• Title/Summary/Keyword: hollow cylinder

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Member Utilization Concept Design for Hollow Circular Section Multi-column Tower Subjected to 10MW Level Wind Turbines (10MW급 풍력발전용 원형강관 멀티기둥타워의 부재유용도 개념설계)

  • Kim, Kyungsik;Kim, Mi Jin
    • Journal of Korean Society of Steel Construction
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    • v.29 no.3
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    • pp.205-215
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    • 2017
  • This study presents an example of conceptual design for hollow circular section multi-column tower system subjected to 10MW level wind load by introducing a method based on member utilization that examine both structural stability and economical efficiency. The basic assumptions for the proto type of a multi-column tower that can replace a single-cylinder tower were suggested and structural models were constructed following the assumptions and analyzed for identifying member forces. Based on the calculated member strengths and acting loads, the member utilization of the proposed multi-column tower structures were calculated for axial force, shear, bending and torsion and evaluaed for suitability as a wind tower. Design parameters such as steel tube dimensions, slenderness ratio, and number of floors for braces was proposed in the acceptable range of member utilization for conceptual design of multi-column wind towers.

Study on the Fluid Dynamics Modeling in Artificial Lung Assist Device (인공 폐 보조장치 내에서의 유체 유동 모델링에 대한 연구)

  • Kim, Gi-Beum;Park, Young-Ran;Kim, Shang-Jin;Hong, Chul-Un;Kang, Hyung-Sub;Kim, Jin-Shang;Kim, Seong-Jong;Kim, Min-Ho
    • Korean Chemical Engineering Research
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    • v.49 no.2
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    • pp.230-237
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    • 2011
  • In this study, the characteristic of fluid flow in the new type lung assist devices has been established using computational fluid dynamics(CFD). For the modeling, the hollow fiber was ignored, and vertical types and tangential types were used for the model. Which was to analyze the flow characteristics of the fluid flow model when there exists 1 and 2 input/output ports, and when the input/output ports is located at the center of the cylinder and at the tangential direction with the cylinder wall. The modeling results showed that it was possible to eliminate no-flow region(stagnant layer) as shown in the vertical type when an inlet and an outlet were installed on the tangential direction of the cylinder as shown in the tangential type. Also, in the tangential type, vortex-type flow appeared as dominant, and it showed a complicated flow not deviated to one side. When the number of input/output was two, there was no deviated flow, and complicated flows were generated all across the tube. From the test result, it was found that input/output of flow was tangential type and complicated flows with no stagnant layer would be generated when there are two inputs/outputs, respectively.

A FEASIBILITY STUDY OF A NAVIER-STOKES FLOW SOLVER USING A KINETIC BGK SCHEME IN TRANSITIONAL REGIME (Kinetic BGK 기법을 이용한 Navier-Stokes 유동 해석자의 천이 영역 적용성 연구)

  • Cho, M.W.;Yang, T.H.;Kwon, O.J.
    • Journal of computational fluids engineering
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    • v.20 no.3
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    • pp.54-61
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    • 2015
  • In the present study, a flow solver using a kinetic BGK scheme was developed for the compressible Navier-Stokes equation. The kinetic BGK scheme was used to simulate flow field from the continuum up to the transitional regime, because the kinetic BGK scheme can take into account the statistical properties of the gas particles in a non-equilibrium state. Various numerical simulations were conducted by the present flow solver. The laminar flow around flat plate and the hypersonic flow around hollow cylinder of flare shape in the continuum regime were numerically simulated. The numerical results showed that the flow solver using the kinetic BGK scheme can obtain accurate and robust numerical solutions. Also, the present flow solver was applied to the hypersonic flow problems around circular cylinder in the transitional regime and the results were validated against available numerical results of other researchers. It was found that the kinetic BGK scheme can similarly predict a tendency of the flow variables in the transitional regime.

Energy extraction from the motion of an oscillating water column

  • Wang, Hao;Falzarano, Jeffrey M.
    • Ocean Systems Engineering
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    • v.3 no.4
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    • pp.327-348
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    • 2013
  • An Oscillating Water Column (OWC) is a relatively practical and convenient device that converts wave energy to a usable form, which is electricity. The OWC is kept inside a fixed truncated vertical cylinder, which is a hollow structure with one open end submerged in the water and with an air turbine at the top. This research adopts potential theory and Galerkin methods to solve the fluid motion inside the OWC. Using an air-water interaction model, OWC design for energy extraction from regular wave is also explored. The hydrodynamic coefficients of the scattering and radiation potentials are solved for using the Galerkin approximation. The numerical results for the free surface elevation have been verified by a series of experiments conducted in the University of New Orleans towing tank. The effect of varying geometric parameters on the response amplitude operator (RAO) of the OWC is studied and modification of the equation for evaluating the natural frequency of the OWC is made. Using the model of air-water interaction under certain wave parameters and OWC geometric parameters, a computer program is developed to calculate the energy output from the system.

An Experimental Study of Nonlinear Viscoelastic Bushing Model for Axial Mode

  • Lee, Seong-Beom;Shin, Jung-Woog;Alan S. Wineman
    • Journal of Mechanical Science and Technology
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    • v.17 no.9
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    • pp.1324-1331
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    • 2003
  • A bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is essentially a hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. The shaft is connected to the suspension and the sleeve is connected to the frame. The cylinder provides the cushion when it deforms due to relative motion between the shaft and sleeve. The relation between the force applied to the shaft or sleeve and its deformation is nonlinear and exhibits features of viscoelasticity. An explicit force-displacement relation has been introduced for multi-body dynamics simulations. The relation is expressed in terms of a force relaxation function and a method of determination by experiments on bushings has been developed. Solutions allow for comparison between the force-displacement behavior by experiments and that predicted by the proposed method. It is shown that the predictions by the proposed force-displacement relation are in very good agreement with the experimental results.

The effects of oxygen-concentration increased by oxygen-enriching membrane on combustion of S.I. engines (기체분리막에 의해 상승된 산소농도가 스파크점화기관의 연소에 미치는 영향)

  • 권병철;김형섭
    • Journal of the korean Society of Automotive Engineers
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    • v.14 no.6
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    • pp.74-80
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    • 1992
  • The purpose of this study is to improve the performance of gasoline engine. Combustion-characteristics orignated from supplying cylinder with fuel-air mixture which was formed by the rise of oxygen-concentration in air with oxygen-enriching membrane have been investigated. The results showed that the poor-limit of oxygen-concentration was increased by shortening combustion-duration because the rise of oxygen-concentration in fuel-air mixture resulted in the promotion of combustion-velocity. Also, the generation of large output of power was expected from combustion in proportion as the amount of oxygen was increased.

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Viscoelastic stress analysis of nonaxisymmetrically heated cylindrical tubes (비축대칭 열하중을 받는 원통튜브의 점탄성 응력해석)

  • 박진석;서금석;김종인
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.15 no.2
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    • pp.396-403
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    • 1991
  • A solution is presented for the computation of the elastic-creep stresses in a hollow cylinder subjected to nonaxisymmetric temperature distribution. The creep problem is treated by the Maxwell creep model. Laplace transformation is used for reformation of the governing equation of elastic problem and Hooke's law in a function of .gamma. , .theta. , and creep constant. The governing equation is set up using the Airy stress function which leads to the biharmonic equation. The solution is obtained by using Fourer series method and Laplace inverse method used to obtain the stress components which include the variation of time. This solution shows excellent agreement with Lamkin's and Boley & Weiner's solution. The viscoelastic stresses are also obtained for the fuel rob tube subjecting nonaxisymmetric thermal load.

Sensitivity Analysis of Fiber Optic Hydrophone for a End-Capped Hollow Cylinder (끝단이 막힌 중공 원통형 광섬유 하이드로폰의 감도 해석)

  • 이종길;윤형규;서인창
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1996.04a
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    • pp.286-290
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    • 1996
  • 수중 음향센서로서 최근에 많이 연구되고 있는 광섬유 하이드로폰(fiber optic hydrophone)의 성능을 예측하기 위하여 광섬유의 편광특성(polarization)에 따른 정규화 감도식 (normalized sensitivity)을 유도하였다. 본 연구에서 사용된 하이드로폰은 광섬유가 끝단이 막힌 중공 원통형 맨드럴(mandrel)에 감긴 구조이며 음압이 하이드로폰에 작용할 때 응력 관계식을 이용하여 정규화 감도식을 유도하였으며 유도된 감도식을 맨드럴의 내외경비에 따라 특성을 수치해석하였다. 균일한 재질의 광섬유에서 맨드럴의 내외경비의 값이 클수록 그리고 맨드럴의 탄성계수의 값이 작을수록 감도가 증가함을 관찰 하였다.

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Experimental Investigation of the Acoustic Signal Detection Performance for an Interfermetric Fiber Optic Hydrophone (실험을 통한 간섭계형 광섬유 청음기의 음향신호 감지성능 연구)

  • 이종길;윤형규;설재수;남성현
    • Journal of KSNVE
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    • v.7 no.6
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    • pp.931-936
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    • 1997
  • Optical fiber sensor is a subject which has been attracted considerable attention in recent years. Detection of sound pressure with optical fibers positioned in the arms of a Mach-Zehnder interferometer is presented in this paper. A fiber length of the order of 150m is wounded is made by hollow cylinder type. To increase the sound signal 3${\times}3$ directional coupler is used. Fiber optic hydrophone is the underwater tank with 2kHz sound source. Finally, it is shown that the fiber optic hydeophone can stably detec 2kHz sound.

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A Study of A Nonlinear Viscoelastic Model for Elastomeric Bushing in Torsional Mode (일래스토메릭 부싱의 회전방향 모두 비선형 점탄성 모델연구)

  • Lee, Seong-Beom
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.2 s.95
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    • pp.194-200
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    • 1999
  • An elastomeric bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. For axial motion case, the relation between the force applied to the shaft and their relative displacement was considered. In this paper, the relation between the moment applied to the shaft and their relative deformation(angle of rotation) is considered for the torsional motion case. Numerical solutions of the boundary value problem represent the exact bushing response for use in the method for determining the moment relaxation function of the bushing. Solutions also allow for comparison between the exact moment-deformation behavior and that predicted the proposed model. It is shown that the predictions of the proposed moment-deformation relation are in very good agreement with the exact results.

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