• 제목/요약/키워드: Shape of Nozzle

검색결과 432건 처리시간 0.033초

파력발전용 횡류형 수력터빈의 성능 및 내부유동 (Performance and Internal Flow of a Cross-Flow Type Hydro Turbine for Wave Power Generation)

  • 최영도;조영진;김유택;이영호
    • 한국유체기계학회 논문집
    • /
    • 제11권3호
    • /
    • pp.22-29
    • /
    • 2008
  • Clean and renewable energy technologies using ocean energy give us non-polluting alternatives to fossil and nuclear-fueled power plants to meet establishment of countermeasures against the global warming and growing demand for electrical energy. Among the ocean energy resources, wave power takes a growing interest because of its enormous amount of potential energy in the world. Therefore, various types of wave power conversion system to capture the energy of ocean waves have been developed. However, suitable turbine type is not normalized yet because of relatively low efficiency of the turbine systems. The purpose of this study is to investigate the internal flow and performance characteristics of a cross-flow type hydro turbine, which will be built in a caisson for wave power generation. Numerical simulation using a commercial CFD code is conducted to clarify the effects of the turbine rotation speed and flow rate variation on the turbine characteristics. The results show that the output power of the cross-flow type hydro turbine with symmetric nozzle shape is obtained mainly from Stage 2. Turbine inlet configuration should be designed to obtain large amount of flow rate because the static pressure and absolute tangential velocity are influenced considerably by inlet flow rate.

Controlled Release of Cyclosporin A from Liposomes-in-Microspheres as an Oral Delivery System

  • Park, Hee-Jung;Lee, Chang-Moon;Lee, Yong-Bok;Lee, Ki-Young
    • Biotechnology and Bioprocess Engineering:BBE
    • /
    • 제11권6호
    • /
    • pp.526-529
    • /
    • 2006
  • The aim of this study was to prepare cyclosporin A-loaded liposome (CyA-Lip) as an oral delivery carrier, with their encapsulation into microspheres based on alginate or extracellular polysaccharide (EPS) p-m10356. The main advantage of liposomes in the microspheres (LIMs) is to improve the restricted drug release property from liposomes and their stability in the stomach environment. Alginate microspheres containing CyA-Lip were prepared with a spray nozzle; CyA-Liploaded EPS microspheres were also prepared using a w/o emulsion method. The shape of the LIMs was spherical and uniform, and the particle size of the alginate-LIMs ranged from 5 to $10\;{\mu}m$, and that of the EPS-LIMs was about $100\;{\mu}m$. In a release test, release rate of CyA in simulated intestinal fluid (SIF) from the LIMs was significantly enhanced compared to that in simulated gastric fluid (SGF). In addition, the CyA release rates were slower from formulations containing the liposomes compared to the microspheres without the liposome. Therefore, alginate-and EPS-LIMs have the potential for the controlled release of CyA and as an oral delivery system.

복합소호형 가스 차단기의 SLF 차단 성능 해석 (Analysis of SLF Interruption Performance in self-blast Gas Circuit Breaker)

  • 박진근;안희섭;최종웅;김영근;조해용
    • 한국기계가공학회지
    • /
    • 제19권9호
    • /
    • pp.24-32
    • /
    • 2020
  • A self-blast type gas circuit breaker has been studied in this study to improve efficiency of interrupting performance of short line fault(SLF). Hot gas flows of gas circuit breaker have been simulated to evaluate interruption performance using CFD. Design parameters such as various types of expansion chamber and nozzles are suggested by using simulation results. Simulated results and experimental ones are compared with previous (ones that of in under development and with capacitor) GCB. Modified new shape of an expansion chamber and nozzle has been suggested to improve the efficiency of gas flow and to provide guidelines for designing self-blast breaker with a higher interruption capability.

고순도 초미립 분체제조를 위한 분무열분해법의 응용 (Application of Spray Pyrolysis Process for Production of Ultra Pure and Fine Powder.)

  • Yu, Jae-Keun;Park, Hee-Beom;Park, Joo-Ill;Han, Jung-Soo;Han, Jin-A;Nam, Yung-Hyeon
    • 한국산학기술학회:학술대회논문집
    • /
    • 한국산학기술학회 2000년도 추계학술대회
    • /
    • pp.39-41
    • /
    • 2000
  • Newly modified spray Pyrolysis system was developed to Produce ultra Pure and fine Powder by spray Pyrolysis Process. In this system, raw material solution was effectively atomized and sprayed into the reaction furnace. Also, thermal decomposition process fully completed in the three zone reaction furnace, and produced powder was effectively collected. A technology to reduce impurities in complex acid solution below 20ppm was also developed. The characteristics of produced powder were studied by changing the reaction conditions such as reaction temperature, the injection velocity of the solution and air, nozzle tip size and concentration of solution. The morphology of powder had spherical shape under the most experimental conditions, and the composition and the particle size distribution were almost uniform. Under the most experimental conditions average particle size of most produced powder was below 100nm.

대면적 임프린트 장비를 위한 LCD Glass 변형 시뮬레이션 연구 (LCD Glass strain Simulation For Large Size Imprint Equipment)

  • 송영중;신동훈;임홍재;장시열;이기성;정재일
    • 대한기계학회:학술대회논문집
    • /
    • 대한기계학회 2007년도 춘계학술대회A
    • /
    • pp.1626-1631
    • /
    • 2007
  • The purpose of the study is to simulate the displacement of the LCD glass during process of a large size imprint. During this process, a small temperature variation makes thermal stress, which causes the horizontal variation of mold and glass. During alignment process to fix the LCD glass on a alignment stage, the vertical displacement is made by the absorption pressure and the shear stress. This study simulates the horizontal displacement of mold and glass due to temperature variation, the vertical displacement depending on the shape of absorption surface fixing the LCD glass in the alignment process, and the horizontal and vertical displacement which occurs in the LCD glass at the alignment process. Algor which is a FEM code for a framework simulation was applied. Temperature variation above ${\pm}$ $0.1^{\circ}C$ on mold and glass causes the horizontal displacement of 150nm due to thermal expansion. The vertical displacement due to the circular is ten times of the case of rectangular absorption nozzle. The displacement of the LCD glass in the alignment process is about 49nm.

  • PDF

블록직선이송 방전연삭에 의한 미세전극 가공 및 그래핀 강화 알루미나 복합소재의 마이크로 홀 가공특성 (Fabrication of Micro-electrodes using Liner Block Moving Electrical Discharge Grinding and Characteristics of Micro-hole Machining of Graphene Nanoplatelet-reinforced Al2O3Composites)

  • 정현아;이창훈;강명창
    • 한국기계가공학회지
    • /
    • 제16권1호
    • /
    • pp.149-156
    • /
    • 2017
  • Graphene nanoplatelet (GNP)-reinforced alumina ($Al_2O_3$) is a promising material for micro-partapplications, particularly micro-nozzle shapes, because of its excellent wearresistance. In this study, a $Al_2O_3$/GNPcomposite with 15 vol% graphene nanoplatelets (GNP) was highly densified and fabricated via spark plasma sintering for micro-electrical discharge drilling (Micro-ED drilling) and the wear resistance property of the composite is evaluated via the ball-on-disk method. In addition, the diameter and shape of the micro-electrodes machined by wire electrical discharge grinding (WEDG), block electrical discharge grinding (BEDG), and new linear block moving electrical discharge grinding (LBMEDG) methods are systematically compared and analyzed to observe the micro-hole machining in the micro-ED drilling of the $Al_2O_3$/15vol% GNP composite.

부상화염에서 예혼합화염과 삼지화염의 천이적 거동(II) (A Transitional Behavior of a Premixed Flame and a Triple Flame in a Lifted Flame(II))

  • 장준영;김태권
    • 대한기계학회논문집B
    • /
    • 제29권3호
    • /
    • pp.376-383
    • /
    • 2005
  • In the paper we investigate characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. In previous study, we showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame. A gas-chromatograph is used to measure concentration field, a smoke-wire system is used to measure streak line, and a PIV system is used to measure velocity field in lifted flame. In the visualization experiment of smoke wire, the flow divergence and redirection reappeared in premixed flame as well as triple flame. Thus we cannot express the flame front of lifted flame has a behavior of triple flame with only flow divergence and redirection. In PIV measurement, flow velocity for those three flames has minimum value at the tip of flame front. To differentiate triple flame and premixed flame, $\Phi$ value of partially premixed fraction is employed. The partially premixed fraction $\Phi$ was constant in premixed flame. In critical flame small gradient appears over the whole regime. In triple flame, typical diffusion flame shape is obtained as parabolic distribution type due to diffusion flame trailing.

레이저 회절 측정기를 이용한 벤츄리 캐비테이션에서의 마이크로버블 발생 특성 연구 (Study on Micro-bubble Generation Characteristics in Venturi Cavitation using Laser Diffractometer)

  • 임윤규;양해정;김영일
    • 드라이브 ㆍ 컨트롤
    • /
    • 제16권1호
    • /
    • pp.1-6
    • /
    • 2019
  • The use of micro bubbles in industrial fields has been increasing in the recent years., particularly micro-bubble sterilization and water purification effects. Various methods have been developed for the generation of micro-bubbles. Depending on the method of generating bubbles, the micro-bubbles can be roughly classified into saturation molding, cavitation and rotation flow types. The objective of this study was to use ventilated tube type as a method of generating micro-bubbles in order to purify large amount of water quality such as lakes and reservoirs. This method shows a difference in efficiency in which micro-bubbles are generated depending on the contact ratio of gas to liquid. The study also investigated the optimal gas liquid contact ratio by applying various orifice methods and investigated the optimum condition of micro-bubble generation by gas Based on this, a technology to develop a micro-bubble generator with a venturi type nozzle shape that has a high water purification effect was developed.

보염기 주위의 연료액적크기와 연소특성에 관한 실험적 연구 (An Experimental Study on the Drop Size and the Combustion Characteristics around the Bluff-body)

  • 황상호;김덕줄
    • 한국분무공학회지
    • /
    • 제8권3호
    • /
    • pp.41-48
    • /
    • 2003
  • This work was performed to investigate the distribution of the fuel droplet size around the bluff-body and the combustion characteristics. The bluff-body is used fur the purpose of increasing the combustion efficiency by stabilizing the flame. Diameters of the bluff-body in this experiment are 6, 8, and 10mm and the impingement angles are $30^{\circ},\;60^{\circ}\;and\;90^{\circ}$. The measurement points were at the distances of 20 and 30 mm axially from the nozzle. The geometry of the bluff-body influenced the spray shape and the combustion characteristics. The SMD was acquired by image processing technique (PMAS), and the mean temperatures were measured by thermocouple. In the condition of ${\theta}=60^{\circ}$, the values of SMD are not greatly varied compared to the other conditions. As the angle of bluff-body was increased, the high temperature region was wider along radial direction. When the air-fuel ratio was larger than 5.2, the NOx concentration was decreased, and an increase in the diameter of the bluff-body decreased the NOx of emission.

  • PDF

신형 수이젝터 개발을 위한 실험연구 (Experimental Study of the Development of New Type Water Ejector)

  • 최현규;문수범;최순열;최순호;김경근
    • 한국마린엔지니어링학회:학술대회논문집
    • /
    • 한국마린엔지니어링학회 2005년도 후기학술대회논문집
    • /
    • pp.35-36
    • /
    • 2005
  • An ejector driven by a liquid is a fluid transfer equipment to be used under a poor suction condition, which means that there exists a possibility to occur a cavitation. It is a highly reliable device because it has no movable part in it, that is only a passive equipment. The ejector is an inevitably necessary one to overcome a poor pumping condition and to mix uniformly two fluids, however it has a low efficiency since it requires a pump for its operation. This study is for the development of a new-type liquid ejector with the application of a nozzle shape alteration, which maximize the suction performance of it. which provides the increased competition with the domestic industries. Also, the increased performance opens a new manufacturing method to use a commercial pipes for the production of an ejector, which is based on a trivial loss of a performance. However, this minor loss can be sufficiently compensated by the increased performance of a new-type ejector. Therefore, the developed ejector by this study can considerably reduce the manufacturing time and cost while its performance is largely increased.

  • PDF