• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 춘계 학술대회논문집
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• pp.228-233
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• 2005

Two-dimensional Stokes flows through a micro channel with a couple of symmetric vertical fins are investigated. At far up- and down-stream from the fins, the plane Poiseuille flow exists in the channel. The slip boundary conditions are applied to take account of the Knudsen number effects. For the analysis, the method of eigen function expansion and collocation method are employed. By the results, the streamline patterns and pressure distributions are shown and the force exerted on the fin and the excess pressure drop due to the fins are determined as functions of the length of the fin and Knudsen number. It may be conjectured that the force and the excess pressure drop are almost independent of the Knudsen number.

• 한국군사과학기술학회지
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• 제8권4호
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• pp.152-158
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• 2005

In this paper, we have proposed a fuel metering unit of ai breathing engine. The proposed valve system consists of a constant pressure drop valve and a metering valve, which are controlled by servovalve. We carried out nonlinear and linear analysis, computer simulation and experimentation to find effects of some factors on system performance. Analysis and experimental results show a good agreement. It is also shown that the system stability is affected by pressure drop of metering valve and inlet pressure of injectors.

• 융복합기술연구소 논문집
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• 제4권2호
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• pp.61-65
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• 2014

Pressure distribution around rotating impeller blades in centrifugal pump has been main issue for design of efficient and high performance automotive water pump. In addition, pressure losses of inlet water pipes should be considered to reduce additional pressure drop and design high performance engine cooling system. In this paper, pressure distribution inside water pump and pressure drop between inlet and outlet of water pump are investigated numerically to design plastic water pump for clean diesel engine application. And the inlet geometry of water pump was considered to analysis the effect of inlet water pipe geometry on pressure distribution around impeller blades and outlet pressure. The prediction results are compared with experimental data to validate and determine optimal operation condition without water pump cavitation. Major design parameters such as blade angle, volute geometry, system pressure, and coolant flow rate are considered to confirm applying possibility of plastic blades to the clean diesel engine.

• 대한기계학회논문집B
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• 제20권7호
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• pp.2277-2288
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• 1996

This study was performed to analyze the cooling effect of heated ribs which are frequently used for cooling of electronic parts, using the numerical method. To prevent the excessive pressure drop due to turbulence promoters for the enhancement of heat transfer rate especially, the effect of the angle of turbulence promoter was investigated by the numerical analysis. Heat transfer rate with turbulence promoters with rectangular cross-section increased by 13% in average, but the coefficient of pressure drop increased by 1.68 times than that without them. In the present study, triangular cross-sectional shape turbulence promoters were suggested and numerically tested. Pressure drop of turbulence promoter with the 30 degree triangular cross-sectional shape decreased by 30% from that of rectangular cross-section promoters while heat transfer rate was almost the same. While with 4 turbulence promoters, the heat transfer rate increased by 21%, the pressure drop increased 4 times. It means that the higher capacity of cooling fan should be needed. With the triangular cross-sectional shape, the size of vortex region at the rear of promoters became considerably smaller, so pressure drop became smaller. The effect of the change of cross-sectional shape was not found in the flow pattern near the ribs, so that heat transfer characteristics in the ribs were not changed.

• 청정기술
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• 제24권4호
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• pp.301-306
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• 2018

최근 미세먼지의 증가로 인해 디젤 자동차로부터 발생되는 PM에 대한 규제가 강화되고 있다. 디젤 자동차의 배기가스를 제거하는 후처리 장치인 매연여과장치(diesel particulate filter, DPF)에 대한 관심이 급증하고 있다. 따라서 DPF 효율 향상의 하나로 DPF 내의 압력강하를 줄여서 필터 및 재생(Regeneration)의 효율을 증가시키고 있다. 본 연구에서는 ANSYS FLUENT를 이용하여 5.66" SiC와 Cordierite DPF의 셀 밀도, 채널 형상, 벽두께, 입 출구 채널 비에 따른 압력강하 영향을 시뮬레이션했다. 실험결과로서 200 CPSI보다 300 CPSI에서 압력강하가 작게 나타났으며, Anisotropy과 O/S 셀이 Isotropy보다 약 1,301 Pa 작은 압력강하를 나타냈다. 공극률은 10% 증가할 때 마다 압력강하가 약 300 Pa씩 작아졌고, 벽 두께에 따른 영향은 0.05 mm 두꺼워질수록 약 500 Pa 씩 커지는 경향을 나타냈다.

• 설비공학논문집
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• 제14권2호
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• pp.116-126
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• 2002

A three dimensional numerical analysis of the corrugated louver fin for a vehicle heat exchanger was performed. The heat transfer rate and the air pressure drop of the corrugated louver fins for a slim heater were compared with experimental results at the same operating conditions. As for the slim heater fin, we found an optimum fin pitch at certain operating conditions. As the fin pitch increased, the air pressure drop decreased. The vertical or flat top fin was superior to the common declined fin in the aspect of heat transfer performance. As the louver length increased, both the heat transfer rate and the air pressure drop increased.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회B
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• pp.2747-2752
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• 2007

A numerical study has been performed on the flow past a two-staged orifice in a rectangular duct. The flow field including the recirculation region behind the orifice was investigated and the pressure drop was calculated. Water was used as a working fluid and the flow was treated as the turbulent flow, of which the Raynolds number was 6000. The main parameters for the pressure drop and the recirculation region were the orifice's inclined angle against the duct, the interval between two orifices, the shape of the orifice's hole having the same area, and the change of the hole position at the same interval. The variation of the flow field was investigated with each parameter. Consequently, it was found that the most dominant parameter influencing the drop of the pressure was the change of the hole position at the same interval between orifices. Especially when the interval between orifices was narrow and the relative position the holes was changed, its effect to the flow field was shown most drastically as a result of this study. The SIMPLER algorithm with FLUENT code was employed to analyze the flow field.

• 대한기계학회논문집B
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• 제23권5호
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• pp.678-686
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• 1999

The purpose of this work is to Investigate the pressure drop and the heat transfer characteristics in the channel of plate heat exchanger with crossed-discrete ribs. The flow is assumed to be three-dimensional, laminar and periodically fully developed. Computations have been carried out for angles of attack from $0^{\circ}$ to $90^{\circ}$ and ratios of rib height from 0.15 to 0.46 for various values of Reynolds and Prandtl numbers. The heat transfer was improved by inclined ribs generating helical vortices and secondary flows. The results show that the pressure drop has a maximum value at $70^{\circ}$ and the heat transfer has a maximum value at $45^{\circ}$. As the rib height increases, the pressure drop and the heat transfer increase quadratically, and the increasing rate of pressure drop is higher than that of the heat transfer. As Reynolds number increases, the pressure drop increases in proportion to the square of Reynolds number and the heat transfer increases linearly.

• Journal of Advanced Marine Engineering and Technology
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• 제38권4호
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• pp.376-382
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• 2014

본 연구의 목적은 물에 대한 판형열교환기의 설계프로그램 개발을 위해 응축열전달계수 및 압력강하에 관한 상관식을 확보하는 것이다. 저온측의 단상유동에 관해서는 Ko의 상관식을 사용하였으며 고온측의 응축이 발생하는 이상유동에 대해서는 Annaiev의 상관식과 Lockhart 모델을 적용하여 알고리즘을 제시하였다. 판형열교환기의 운전가능한 범위내에서 상관식의 오차는 상용코드와 비교시 20%이내를 나타냈다.

• 한국추진공학회지
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• 제15권6호
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• pp.47-55
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• 2011

본 논문에서는 매니폴드 내의 튜브 라운드 적용에 따른 고온 고압 튜브형 열교환기에서의 압력강하와 열성능을 분석하기위해 전산해석을 수행하였다. 튜브형 열교환기에서의 압력강하와 열성능은 튜브라운드의 위치에 많은 영향을 받는다. 튜브 라운드에 따른 연구는 튜브 입구, 튜브 출구, 그리고 튜브 양쪽 세 가지 위치에 따라 수행하였다. 본 연구에서, 튜브 양쪽에 라운드를 적용한 경우에는 가장 낮은 압력강하와 감소된 열전달을 보였지만 튜브 출구에 라운드를 적용한 경우에는 압력강하와 열전달 모두 기본형상에 비하여 좋은 특성을 보였다.