• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.546-550
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• 2008

In this study, 3-dimensional Computational Fluid Dynamics (CFD) analysis was induced to simulate air flow and particle motion in the axial flow cyclone separator. The commercialized CFD code FLUENT was used to visualize pressure drop and particle collection efficiency inside the cyclone. We simulated 4 cyclone models with different shape of vane, such as turning angle or shape of cross section. For the air flow simulation, we calculated the flow field using standard ${\kappa}-{\varepsilon}$ turbulence viscous model. Each model was simulated with different inlet or outlet boundary conditions. Our major concern for the flow filed simulation was pressure drop across the cyclone. For the particle trajectory simulation, we adopted Euler-Lagrangian approach to track particle motion from inlet to outlet of the cyclone. Particle collection efficiencies of various conditions are calculated by number based collection efficiency. The result showed that the rotation angle of the vane plays major roll to the pressure drop. But the smaller rotation angle of vane causes particle collection efficiency difference with different inlet position.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.561-566
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• 2011

In this paper, 1-D design of axial flow hydraulic turbine including runner blades, spiral casing with distributors(guide vanes and stay vane), and draft tube was conducted and then 3-D flow analysis was carried out using CFX-12.1. The results of 3 runners showed that with an increase in the number of blades, the flow rate and the power of the turbine system increased. On the other hand. the runner loss was not directly connected with the number of blades. As a result, proper blade number could be selected and more than 100kW small hydraulic turbine could be designed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.6 no.2
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• pp.103-109
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• 1994

An experimental study is performed on the flow characteristics of a swirl-jet diffuser for factory ventilation. Swirl number ranges from 0(nonswirl jet) to 0.6 when the angle of swirl vane is 60 degree. As swirl becomes strong, the maximum velocity in the plane perpendicular to jet axis decreases fast and the uniformity of velocity becomes good, particularly in the ventilated area. The similarity in velocity profiles has been found for axial velocity from even when swirl number equals 0.6. The flow characteristics of the swirl-jet which has the swirl number of 0.6 is thought to be the best among these three swirl numbers for factory ventilation. However, the pressure drop in the diffuser increases as the swirl becomes strong. This should be considered in the design of the total ventilation system including a duct system.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.2
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• pp.34-44
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• 1985

Swirling flows have commonly used for a number of years for the stabilization of high- intensity combustion processes. In general, these swirling flows are poorly understood because of their complexity. This paper, therefore, deals with the experimental study on turbulent diffusion flames with swirling flow in unburned flow field by using a model combustor. The purpose of this study is to investigate quantitatively the swirling air jets issuing from vane swirlers. The fundamental experiments have been performed for the local velocity distribution, turbulence intensity and Schlieren photograph in th jets issuing into the atmosphere.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.3215-3220
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• 2007

Gas-liquid separator has been designed for the sake of reducing expenses associated with production operations. To date, a number of gas-liquid separators have been installed and put to use for various applications. Despite the advantages of simple and compact configuration of separator with no moving part, its efficient operation is limited in terms of total pressure losses, separation performance and flow-induced noise and vibration, which are closely associated with the very complicated flow phenomena involved. In the present study, a gas-liquid centrifugal separator with a swirl vane is investigated for the purpose of water separation from compressed moisture air. The 3D Navier-Stokes equations are numerically solved using a fully implicit finite volume scheme. Based upon the obtained solutions, tangential velocities, centrifugal forces, vortices and total pressure losses are analyzed to find out the best design parameters. From the present study, several attempts are made to improve the performance of conventional separators of centrifugal type.

• The KSFM Journal of Fluid Machinery
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• v.18 no.5
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• pp.19-25
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• 2015

As a core component of a hydropower station, hydro turbines play a vital role in the integration of a power station. Research on the technology of hydro turbine is continuously increasing with the development of water electricity. On the basis of one-dimensional loss analysis, for three-dimension design, there are a lot of dimension of the internal flow passage shapes that are determined by experience. Therefore, the effect of the internal flow passage shapes on the performance and internal flow characteristics of a Francis hydro turbine model is investigated in this study. In this study, the small curvature of runner blade trailing edge shape is good for improving the efficiency of Francis turbine. The straight stay vane leading edge is good for suppressing the secondary flow. Moreover, suitable tongue passage shape and stay vane number improve the performance of the turbine considerably.

• Journal of Power System Engineering
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• v.21 no.2
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• pp.48-56
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• 2017

The steady-state, incompressible and three-dimensional numerical analysis was carried out to evaluate the velocity fields around the seabed tiller used for the improvement of the seabed soil and the pulling force and buoyancy generated by driving the seabed tiller. The turbulence model used in this study is a realizable $k-{\varepsilon}$ well known to be excellent for predicting the performance of the flow separation and recirculation flow as well as the boundary layer with rotation and strong back pressure gradient. As a results, a typical vortex pair appears near the adjacent rotor vane tip. When the current is stopped, there is no force when pulling the seabed tiller, but when the current flows at 1.2 knots, the force acts on the downstream side and the pulling force is much greater. In stationary currents, the buoyancy of the seabed tiller acts more strongly towards the seabed as the number of rotations of the rotor increases, but acts more strongly toward the sea surface at 1.2 knots of current.

• Journal of the Korean Geotechnical Society
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• v.16 no.2
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• pp.115-123
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• 2000

Piezocone Penetration Test has been performed in the soft ground over the site preparation area at Inchon International Airport(IIA). With the pore pressure dissipation test results, the changes in the permeability and the coefficient of consolidation in clayey soil were checked and the differences of the undrained shear stength verified the soft ground improvement effect from vane test and piezocone test both before and after the improvement. From the results, thin sand seam was found and this caused a big difference in the coefficient of permeability and consolidation. The coefficient of consolidation was high in the upper marine deposit and relatively low in lower marine deposit. It was found that the reduction of void ratio by preloading resulted in the reduction of coefficient of consolidation after the ground improvement. In addition, there were some variations of undrained shear strength when the number of 15 or 18 was used as the coefficient of piezocone(Nkt). However, when the average value of undrained shear strength calculated using Nkt=10 was applied, the result indicated the similar average value with the result of vane test and the increasing rate of strength( Δsu/Δ$\sigma$≒0.38) also showed the similar distribution.

• The KSFM Journal of Fluid Machinery
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• v.17 no.2
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• pp.5-11
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• 2014

Small hydro power, among other renewable energy resources, has been evaluated to have enough development value because it is a clean, renewable and abundant energy resource. In addition, small hydro power has the advantage of low cost development by using existing facilities like sewage treatment plants, water works and similar resources. But in the case of small hydro power systems, there are problems with degraded operation efficiency of turbine due to changes in flow rates. In order to overcome this, variable speed control can be achieved by using the power rectifier and permanent magnetic synchronous generator(PMSG) as a possible method to respond to the changes in flow rates. In this study, a commercial ANSYS CFD code was used to analyze the performance of 10kW class propeller hydro turbine and to also investigate flow characteristics at variable flow rates and runner vane.

• Progress in Superconductivity and Cryogenics
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• v.22 no.4
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• pp.57-61
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• 2020

Cooling by gas helium circulation can be used for various HTS (high temperature superconductor) magnets operating at 20~40 K, and a cryogenic blower is an essential device for circulating gas helium in the cooling system. The performance of the cryogenic blower is determined by various design parameters such as the impeller diameter, the blade number, the vane angle, the volute cross-sectional area, and the rotating speed. The trailing edge angle and the height of impeller vane are also key design factors in determining the blower performance. This study describes the design, fabrication and performance evaluation of cryogenic blower to produce a flow rate of 30 g/s at 5 bar, 35 K gas helium. The impeller shape is designed using a specific speed/specific diameter diagram and CFD analysis. After the fabrication of the cryogenic blower, a test equipment is also developed using a GM cryocooler. The measured flow rates and the pressure differences are compared with the design values at various rotating speeds and the results show a good agreement. Isentropic efficiency is also evaluated using the measured pressures and temperatures.