• 대한기계학회논문집B
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• 제32권2호
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• pp.83-91
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• 2008

A three-dimensional computation was conducted to understand effects of the low Reynolds number on the performance in a low-speed axial compressor at the design condition. The low Reynolds number can originates from the change of the air density because it decreases along the altitude in the troposphere. The performance of the axial compressor such as the static pressure rise was diminished by the separation on the suction surface with full span and the boundary layer on the hub, which were caused by the low Reynolds number. The total pressure loss at the low Reynolds number was found to be greater than that at the reference Reynolds number at the region from the hub to 85% span. Total pressure loss was scrutinized through three major loss categories in a subsonic axial compressor such as the profile loss, the tip leakage loss and the endwall loss using Denton#s loss model, and the effects of the low Reynolds number on the performance were analyzed in detail.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2007년도 춘계 학술대회논문집
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• pp.138-141
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• 2007

A three-dimensional computation was conducted to understand effects of the low Reynolds number on the performance in a low-speed axial compressor at the design condition. The low Reynolds number can originates from the change of the air density became it decreases along the altitude in the troposphere. The performance of the axial compressor such as the static pressure rise wag diminished by the separation on the suction surface and the boundary layer on the hub, which were caused by the low Reynolds number. The total pressure loss at the low Reynolds number was found to be greater than that at the reference Reynolds number at the region from the hub to 90% span. Total pressure loss was scrutinized through three major loss categories in a subsonic axial compressor such as profile loss, tip leakage loss and endwall loss using Denton's loss model, and effects of the low Reynolds number on the performance were analyzed in detail.

• 대한기계학회논문집
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• 제17권8호
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• pp.2110-2121
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• 1993

A numerical investigation has been carried out for the flow characteristics after exchange of some filters from the original layer to the new low pressure loss layer with equal filtering efficiency. The solution domain includes upper plenum, filter layer, clean space, access panels, and lower plenum. The concept of the distributed pressure resistance was applied to describe the momentum loss in filter layer and access panels. The evolution of the flow field is simulated using the low Reynolds number k-.epsilon. over bar turbulent model and SIMPLE algorithm based on the finite volume method. As a result, after the exchange of filter layer the power requirement can be reduced by 8-9 percent. The results also demonstrate that the perpendicularity of the flow near access panels may become worse at new filter layer than origianl filter layer. But the situation can be recovered by adjusting the jopening ratio of access panels.

• 한국추진공학회지
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• 제14권1호
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• pp.48-55
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• 2010

본 논문에서는 엔진고공환경 시험설비의 엔진 입구 덕트에서 측정한 전압력과 정압력 및 전온도를 통해 실시간으로 공기유량을 계산하고, 압력프로파일을 이용하여 경계층 레이크를 장착하지 않았을 경우에도 공기유량을 예측할 수 있는 방법을 기술하였다. 또한, 엔진입구배관에 걸친 덕트 연결부를 통한압력손실을 예측하고, 이를 통해 공기유량을 보정함으로써, 고공환경시험설비에서의 공기유량측정의 신뢰도를 향상시키고 설비유지측면에서의 운용성을 보고자 하였다.

• 항공우주기술
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• 제6권2호
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• pp.29-34
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• 2007

본 논문에서는 엔진고공환경 시험설비의 엔진 입구 덕트에서 측정한 전압력과 전온도를를 통해 실시간으로 공기유량을 계산하고, 압력프로파일을 이용하여 경계층 레이크를 장착하지 않았을 경우에도 공기유량을 예측할 수 있는 방법을 기술하였다. 또한, 엔진입구배관에 걸친 덕트 연결부를 통한 압력손실을 예측하고, 이를 통해 공기유량을 보정함으로써, 고공환경시험설비에서의 공기유량측정의 신뢰도를 향상시키고 설비유지측면에서 운용성을 보고자 하였다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2002년도 학술발표회 발표논문집
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• pp.337-340
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• 2002

The purpose of this study is to evaluate the loss volume of base soil materials with the grain size range of filter materials for agricultural reservoir. The test results show that the loss volume is increased with the hydraulic pressure, and the amount of loss volume for same sample is different with the filter range.

• 한국추진공학회지
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• 제20권4호
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• pp.94-103
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• 2016

액체로켓엔진에서의 재생냉각 채널은 높은 온도의 연소가스로부터 연소실 내벽을 효율적으로 냉각하기 위해 사용되며, 냉각채널 설계를 위해서는 열전달 특성과 압력손실 특성을 미리 예측하여야 한다. 본 연구에서는 서로 다른 형상을 갖는 5개의 냉각채널을 설계하고, 커터와 엔드밀로 채널을 제작하였다. 채널을 흐르는 유속과 후단 압력조건을 달리하여 가공방법, 채널 형상, 유동조건에 따른 압력손실을 실험적으로 측정하여 해석결과와 비교를 수행하였다. 동일 형상 및 유동조건에서 커터로 가공된 채널이 엔드밀로 가공된 채널보다 압력손실이 적었다. 또한 채널 형상, 유동조건에 따라 실험결과와 해석결과의 압력손실 비가 달라짐을 확인할 수 있었다.

• Nuclear Engineering and Technology
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• 제28권3호
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• pp.280-289
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• 1996

The pressure drop of twelve fuel bundle string in the CANDU-6 fuel channel is equal to the sum of the eleven junction pressure losses, the bundle string entrance and exit pressure losses, the skin friction pressure loss, and other appendage pressure losses, where the junction loss is dependent on the bundle end faces and angular alignments of the junctions. The results of the single junction pressure drop tests in a short rig show that the most probable pressure drop of the eleven junctions was analytically equal to the eleven times of average pressure drop of all the possible single junction pressure drops, and also that the largest and smallest junction pressure drops across the eleven junctions probably occurred only with BA and BB type junctions, respectively, where A and B denote the bundle end sides with an end-plates on which a company monogram is stamped and unstamped, respectively.

• 한국정밀공학회지
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• 제19권2호
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• pp.220-227
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• 2002

The design of suction muffler for compressor aims to achieve a maximum noise reduction and a minimum pressure loss. Until now, the design process has been performed experimentally rather than theoretically. In this paper, to achieve the maximum noise reduction and minimum pressure loss. we studied the effect of the shape and volume of the expansion tube of the muffler on TL and pressure drop. We made an extensive use of computer program such as SYSNOISE. FLUENT, and STAR-CD to calculate the TL and pressure distribution of suction muffler. The design of the muffler is optimized with respect to flow loss and TL. Experiments are performed to check the result of design change, which proves satisfactory results. It is expected that this process can reduce time to design a muffler in the fields.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.1354-1359
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• 2007

This paper discusses the acoustic performance of simple expansion chamber using computational fluid dynamics(CFD). The CFD model consists of an axisymmetric grid with a single period sinusoid of acceptable amplitude and duration imposed at the inlet boundary condition. The time history of the static pressure is recorded at two points, one in the inlet pipe and one point in outlet pipe. The time history of the static pressure is converted to the frequency domain using Fourier Transform and the transmission loss (TL) of the muffler is obtained from the ratio of the static pressure at the inlet and outlet pipe. The transmission loss of CFD result is compared with that of the computational acoustic analysis using the boundary element method (BEM). There are some differences in two results due to the pressure drop according to the inlet and outlet pipe length. Therefore, the effects of the pressure drop to the transmission loss have to be considered.