• 대한기계학회논문집B
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• 제32권2호
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• pp.107-116
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• 2008

The jet pumps are widely used to transfer the fuel between the tanks in an aircraft fuel supply system. However detailed design procedures for determining the size of components of the jet pumps are not known so well. In this paper, the flow characteristics of the jet pump, which is applied in the fuel transfer system for the smart UAV (Unmanned Aerial Vehicle), were experimentally investigated using the acrylic jet pump model for the visualization of the internal flow. The pressure distributions within the jet pump were measured, and then the loss coefficients of each part were calculated. The effects of Reynolds number and the distances (S) between the exit of the primary nozzle and the mixing chamber entrance were investigated. In addition, cavitation phenomena were considered through the flow visualization inside the jet pump. As a conclusion from the experiment, the contraction shape of the primary nozzle has a strong effect on the loss coefficient of the nozzle and the cavitation occurrence. Cavitation starts around the nozzle exit, and then it propagates to the full flow fields of the jet pump.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 춘계학술대회 논문집
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• pp.581-587
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• 2014

Intake silencers of high performance and with less pressure drop are developed for a household oxygen generator. First, the acoustic power of the target oxygen generator are experimentally evaluated according to ISO code. Then, the transmission loss of and the flow characteristics inside the existing intake silencer are predicted and analyzed. On a basis of these results, two intake silencers are proposed, which are designed to induce the swirling flow inside the intake silencer and thus to reduce the flow loss. The predicted TL and the pressure drop for these two new silencers are compared to the existing one, which shows that the proposed ones have higher TLs as well as less pressure drop. The reason for these improvements are explained by investigating the flow characteristics of the new silencers in detail.

• 한국추진공학회지
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• 제1권2호
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• pp.41-47
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• 1997

본 연구에서는 이중 orifice를 지나는 압축성 유동을 해석하기 위하여 압축성 유체에 대한 이론계산을 수행하였다. 이중 orifice의 단면적비, orifice 상류의 마하수 및 orifice 사이의 전압손실을 변화시켜, orifice로 인하여 발생하는 축류부에서 유동이 초우크하게 되는 조건을 구하였다. 본 연구의 결과로부터 유동의 초우크 현상은 orifice 단면적비뿐만 아니라 전압손실에도 의존함을 알 수 있다.

• 한국소음진동공학회논문집
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• 제22권10호
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• pp.994-1002
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• 2012

Acoustic power transmission loss(TL) is an important performance of the muffler system. TL will be affected by the velocity of the fluid in duct since acoustic pressure varies according to the fluid velocity. In this paper, two kinds of fluid model, potential flow and turbulent flow, for the fluid flowing in simple expansion chamber are considered. The effects of their two fluid models in acoustic TL are investigated for the straight and L-shaped simple expansion chamber. In higher frequency range, the characteristics of TL of the two fluid models show different results. The variation of TL according to the fluid velocity is shown more distinctly when turbulence model is used. Turbulent flow model should be used to obtain better estimation of acoustic TL in higher frequency range.

• 한국소음진동공학회논문집
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• 제24권11호
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• pp.846-853
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• 2014

High performance intake silencer with low pressure drop are developed for a household oxygen generator. First, the acoustic power of the target oxygen generator are experimentally evaluated according to ISO code. Then, the transmission loss of and the flow characteristics inside the existing intake silencer are predicted and analyzed. On a basis of these results, two intake silencers are proposed, which are designed to induce the swirling flow inside the intake silencer and thus to reduce the flow loss. The predicted TL and the pressure drop for these two new silencers are compared to the existing one, which shows that the proposed ones have higher TL as well as low pressure drop. The reason for these improvements are explained by investigating the flow characteristics of the new silencers in detail.

• Nuclear Engineering and Technology
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• 제53권8호
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• pp.2547-2555
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• 2021

The frequency of reactor coolant leakage is expected to increase over the lifetime of a nuclear power plant owing to degradation mechanisms, such as flow-acceleration corrosion and stress corrosion cracking. When loss of coolant accidents (LOCAs) occur, several parameters change rapidly depending on the size and location of the cracks. In this study, leak flow during LOCAs is predicted using a deep fuzzy neural network (DFNN) model. The DFNN model is based on fuzzy neural network (FNN) modules and has a structure where the FNN modules are sequentially connected. Because the DFNN model is based on the FNN modules, the performance factors are the number of FNN modules and the parameters of the FNN module. These parameters are determined by a least-squares method combined with a genetic algorithm; the number of FNN modules is determined automatically by cross checking a fitness function using the verification dataset output to prevent an overfitting problem. To acquire the data of LOCAs, an optimized power reactor-1000 was simulated using a modular accident analysis program code. The predicted results of the DFNN model are found to be superior to those predicted in previous works. The leak flow prediction results obtained in this study will be useful to check the core integrity in nuclear power plant during LOCAs. This information is also expected to reduce the workload of the operators.

• 한국기계가공학회지
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• 제21권7호
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• pp.64-70
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• 2022

The aim of this study is to improve the purification efficiency of odor gas by increasing the contact area between an odor gas and adsorbent. To analyze the flow in the adsorption tower, the flow characteristics in the hollow activated carbon-adsorption tower are identified by applying the loss model, which is a porous flow analysis model. The flow characteristics are investigated for pressure loss, velocity distribution, turbulent kinetic energy, and residence time distribution. The results show that the hollow adsorption tower performs better than the solid adsorption tower in terms of pressure loss and performance. The inner diameter of the hollow region inside the adsorption tower is 0.64 m (Di/Do = 0.37). Furthermore, the adsorbent performance is unaffected even when adsorbent stages are installed to replace the adsorbent.

• 한국수자원학회논문집
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• 제43권5호
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• pp.445-453
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• 2010

도시 우수 배수 시스템에서 우수 관거는 개수로 흐름 상태로 가정하여 설계되었기 때문에 합류맨홀에서의 에너지 손실은 일반적으로 중요하게 고려되지 않았다. 그러나 과부하흐름에서 에너지 손실은 관거의 배수능력을 저하시켜 도심지역의 침수피해를 가중시키는 요인이 된다. 그러므로 과부하 합류맨홀 내에서의 수두 손실을 분석할 필요가 있다. 본 연구에서는 합류맨홀에 대한 문헌조사 및 현장조사를 실시하여 실험장치를 제작하고 실험조건을 선정하였다. 선정된 실험조건인 맨홀 형상 조건(사각형, 원형), 유출유량($Q_3$)에 대한 측면유입유량($Q_2$)의 비($Q_2/Q_3$) 및 실험 유량(2.0, 3.0, $4.0{\ell}$/sec)을 변화시키면서 실험을 실시하였다. $Q_2/Q_3$가 증가할수록 손실계수가 증가하므로 과부하 합류맨홀에서의 손실계수는 측면 유입관로의 유입유량의 영향을 크게 받는다고 판단된다. 맨홀의 형상변화 및 유량변화에 따른 손실계수는 거의 동일하게 산정되었다. 또한, $Q_2/Q_3$와 손실계수의 관계식을 제시하였다.

• 한국산업융합학회 논문집
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• 제3권3호
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• pp.265-273
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• 2000

Basic simulation program for Vuilleumier cycle heat pump was developed that can use precise VMHP design and analysis. VMHP system was divided 11 sections in simulation. Simulation was used adiabatic model analysis and that considered with heat transfer performance for heat exchanger, regenerator loss, conduction loss, shuttle loss, pumping loss and pressure loss by flow friction. Specially, friction loss of connection pipe between heat compression side and heat pump side, leakage of rod seal and piston seal was considered in the analysis.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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• pp.284-289
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• 2002

The objective of this study is to document the secondary flow and the total pressure loss distribution in the contoured endwall installed linear turbine cascade passage and to propose an appropriate height of the contoured endwall which shows the best loss reduction among the simulated contoured endwall. In this study, three different contoured endwalls have been tested which have different height. This study was performed by numerical method and the result showed the contoured endwall which has the height of $5\%$ of the axial chord showed the best loss reduction rate.