• Title/Summary/Keyword: 수직 항력

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Mass Estimated Adaptive Controller for Nonlinear Friction Compensation in Linear Motor System (선형모터 시스템의 비선형 마찰 보상을 위한 질량 추정형 적응 제어기)

  • Lee, Jin-Woo;Sun, Jung-Won;Lee, Young-Jin;Suh, Jin-Ho;Lee, Kwon-Soon
    • Proceedings of the KIEE Conference
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    • 2005.07d
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    • pp.2558-2560
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    • 2005
  • 본 논문에서는 마찰력과 질량은 수직항력에 의해 관계하고, 시스템 입출력 관계에서도 도출할 수 있음에 착안하여, LuGre 모델을 기반으로 하는 수직항력 관측이 가능한 보상기 적용과 동시에 제어 입력과 시스템 출력 관계를 적응규칙을 통해 질량추정기를 설계하여 제어 입력의 스케일로 사용함으로써 그 성능을 더욱 향상시키고자 하였다.

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Development and Application of Depth-integrated 2-D Numerical Model for the Simulation of Hydraulic Characteristics in Vegetated Open-Channels (식생 수로에서의 수리특성 모의를 위한 수심적분 2차원 수치모형의 개발 및 적용)

  • Kim, Tae Beom;Bae, Hea Deuk;Choi, Sung-Uk
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.30 no.6B
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    • pp.607-615
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    • 2010
  • Vegetation drag tends to raise water level by retarding the flow. Previous studies have focussed on either the vertical structure modeling or the one-dimensional modeling, which can hardly be used to simulate the vegetative streams in practical engineering. Therefore, this paper presents a two-dimensional numerical model based on the depth-averaged flow equations. Vegetation drags are reflected in the flow equations, assuming non-flexible rigid cylinders. For validations, flow properties measured in both rectangular and compound channels are compared with simulated data, showing good agreement. Then, the model is applied to a reach in the Han River and the impact of floodplain vegetation on the flow is investigated.

A Study of Three Dimensional Flow Characteristics near the Porous Wall (다공성 방풍벽의 3차원 유동특성)

  • Kim, Sung-Hoon;Kim, Il-Hyun;Chang, Young-Bae
    • Journal of Energy Engineering
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    • v.28 no.4
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    • pp.19-28
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    • 2019
  • A study has been done on the three dimensional turbulent flow characteristic near the porous wall. The porous holes are considered by penetrating the wall in regular arrangement, and porosity is controlled by diameter of holes. Flow characteristics near the three dimensional porous wall are compared with field test results and self-generated experimental results. FLUENT is employed for computational analysis on the effect of three dimensional porosity with flow and pressure characteristics. As a result, drag coefficient is defined and compared for three dimensional effect. The drag coefficient is mostly a function of porosity, whereas the effect of Reynolds number is minimal, and its correlation is presented in terms of three dimensional porosity.

Physically-Based Simulation of Chinese Top (물리 기반 차이니즈탑 시뮬레이션)

  • 송병수;김은주;유관우
    • Proceedings of the Korean Information Science Society Conference
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    • 2004.04a
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    • pp.907-909
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    • 2004
  • 에어포일(airfoil)이 공기속을 지날 때 양력이 발생한다. 공간상을 비행하는 물체에는 중력, 추력, 양력, 항력의 네 가지 힘이 작용한다. 본 논문에서는 항공역학의 연구결과를 바탕으로 차이니즈탑이란 물체가 회전하면서 수직상승과 호버링 그리고 하강하는 동안의 운동형태를 사실적이면서도 실시간으로 구현한다. 그 결과는 게임이나 비행 시뮬레이션에 응용할 수 있다.

Numerical Simulation of Laminar Flows for a Circular Cylinder Vertically Piercing Free Surface (수직원통 주위의 자유표면 층류운동의 수치해석)

  • Bum-Sang Yoon;Yoon-Ho Kim
    • Journal of the Society of Naval Architects of Korea
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    • v.30 no.1
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    • pp.104-114
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    • 1993
  • In this paper, effects of free surface on viscous flow is investigated. Continuity equation coupled with Navier-Stokes equations are solved numerically by using an artificial compressibility method[1, 2]. The body-fitted generalized curvilinear coordinate system is employed to deal with arbitrary body shape. The IAF scheme with finite difference method is used to solve the equations, and a diagonal algorithm is applied to time-varying Jacobian matrices for the computational economics. Free surface shape is obtained by applying zero pressure condition to still water surface at each time step. A numerical test is made for larminar flow around a circular cylinder vertically piercing the free surface. Computed flow patterns are largely affected by the existance of free surface in low Reynolds number flows treated in this paper. Free surface causes viscous pressure drag to vary much in depth direction in accordance with the variations of flow pattern.

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Multiphase Simulation of a Liquid Jet in a Lab-scale Ramjet Combustor (모형 램젯 연소기에서 액체제트의 다상유동 해석)

  • Oh, Jeong-Seog;Lee, Won-Nam;Lee, Jong-Geun;Santavicca, Dominique A.
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2010.11a
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    • pp.386-392
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    • 2010
  • The multiphase simulation of a liquid jet in a lab-scale ramjet combustor with a plain orifice type injector was studied with a commercial CFD tool, a FLUENT program. The objectives of the current study are to analysis the breakup characteristics of a hexane liquid jet in a cross flow and to derive the correlation between flow conditions and drag force coefficients in a test section. From the result of a numerical simulation, we concluded that a DPM and Realizable $k-{\varepsilon}$ model with an enhanced wall treatment were available to simulate the multiphase flow simulation. And the calculated distribution of a hexane vapor concentration was well-matched with experimental results.

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A Study on the Development of Wind Turbine using the lift and drag for the Offshore (양력 및 항력 조합형 해상용 풍력발전기 개발에 관한 연구)

  • Kim, Namhun;Lee, Byeongseong;Yoon, Yangil;Oh, Jinseok
    • 한국신재생에너지학회:학술대회논문집
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    • 2010.06a
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    • pp.183.3-183.3
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    • 2010
  • This is the research of wind turbine that is designed to supply power to offshore buoy system. In order to reach maximum efficiency in limited space, vertical axis wind turbine was used. Vertical axis wind turbine system that was applied in this research has the form of lift and drag blade combined to achieve high efficiency at both high and low speed. In addition, support system was designed and developed to suit the offshore condition.

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