• 제목/요약/키워드: 양정(head)

검색결과 102건 처리시간 0.025초

난류모형을 적용한 엔진 연료실의 유동해석 (Flow Analysis in the Fuel Chamber of Engine by Applying Turbulent Models)

  • 곽승현
    • 한국항해항만학회지
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    • 제30권5호
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    • pp.369-374
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    • 2006
  • 복잡한 연료실 내의 유동현상을 난류모형을 적용하여 해석하였다. 적용한 모형은 $k-\varepsilon,\;k-\omega$, spalart-allmaras, reynolds stress이고, 연로실내의 격자는 혼합격자(hybrid grid) 이다. 속도벡터, 압력분포, 반복계산(iteration)에 의한 잔류치(residual), 동력학적 양정(dynamic head) 등을 모사하였다. 4개의 난류모형을 연료실 유동에 적용하였다. 3차원 수치실험에 앞서, 수치검증을 위하여 2차원 물체 주위의 점성유동을 $k-\varepsilon$ 난류모형을 적용하여 모사하였고 항력계수를 비교하였다.

지하수 모델링 기법을 이용한 인공함양정 최적 위치 평가 (Determining Optimal Locations of an Artificial Recharge Well using an Optimization-coupled Groundwater Flow Model)

  • 이현주;구민호;김용철
    • 한국지하수토양환경학회지:지하수토양환경
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    • 제19권3호
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    • pp.66-81
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    • 2014
  • A Fortran program was developed to determine the optimal locations of an artificial recharge well. Three objective functions were considered: (1) maximizing the recovery rates, (2) maximizing the injection rates, and (3) minimizing the coefficient of variation of the increased pumping rates. We also suggested a new aggregate objective function which combined the first and the third objective functions. The model results showed that locating the injection well inside the cluster of pumping wells was desirable if either the recovery or the injection rate was taken into account. However, the injection well located outside the cluster evenly increased the pumping rates in existing pumping wells. Therefore, for clustered pumping wells, installing an injection well at the center or the upstream of the pumping wells seems beneficial. For linear arrangement of pumping wells parallel to the constant head boundary, locating the injection well in the upstream was recommended. On the contrary, in case of the linear arrangement perpendicular to the constant head boundary, the injection well installed on both sides of the central part of the pumping wells was preferable.

터보펌프 인듀서에 대한 극저온 성능시험 (Cryogenic Performance Test of a Turbopump Inducer)

  • 김진선;김진한;홍순삼
    • 한국추진공학회지
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    • 제11권1호
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    • pp.64-70
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    • 2007
  • 액체로켓엔진용 터보펌프의 인듀서에 대하여 액체질소를 매질로 하는 성능시험장치를 개발하였다. 그리고 이 시험장치에서 산화제펌프의 인듀서를 대상으로 수력 성능시험 및 캐비테이션 성능시험을 수행하였다. 액체질소를 매질로 하는 경우와 상온의 물을 매질로 하는 경우를 비교하면, 양정-유량의 수력 성능은 두 경우 비슷하였으나, 캐비테이션 성능은 액체질소의 경우가 우수한 결과를 보였다. 이는 캐비테이션의 열역학적 효과로 인한 것이다.

CFD에 의한 입형 다단 원심펌프 유동특성에 관한 연구 (A Study on Flow Characteristics of Vertical Multi-stage Centrifugal Pump by CFD)

  • 모장오;남구만;김유택;이영호
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2002년도 유체기계 연구개발 발표회 논문집
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    • pp.402-407
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    • 2002
  • A commercial CFD code is applied to analyze the 3-D viscous flow field within vertical multi-stage centrifugal pimp including impeller with 6 blades and guide vane with 11 blades and is performed by changing flow rate from 10 to $26\;m^3/h$ at the constant 3500rpm. The purpose of this 3-D numerical simulation is to confirm how much the effect of blade inlet angle of guide vane has an influence on the performance of vertical multi-stage centrifugal pimp. these results performed by $20^{\circ},\;30^{\circ}$ inlet angle of guide vane are compared with grundfos performance data. The vertical multi-stage pump consist of the impeller, guide vane, and cylinder. The characteristics such as total pressure coefficient total heat shaft horse power, power efficiency, discharge coefficient are represented according to flow rate changing.

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흡입 유로 형상이 터보펌프의 성능 및 캐비테이션에 미치는 영향에 관한 실험적 연구 (An Experimental Study on Influence of Suction Path to Performance and Cavitation for Turbopump)

  • 강병윤;추성한;강신형
    • 한국유체기계학회 논문집
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    • 제16권2호
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    • pp.21-26
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    • 2013
  • Super-cavitating vehicle which is operating under water speeds up to 100m/s. In this process super-cavitation around body reduces frictional resistance. This paper introduces experimental study on different width of suction path as there is a warhead in the torpedo. Hydraulic performances of turbopump at non-cavitating condition does not display a significant differences depending on different width of suction path. However, cavitation performance of each model shows obvious differences in the same condition of experience. In case of radial inlet, the value of critical NPSH(which indicates 3% head drop) increases about 20% in comparison of axial inlet.

견관절의 상완골 두 치환술 (Hemiarthroplasty of the Shoulder)

  • 신영식;양정호;김동근
    • Clinics in Shoulder and Elbow
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    • 제1권1호
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    • pp.12-18
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    • 1998
  • To purpose of this study was to evaluate clinical results between rheumatoid arthritis shoulder cases and traumatic proximal humerus fracture cases. Fourteen patients who had been shoulder hemiarthroplasties between March 1991 to July 1996, six had rheumatoid arthritis and eight had comminuted proximal humerus fracture by the various trauma. Neer II prothesis were implanted in twenty cases and global prothesis were implanted in two cases. The follow up period was 15 months to 36 months. To evaluate this study, we used the UCLA shoulder rating. We were able to follow up thirteen cases for more than fifteen months, of which five cases had excellent, five cases had good, two cases had fair and one case had poor. And the results were better for patients with rheumaroid arthritis than for patients with trauma.

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터보펌프 인듀서에 대한 극저온 성능시험 (Cryogenic Performance Test of a Turbopump Inducer)

  • 홍순삼;김진선;김진한
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2006년도 제26회 춘계학술대회논문집
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    • pp.93-99
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    • 2006
  • 액체로켓엔진용 터보펌프의 인듀서에 대하여 액체질소를 매질로 하는 성능시험장치를 개발하였다. 그리고 이 시험장치에서 산화제펌프의 인듀서를 대상으로 수력 성능시험 및 캐비테이션 성능시험을 수행하였다. 액체질소를 매질로 하는 경우와 상온의 물을 매질로 하는 경우를 비교하면, 양정-유량의 수력 성능은 두 경우 비슷하였으나, 캐비테이션 성능은 액체질소의 경우가 우수한 결과를 보였다. 이는 캐비테이션의 열역학적 효과로 인한 것이다.

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지역농업자원의 6차 산업 활성화 방안 : 전문가 실증연구를 중심으로 (Empirical Study on the Activation Plan for 6th Industrialization of Rural Agricultural Resources : Focus on the Field Experts and the Complementary Demand)

  • 양정임;이정희;황대용
    • 농촌계획
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    • 제20권3호
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    • pp.111-120
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    • 2014
  • This study aims to investigate the residents' and village leaders' complementary demand for the regional economic vitalization and 6th industrialization in the rural. Based on the field expert'(the head of the village or the chairmen of the farming association) interview, the study was conducted. For the study, 42 villages where selected to consider as 6th industry. Cross table were conducted to see if there were any differences of demand and consideration for between the type of 6th industries. This article further improve the rural environment for 6th industrialization, improve the policy measures in that rural can plan the basis for an effective strategy can be.

낙동강 하류지역의 저수지, 하천 및 지하수위 자료의 상관관계 분석 (Correlation Analysis with Reservoir, River, and Groundwater Level Data Sets in Nakdong River Watershed)

  • 양정석;유가영;안태연;김정은
    • 한국수자원학회:학술대회논문집
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    • 한국수자원학회 2008년도 학술발표회 논문집
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    • pp.1151-1154
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    • 2008
  • The water level data sets among hydrologic observation data are correspond to the hydraulic head for each observation point and determine flow direction. The level difference among reservoir, river, and groundwater determines groundwater flow direction, just like water flows in the downstream direction because the water level of upstream point is higher than that of downstream point. We can analyze the relationship among the components in hydrologic cycle by comparing the water level differences. This research dealt with the data from Nakdong river watershed in Gyungsangnam-Do. Three data group are used for the analysis and onr group is composed of reservoir, river, and groundwater data sets. The data sets are closely(within 10 km) located in the interested area.

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양쪽 흡입 원심펌프의 성능해석에 대한 연구 (A Study of Performance Analysis for a Double-Suction Centrifugal Pump)

  • 정경남;박편구;조현준;이상구
    • 한국유체기계학회 논문집
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    • 제4권4호
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    • pp.7-15
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    • 2001
  • Flow analysis was carried out for a double-suction centrifugal pump. Impeller-only models and a full pump model were used to simulate the velocity field and the pressure field of the pump. Heads and efficiencies were calculated with flow rates in order to obtain general performance of the pump. The calculation results were compared to the experimental data, and satisfactory results were obtained. Thus, it may be said that the CFD serves as a useful tool for pump designs.

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