• 제목/요약/키워드: Multi Nozzle

검색결과 201건 처리시간 0.034초

차세대 인공위성 전기저항제트 가스추력기의 다물리 수치모사 (MULTI-PHYSICAL SIMULATION FOR THE DESIGN OF AN ELECTRIC RESISTOJET GAS THRUSTER IN THE NEXTSAT-1)

  • 장세명;최진철;한조영;신구환
    • 한국전산유체공학회지
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    • 제21권2호
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    • pp.112-119
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    • 2016
  • NEXTSat-1 is the next-generation small-size artificial satellite system planed by the Satellite Technology Research Center(SatTReC) in Korea Advanced Institute of Science and Technology(KAIST). For the control of attitude and transition of the orbit, the system has adopted a RHM(Resisto-jet Head Module), which has a very simple geometry with a reasonable efficiency. An axisymmetric model is devised with two coil-resistance heaters using xenon(Xe) gas, and the minimum required specific impulse is 60 seconds under the thrust more than 30 milli-Newton. To design the module, seven basic parameters should be decided: the nozzle shape, the power distribution of heater, the pressure drop of filter, the diameter of nozzle throat, the slant length and the angle of nozzle, and the size of reservoir, etc. After quasi one-dimensional analysis, a theoretical value of specific impulse is calculated, and the optima of parameters are found out from the baseline with a series of multi-physical numerical simulations based on the compressible Navier-Stokes equations for gas and the heat conduction energy equation for solid. A commercial code, COMSOL Multiphysics is used for the computation with a FEM (finite element method) based numerical scheme. The final values of design parameters indicate 5.8% better performance than those of baseline design after the verification with all the tuned parameters. The present method should be effective to reduce the time cost of trial and error in the development of RHM, the thruster of NEXTSat-1.

이중 콘형 부분 예혼합 GT 노즐의 다단 연소특성 (Characteristics of Multi staged Combustion on a Double-cone Partial Premixed Nozzle)

  • 김한석;조주형;김민국;황정재;이원준
    • 한국가스학회지
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    • 제24권1호
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    • pp.49-55
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    • 2020
  • 산업용 혹은 발전용 가스터빈에 사용되는 이중 콘형 예혼합 연소기의 다단 연소 특성을 이해하기 위하여 실험적연구를 수행하였다. 이를 위하여 기존에 모두 경사면에 공급되는 연료를 콘부분으로 일부 할애하는 방식으로 다단연소 방식을 구성하였으며 콘에서 분사되는 연료공급은 축방향과 콘 경사면 방향으로 하였다. 다단연소 연소특성을 이해하기 위하여 콘에서의 연료 분사 방향과 연료 분배율 변화에 대한 NOx와 CO의 배출 농도 그리고 벽면 온도분포를 측정하였다. 그 결과 총 연료에 대한 콘으로의 분배율이 3%인 경우 콘에서의 연료 분사방향에 관계없이 노즐내의 예혼합 영역에서 연료가 공기와 균일하게 혼합됨으로서 연소영역의 고온점 감소에 의하여 NOx 배출 농도가 감소된다. 그러나 콘에서 축방향으로 분사되는 연료분배율이 8%로 증가하는 경우 노즐 내부 예혼합 영역으로의 화염 역화로 인하여 NOx의 배출농도가 오히려 증가하게 된다.

전기수력학 프린팅의 분사 특성 변화에 대한 실험적연구 (An experimental study for characteristic change of Electrohydrodynamic jetting)

  • 김효준;정종렬;양중근;정재원
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.1913-1916
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    • 2008
  • Electrohydrodynamic (EHD) printing has gained significant interest after a direct writing with a resolution of a few tens nanometer was demonstrated using EHD. Basically, EHD use the electric field to generate droplet which is much smaller than nozzle diameter, so that high resolution printing is possible and the clogging problem can be alleviated as well. However, to adapt this technology to the real application, the fundamental studies are necessary to stabilize EHD jetting, to maximize jetting frequency, and to optimize the design of multi EHD nozzle, etc. In this study, by imaging EHD jetting using high speed camera and measuring the current, the effect of electric field intensity and back pressure on jetting frequency and jetting diameter were studied.

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발전용 희박예혼합 가스터빈 연소기 내부유동 특성 해석 (A Numerical Analysis of the Flow Characteristics in a Lean Premixed Gas Turbine Combustor for Power Generation)

  • 정재화;서석빈;안달홍;김종진
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 춘계학술대회논문집B
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    • pp.847-852
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    • 2000
  • Three dimensional CFD investigations are carried out to understand the complex flow field in a gas turbine combustor with multi-element fuel injectors. The gas turbine considered here is the GE7FA model which has aye fuel injectors in each combustor can and utilizes lean-premixed combustion to meet nitric oxide emission requirements. Detailed three-dimensional flow characteristics and fuel-air mixture formation process inside the fuel nozzle and gas turbine combustor including five swirl nozzle tips are analyzed using commercial FLUENT code.

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CFD를 이용한 소화시스템 노즐의 분무 특성에 대한 연구 (The Study of a Atomizing Characteristics of a Nozzle in a Fire Extinguishing System for using CFD)

  • 최관수;정영권;김영수;김인관
    • 대한설비공학회:학술대회논문집
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    • 대한설비공학회 2008년도 하계학술발표대회 논문집
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    • pp.1184-1189
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    • 2008
  • This paper is a study about characteristics of the SSC-1 nozzle, which is used in a fire extinguishing system in a ship. Through this paper, we can find that the traces and elements’ distributions obtained from experiments are as the same as the simulation analysis results of CFD program. At the point of 100mm, the $\alpha$ is 34.9 in the CFD analysis, and it is 32.5 in the experiment. This shows that there is no big different between the CFD analysis and the experiment result. And the average elements velocity is similar to the SMD.

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고유량 정전분무를 위한 다중 홈노즐 특성 연구 (Characteristics of Multiplexed Grooved Nozzles for High Flow Rate Electrospray)

  • 김경태;김우진;김상수
    • 대한기계학회논문집B
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    • 제31권10호
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    • pp.848-854
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    • 2007
  • The electrospray operated in the cone-jet mode can generate highly charged micro droplets in an almost uniform size at low flow rates. Therefore, the multiplexing system which can retain the characteristics of the cone-jet mode is inevitable for the electrospray application. This experiment reports the multiplexed grooved nozzle system with the extractor. The effects of the grooves and the extractor on the performance of the electrospray were evaluated through experiments. Using the grooved nozzle, the stable cone-jet mode can be achieved at the each groove in the grooved mode. Furthermore, the number of nozzles per unit area is increased by the extractor. The multiplexing density is 12 jets per $cm^2$ at 30 mm distance from the nozzle tip to the ground plate. The multiplexing system for the high flow rate electrospray is realized with the extractor which can diminish the space charge effect without sacrificing characteristics of the cone-jet mode.

화력발전 배가스 탈질 환원제의 혼합특성 (A Mixing Characteristic of De-NOx Reducing Agent for Flue Gas in Thermal Power Generation)

  • 최항석;김관태;김석준;정상현;송영훈;홍성호;이준엽
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
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    • pp.79-85
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    • 2006
  • In this study, to increase the mixing between flue gas and reducing agent, new shapes of $NH_3$ ejection nozzles are designed and experimentally and numerically tested. The nozzles have six holes perpendicular to the ambient flue gas flow and the tilting angle between direction of ambient flow and the hole axis is varied. To evaluate the mixing efficiency of the proposed nozzles, numerical and experimental tests are applied to several flow conditions comparing with single hole nozzle, which is commonly used in conventional SCR process. From the results the nozzle with tilted multi-holes has the large region of high turbulent intensity compared with conventional single hole nozzle. This is originated from the high vorticity near the upstream of the jet flow issuing from the hole. The high turbulent intensity and vorticity magnitude lead to enhanced mixing between flue gas and reducing agent. Hence, the most suitable moral ratio between NOx and reducing agent for the catalytic reaction can be obtained on behalf of the intensified scalar mixing within shorter physical mixing length.

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다관절 조작기의 그래픽 시뮬레이션 (Graphic Simulation of the Multi-joint Manipulator)

  • 이종열;송태길;김성현;박병석;윤지섭
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 2001년도 춘계학술대회 논문집
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    • pp.631-634
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    • 2001
  • In this study, the graphic simulation system of multi joint manipulator is developed to analyze and optimize the remote handling processes for the spent fuel assembly. This system consists of a 3-D graphical modeling system, a device assembling system, and a motion simulation system. To analyze and optimize the processes involved in multi-joint manipulator operation such as NFBC transportation process and bottom nozzle removal process, the virtual work place is implemented using a computer graphic technology. This virtual workcell is exactly same as that of the real environment. This graphic simulation system of the multi-joint manipulator can be effectively used for designing the main processes and maintenance processes of the spent fuel management.

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다성분연료 분무에 있어서 증발과정의 해석모델 제안 (Propose an Analysis Model of Evaporation Process in Multi-Component Fuel Spray)

  • 염정국;전중지지
    • 대한기계학회논문집B
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    • 제33권5호
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    • pp.373-380
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    • 2009
  • The evaporation process of multi-component fuel is different from one of a single component, because the properties of each component affects among the components. In actual engine, the spatial distribution of fuel vapor concentration dominates auto-ignition and initial combustion, and depends on the volatility and diffusivity of each component fuel contained in the multi-component fuel. Then, this study proposes a simplified numerical scheme for analysis of evaporation process of multi-component fuel sprays. Evaporation process is calculated by KIVA-II code based on the simple two-phases region that is approximated by modified saturated liquid-vapor line, which was obtained by connecting the 50% distillation temperature for each component under several pressure fields. Consequently, it can be quantitatively simulated that vapor of low boiling fuel component mostly exists around nozzle and spray tip region, the high boiling duel component, on the other hand, mostly appears near the spray tip.

High Throughput Dispensing Using Multi Port Jet

  • Ahmadi, Mani;Babiarz, Alec;Suriawidjaja, Floriana;Jardins, Stephen Des
    • 한국정보디스플레이학회:학술대회논문집
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    • 한국정보디스플레이학회 2008년도 International Meeting on Information Display
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    • pp.1175-1178
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    • 2008
  • Flat panel display manufacturers are always investigating new techniques to improve productivity and reliability. For fluid dispense processes, Jet dispensing has shown benefits over traditional needle dispensing. Recent advancements in nozzle design and construction techniques enable jet dispensing capabilities far exceeding what has been previously achieved.

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