• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.3
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• pp.296-305
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• 1995

A numerical study was undertaken to clarify the mechanisms of heat transfer in fluid-particle suspension flows. Such flows, including fluidization, are of considerable industrial importance. The present study uses 2-D numerical computations of collisions of normal incidence between a particle and a wall. By comparing the results using (a) adiabatic boundary conditions on the particle and (b) uniform, elevated temperature conditions on the particle, the contributions of fluid-mediated conduction and particle induced convection were successfully separated. Computational expedience led to the use of a transient conduction thermal layer as the background thermal field for the analysis. The results shows that the effect of particle movement is very small until the particle reaches a distance of one to one half diameter away from the wall. The gas-mediated conduction effect is dominant over the induced gas convection effect when Pe is small and the induced gas convection effect becomes significant as Pe increases.

• Journal of computational fluids engineering
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• v.6 no.4
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• pp.8-14
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• 2001

The phenomena of two-phase suspension flows appear widely in nature and industrial processes. Hence, it is of great importance to understand the mechanism of the gas-solid two-phase flows. In the present study, the numerical simulation has been approached by utilizing the Eulerian-Lagrangian methodology for describing the characteristics of the fluid and particulate phases in a vertical pipe and a 90°square-sectioned bend. The continuous phase(gas phase) is described by the Eulerian formulation and a κ-ε turbulence model is employed to find mean and turbulent properties of the gas phase. The particle properties(velocity and trajectory) are then described by a Lagrangian approach and computed using the mean velocity and turbulent fluctuating velocity of the gas phase. The predictions are compared with measurements by laser-Doppler velocimeter for the validation. As a result, the calculated results show good agreements.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.11 no.6
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• pp.104-110
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• 1997

In thes paper, the soung signals due to the collisions against the inside wall by conductint particles with in coaxial cylindrical electrodes, and the corresponding frequency spectrum are analyzed and discribed.Thesesound signals were detected and measured using ultrasonic and vibration sensors attached to the exterior of the GIS enclosure. In the case where a particls is bouncing about between these coaxoal electrodes, the sound signal was found to be more than 10[dB] greater than the background noise due to no particlel. Also, in the case where a particle collides and insulation breakdown caesed by the particle made it possible to determine the condition of the insulation inside the sealed GIS. Lastly, the relationship between the peak amplitude and RMS voltage of the measured signal, the diameter and length of the particle was analyzed. Using thes analysis, it is possible to confirm the size of particle.