• Title/Summary/Keyword: Rotating Circular Cylinder

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The Flow Field Characteristics of a Rotating Circular Cylinder near a Plane Wall (벽면에 근접해서 회전하는 원주의 유동장 특성)

  • Kang, Myung-Hun;Kim, Kwang-Seok;Ro, Ki-Deok
    • Journal of Advanced Marine Engineering and Technology
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    • v.31 no.2
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    • pp.166-172
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    • 2007
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder. the space ratios $H/D(H/D=0.05{\sim}0.5)$ between cylinder and plane wall and the velocity ratios ${\alpha}({\alpha}=0{\sim}{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with increasing the space ratios and the velocity ratios. the lower separation point was more shifted in the rotating direction with them.

The Magnus Effect of a Rotating Circular Cylinder near a Plane Wall (벽면근처에서 회전하는 원주의 마그너스 효과)

  • Ro, Ki-Deok;Kim, Kwang-Seok
    • 한국가시화정보학회:학술대회논문집
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    • 2006.12a
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    • pp.42-47
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    • 2006
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder, the space ratios H/D$(H/D=0.05\sim0.5)$ between cylinder and plane wall and the velocity ratios $\alpha(\alpha=0\sim{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with the space ratios and with the velocity ratios, the lower separation point was more shifted in the rotating direction with them.

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The Magnus Efface of a Rotating Circular Cylinder Near a Plane Wall (벽면 근처에서 회전하는 원주의 마그너스 효과)

  • Ro, Ki-Deok;Kim, Kwang-Seok;Oh, Se-Kyeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.31 no.11
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    • pp.957-962
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    • 2007
  • The flow around a rotating circular cylinder near a plane wall is investigated by the measurement of the lift acting on the cylinder and by the flow visualization using the hydrogen bubble technique in the circulating water tank. The experimental parameters are the rotating direction of the cylinder, the space ratios H/D($H/D=0.05{\sim}0.5$) between cylinder and plane wall and the velocity ratios ${\alpha}({\alpha}=0{\sim}{\pm}2.0)$. In the case of clockwise, the lift on the rotating circular cylinder was increased with the reduction of the space ratios and with the velocity ratios, the upper separation point was more shifted in the rotating direction with them. In the case of anticlockwise, the absolute value of the lift on the rotating circular cylinder was increased with the space ratios and with the velocity ratios, the lower separation point was more shifted in the rotating direction with them.

Flow and Fluid Force around a Rotating Circular Cylinder with Square Grooves (정방형 홈을 가진 회전원주 주위의 유동과 유체력)

  • Kang, Myeong-Hoon;Ro, Ki-Deok;Kong, Tae-Hue
    • Proceedings of the KSME Conference
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    • 2004.11a
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    • pp.1460-1465
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    • 2004
  • Flow patterns around a rotating circular cylinder having square dimpled surface were visualized by the hydrogen bubble technique at velocity ratios from a=0 to 4.8 and Reynolds number of $Re=1.0{\times}10^{4}$. The wake region of the cylinder was reduced as the velocity ratios increase and was smaller than that of the smooth cylinder without dimples at the same velocity ratio. The hydrodynamic characteristics on the cylinder was investigated by measuring of lift and drag at velocity ratios from a=0 to 4.1 and Reynolds number from $Re=1.2{\times}10^{4}$ to $Re=2.0{\times}10^{4}$. As the velocity ratios increase, the average lift and drag coefficients were increased and at the same velocity ratio, the average lift was larger but the average drag was smaller than that of the smooth cylinder.

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Flowfield Characteristics of a Rotating Circular Cylinder Having Square Dimpled Surface (정방형 딤플을 가진 회전원주의 유동장 특성)

  • Ro, Ki-Deok;Kang, Myeong-Hoon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.28 no.4
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    • pp.486-492
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    • 2004
  • Flow patterns around a rotating circular cylinder having square dimpled surface were visualized by the hydrogen bubble technique at velocity ratios from a=0 to 4.8 and Reynolds number of Re=1.0${\times}$10$^4$. The wake region of the cylinder was reduced as the velocity ratios increase and was smaller than that of the smooth cylinder without dimples at the same velocity ratio. The hydrodynamic characteristics on the cylinder was investigated by measuring of lift and drag at velocity ratios from a=0 to 4.1 and Reynolds number from Re=1.2${\times}$10$^4$ to Re=2.0${\times}$10$^4$. As the velocity ratios increase, the average lift and drag coefficients were increased and at the same velocity ratio, the average lift was larger but the average drag was smaller than that of the smooth cylinder.

Effect of the rotation on a non-homogeneous infinite cylinder of orthotropic material with external magnetic field

  • Hussein, Nahed S.;Bayones, F.S.;Mahmoud, S.R.
    • Structural Engineering and Mechanics
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    • v.54 no.1
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    • pp.135-148
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    • 2015
  • The present investigation is concerned with a study effect of magnetic field and non-homogenous on the elastic stresses in rotating orthotropic infinite circular cylinder. A certain boundary conditions closed form stress fields solutions are obtained for rotating orthotropic cylinder under initial magnetic field with constant thickness for three cases: (1) Solid cylinder, (2) Cylinder with a circular hole at the center, (3) Cylinder mounted on a circular rigid shaft. Analytical expressions for the components of the displacement and stress fields in different cases are obtained. The effect of rotation and magnetic field and non-homogeneity on the displacement and stress fields are studied. Numerical results are illustrated graphically for each case. The effects of rotating and magnetic field and non-homogeneity are discussed.

Numerical simulation of flow past a rotating and rotary oscillating circular cylinder on unstructured meshes

  • Bai, Wei
    • Coupled systems mechanics
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    • v.2 no.2
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    • pp.191-214
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    • 2013
  • The unsteady flow past a circular cylinder which starts rotating or rotary oscillating impulsively from rest in a viscous fluid is investigated for Reynolds numbers Re=200 and 1000, rectilinear speed ratios ${\alpha}$ between 0.5 and 5.0, and forced oscillating frequencies $f_s$ between 0.1 and 2.0. Numerical solutions of the Navier-Stokes equations are obtained by using a finite volume method on an unstructured colocated grid. The objective of the study is to examine the effect of the rotating and rotary oscillating circular cylinder on the flow patterns and dynamics loads. The numerical results reveal that the $K\acute{a}rm\acute{a}n$ vortex street vanishes entirely behind the rotating cylinder when the ratio ${\alpha}$ exceeds the critical value, and the vortex shedding behind the rotary oscillating cylinder undergoes mainly three modes named 'synchronization', 'competition' and 'natural shedding' with the increase of $f_s$. Based on the amplitude spectra analysis of the lift coefficients, the regions of the classification of flow structure modes are presented, which provide important references for the flow control in the ocean engineering.

Numerical Simulation on Laminar Flow past a Rotating Circular Cylinder (회전하는 원형 실린더 주위 층류유동장의 수치 시뮬레이션)

  • Park, Jong-Chun;Moon, Jin-Kook;Yoon, Hyun-Sik;Lee, Byung-Hyuk;Chun, Ho-Hwan;Suh, Sung-Bu
    • Journal of Ocean Engineering and Technology
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    • v.19 no.3
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    • pp.1-10
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    • 2005
  • The effect of rotation on the unsteady laminar flaw past a circular cylinder is numerically investigated in the present study. The numerical solutions for the 2D Navier-Stokes equation obtained, using two different numerical methods. One is an accurate spectral method and the other is a finite volume method(FVM). First, the flaw around a stationary circular cylinder is investigated to understand the basic phenomenon of flaw separation and bluff body wake. Next, the flow characteristics of the laminar flow, past a rotating circular cylinder, are investigated, using a FVM developed in this study. By the effect of rotation, it is seen that values of lift increase, while the values of mean drag decrease. Further, the criteria of angular velocity, at which the Karman vorteces disappear, is also determined.

Image Processing Technique for Rotational Velocity Measurements in a Circular Cylinder (영상처리 기법을 이용한 원통형 용기내의 회전유속의 측정)

  • Kim, J.W.;Eum, C.S.;Lim, T.G.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.1
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    • pp.13-19
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    • 1995
  • An experimental investigation has been made for flow in a circular cylinder with a rotating bottom disk. Flow system considered in this paper is a characteristic model of interior flows of an electric washing machine. Flows in a tub of an electric washing machine are driven by a rotating bottom disk called a pulsator. The simple and characteristic model was composed of a circular cylinder with impulsively rotating endwall disk and a viscous fluid in it. Rotational motion of the pulsator is periodic and alternative in rotation direction. The flow field in the interior region is governed by a horizontal boundary layer forms on the impulsively rotating disk. Experimental approach was accomplished by adopting an image processing technique for velocity measurements. Comprehensive details of the flow structure are presented. Also a meridional circulation is obtained by tracking image particles suspended in the fluid. Flow structure and data are successfully procured for this complex rotating flow field.

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Study of geometric effects on vortex breakdown in a rotating axisymmetric circular cylinder (회전하는 축 대칭 원통형 용기에서의 기하학적 영향에 따른 와동붕괴에 관한 연구)

  • Kim Jae Won;Kim Nam Wook;Byun Sam Mon
    • 한국전산유체공학회:학술대회논문집
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    • 2004.03a
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    • pp.35-41
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    • 2004
  • A numerical investigation has been made for flows in an axisymmetric circular cylinder with a rotating cone located at the bottom of the container. The axisymmetric container is completely filled with a viscous fluid. Major parameter for the present research is the vertex angle of the cone, otherwise Reynolds number of fluid and aspect ratio of the vessel is fixed. Main interest is in vortex breakdown of meridional circulation by rotation of the cone with respect to the longitudinal axis of the cylinder. The method to this problem is numerically to integrate momentum and continuity equations on a generalized body fitted grid system. The pattern of vortex breakdown is quite different from that in a right circular cylinder with flat end wall disks. Flow visualization photographs of a preceeding work are compared with the present numerical results.

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