• 제목/요약/키워드: Pressure loss coefficient K

검색결과 126건 처리시간 0.02초

The Evaluation of 16x16 JDFA Pressure Loss Coefficients Using the Fuel Assembly Compatibility Test System

  • Lim, Hyun-Tae;Jun, Byung-Soon;Kim, Hong-Ju;Jeon, Kyeong-Lak
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1996년도 춘계학술발표회논문집(2)
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    • pp.254-259
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    • 1996
  • The hydraulic tests for 16$\times$16 JDFA were performed to obtain the pressure loss coefficients using the FACTS. The pressure loss coefficients are calculated by converting the each properties of experimental values for inlet region, mixing vane grid, outlet region and core region by performing a power fit of the pressure loss coefficient values to the corresponding Reynolds number. The test results are compared with the existing calculated values and evaluated by using the CALOPR code in terms of pressure drop. It is turned out that the differences between the test results and the calculated values are about by 3.8% for the pressure loss coefficients and by 8.5% for the pressure drop.

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수두손실률에 의한 방조제 침투류 감시기법 개발 (Development of the Seepage flow Monitoring Method by the Hydraulic Head Loss Rate on Sea Dike)

  • 임성훈;윤창진;김성필;허준;강병윤
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2010년도 추계 학술발표회
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    • pp.60-68
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    • 2010
  • In this study, the seepage flow monitoring method by hydaulic head loss rate graph was developed for the purpose of monitoring the seepage flow from the see side or from the lake on sea dike in which seepage force was varied periodically. The hydraulic head loss rate was defined in this method. The value of the rate is in the range from 0 to 1. the value of 0 means perfectly free flow of seepage. the value of 1 means perfect waterproofing. The value of coefficient of determination in the hydraulic head loss rate graph closer to 1 means that the seepage flow way is stable. The value of coefficient of determination in the hydraulic head loss rate graph closer to 0 means that the hole may exist or the piping may be in the progress. The pore water pressure data measured in Saemangeum sea dike was analyzed with the developed method The result showed that the variation of seepage flow state was detected sensitively by this method and the interception effect of sea dike could be estimated quantitatively.

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압력면익단소익이 터빈 동익 압력면스퀼러팁 하류의 팁누설유동 및 압력손실에 미치는 영향 (Effects of Pressure-Side Winglet at an Elevation of Tip Surface on the Tip-Leakage Flow and Aerodynamic Loss Downstream of a Turbine Blade Equipped with Pressure-Side Squealer Tip)

  • 천주홍;이상우
    • 대한기계학회논문집B
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    • 제40권10호
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    • pp.645-651
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    • 2016
  • 본 연구에서는 압력면익단소익의 폭이 터빈 동익 압력면스퀼러팁 하류의 팁누설유동 및 압력손실에 미치는 영향에 대하여 연구하였다. 팁간극비 h/s = 1.36%에 대하여, 흡입면스퀼러의 높이는 $h_p/s=3.75%$로 일정하게 유지하고, 압력면익단소익의 폭은 w/p = 2.64%, 5.28%, 7.92%, 10.55% 등으로 변화시키면서 실험을 수행하였다. 일반적으로 압력면익단소익의 폭이 증가할수록, 통로와류 영역에서의 압력손실은 감소하였지만 팁누설유동 영역에서는 압력손실이 오히려 증가하였다. 그 결과 익단소익의 폭이 증가할수록, 질량평균 압력손실은 매우 소폭 감소하는 경향을 보였다. 본 연구 결과, 압력면스퀼러팁에 설치된 압력면익단소익은 압력손실 저감에 거의 기여를 하지 못함을 확인할 수 있었다.

An Experimental Investigation of Side-Orifice Effects on Pressure Drop for Single-Phase Flow

  • Seo, Kyong-Won;Chun, Moon-Hyun;Nam, Ho-Yun;Park, Seok-Ki;Lee, Yong-Bum
    • 한국원자력학회:학술대회논문집
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    • 한국원자력학회 1996년도 추계학술발표회논문집(1)
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    • pp.295-300
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    • 1996
  • To investigate the effects of the side-orifice on the pressure drop for single-phase flow, a series of experiments have been carried out with 16 different downstream test sections with various combinations of side-orifice shapes, different numbers of side-orifices, and different arrangements of the side-orifice using water as a working fluid. From the measurements of the pressure drop and the flow rate, the pressure loss coefficient of the side-orifice(s) has been evaluated. Based on the total number of 529 present data, an empirical correlation for the pressure loss coefficient has been developed in terms of Reynolds number and geometric parameters, such as area ratio, equivalent diameter, leading edge, and average width of side-orifice.

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파일 방파제의 소파성능 해석 (Analysis on Wave Absorbing Performance of a Pile Breakwater)

  • 조일형;고혁준
    • 한국해양공학회지
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    • 제21권4호
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    • pp.1-7
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    • 2007
  • Based on the eigenfunction expansion method, the wave-absorbing performance of a square or circular pile breakwater was investigated. Flow separation resulting from sudden contraction and expansion is generated and is the main cause of significant energy loss. Therefore, evaluation of an exact energy loss coefficient is critical to enhancing the reliability of the mathematical model. To obtain the energy loss coefficient, 2-dimensional turbulent flow is analyzed using the FLUENT commercial code, and the energy loss coefficient can be obtained from the pressure difference between upstream and downstream. It was found that energy loss coefficient of circular pile is 20% that of a square pile. To validate the fitting equation for the energy loss coefficient, comparison between the analytical results and the experimental results (Kakuno and Liu, 1993) was made for square and circular piles with good agreement. The array of square piles also provides better wave-absorbing efficiency than the circular piles, and the optimal porosity value is near P=0.1.

이중구조팬의 Conic Winglet 최적설계 (Optimal Design for a Conic Winglet of a Dual Type Combined Fan)

  • 김진욱;김우택;류민형;조이상;조진수
    • 한국항공우주학회지
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    • 제44권6호
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    • pp.468-476
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    • 2016
  • 본 연구에서는 이중구조를 갖는 팬의 날개 끝에서 발생하는 손실을 저감시키기 위하여 바깥 날개 끝 익형단면을 세 축으로 회전시키는 Conic winglet을 적용하였다. 손실을 계산하기 위하여 CFD 전산해석을 수행하였으며, 최소의 손실을 얻기 위하여 최적화를 수행하였다. 최적화 결과 Conic winglet은 바깥 날개 끝의 후단 부근에서 압력면 쪽으로 휘어진 형상을 보였으며 이 형상은 날개 끝에서 발생하는 전압력 손실을 3.24 % 저감시켰다.

극저온 선형 팽창기용 리드밸브의 기하학적 형상변화에 따른 유동 특성 연구 (A Study on the Flow Characteristics of Reed Valve with Variable Geometric Variations for Cryogenic Linear Expander)

  • 정은아;김지우;염한길;윤소남
    • 드라이브 ㆍ 컨트롤
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    • 제12권4호
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    • pp.48-53
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    • 2015
  • This paper deals with the flow characteristics of a reed valve analyzed using computational dynamics(CFD) for optimal design. The seat sizes of the valve are modeled asØ6[mm] and Ø8[mm] to compare the flow characteristics. The inlet boundary condition is entered at 10[kPa], 15[kPa], 20[kPa], and 30[kPa] and the outlet boundary condition is set to the atmospheric pressure. The flow coefficient(C) and pressure loss coefficient(K) are calculated from the results of flow analysis. From the analysis results, it was confirmed that the flow coefficient of a reed valve having a seat size of Ø6[mm] is greater than that having a seat size of Ø8[mm], and the coefficient of pressure loss of a valve with a seat size of Ø6[mm] is lower than the Ø8[mm] size valve.

SI 엔진의 스로틀 밸브에서 유동장 특성에 대한 실험해석 (An Experimental Study on a Flowfield Characteristics in a Throttle Valve of SI Engine)

  • 김성초;김철;최종근;이석정
    • 대한기계학회논문집B
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    • 제25권7호
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    • pp.967-974
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    • 2001
  • Experimental investigations on the flow characteristics of downstream region of a butterfly valve, which is used in SI engine, have been conducted according to Reynolds number and valve angle. Measurement programs of the flowfield using x-type of hotwire anemometry include the mean and fluctuating velocity, turbulnet intensity, shear stress, power spectrum and pressure loss coefficient. Experimental results show that flow characteristics and independent of relatively high Reynolds number; 60,000 and 80,000. It is also seen that streamwise mean velocities have relatively large velocity gradient around the butterfly valve with increasing the valve opening angle and this trend appears even in the far downstream region. The distributions of turbulent intensity and shear stress show irregular behavior regardless of the valve opening angle and those of the case of the valve opening angle of 45°are the largest. The pressure loss coefficient of the body surface of the throttle valve increases mildly with the increase of Reynolds number and increases rapidly with the reduction of the valve opening angle.

자동차용 터보차저의 오버헝 압축기 볼류트의 두 형태에 대한 유동장 특성 (Flow Characteristics of Two Types of Overhung Compressor Volute for Automobile Turbocharger)

  • ;이근식
    • 대한기계학회논문집B
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    • 제38권1호
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    • pp.25-30
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    • 2014
  • 자동차용 터보차저 원심압축기의 오버헝 볼류트의 두 가지 타입에 대한 유동장 특성이 수치적으로 연구되었다. 볼류트의 성능을 높이기 위해서는 높은 압력회복계수와 낮은 손실계수를 갖도록 함이 필요하다. 본 연구에서는 디퓨저 입구각을 $24^{\circ}$, 질량유량을 0.055 kg/s 로 유지하고 두 가지 타입의 오버헝 볼류트에 대한 유동장 특성을 조사하였다. 하나는 1 개의 원호로 이루어진 볼류트 단면(타입 1)이며, 다른 하나는 3 개의 원호로 이루어진 볼류트 단면(타입 2)이다. 타입 2 볼류트가 타입 1 볼류트 보다 원주방향 전체를 통틀어 높은 압력회복계수와 낮은 손실계수를 보여주었다.

도파관 배열에 의한 국부저항계수 산정 (Evaluation of Local Loss Coefficients for Different Waveguide-Below-Cutoff (WBC) Arrays of Electromagnetic Pulse (EMP) Shied in Buildings)

  • 방승기;채영태
    • 설비공학논문집
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    • 제29권7호
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    • pp.366-372
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    • 2017
  • The objective of this study was to characterize Waveguide-Blow-Cutoff (WBC) array for Electromagnetic Pulse (EMP) shield in air duct or water pipe, the typical pathway of pulse in indoor space with critical electronic device. A numerical investigation with three different WBC designs (circular, rectangular, and hexagonal or honeycomb) was conducted to satisfy recommended shielding effectiveness (SE) levels from 80 dB to 140 dB. Pressure drop between upstream and downstream of EMP shields based on WBC arrays was also investigated to understand air flow feature in air duct of HVAC system. Results showed that honeycomb geometry outperformed other shapes in terms of reducing the depth of EMP shield, thus providing better air flow in duct path with lower local loss coefficient in HVAC system under SE requirements.