• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.10
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• pp.2589-2595
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• 2009

An electromagnetic pump has been designed using Load Distribution Method and Equivalent Circuit Method, and installed in a liquid metal flow system. The relation between the driving power of he electromagnetic pump and the flow rate was proposed. Also, the flow velocity and flow rate has been calculated by treating the Lorentz force as a source term in the Navier-Stokes equation. The calculation results were analyzed and compared with data from a commercial Code, FLUENT. They agreed well with each other within an error of 5%.

• Journal of the Korean Society of Propulsion Engineers
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• v.14 no.2
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• pp.1-9
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• 2010

LES(Large eddy simulation) of breakup and droplet atomization of a liquid jet into cross turbulent flow was performed. Two phase flow of gas and liquid phases were modeled by the mixed numerical scheme of both Eulerian and Lagrangian methods for gas and liquid droplet respectively. The breakup process of a liquid column and droplets was observed by implementing the blob-KH wave breakup model. The penetration depth into cross flow was comparable with experimental data for several variants of the liquid-gas momentum flux ratio by varying liquid injection velocity. SMD(Sauter Mean Diameter) distribution downstream of jet was analyzed.

• Journal of the Korean Society of Propulsion Engineers
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• v.20 no.2
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• pp.39-45
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• 2016

In a coaxial porous injector, a gas propellant is injected through the porous cylinder surface to the liquid jet which is encircled by a porous cylinder. In this study, to observe the differences in disintegration mechanisms between a shear coaxial injector and a coaxial porous injector, cold-flow tests and 2-D axisymmetric numerical analysis have been carried out. The shadowgraph images and Sauter mean diameters were compared in similar experimental conditions, and the effects of velocity distributions at the inner injector region on the disintegration of liquid jet were investigated through the numerical calculations. As a result, in high air mass flow rate condition, the disintegration performance of coaxial porous injector is better than shear coaxial injector, in spite of a lower velocity at the inner injector region.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.05a
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• pp.141-144
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• 2009

An injector plays an important role in the process of an efficient combustion in liquid-rocket engines (LRE). This paper is focused on the injection performance of a small LRE-injector by employing the spray characteristic parameters made up of the velocity, Sauter mean diameter, and turbulence intensity. An experimental investigation is carried out with the aid of a dual-mode phase Doppler anemometry (DPDA) according to the injection pressure variation and along transverse axis, spatially. The Weber number and Reynolds number are used to characterize the atomization and turbulence nature of injector spray.

• Journal of the Korean Society of Marine Environment & Safety
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• v.2 no.1
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• pp.1-10
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• 1996

초음파는 액체 및 고체의 매질 속에서도 그 전달 특성이 우수하여 수중 물체의 감지, 지질 조사 자원탐사뿐만 아니라, 의학 분야에서도 널리 사용되고 있다. 물체유동정보 측정방식에는 연속파를 이용한 도플러식과 펄스 신호를 이용한 도플러는 거리 분해능이 좋으므로 깊이에 따른 속도 정보를 쉽게 얻을 수 있는 장점이 있으나, 수신되는 도플러 신호가 탐촉자의 특성과 매질 속에서의 전파특성 등에 의하여 송신된 신호와 파형이 다르고 복잡한 주파수 특성을 가지므로 연속파에서와 같이 도플러 주파수를 직접 측정하기 곤란하다. 도플러 주파수를 검출하기 위하여 여러 방법이 개발되어 있으나, 측정거리와 측정속도의 제약과 더불어, 실시간(real time) 처리에 의한 분포적 측정이 어려운 실정이다. 본 연구에서는 시간 영역에서 국소 데이터를 이용하여 펄스 신호의 위상을 정의하고 실시간에서 펄스 신호를 위상으로 변환하는 신호 처리법을 제안하였다. 또한 이 신호 처리법을 응용하여 측정 범위의 위상 곡선에서 위상 차를 계산함으로써 평균 가속도와 유동속도정보를 분포적으로 얻을 수 있는 새로운 펄스 도플러 기법을 제안하였으며, 모델 신호를 만들어 제안된 방법의 유용성을 검토하였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.39 no.2
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• pp.119-124
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• 2015

Numerical study on the new design of the liquid mass flow meter in infinitesimal flow rate for semiconductor production is performed. The heater and thermistor are wired on the circular tube about 0.3mm inner diameter with designed gap between them. After the time interval from the single pulse heating the thermistor reaches its peak temperature and this time interval is almost inversely proportional to the liquid mass flow rate. The axial conduction in tube wall and convection through the flow is combined. As a result, the peak temperature moving velocity is much smaller than flow mean velocity and there is no linear relationship between them. In this study, the effects of design parameters such as the tube inner/outer diameter, wired heater width, and the gap between heater and thermistor are investigated and the trends of optimization in these parameters are discussed.

• Transactions of the Korean Society of Automotive Engineers
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• v.4 no.3
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• pp.176-186
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• 1996

The phenomena of drag reduction using small quantities of a liner macromolecules has attracted the attention of many experimental investigations. On the other hand drag reduction in two phase flow can be applied to the transport of crude oil, phase change system such as chemical reactor, pool and boiling flow, and to flow with cavitation which occurs pump impellers. But the research on dragreduction in two phase flow is not sufficient. The purpose of the present work is to evaluate the drag reduction by measuring pressure drop, void fraction, mean liquid velocity and turbulent intensity whether polymer additives a horizontal single and two phase system or not. Flow pattern of air-water two phase flow was classified by electrical conductivity probe signal. Velocities and turbulent intensities of signal were measured simultaneously with a Hot-film anemometer.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.35-44
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• 2004

In this study, one dimensional aerodynamic and structural study of a partial admission turbo pump turbine was performed. A turbine consists of a nozzle, rotor, outlet guide vanes. The aerodynamic characteristics of each component was derived from the governing equation and validated from the CFD calculations. One-dimensional basic design such as velocity triangles was conducted from the mean line analysis and modified from the 2-D and 3-D CFD analysis. The blade profile was determined by the CFD optimization. The thermal stress analysis and structural analysis are needed to be studied in the next design stage.

• The Journal of the Acoustical Society of Korea
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• v.14 no.2
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• pp.5-15
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• 1995

An application of the cross correlation technique by adopting ultrasonic waves for water pipe flow measuring purpose is studied. It is a non-intrusive flow metering method by determining the time of the flight of the flow turbulent noise and its non-obstructing mechanism enables to reduce process energy loss due to the flowmeter obstruction. A digital signal processor for the purpose of the real time Fourier transform was employed for the fast time calculation of the flow velocity. The overall accuracy was found as about $1\%$ for flow velocities from 0.25 m/s up to 16 m/s and for the pipe inside diameters from 50mm to 248mm. The cross correlation technique can be used for the tap water utility including most common liquid flows.

• Journal of the Korean Institute of Gas
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• v.18 no.6
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• pp.1-6
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• 2014

This study is based on a investigation regarding the evaporation rate of a volatile liquid(methanol, tetrahydrofuran, xylene) according to changes of the temperature and wind. The weight of a volatile liquid was standardized to 24 g and the mixture was formed with the same weight ratio. In order to discover about the effect of the wind velocity, small fan was installed at 10 cm above the entrance and 30 cm away in the direction of the cylinder. The effect of the wind velocity was tested at 0 m/s, 1.63 m/s, 2.03 m/s respectively and the effect of the temperature on the volatile liquid was experimented at the temperature of $21^{\circ}C$, $32^{\circ}C$, $52^{\circ}C$ in the constant temperature water base. As a result, in case of Xylene, the evaporation rate of the tetrahydrofuran and methanol showed 1.4 mg/min, 19.8 mg/min and 10.2 mg/min respectively. Also, the effect of the evaporation rate on the temperature of the volatile liquid and on the velocity of wind was shown to be very sensitive. At the same time, the evaporation rate of the mixture showed large difference compared to that of the single volatile liquid.