is demonstrated that the circumferential wall heat conduction influences local Nusselt numbers of one-dimensional and two-dimensional solutions.

• Journal of the Semiconductor & Display Technology
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• v.10 no.2
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• pp.109-113
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• 2011

Hot air flow simulations of the wet station dryer module for the solar cell cleaning were conducted. Air incident angles such as to the substrates ($45^{\circ}$), to the bottom ($90^{\circ}$), and to the wall ($135^{\circ}$) were considered. Based on the simulated velocity and temperature profiles, appropriate incident angle was proposed, and it was well matched to experimental results. Additionally, uniform and non-uniform air hole sizes of the tube were compared for the uniform air flow distribution through the batch.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2005.11a
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• pp.915-918
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• 2005

Acoustic holography uses Kirchhoff·Helmholtz integral equation and Green's function which satisfies Dirichlet boundary condition Applications of acoustic holography have been taken to the sound field neglecting the effect of flow. The uniform flow, however, changes sound field and the governing equation, Green's function and so on. Thus the conventional method of acoustic holography should be changed. In this research, one possibility to apply acoustic holography to the sound field with uniform flow is introduced through checking for the plane wave in a duct. Change of Green's function due to uniform flow and one method to derive modified form of Kirchhoff·Heimholtz integral is suggested for 1-dimensional sound field. Derivation results show that using Green's function satisfying Dirichlet boundary condition, we can predict sound pressure in a duct using boundary value.