• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.4 no.4
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• pp.299-305
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• 1992

Saltation occurs in horizontal flow of solid and gas when the carrier gas velocity is small enough to permit enough to settling of the solid particles within the transport line. So we should examine the pneumatic flow system to lessen the unbured carbon in the power plant. In this paper the saltation velocity was studied on the various solid flow rate in the constant pipe diameter and on the various temperatures of the flow gas. The air velocity in the power plant transport lines was also surveyed in order to compare with the saltation velocity. As the solid flow rate increased in the constant diameter, saltation velocity increased and as the temperater of the flow gas inereased in the transport line, saltation velocity also increased.

• 한국가시화정보학회:학술대회논문집
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• 2005.12a
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• pp.11-16
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• 2005

Saltation is the most important mechanism of wind-blown sand transport. Till now the interaction between wind and sand has not been fully understood. In this study the saltation of sand sample taken from Taklimakan desert was tested in a simulated atmospheric boundary layer. The captured particle images containing both the tracers for wind and saltating sand, were separated by a digital phase mask technique. Both PIV and PTV methods were employed to extract the velocity fields of wind and the dispersed sand particles, respectively. The mean streamwise wind velocity field and turbulent statistics with and without sand transportation were compared, revealing the effect of the moving sand on the wind field. This study is helpful to understand the interaction between wind and blown sand (in saltation), and provide reliable experimental data fur evaluating numerical models.

• Journal of Biosystems Engineering
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• v.23 no.2
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• pp.105-114
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• 1998

Granule application with a boom has merits of accurate application and high field efficiency. In order to develop a boom granule applicator, aerodynamic properties of agrichemicals should be investigated. This study was accomplished to investigate aerodynamic properties of granules and factors affecting on them. The tested agrichemicals were urea, compound fertilizer (17-21-17), sand and zeolite. Basic physical properties of granules such as true density, sphericity, and arithmetic mean diameter for those materials were analyzed. Regression equations for pickup velocity (v$_{p}$) and saltation velocity (v$_{s}$) were proposed by the data transformation and the multi-regression analysis as follows : (equation omitted) where, 0< s < 1, 0< λ$_{i}$< 3, 35 < D/d$_{p}$ < 350, 1000 $_{p}$/p$_{a}$ < 2500 The range of pickup velocity of fertilizers and other agrichemicals were shown to be 10-16m/s and 9-13m/s, respectively. The saltation velocity of fertilizer and other agrichemicals were 3 m/s and 4 m/s, respectively.y.ively.y.y.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.1442-1447
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• 2004

A significant amount of labor hour is being spent for clean up spent abrasives after blasting. So, for improving the efficiency of abrasive(grit) recovery process which acts as the neck of a battle in preceding coating stage, it was established the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimentally evaluated the effect of design parameters such as flow pattern, saltation velocity and pressure drop on the efficiency of the abrasive recovery system. And, by optimizing the operating parameter such as the length and diameter of suction hose, specification of recovery device, recovery mouth and hose connection method, a method which can dramatical1y increase the efficiency of abrasive recovery system, is derived.

• Special Issue of the Society of Naval Architects of Korea
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• 2005.06a
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• pp.198-205
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• 2005

Reduction of labor hour for cleaning up of the used abrasives after blasting. is attempted by improving the efficiency of abrasive recovery process in the protective coating of ship's block, For this purpose, the theoretical background for pneumatic transport technology in the abrasive recovery system as well as experimental evaluation on the effect of design parameters such as flow pattern, saltation velocity and pressure drop on the efficiency of the abrasive recovery system are employed . By optimizing the operating parameters such as the length and diameter of the suction hose, specification of recovery device and recovery mouth, a new method which can dramatically increase the efficiency of abrasive recovery system, is proposed.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.740-745
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• 2000

Effects of porous fences on the wind erosion of sand particles from a triangular pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Particle motion was visualized to see the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the fence porosity ${\varepsilon}$. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity ${\varepsilon}=30%$ was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles.

• Journal of Environmental Science International
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• v.4 no.1
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• pp.29-40
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• 1995

Transport rate of windblown dusts such as soil, sand, snow is proportionate to $U*_^3 and U_*$, friction velocity, approximately to flow velocity of ink Therefore, through measurement and the flow velocity of wind, it turned out that, considering different velocity distributions caused by downstream distance and porosity percent, windbreaks with appropriate porosity rate to the Protection area should be chosen for the optimal fence effect. In the economic respects better are fences with gap of 20%~30%. Among the windbreaks to have the optimal fence effect.

• Journal of Korean Society for Atmospheric Environment
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• v.16 no.6
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• pp.633-640
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• 2000

The effects of structure modification of the vortex finder on the collection efficiency and pressure drop have been investigated. The pressure drop in a cyclone having the two stage vortex finder is higher than that in a conventional cyclone and increases proportionally with the increase of square of gas inlet velocity in both cases. The pressure drop of both conventional cyclone of friction resistance at the boundary layer. The collection efficiency of fine dust has been enhanced by addition of vortex finder in a conventional cyclone and gas inlet velocity showing maximum dust removal efficiency increase to 17 m/s(1.7 times of saltation velocity). Optimum size of two stage vortex finder has been induced to 13 cm I.D$\times$2.6cm Length from the results of overall dust collection efficiency. Previous models were tested for the simulation of collection efficiency of cyclone having two stage vortex finder and the Dietz model predict the similar value with experimental results of the present study.

• 한국해양학회지
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• v.27 no.2
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• pp.145-153
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• 1992

From the analyses of 16 bottom sediment samples and current data obtained during field expert ments from August to September 1987, the textural characteristics and transport mode of sand grains of a tidal sand ridge in Gyeonggi Bay are studied. The textural characteristic of the bottom sediments are diverse depending on their location on the tidal sand ridge. Sands on the crest are well sorted. near symmetric in skewness. leptokurtic in kurtosis. and are unimodal in peakedness. On the other hand, Poorly sorted gravelly sands in the trough are coarse skewed in skewness and plartkurtic in kurtosis. The mean values of U/SUB 100/ (velocity at one meter above bottom) and U/SUP */ (boundary shear velocity) are calculated to be 41.4 cm/sec and 2.39 cm/sec, respectively. From the analyses of characteristics of the sediments and currents in the study area, it can be concluded that almost all the sands of the tidal sand ridge (esp. on the crest) are transported as bedload (mainly as saltation).

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.9
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• pp.1175-1184
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• 2000

Effects of porous wind fences on the wind erosion of particles from a triangular sand pile were investigated experimentally. The porous fence and sand pile were installed in a simulated atmospheric boundary layer. The mean velocity and turbulent intensity profiles measured at the sand pile location were well fitted to the atmospheric boundary layer over the open terrain. Flow visualization was carried out to investigate the motion of windblown sand particles qualitatively. In addition, the threshold velocity were measured using a light sensitive video camera with varying the particle size, fence porosity $\varepsilon$ and the height of sand pile. As a result, various types of particle motion were observed according to the fence porosity. The porous wind fence having porosity $\varepsilon$=30% was revealed to have the maximum threshold velocity, indicating good shelter effect for abating windblown dust particles. With increasing the sand particle diamter, the threshold velocity was also increased. When the height of sand pile is lower than the fence height, threshold velocity is enhanced.