• 제목/요약/키워드: Hydraulic structure

검색결과 819건 처리시간 0.03초

유압유 점도가 액추에이터 성능에 미치는 영향 (Effects of Viscosity of Hydraulic Oil on the Performance of Actuator)

  • 김진형;한수민;김윤제
    • 한국유체기계학회 논문집
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    • 제19권1호
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    • pp.31-36
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    • 2016
  • Hydraulic actuator is a primary component of the hydraulic valve systems. In this study, the thrust performance of hydraulic actuator was studied with different values of viscosity of hydraulic oil and rod diameter. Numerical analysis was performed using the commercial CFD code, ANSYS with 2-way FSI(Fluid-Structure Interaction) method and $k-{\varepsilon}$ turbulent model. Results show that increase in viscosity of hydraulic oil reduces the thrust of hydraulic actuator. In order to satisfy the output required of the actuator, it is necessary to compensate for the operating pressure. The results of pressure, velocity and thrust efficiency distributions in the hydraulic actuator were graphically depicted.

Modeling and testing for hydraulic shock regarding a valve-less electro-hydraulic servo steering device for ships

  • Jian, Liao;Lin, He;Rongwu, Xu
    • International Journal of Fluid Machinery and Systems
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    • 제8권4호
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    • pp.318-326
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    • 2015
  • A valve-less electro-hydraulic servo steering device (short: VSSD) for ships was chosen as a study object, and its mathematic model of hydraulic shock was established on the basis of flow properties and force balance of each component. The influence of system structure parameters, changing rate of motor speed and external load on hydraulic shock strength was simulated by the method of numerical simulation. Experiment was designed to test the hydraulic shock mathematic model of VSSD. Experiment results verified the correctness of the model, and the model provided a correct theoretical method for the calculation and control of hydraulic shock of valve-less electro-hydraulic servo steering device.

가압형 정삼투 시 압력에 따른 정삼투막의 Structure Parameter 변화양상 예측 (Structure Parameter Change Estimation of a Forward Osmosis Membrane Under Pressurized Conditions in Pressure-assisted Forward Osmosis (PAFO))

  • 국승호;김성조;이진우;황문현;김인수
    • 멤브레인
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    • 제26권3호
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    • pp.187-196
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    • 2016
  • 최근 정삼투(FO) 공정의 성능향상을 위해 유입수에 낮은 수압을 가하는 가압형 정삼투(PAFO) 공정이 관심을 받고 있다. Structure parameter는 FO 및 PAFO 공정 운전시 유도용질의 확산 저항성(Solute resistivity)을 결정하며, 이는 Solution-diffusion model (S-D model)을 통한 수투과 및 염투과 성능 예측을 지배하는 인자 중에 하나이다. 본 연구는 S-D model을 이용하여 가압형 정삼투시 유입수 측에 가해지는 압력에 따른 Structure parameter 변화 양상을 예측하고자 하였다.

유압 브레이커의 구조 소음.진동 저감을 위한 브래킷 하우징의 구조 개선에 관한 연구 (A Study on the Structure Improvement of Bracket Housing for Structural Noise and Vibration Reduction in Hydraulic Breaker)

  • 김봉석;김민기;변동우;이성민;이수훈
    • 한국정밀공학회지
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    • 제23권11호
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    • pp.108-115
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    • 2006
  • A hydraulic breaker is widely utilized for many civil engineering areas for the purpose of destroying objects such as rocks, concrete, or road. However, since the high-level noise and vibration by a hydraulic breaker is one of the major sources of environmental noise and recently the environmental regulations on construction equipments are also getting more strengthened, in order to solve such problems, it is certainly necessary to design and develop a hydraulic breaker with low noise and low vibration. This research is to understand the noise characteristics through the noise test and acoustic analysis of the bracket housing in a hydraulic breaker and to identify the element part to be modified based on the result of the element contribution analysis. An improved breaker model including X-typed rib shows the result of low-noise level within target frequency band compared with a commercial breaker model.

방출 수 에너지 하베스팅을 위한 수차 설계에 관한 연구 (A Study of Hydraulic Turbine Design for The Discharge Water Energy Harvesting)

  • 정한석;김충혁
    • 한국전기전자재료학회논문지
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    • 제34권1호
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    • pp.78-83
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    • 2021
  • We modeled the helical turbine and three modified helical turbines for the structure of the hydraulic turbine for discharge water energy harvesting. A structure that can reduce the load applied to the blade by placing a center plate is our basic concept. The shape was reduced to 1/5, fixed to a size of 240 mm in height and 247 mm in diameter, and modeled by changing the width and the angle of the hydraulic turbine blade. The pipe inner diameter of the simulation pipeline equipment is 309.5 mm, and the simulation section was 4 m in the entire section. The flow velocity was measured for two cases, 1.82 m/s and 2.51 m/s, with the parameters being the amount of power generation, hydraulic turbine's torque, and hydraulic turbine's rotation speed. The measurement results confirmed that the flow velocity at the center, which has no pipe surface resistance, has a great influence on the amount of power generation; therefore, the friction area of the turbine blade should be increased in the center area. In addition, if the center plate is placed on the helical turbine, durability can be improved as it reduces the stress on the blade.

해빈류장의 수치 시뮬례이션 - 이안 구조물 건설에의 적용 - (Numerical Simulation of Nearshore Current Field - Application to structure of offshore breakwater construction -)

  • 박종화;이순혁
    • 한국농공학회:학술대회논문집
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    • 한국농공학회 1998년도 학술발표회 발표논문집
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    • pp.305-310
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    • 1998
  • This research conducted concerning measures for the influence reduction to an investigation in the structure of offshore breakwater maintenance, an evaluation, a reexamination of the forecast, and a peripheral sediment transport environment. Furthermore, it aimed at the establishment of the beach transformation forecast method based on a hydraulic model study and a numeric simulation. A good result was obtained from a hydraulic model experiment and a numeric simulation as part of the basic research. And a qualitative evaluation of the flow field around the structure became possible since a numeric simulation examined flow field characteristics.

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가변구조를 이용한 전기-유압서어보계의 위치제어에 관한 연구 (A study on the position control of an electro-hydraulic servomechanism using variable structure system)

  • 허순영;권기수;하석훈;이진걸
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1988년도 한국자동제어학술회의논문집(국내학술편); 한국전력공사연수원, 서울; 21-22 Oct. 1988
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    • pp.299-304
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    • 1988
  • This paper describes the application of the variable structure control(VSC) concept for the position control of electro-hydraulic servomtor system. The basic philosopy of VSC is that the structure of the feedback control is altered as the state crosses discontinuity surfaces in the state surface with the result that certain desirable properties are achieved. The switching of the control function yields total(or selective) invariance to system parameter variations and disturbances, and closed loop eigen value placement in time-varing and uncertain systems.

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Dam-reservoir-foundation interaction effects on the modal characteristic of concrete gravity dams

  • Shariatmadar, H.;Mirhaj, A.
    • Structural Engineering and Mechanics
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    • 제38권1호
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    • pp.65-79
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    • 2011
  • Concrete hydraulic structures such as: Dams, Intake Towers, Piers and dock are usually recognized as" Vital and Special Structures" that must have sufficient safety margin at critical conditions like when earthquake occurred as same as normal servicing time. Hence, to evaluate hydrodynamic pressures generated due to seismic forces and Fluid-Structure Interaction (FSI); introduction to fluid-structure domains and interaction between them are inevitable. For this purpose, first step is exact modeling of water-structure and their interaction conditions. In this paper, the basic equation involved the water-structure-foundation interaction and the effective factors are explained briefly for concrete hydraulic structure types. The finite element modeling of two concrete gravity dams with 5 m, 150 m height, reservoir water and foundation bed rock is idealized and then the effects of fluid domain and bed rock have been investigated on modal characteristic of dams. The analytical results obtained from numerical studies and modal analysis show that the accurate modeling of dam-reservoir-foundation and their interaction considerably affects the modal periods, mode shapes and modal hydrodynamic pressure distribution. The results show that the foundation bed rock modeling increases modal periods about 80%, where reservoir modeling changes modal shapes and increases the period of all modes up to 30%. Reservoir-dam-foundation interaction increases modal period from 30% to 100% for different cases.

지하수-터널 수리상호작용에 따른 터널의 장기거동 연구 (A study on the long-term behavior due to the hydraulic interaction between ground water and tunnel)

  • 신종호;신용석;안상로;박동인
    • 한국지반공학회:학술대회논문집
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    • 한국지반공학회 2006년도 춘계 학술발표회 논문집
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    • pp.239-248
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    • 2006
  • The interaction between ground water and structure is complicated behavior which cannot be easily investigated In the laboratory and monitored in the fields. In this study numerical simulation of the interactive behavior was performed using sophisticated coupled-finite element method. Hydraulic behavior of structure is modeled using solid elements with finite Permeability. Recovery of ground water table in the long-term is considered by controlling hydraulic boundary conditions. The results showed that the interaction effect is significant. Particularly non-symmetry in the lining permeability resulted in highly unbalanced pore water pressure which may cause detrimental effects on inner linings of tunnels acting as drains.

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직접 외란 추정을 통한 역구동성 유압 구동 시스템의 임피던스 제어 (Impedance Control of Backdrivable Hydraulic Actuation Systems with Explicit Disturbance Estimation)

  • 유선겸;정완균
    • 로봇학회논문지
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    • 제14권4호
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    • pp.348-356
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    • 2019
  • The backdrivable servovalve is a desirable component for force and interaction control of hydraulic actuation systems because it provides direct force generation mechanical impedance reduction by its own inherent backdrivability. However, high parametric uncertainty and friction effects inside the hydraulic actuation system significantly degrade its advantage. To solve this problem, this letter presents a disturbance-adaptive robust internal-loop compensator (DA-RIC) to generate ideal interactive control performance from the backdrivable-servovalve-based system. The proposed control combines a robust internal-loop compensator structure (RIC) with an explicit disturbance estimator designed for asymptotic disturbance tracking, such that the controlled system provide stable and ideal dynamic behavior for impedance control, while completely compensating the disturbance effects. With the aid of a backdrivable servovalve, we show that the proposed control structure can be implemented based on a simplified nominal model, and the controller enables implementation without accurate knowledge of the target system parameters and disturbances. The performance and properties of the proposed controller are verified by simulation and experiments.