• 한국유체기계학회 논문집
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• 제8권3호
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• pp.42-47
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• 2005

Effects of a booster inducer on the suction performance of turbopumps are investigated in this paper. To see the effect of the booster inducer, suction performance tests are conducted with and without the booster inducer for three turbopumps. It is shown that the booster inducer can enhance the suction performance of turbopumps when the tip clearance of the main inducers are relatively large. Numerical analysis are also carried out to see the effects of the booster inducer on the performance of the main inducer. The booster inducer is shown to increase the static pressure at the inlet of the main inducer and prevent growing of inlet back flows which are believed to have deleterious effects on the suction performance of the inducer.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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• pp.552-557
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• 2004

Effects of a booster inducer on the suction performance of turbopumps are investigated in this paper. To see the effect of the booster inducer, suction performance tests are conducted with and without the booster inducer for three turbopumps. It is shown that the booster inducer can enhance the suction performance of turbopumps when the tip clearance of the main inducers are relatively large. Numerical analysis are also carried out to see the effects of the booster inducer on the performance of the main inducer. The booster inducer is shown to increase the static pressure at the inlet of the main inducer and prevent growing of inlet back flows which are believed to have deleterious effects on the suction performance of the inducer.

• International Journal of Naval Architecture and Ocean Engineering
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• 제4권4호
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• pp.477-487
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• 2012

We investigated the aerodynamic characteristics of a three-dimensional (3D) wing with an endplate in the vicinity of the free surface by solving incompressible Navier-Stokes equations with the turbulence closure model. The endplate causes a blockage effect on the flow, and an additional viscous effect especially near the endplate. These combined effects of the endplate significantly reduce the magnitudes of the velocities under the lower surface of the wing, thereby enhancing aerodynamic performance in terms of the force coefficients. The maximum lift-to-drag ratio of a wing with an endplate is increased 46% compared to that of wing without an endplate at the lowest clearance. The tip vortex of a wing-with-endplate (WWE) moved laterally to a greater extent than that of a wing-without-endplate (WOE). This causes a decrease in the induced drag, resulting in a reduction in the total drag.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2000년도 추계학술대회 논문집
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• pp.502-506
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• 2000

In this study, an experimental method measuring the scroll under the temperature distribution similar to the operating condition is proposed and the results are presented. Direct measurement of the actual thermal stress is very difficult because of the rapid and complex motion of the orbiting scroll. Therefore, the experimental condition is provided on the stationary scroll heated in the electric furnace and, then, the mechanical stress and the effects of refrigerant are excluded from the resulting measurement. The experimental results are compared with these of FEM, both showing good agreement.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권3호
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• pp.132-139
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• 2003

The effects of casing shapes on the performance and the interaction between an impeller and a casing in a small-sized centrifugal compressor are investigated. Especially, numerical analyses are conducted for the centrifugal compressor with both a circular casing and a volute one. The optimum design for each element (i.e., impeller, diffuser and casing) is important to develop an efficient and compact compressor using alternative refrigerant as working fluids. Typical rotating speed of the compressor is in the range of 40,000∼45,000 rpm. The impeller has backswept blades due to tip clearance and a vane diffuser has wedge type. In order to predict the flow pattern inside an entire impeller, vaneless diffuser and casing, calculations with multiple frames of reference method between the rotating and stationery parts of the domain are carried out. For computations of compressible turbulent flow fields, the continuity and time-averaged Navier-Stokes equations are employed. To evaluate the performance of two types of casings, the static pressure recovery and loss coefficients are obtained for various flow rates. Also, static pressure distributions around casings are studied for different casing shapes, which are very important to predict the distribution of radial load. The static pressure around the casing and pressure difference between the inlet and outlet of the compressor are measured for the circular casing.

• 대한기계학회논문집B
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• 제35권8호
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• pp.781-787
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• 2011

본 연구에서는 4단으로 구성된 LNG 플랜트용 프로판 냉매 원심 압축기 각 단의 설계점에 대해 상용 코드를 이용하여 공력설계를 하였다. 1차원 공력 설계 결과와 3차원 유로 형상의 타당성은 유동해석을 통해 확인하였다. 특히 입구전압이 높고 회전수가 큰 4단 압축기 임펠러의 유로와 베인리스 디퓨저 내부 유동에 대한 속도장, 압력장 및 엔트로피 등의 유동특성에 대해 고찰하였고, 아울러 익단 간극이 유동장에 미치는 영향에 대해서도 알아보았다. 본 연구 결과는 프로판 냉매 압축기의 시스템 제작에 활용될 것이며 추후 실제 실험결과와 비교하고자 한다. 향후 설계된 프로판 냉매압축기에 대한 LNG 플랜트에서의 실증시험을 통해 구체적인 설계결과에 대한 평가 및 설계 개선이 이루어지리라 생각한다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.638-641
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• 2008

Computational investigation was conducted to study the effects of the shape parameter of shroud on the performance of the outdoor unit of an air-conditioners. For this study the Design of Experiment(4-factor 3-level) was created and the an automatic program was composed using VBA to reduce the load of pre-process for CFD. The estimated mathematical equation was produced from this analysis and it was found that the gap between fan and shroud affects more heavily than the other parameters. As a result, the composition of the best parameters was verified that its flow rate was increased by 10 percents and sound pressure level was reduced by 1.2 dBA compare with the worst. And finally, a kind of Propeller fan with blades which were attached to the shroud, so-called 'ProBeller Fan' was introduced in this study.

• 대한기계학회논문집B
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• 제21권10호
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• pp.1339-1349
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• 1997

A numerical method of calculating the performance of a scroll compressor for refrigerant R-22 and R-134a is presented in this paper. A series of involute curves are employed for the scroll wrap design and the compression volume is investigated geometrically. The radial leakage flow rate through tip clearance is calculated by the two-dimensional compressible flow. On the basis of the results, quasi one-dimensional leakage modeling can be applied to the performance analysis of a scroll compressor, more effectively. Furthermore, the heat transfer effect between scroll wrap and working fluid in compression chamber is considered for the performance analysis. As the results of this study, the effects of the radial and tangential leakage flow rate and heat transfer on the scroll compressor performance are derived precisely. These results may provide the guideline for the design and development of a real scroll compressor.

• The Korean Journal of Physiology
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• 제19권1호
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• pp.25-33
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• 1985

Renal arterial infusion of renotropic agents has been a very useful technique in the renal function studies. This type of experiments have usually been conducted in the large animals such as dogs and sheep. In these animals a catheter can be placed in the site without much disturbances of renal blood flow. Rabbits as an experimental model, however, caused a disturbances of renal blood flow by a catheterization of renal artery by its properties. Therefore we have developed a new technique that allows a simple and selective access to one side of renal arteries and the other as a control, without any disturbances of renal function. The distance between the both bifurcations of renal arteries on abdominal aorta is about 7 mm. To locate the tip of catheter on one side renal artery, ascending cannulation performed via femoral artery was done. We did an experiment with the technique to clarify the effect of calmodulin inhibitor on the renal function. One of the phenothiazine derivatives, trifluoperazine known as a powerful calmodulin inhibitor. Trifluoperazine, actual dose ranges of $2.76-5.20\;ug\;{\cdot}\;kg^{-1}\;{\cdot}\;min^{-1}$, increased urine volume and glomerular filtration rate significantly. Significant increases in urinary excretion of sodium, chloride and potassium were found. Fractional excretion of sodium and free water clearance increased significantly. These data suggest that this new technique is very useful in field of renal physiology and that striking effect of trifluoperazine on the renal function may be caused by increasing the renal hemodynamics, and by the inhibition of sodium, chloride and potassium reabsorption in the renal tubules.

• Geomechanics and Engineering
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• 제10권5호
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• pp.599-615
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• 2016

The present research presents experimental and finite element studies to investigate the behavior of piled raft-tunnel system in a sandy soil. In the experimental work, a small scale model was tested in a sand box with load applied vertically to the raft through a hydraulic jack. Five configurations of piles were tested in the laboratory. The effects of pile length (L), number of piles in the group and the clearance distance between pile tip and top of tunnel surface (H) on the load carrying capacity of the piled raft-tunnel system are investigated. The load sharing percent between piles and rafts are included in the load-settlement presentation. The experimental work on piled raft-tunnel system yielded that all piles in the group carry the same fraction of load. The load carrying capacity of the piled raft-tunnel model was increased with increasing (L) for variable (H) distances and decreased with increasing (H) for constant pile lengths. The total load carrying capacity of the piled raft-tunnel model decreases with decreasing number of piles in the group. The total load carrying capacity of the piles relative to the total applied load (piles share) increases with increasing (L) and the number of piles in the group. The increase in (L/H) ratio for variable (H) distance and number of piles leads to an increase in piles share. ANSYS finite element program is used to model and analyze the piled raft-tunnel system. A three dimensional analysis with elastoplastic soil model is carried out. The obtained results revealed that the finite element method and the experimental modeling are rationally agreed.