• 한국전산유체공학회지
• /
• 제14권3호
• /
• pp.1-8
• /
• 2009

Diverging channel from gas engine exit to the inlet section of Heat Recovery Steam Generator (HRSG) has been re-designed for 1 MW system. To improve the uniformity in velocity and temperature distribution of existing design(Case A and B), two additional test geometries have been chosen for the numerical simulation. At first, gas burner exit section has been centered to the inlet section of the boiler(Case C) and uniformity in velocity and temperature distribution has been improved considerably. Secondly, the diverging channel length can be further reduced to compact geometry with new guide vane design (Case D and E). Proposed design shows overall improvement in uniformity in velocity and temperature distribution compared to existing one.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
• /
• pp.285-288
• /
• 2004

This study presents a numerical procedure to optimize the shape of dimple surface to enhance turbulent heat transfer in rectangular channel. The response surface based optimization method is used as an optimization technique with Reynolds-averaged Wavier-Stokes analysis of fluid flow and heat transfer with shear stress transport (SST) turbulence model. The dimple depth-to -dimple print diameter ratio, channel height- to- dimple print diameter ratio. and dimple print diameter-to-pitch ratio are chosen as design variables. The objective function is defined as a linear combination of heat transfer coefficient and friction drag coefficient with a weighting factor. Full factorial method is used to determine the training points as a mean of design of experiment.

• 한국농공학회:학술대회논문집
• /
• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
• /
• pp.465-472
• /
• 1999

Hydraulic model tests are performed to find economical and hdrqulically stable design of cooling water intake channel of steam power plant. The result of tests show that the standard distributiion of y-components in the chamber of CWP(circulating Water Pump) are recommended below 3.5 to maintain hydraulic stability, so that this value is considered as the design criteria. Common basin is necessary to improve the hydraulic stability of inflow, however the longer basin does not always improve the hydraulic stability , and the optimal length of basin can be found in some range. From the results the flow stability maintained the best condition when the length of basin is 7.2m. Beside the standard tests the auxiliary tests like edge , baffle, trapezoidal section and increase of pump capacity are carried out based on the optimal condition foudn in the standard tests. From the series of tests the economical and hydraulically stable design of intake channel was proposed.

• 유체기계공업학회:학술대회논문집
• /
• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
• /
• pp.89-94
• /
• 2002

n general, the function of intake structure, whether it be a open channel, a fully wetted tunnel, a sump or a tank, is to supply an evenly distributed flow to a pump station. An even distribution of flow, characterized by strong local flow, can result in formation of surface or submerged vortices, and with certain low values of submergence, may introduce air into pump, causing a reduction of capacity and efficiency, an increase in vibration and additional noise. Uneven flow distribution can also increase or decrease the power consumption with a change in total developed head. To avoid these sump problems pump station designers are considered intake structure dimensions, such as approaching upstream, baffle size, sump width, width of pump cell and so on. From this background, flow characteristics of intake within sump are investigated numerically to obtain the optimal sump design data. The sump model is designed in accordance with HI code.

• Journal of Advanced Marine Engineering and Technology
• /
• 제38권10호
• /
• pp.1269-1274
• /
• 2014

Due to the presence of Dean flow in curved ducts, helical channels have drawn attention recently because of the practical industrial applications. The manipulation of fluids through microfluidic devices is widely used in many scientific and industrial areas. In the present study, numerical simulations were performed on a helical microchannel to predict the impact of different design parameters that affect Dean flow. Important geometric parameters such as the channel cross section, pitch, radius of curvature, and number of turns were considered for the analysis. The study also incorporates the effect of varying flow rate on Dean flows. It was found from the simulation results that microchannel cross section and pitch have a significant impact on maintaining the Dean flow, compared to the radius of curvature, number of turns, and flow rate.

• 한국해안·해양공학회논문집
• /
• 제21권5호
• /
• pp.391-404
• /
• 2009

삼천포 화력발전소에서 냉각수로 이용되고 방류되는 해수를 이용한 소수력 발전소를 건설하였다. 본 연구에서는 해양소수력 발전소 건설시 가장 중요한 문제인 기존 화력발전소의 순환수 계통에 미치는 영향을 평가하기 위한 방안으로 배수로 수위의 해양소수력 건설 이전, 건설 중, 건설 이후 해양소수력 운전 상태에서의 변화를 예측한 값과 실제 계측값을 분석하였다. 설계시 일반적으로 이용되는 개수로 수리식에서부터 Flow 3D를 이용하여 3차원적인 수리해석 기법을 이용하는 것까지 다양한 예측을 시도하였고 관측을 통하여 검증하고자 하였다. 예측치와 실제 관측치의 비교 결과, 수위의 전체적인 평균값은 예측치와 관측치가 유사하였지만 수위의 변화 폭은 건설 중과 해양소수력 운전 상태에서 매우 크게 나타났다. 또한, 소수력 건설 이전에는 표준위어식과 Honma식의 예측값이 관측값과 가장 유사하였으나, 소수력 건설 이후에는 HEC-2, HEC-RAS, Flow-3D의 예측값이 실측값과 가까운 결과를 보였다.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 1995년도 추계 학술대회논문집
• /
• pp.12-28
• /
• 1995

CFD techniques are widely used for the design and development of turbomachinery. The design and performance prediction, evaluation of performace and analysis are all important for the successful development of the machinery. The characteristics of the sturcture and performace of the centrifugal compressor are reviewed for the effective application of CFD techniques. The examples of flow calculations through an impeller and a channel diffuser are presented and phenomenological aspects are discussed. The future research topics of CFD area are also suggested.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2005년도 춘계학술대회 논문집
• /
• pp.35-40
• /
• 2005

선박의 조종운동은 선체와 프로펠러 그리고 타의 연성 운동의 결과로서 선박 조종성능을 향상시키기 위해서는 각 요소의 적절한 평가 및 보완이 필요하다. 본 연구에서는 조종성능 향상 기법의 일례로 특수타의 일종인 플랩타 주위의 유동특성을 유동가시화 시험기법과 PIV 해석을 이용하여 알아본다.

• Nuclear Engineering and Technology
• /
• 제39권4호
• /
• pp.349-358
• /
• 2007

A single-beam gamma densitometer is utilized to measure the average void fraction in a small diameter stainless steel pipe under critical flow conditions. A typical design of a single-beam gamma densitometer is composed of a sealed gammaray source, a collimator, a scintillation detector, and a data acquisition system that includes an amplifier and a single channel analyzer. It is operated in the count mode and can be calibrated with a test pipe and various types of phantoms made of polyethylene. A good average void fraction is obtained for a small diameter pipe with various flow regimes of the core, annular, stratified, and bubbly flows. Several factors influencing the performance of the gamma densitometer are examined, including the distance between the source and the detector, the measuring time, and the ambient temperature. The void fraction is measured during an adiabatic downward two-phase critical flow in a vertical pipe. The test pipe has an inner diameter of 10.9 mm and a thickness of 3.2 mm. The average void fraction was reasonably measured for a two-phase critical flow in the presence of nitrogen gas.

• 한국전산유체공학회지
• /
• 제17권2호
• /
• pp.107-112
• /
• 2012

We explored the dynamic motions and the lateral equilibrium positions of an elastic capsule in channel flow at moderate Reynolds number varying Re, aspect ratio, size ratio, membrane stretching and bending coefficient. The transition of tank-treading/swinging to tumbling motion was observed in the simulations and the transition of dynamic motions for capsules resulted in different trend of the variation in the lateral equilibrium positions. Though other conditions were similar, the capsule with tumbling motion migrated closer to the wall than that with tank-treading motion.