• 공업화학
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• 제21권3호
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• pp.258-264
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• 2010

대형 선박과 발전소 및 화학 공장 등을 구성하는 배관 및 계통은 다양한 구성요소들로 이루어져 있다. 밴드, 티, 급격 확대, 급격축소, 오리피스와 같은 이러한 구성요소들은 시스템 전체의 압력강하를 유발한다. 집중변수모델을 사용하여 구성요소들에 의한 압력손실은 계산할 시에는 압력손실계수인 k-factor가 제공되어야 한다. 일반적으로 많은 공학 분야에서 k-factor의 계산에 Idelchik 모델이 사용되어 왔다. 본 연구에서는 전산유체역학 해석을 통하여 압력손실계수를 계산하고 그 결과를 Idelchik이 제안한 압력손실계수와 비교하였다. 이는 복잡한 유동영역의 압력손실계수 계산에 전산유체역학 코드의 활용성을 검증하기 위함이다. 해석결과, 레이놀즈 응력 모델이 압력손실계수를 가장 잘 예측하고 있다. 전산유체역학을 통한 압력손실계수 평가는 사용된 난류모델에 영향을 받지만 압력손실계수를 잘 예측하고 있으므로 압력손실 계산에 전산유체역학 코드를 사용하는 것은 타당하다고 판단된다.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.142-149
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• 2000

The results of stand and field testing of a combustion chamber for a heavy-duty 150 MW gas turbine are discussed. The model represented one of 14 identical segments of a tubular multican combustor constructed in the scale 1:1. The model experiments were executed at a pressure smaller than in the real gas turbine. The combustion efficiency, pressure loss factor, pattern factor, liner wall temperature, flame radiation, fluctuating pressure, and NOx emission were measured at partial and full load for both model and on-site testing. The comparison of these items of information, received on similar modes in the stand and field tests, has allowed the development of a method of calculation and the improvement of gas turbine combustors.

• Journal of Mechanical Science and Technology
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• 제15권9호
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• pp.1319-1327
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• 2001

The results of stand and field testing of a combustion chamber for a heavy-duty 150 MW gas turbine are discussed. The model represented one of 14 identical segments of a tubular multican combustor constructed 1:1 scale. The model experiments were executed at a lower pressure than that in a real gas turbine. Combustion efficiency, pressure loss factor, pattern factor, liner wall temperature, flame radiation, fluctuating pressure and NOx emission were measured at partial and full loads for both model and on-site testing. The comparison of these items in the stand and field test results led to has the development of a method of calculation and the improvement of gas turbine combustors.

• 상하수도학회지
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• 제34권3호
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• pp.221-230
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• 2020

In actual seawater desalination plant, the pressure loss due to frictional force of pipe is about 3~5 bar. Also, the pressure loss at pipe connection about 1~3 bar. Therefore, the total pressure loss in the pipe is expected to be about 4~8 bar, which translates into 0.111 to 0.222 kWh/㎥ of energy when converted into the Specific Energy Consumption(SEC). Reducing energy consumption is the most important factor in ensuring the economics of seawater desalination processes, but pressure loss in piping is often not considered in plant design. It is difficult to prevent pressure loss due to friction inside the pipe, but pressure loss at the pipe connection can be reduced by proper pipe design. In this study, seawater desalination plant piping analysis was performed using a commercial network program. The pressure loss and SEC for each case were calculated and compared by seawater desalination plant size.

• 상하수도학회지
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• 제23권1호
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• pp.107-112
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• 2009

This study was conducted for verification and systematization of estimation method about the headloss using CFD(Computational Fluid Dynamics). Head loss which happens between the inlet and outlet of in-line mixer can be a major factor for the design and construction. Also, this Case studies about the sensitivity related to the velocity in the piping system. As result, program's default calculation function was used to get each side's total pressure and the differential of each total pressure could be defined as head loss from in-line mixer. In the case of adopting pipe surface friction factor and geometry loss, Calculation residual can be much more reduced. It was found that residual of value between CFD method and field test ranged about 3 through 18 precent.

• 한국항공운항학회지
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• 제26권2호
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• pp.83-90
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• 2018

This paper describes a case study on the design factor analysis of vertical wind tunnel for skydiver's training or experiencing of paradropping exercise in the air. The case study of vertical wind tunnel design is to provide the knowledges on effects of parameter's variation when it is applied to overall or partial duct of tunnel circuit. The analysis of design parameters based on pressure loss are produced one by one through the tunnel components from the flight chamber because the wind tunnel must satisfy the requirement of flight chamber such as flow speed, quality and quantity. Results shows the various effects of parameter variation with pressure loss in the wind tunnel circuit. Pressure loss should be based on the determination of fan and power system which can be selected from market or new design.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1266-1274
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• 2006

A numerical study is performed to investigate the effect of inner surface roughness and micro-particles on adiabatic single phase frictional pressure drop in a perfect square micro channel. With the variation of particles sizes (0.1 to $1{\mu}m$) and occupied volume ratio (0.01 to 10%) by particles, the Eulerian multi-phase model is applied to a $100{\mu}m$ hydraulic diameter perfect square micro channel in laminar flow region. Frictional pressure loss is affected significantly by particle size than occupied volume ratio by particles. The particle properties like density and coefficient of restitution are investigated with various particle materials and the density of particle is found as an influential factor. Roughness effect on pressure drop in the micro channel is investigated with the consideration of roughness height, pitch, and distribution. Additionally, the combination effect by particles and surface roughness are simulated. The pressure loss in microchannel with 2.5% relative roughness surface can be increased more than 20% by the addition of $0.5{\mu}m$ diameter particles.

• 한국가시화정보학회지
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• 제4권2호
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• pp.76-80
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• 2006

The data for friction factor of the pipe correlated by Reynolds number and relative roughness have been reported well as a Moody chart. However, the results for corrugated shapes have been not investigated sufficiently. In this research, therefore, the pressure drop and friction factor are obtained. Flexible metal tubes with corrugations for the measurement are made of stainless steel plates. The kinds of tubes for the measurement are 5 annular types and helical types. The pressure drop & the velocity of the flow are obtained by micromanometer & digital pressure sensor, supplying dry air at several steps. Then the pressure drop is calculated for each tube, using the obtained data. The result shows that the pressure drop is strongly influenced by the viscous dissipation of kinetic energy due to the circulation of flows, rather than a viscous friction loss. The pressure drop increased consistently as the Reynolds number increases.

• 한국화재소방학회논문지
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• 제33권2호
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• pp.63-67
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• 2019

본 연구에서는 호스릴옥내소화전의 압력손실 실험을 실시한 후 각 요소의 압력 손실에 미치는 영향을 비교 분석하였다. 첫째, 호스릴옥내소화전의 호스릴 길이에 따른 압력손실 실험에서, 호스릴의 길이가 길어짐에 따라 압력 손실이 증가하였으며, 이는 25 m 호스를 기준으로 일반 옥내소화전 호스에 비하여 38.86% 만큼 압력손실이 증가하는 것을 알 수 있었다. 둘째, 단위 길이 당 호스릴의 압력손실은 $.13{\sim}.15kgf/cm^2$으로 측정되었다. 셋째, 유량의 변화에 따른 압력손실 실험에서는 일반 배관 유동에서의 유량-압력손실 관계(${\Delta}P{\sim}Q^2$)와 유사한 결과를 얻을 수 있었다. 이 연구 결과는 호스릴옥내소화전이 사용되는 건축물에 펌프의 양정계산, 호스릴옥내소화전의 성능위주소방설계에 기초자료로 활용될 수 있을 것이다.

• Design & Manufacturing
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• 제13권2호
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• pp.37-43
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• 2019

This study conducted a research as to condensation heat transfer friction loss headby using three types of flat micro multi-channel tubes with different processing of micro-fin and number of channels inside the pipes and different sizes of appearances. In addition, identical studies were conducted by using smoothing circular tubes with 5mm external diameter to study heat enhancement factor and pressure drop penalty factor. 1) The friction head loss showed an increase as the vapor quality and mass flux increased. In case of saturation temperature, it shows an increase as it gets lower. These factors are the reason occurring as the lower the saturation temperature is, the higher the density of refrigerant vapor gets. The influence of heat flux is similar as the dryness is low, but as it gets higher, it lowers in heat flux, and as the high temperature of high heat flux, it is a factor that occurs as the density gets lower. 2) RMS error of the in case of friction head loss, it showed to be predicted as 0.45~0.67 by Chisholm, Friedel, Lockhart and Martinelli. 3) As forfriction head loss penalty factor, the smaller the aspect ratio is, the larger the penalty factor gets, and as for the effect of micro-fin, the penalty factor increased because it decreases to the gas fluid the way groove for the refrigerant's flow.