• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.12
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• pp.1265-1272
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• 2011

We performed numerical simulations of the recirculation flow of an electrolyte fluid in a circular container driven by an AC electromagnetic force for solving continuity and momentum equations. We also conducted an experiment to obtain flow data, which were in good agreement with the numerical simulation results. Furthermore, we performed a parametric study on both numerical and experimental aspects and found that the fluid velocity increases with an increase in the electrolyte concentration and magnetic intensity and with a decrease in the fluid depth and AC frequency.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.805-811
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• 2009

An oxidizer pump of a turbopump for a 30-ton class gas generator cycle engine was tested in the medium of liquid oxygen. The turbine was driven by cold hydrogen gas in the test. The oxidizer pump was operated stably at both design and off-design conditions, satisfying the performance requirements. The pump head coefficient from the liquid oxygen test was 2~3% lower than that from the water test. The power required to run the oxidizer pump was well balanced with the power produced by the turbine.

• Journal of IKEEE
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• v.23 no.2
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• pp.524-528
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• 2019

Although different types of discharge cells exist, in common it is the primary goal for all discharge cells to have lower drive voltages and higher efficiency characteristics. To improve these factors, many studies are conducted that prolong the discharge path inside the discharge cell or change the composition of the working gas. In this paper, the two-dimensional fluid simulation was used to calculate the discharge voltage (firing voltage and sustain voltage) and the change in luminance and luminous efficacy according to the change in gap distance between discharge electrodes. In addition, we looked at changes in various charged particles, exciting particles and VUV particles, and studied the causes of the resulting values.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.238-238
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• 2021

토목 구조물에서 수문 (Gate)은 다양한 시설에서 설계되어 적용되고 있다. 이런 수문은 용도나규모, 사용재료, 구동방식에 의해 다양하게 분류되는데, 본 글에서 다룰 Girder 타입의 Sluice Gate 는 가장 많은 분야에서 포괄적으로 적용되는 수문 형식중 하나이다. 일반적으로 2m×2m 미만의 소규모 수문에서는 수문설계에 수리계산이나 응력검토를 요하지 않으나, 높이 5m 가 넘는 대형 수문의 경우 비체의 무게가 수십톤에 달하기 때문에 정수역학이나 동수역학과 같은 수리학적 설계가 반드시 필요하다. 수문설계는 크게 세 가지 해석을 다루는데, 첫 번째는 정수역학 또는 동수역학적 거동에 대한 수문 비체의 구조해석이고 두 번째는 수문의 상승 및 하강을 위한 권양장치 및 수문비체, 구동장치 등의 계산이며 마지막으로는 수문의 형상과 수류형상에 따른 수문의 진동해석 이다. 본 글에서는 두 번째에 해당하는 수문의 상승 및 하강에 영향을 미치는 수리학적 요소들을 통해 가장 합리적인 수문형상설계에 대해 논하고자 한다. 특히 국내에서는 Girder 타입의 수문설계에서 수문하단부 sill 부근의 형상을 쐐기 형태로 일률적으로 적용하고 있는데, 이를 개선하여 유체역학적으로나 경제적으로 보다 유리한 설계안을 본 글을 통해 제안하고자 한다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.243-247
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• 2005

Hydraulic performance test was conducted for a fuel pump of a liquid rocket engine turbopump. The pump driven by an electric motor was tested in water environment. It is experimentally shown that the inducer had very small effect on the pimp's head and efficiency but great effect on the pump's cavitation performance. Additionally, inducer test was carried out to investigate the effect of the inducer on the pump in detail, and it was found that the pump had a critical cavitation number when the inducer head dropped by $55\%$.

• Journal of computational fluids engineering
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• v.4 no.1
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• pp.8-18
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• 1999

In devising a numerical approximation for the convective spatial transport of a fluid mechanical quantity, it is noted that the convective motion of a scalar quantity occurs in one-way, or from upstream to downstream. This consideration leads to a new scheme termed a pure upwind difference scheme (PUDS) in which an estimated value for a fluid mechanical quantity at a control surface is not influenced from downstream values. The formal accuracy of the proposed scheme is third order accurate. Two typical benchmark problems of a wall-driven fluid flow in a square cavity and a buoyancy-driven natural convection in a tall cavity are computed to evaluate performance of the proposed method. for comparison, the widely used simple upwind scheme, power-law scheme, and QUICK methods are also considered. Computation results are encouraging: the proposed PUDS sensitized to the convection direction produces the least numerical diffusion among tested convection schemes, and, notable improvements in representing recirculation of fluid stream and spatial change of a scalar. Although the formal accuracy of PUDS and QUICK are the same, the accuracy difference of approximately a single order is observed from the revealed results.

• The KSFM Journal of Fluid Machinery
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• v.19 no.6
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• pp.68-74
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• 2016

Hydraulic fracturing of wells during oil and gas (O&G) exploration consumes large volumes of fresh water and generates larger volumes of contaminated wastewater with high salinity. It is critical to treat and reuse the O&G wastewater in a cost-effective and environmentally sound manner for sustainable industrial development and for meeting stringent regulations. Recently, forward osmosis (FO) has been examined if it is a promising solution for treatment and desalination of complex industrial streams and especially fracturing flowback and produced waters. In the present study, the performances of a plate-and-frame FO membrane element and a module (6 elements combined in series) were investigated for concentrating high TDS wastewater. An FO module has achieved up to 64 % water recovery (i.e., concentration factor of 2.76) from 10,000 ppm wastewaters and can concentrate feed streams salinities to greater than 30,500 ppm.

• The KSFM Journal of Fluid Machinery
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• v.9 no.2 s.35
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• pp.30-38
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• 2006

An aerodynamic design for centrifugal compressor which was applied to medium speed diesel engine has been done. First of all, exact compressor specifications must be defined by accurate engine system matching. This matching program has been developed. Using the meanline prediction method, geometric design and performance curves for compressor were established and verified by comparing three dimensional viscous CFD results. The deviation at the design point was about 2.3%. Combustor has been designed and manufactured for the performance test of medium speed diesel engine turbocharger. Fuel nozzle of combustor was designed and its characteristics was analyzed by PIV and PDPA test equipment. Through these results, spray characteristics were studied and flow coefficient equation was deduced.

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.177-180
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• 2004

The development of a tilting train with construction of electric line on the conventional railway is required for speed-up on the conventional railway with many curving sections. For development of tilting train, the study and development of the tilting system and tilting bogie having the different mechanism with a general high speed train will play a main role for improving the technology in the field of Korean railway The study and development of the pantograph tilting mechanism in order to keep a good contact behavior between a pantograph and a contact wire by tilting a pantograph on the opposite direction of the vehicle tilting direction. In this study, we analyzed the aerodynamic characteristic of a developing pantograph on the tilting train and obtained the contact force with catenary by aerodynamic lift force by the aerodynamic analysis. We also performed the numerical analysis for design the device controlling lift force on a pantograph. From the aerodynamic simulation and parameter study for a device to control the lift force, we will suggest the various shape and the optimal shape of it corresponding to a developing tilting pantograph. The Fluent software is used for the calculation of flow profile in this study.

• Journal of computational fluids engineering
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• v.17 no.1
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• pp.86-93
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• 2012

A numerical investigation is conducted to search for the optimal flow rate for a rotating-disk chemical vapor decomposition reactor operating at a high temperature and a low pressure. The flow of a gas mixture supplied into the reactor is modeled by a laminar flow of an ideal gas obeying the kinetic theory. The axisymmetric two-dimensional flow in the reactor is simulated by employing a CFD package FLUENT. With operating pressure and temperature fixed, numerical computations are performed by varying rotation rate and flow rate. Examination of the structures of flow and thermal fields leads to a flow regime diagram illustrating that there are a stable plug-like flow regime and a few unfavorable flow regimes induced by mass unbalance or buoyancy. The criterion for sustaining a plug-like flow regime is discussed based on a theoretical scaling argument. Interpretation of the flow regime map suggests that a favorable flow is attainable with a minimum flow rate at the smallest rotation rate guaranteeing the dominance of rotation effects over buoyancy.