• Journal of Advanced Marine Engineering and Technology
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• v.27 no.7
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• pp.899-905
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• 2003

Mixers are used in several industrial applications where it is necessary to strongly mix reactants in a short period of time (eg. reaction injection molding, ceramics manufacturing, crystallization). However, despite their widespread use, mixing flow characteristics in these systems have not been rigorously investigated. Influence of blade shapes on the mixing time and the power consumption per unit volume in two kinds of impeller including the mixing effects are studied by PIV experiment. A series of the experiments were carried out to achieve a better mixing effect in simple baffle arrangement and tall vessel with modified impellers(two kinds of blades : pitched blade turbine and rushton turbine). Results show that periodic vortex from the mixing layer is predominant and related unsteady flow characteristics prevail over the entire region.

• Journal of the Korean Geotechnical Society
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• v.23 no.3
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• pp.133-140
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• 2007

DCM (Deep Cement Mixing Method) has been applied to build structures such as self-supported earth retaining walls. DCM columns should be penetrability into the stiff layer to assure the self-supporting ability. On the penetration increase of blade attached to the DCM mixing tools, a spiral mixing blade has been revised. Penetration characteristics of spiral blades in the stiff soil layer were evaluated through Gimhae and Incheon areas. The spiral mixing blades could penetrate into the stiff soil layers which have the N-value of greater than 30 although the penetration rate is somewhat slow. Penetration characteristics and economical efficiency should be discussed to determine the critical depth of the spiral mixing blade because the penetration efficiency can decrease in the stiff layer in this paper.

• 유체기계공업학회:학술대회논문집
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• 1998.12a
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• pp.49-54
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• 1998

The flow inside an axial turbomachinery with multi-stage can be characterized as unsteady phenomena. In order to predict accurately these complex unsteady flow patterns including rotor-stator interaction effects, enormous computer resources are required. So it is not compatible in preliminary design process. In this study, steady coupled blade row flow with rotor-stator interaction solver is developed using interrow mixing model and used to predict the performance of the axial fan. To verify the computational method, the calculations are compared with experimental results and show satisfactory agreement with them. The interaction effects on the performance of the axial fan have also been studied by comparing the results of steady coupled blade row and steady single blade row flow calculation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2001.11a
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• pp.11-14
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• 2001

3-D compressible flow analysis was conducted by using mixing plane method for turbine system which is consisted of partial admission nozzle and rotor. Computational results are shown oblique shock wave in blade leading and trailing edge and also shown flow separation along suction surface of blade due to abrupt blade curvature. But computational results are well agree with 1-D calculation results and experimental data.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.4
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• pp.363-370
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• 2017

This paper is concerned with the evaluation of mixing performance of a particle mixer, which consists of a vertical cylindrical vessel and a rotating impeller with several blades. We consider four design variables for the mixer blades, such as the angle, length, and number of blades, and the gap between the blades and the vessel bottom. The particle mixing process due to the impeller rotation is simulated using the discrete element method, and the mixing performance is quantitatively evaluated by introducing a mixing index. Analyzing the main effects and interactions of the four design variables through the design-of-experiments approach, it is concluded that the blade angle has the most dominant influence on the mixing performance whereas the gap has no significant influence. In addition, we determine the best combination of design parameters to maximize the mixing performance.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.6
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• pp.192-199
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• 2008

The key issues for the reduction technologies of the exhaust gas from diesel engine being developed are to reduce particulate matters and NOx. The SCR system is known to be one of the most efficient and stable technologies to remove NOx through the mixing of NOx and urea solution. In the present research, the effects of mixer configurations of SCR system have been investigated to enhance the SCR performance. First, a Schlieren technique is employed to visualize the mixing characteristics of urea solution and exhaust gas. The results show that a mixer is essential to obtain proper fluid mixing. In addition, numerical studies have been made to understand the mixing characteristics through the comparison of the mal-distribution index of concentration at the several locations of the diffuser. In particular, the effects of number of blade and mixer angles on mixing characteristics were studied. The results show that the blade angle has a larger effect on the mixing characteristics than the number of blades.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.6
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• pp.174-184
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• 1998

The situation frequently occurs in which the input torque capacity of the torque converter should be changed. It is known that the modification of the outlet blade angles of the torque converter elements is suitable for such situation with the outer diameter of flow path of the converter maintained. But so far it has been difficult to predict correctly the converter characteristics as well as the effect of outlet angles on torque capacity in the past numerical methods. In the present numerical method introducing the interrow mixing planes, the torque capacity was satisfactorily estimated and it was shown that the torque capacity could be effectively changed by modifying the outlet blade angles of pump and stator.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.7
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• pp.831-840
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• 1999

In this work, an aerothermodynamic calculation model for cooled axial flow turbine blades with trailing edge ejection is suggested and a mean line performance analysis of a turbine stage with nozzle cooling is carried out. A unique model regarding the interaction between coolant and main gas is proposed, while existing correlations are adopted to predict viscous loss and blade outflow angle. The interactions considered are the heat transfer from main gas to coolant and the temperature and pressure losses by the mixing of two streams due to the trailing edge coolant ejection. For a stator blade without ejection, trailing edge loss calculated by the trailing edge analysis is compared with that calculated by loss correlation. The effect of heat transfer effectiveness of coolant passage on the mixing loss is analyzed. For a model turbine stage with nozzle cooling, parametric analyses are carried out to investigate the effect of main design variables(coolant mass flow ratio, temperature and ejection area) on the stage performance.

• 유체기계공업학회:학술대회논문집
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• 2002.12a
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• pp.131-136
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• 2002

A computational analysis using Reynolds stress model in FLUENT is conducted to give a clear understanding of the effect of blade loading on the structure of tip leakage flow in a forward-swept axial-flow fan at design condition ($\phi$=0.25) and off-design condition ($\phi$=0.21 and 0.30). The roll-up of tip leakage flow starts near the minimum static wall pressure position, and the tip leakage vortex developes along the centerline of the pressure trough within the blade passages. Near tip region, a reverse flow induced by tip leakage vortex has a blockage effect on the through-flow. As a result, high momentum region is observed below the tip leakage vortex. As the blade loading increases, the reverse flow region is more inclined toward circumferential direction and the onset position of the rolling-up of tip leakage flow moves upstream. Because the casing boundary layer becomes thicker, and the mixing between the through-flow and the leakage jet with the different flow direction is enforced, the streamwise vorticity decays more fast with blade loading increasing. The computational results show that a distinct tip leakage vortex is observed downstream of the blade trailing edge at $\phi$=0.30, but it is not observed at $\phi$=0.21 and 0.25.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.4
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• pp.294-304
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• 2003

An experimental analysis using three-dimensional laser Doppler velocimetry(LDV) measurement and computational analysis using the Reynolds stress model in FLUENT are conducted to give a clear understanding of the effect of blade loading on the structure of tip leakage flow in a forward-swept axial-flow fan operating at the maximum efficiency condition ($\Phi$=0.25) and two off-design conditions ($\Phi$=0.21 and 0.30). As the blade loading increases, the onset position of the rolling-up of tip leakage flow moves upstream and the trajectory of tip leakage vortex center is more inclined toward the circumferential direction. Because the casing boundary layer becomes thicker and the mixing between the through-flow and the leakage jet with the different flow direction is enforced, the streamwise vorticity decays more fast with the blade loading increasing. A distinct tip leakage vortex is observed downstream of the blade trailing edge at $\Phi$=0.30, but it is not observed at $\Phi$=0.21 and 0.25.