• 제목/요약/키워드: hole water

검색결과 455건 처리시간 0.024초

정유량 밸브의 카트리지의 오리피스 구멍의 유출계수 (Discharge Coefficients of Orifice Hole in the Cartridge of Constant Flow Control Valve)

  • 유선학;강승덕;양의석;박경암
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2004년도 유체기계 연구개발 발표회 논문집
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    • pp.305-308
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    • 2004
  • The constant flow control valve is used to control the flow rate of heating water in the large apartment complex and buildings. It is important to have similar heating flow rate in the apartments, even though the apartment is top or bottom floors. To achieve those purposes, the constant flow control valve was developed. The performance of this control valve is effected by hole area and discharge coefficients of the cartridge holes. The discharge coefficients of orifice hole in the cartridge were testes with various sizes of holes and various flow direction in the holes. The discharge coefficients decreased as the hole size increased due to the collision at the cartridge wall of water jet. The effects of the flow direction at the hole were not significant on the discharge coefficients.

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미세구멍의 방전가공에 관한 연구 (A Study on Micro-Hole Drilling by EDM)

  • 윤재웅;양민양
    • 대한기계학회논문집
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    • 제14권5호
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    • pp.1147-1154
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    • 1990
  • 본 연구에서는 초음파 화학 가공(ultrasonicassisted chemical mahining)을 이용하여 100$\mu\textrm{m}$이하의 전극봉을 제작하였고 제작한 전극을 이용하여 미세구멍을 방전 가공함으로써 가공특성을 파악하고, 방전액을 각각 등유(kerosene)와 물로하여 구멍의 표면을 비교, 분석하였으며 전극의 지름, 가공물의 두께에 대한 오버컷과 경사도(tap- er) 그리고 전극의 마멸을 조사하였다.

ENTRAINMENT OF SEDIMENT PARTICLES FROM SCOUR HOLE BY TURBULENT VORTICES DOWNSTREAM OF HYDRAULIC STRUCTURE

  • Kim, Jin-Hong;Lee, Sam-Hee
    • Water Engineering Research
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    • 제2권4호
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    • pp.261-268
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    • 2001
  • This study presents the estimation of the entrainment velocity of sediment particles from the scour hole. Sediment particles are entrained from the scour hole downstream of hydraulic structures by the turbulent vortices. Mathematical form of the entrainment velocity of sediment particles from the scour hole was obtained using the impulse-momentum equation with given value of the vertical component of turbulent velocity of the line vortex. Also, its probability density distribution was obtained with the results that the probability density distribution of the vertical turbulent velocity followed the normal distribution. Experimental results of the entrainment velocity of sediment particles showed relatively good agreements with theoretical ones.

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전기탈이온시스템 응용을 위한 주기적 홀을 갖는 금속 전극 제작에 관한 연구 (A Study on the Fabrication of Periodic Holes on Metal Electrode for Electrodeionization System Application)

  • 여종빈;선상욱;이현용
    • 한국전기전자재료학회논문지
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    • 제26권3호
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    • pp.227-231
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    • 2013
  • Electrodeionization is a hybrid separation process of electrodialysis and ion exchange to produce high purity water under electric field. This article provides a fabrication result of hole patterned metal electrode for elecrodeionization system. The hole patterns have been fabricated by nanosphere lithography (NSL). The technique utilizes the self-assembled nanospheres as lens-mask patterns and collimated laser beam source. The hole patterns have a periodic array structure. The images of hole pattern on metal electrode prepared were observed by SEM. We believe that the periodic hole patterned metal electrode structure is a useful device applicable for metal mat electrode in electrodeionization system.

VORTEX STRUCTURE IN THE SCOUR HOLE BY GATE OPENING OF HYDRAULIC STRUCTURE

  • Kim, Jin-Hong;Choe, Jae-Wan
    • Water Engineering Research
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    • 제1권1호
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    • pp.83-92
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    • 2000
  • Jet flow can occur by gate opening at downstream of a hydraulic structure such as weir of drainage gate. If the stream bed is not hard or the bed protection is not sufficient, vortex erosion occurs and a resulting scour hole will be formed due to the high shear stress of the jet flow. Once the scour hole is formed, a vortex occurs in ti and this vortex causes additional erosion. If this erosion continues and reaches to the hydraulic structure, it can undermine the bottom of the hydraulic structure and this will lead to failure of the structure itself. Thus, it is necessary to define the physical features of the vortex structure in the scour hole for the design of the bed protection. This study presents the turbulent vortex structure in the scour hole by the gate opening of the hydraulic structure. Characteristics of vortex motion, circulation, vortex scale and vortex were analyzed through experiments. Experimental results of the vortex velocity were compared with theoretical ones. From these, circulation and vortex scale were obtained with known values of inflow depth, inflow velocity and scale of scour hole

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증기발생기 급수링 관통손상 원인 및 영향 고찰 (Study on Cause and Effect of SG Feed Water Ring Through-Wall Hole)

  • 이성호;이요섭
    • 한국압력기기공학회 논문집
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    • 제11권1호
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    • pp.61-68
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    • 2015
  • The function of Feed Water Ring is to provide the flow path from Feedwater Nozzle to inside of SG(steam generator). Significant amounts of general FAC on the outside of the Feed Water Ring are not likely due to the low flow velocities in this area. However, on the interior of the Feed Water Ring, there may be areas of local higher flow velocity which could lead to higher FAC rates. These may include the inlet tee from the Feedwater Nozzle into the Feed Water Ring, the areas where the Feed Water Ring changes diameter, and especially the entrance area to the J-Nozzles. In this paper, the results of root cause analysis of through-wall hole observed at domestic WH 51F SG Feed Water Ring and its effect on the integrity and performance of SG are described. And, the maintenance strategy for WH 51F SG Feed Water Ring and the monitoring strategy for Downcomer Feed Water Ring of CE System 80 SG are presented.

Test Results of Friction Factor for Round-Hole Roughness Surfaces in Closely Spaced Channel Flow of Water

  • Ha, Tae Woong
    • Journal of Mechanical Science and Technology
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    • 제18권10호
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    • pp.1849-1858
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    • 2004
  • For examining friction-factor characteristics of round-hole pattern surfaces which are usually applied on damper seals, flat plate test apparatus is designed and fabricated. The measurement method of leakage and pressure distribution along round-hole pattern specimen with different hole area is described and a method for determining the Fanning friction factor is discussed. Results show that the round-hole pattern surfaces provide a much larger friction factor than smooth surface, and the friction factor vs. clearance behavior yields that the friction factor generally decreases as the clearance increases unlike the results of Nava's flat plate test. As the hole depth is decreased, the friction factor is increased, and maximum friction factor is obtained for 50% of hole area. Since the present experimental friction factor results show coincident characteristics with Moody's friction factor model, empirical friction factors for round-hole pattern surfaces are obtained by using the Moody's formula based on curve-fit of the experimental data. Results of Villasmil's 2D CFD simulation support the present experimental test result.

공벽유지용 유체에 따른 대구경 현장타설말뚝의 하중전이특성 (Load Transfer Characteristics on Drilled Shafts by Hole Stability Fluids)

  • 임대성;박성완;박정환;오세훈
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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    • pp.1100-1105
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    • 2008
  • In most drilled shafts construction sites, it is common, depending on the site condition, to use either water or slurry as fluids for maintaining stability of the holes, however, there are yet no design manuals by hole stability fluids. In this paper, in order to evaluate load transfer characteristics of the drilled shafts by hole stability fluids, two test piles are constructed over the soft ground of the lower Busan Bay based on the Bi-directional Pile Load Test. The test results showed that no ultimate states has found under the condition of applied loads with fresh water and slurry as hole fluids for drilled shafts. Then, the load transfer behavior were estimated with the data measured in fields and the effect of hole stability fluids were compared. All these results are presented in the paper.

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