• Title/Summary/Keyword: 3 Dimensional Enclosure

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Active control of noise induced by rotating machines - A 3-dimensional enclosure case (회전기에 의한 소음 제거를 위한 능동 소음 제어 - 3차원 공간의 경우)

  • Nam, Hyun-Do;Ahn, Dong-Jun;Lee, Ho-Seok
    • Proceedings of the KIEE Conference
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    • 1993.07a
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    • pp.290-292
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    • 1993
  • In this paper, analysis of the noise induced by rotating machines and the mode analysis of a 3-dimensional enclosure are presented. Adaptive active noise control algorithms for the multi-channel case are proposed. Computer simulations were done to show usefulness of the designed algorithm in a 3-dimensional enclosure case.

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The natural convection in a three dimensional enclosure using color capturing technique and computation (색상 포착 기법과 수치계산을 이용한 3차원 밀폐 공간내의 자연대류 연구)

  • Lee, Gi-Baek;Kim, Tae-Yeong;Yang, Jang-Sik
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.21 no.12
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    • pp.1595-1607
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    • 1997
  • The natural convection of a horizontal layer heated from below in a three-dimensional rectangular enclosure was dealt with both numerically and experimentally. The aspect ratios are 1:2:3.5 and Boussinesq fluid is water with the Prandtl number of 5.0. This experimental study showed how to measure the variation of temperature field in a 3-D rectangular enclosure with small aspect ratios by using TLC(Thermochromic Liquid Crystal) and color capturing technique. The experimental temperature field had periodic characteristics of 75 sec at Ra=2.37*10$^{5}$ . But the numerical convection flow had periodic characteristics of 79 sec at the same Rayleigh number. In three dimensional computation it was found that the convection roll structure bifurcated from four rolls to two rolls as the Rayleigh number is increased.

Effect of Aspect Ratio of Enclosure with Inner Circular Cylinder on Three-Dimensional Natural Convection (원형 실린더가 존재하는 밀폐계의 종횡비 변화가 3차원 자연대류 현상에 미치는 영향)

  • Lee, Jeong Min;Seo, Young Min;Ha, Man Yeong
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.40 no.11
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    • pp.717-726
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    • 2016
  • This study evaluated the effect of aspect ratio of an enclosure with a heated inner circular cylinder on three-dimensional natural convection. The immersed boundary method was used to model the inner circular cylinder based on the finite volume method. The Rayleigh number was varied between $10^5$ and $10^6$, and the Prandtl number was maintained at 0.7. The aspect ratio of the three-dimensional enclosure was changed in steps of 1 within a range of 1-4 by increasing the width of the enclosure. In this study, the flow and thermal fields in the enclosure reached the steady state, and showed a mirror-symmetric pattern with respect to the center plane (x=0). In addition, the surface-averaged Nusselt number of the inner circular cylinder increased, while the total surface-averaged Nusselt number of the enclosure walls decreased with increase in the aspect ratio of the enclosure.

Effect of a Solid Insert on Thermal Stratification in a Side-Heated Natural Convection Enclosure (측면가열 자연대류 밀폐공간에서 고체 삽입물이 열성층화에 미치는 영향)

  • 김수현
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.16 no.3
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    • pp.211-217
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    • 2004
  • Effect of a solid insert on thermal stratification in the natural convection enclosure is numerically investigated. The enclosure consists of two differently heated vertical walls and two adiabatic horizontal walls. A solid insert is located in the middle of the enclosure. The non-dimensional governing equations are solved by using the SIMPLER algorithm. The computations are carried out with the variations of thermal conductivity, width and height of the solid insert. The Prandtl number of the fluid in an enclosure is fixed at Pr=0.71, Two cases of Rayleigh number are considered in the present study, i.e., Ra:10$^3$ and 10$^{6}$ . The thermal stratification attenuates as thermal conductivity, width, and height of the solid insert are increased. As the thermal conductivity ratio of a solid insert to fluid increases beyond (equation omitted)10$^3$, the thermal stratification ratio shows an asymptotic value.

Discrete Ordinates Interpolation Method Applied to Irregular Three-Dimensional Geometries (불규칙한 3차원 형상에 응용된 구분종좌표보간법)

  • Cha, Ho-Jin;Song, Tae-Ho
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.24 no.6
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    • pp.814-821
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    • 2000
  • The Discrete Ordinates Interpolation Method (DOIM) is tested in three-dimensional enclosures. The radiative transfer equation (RTE) is solved for a linear source term and the DOIM is formulated for a gray medium. Several interpolation methods can be applied to the DOIM scheme. Among them, the interpolation method applicable to an unstructured grid system is discussed. In a regular hexahedron enclosure, radiative wall heat fluxes are calculated and compared with exact solutions. The enclosure has an absorbing, emitting and nonscattering medium and a constant temperature distribution. These results are obtained with varying optical depths (xD = 0.1, 1.0, 10.0). Also, the same calculations are performed in an irregular hexahedron enclosure. The DOIM is applied to an unstructured grid system as well as a structured grid system for the same regular hexahedron enclosure. They are compared with the exact solutions and the computational efficiencies are discussed. When compared with the analytic solutions, results of the DOIM are in good agreement for three-dimensional enclosures. Furthermore, the DOIM can be easily applied to the unstructured grid system, which proves the reliability and versatility of the DOIM.

An experimental and numerical study on natural convection-radiation conjugate heat transfer in a three-dimensional enclosure having a protruding heat source (돌출 열원을 갖는 3차원 밀폐 공간내에서의 자연대류-복사 복합 열전달에 대한 실험적 및 수치적 연구)

  • Baek, Chang-In;Lee, Gwan-Su;Kim, Woo-Seung
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.20 no.10
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    • pp.3344-3354
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    • 1996
  • An experimental and numerical study on the three-dimensional natural convection-radiation conjugate heat transfer in the enclosure with heat generating chip has been performed. A 3-dimensional simulation model is developed by considering heat transfer phenomena by conduction-convection and radiation. Radiative transfer was analyzed with the discrete ordinates method. Experiments are conducted in order to validate the numerical model. Comparisons with the experimental data show that good agreement is obtained when the radiation effect is considered. The effects of the thermal conductivity of the substrate and power level on heat transfer are investigated. It is shown that radiation is the dominant heat transfer mode and the conductivity of the substrate has important effects on the heat transfer in the enclosure.

Active Noise Control of Reverberant Sound Field Using the Multi-Channel Adaptive Algorithm (다채널 적응 알고리즘을 이용한 잔향 음장에서의 능동소음제어에 관한 연구)

  • Kim, H.S.;Sohn, D.G.;Oh, J.E.
    • Transactions of the Korean Society of Automotive Engineers
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    • v.3 no.6
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    • pp.23-29
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    • 1995
  • In this study, Active noise controlis implemented with single channel and multi-channel adaptive algorithm in 3 dimensional reverberant enclosure sound. field, which occurrs in complicated acoustic mode. First, for the one case excited with the resonant frequency of an enclosure, a target of control and the other cases excited with band-pass filtered random noise(100~400Hz), it is implemented to control reducing interior noise of enclosure with single channel and realtime multi-channel adaptive algorithm for global noise reduction in enclosure.

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Effect of Inner Circular Cylinder Size on Three-Dimensional Natural Convection in Cubical Enclosure (내부 원형 실린더의 크기가 정육면체 밀폐계 내부의 3 차원 자연대류 현상에 미치는 영향)

  • Seo, Young Min;Choi, Changyoung;Ha, Man Yeong;Park, Sang Hu
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.38 no.12
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    • pp.975-982
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    • 2014
  • This study evaluates the effect of a heated circular cylinder's size on three-dimensional natural convection in a cubical enclosure. The Rayleigh number was varied between $10^3$ and $10^5$, and the Prandtl number was maintained at 0.7. In this study, the radius of the circular cylinder was changed by 0.1 L within a range of 0.1-0.4 L. The thermal and fluid flow characteristics were regarded to be independent of time in the range of the Rayleigh number and cylinder radius considered in this study. The surface-averaged Nusselt numbers of the cylinder and the enclosure were found to increase with the increase in the radius of the cylinder. The effect of the cylinder's size on natural convection in the enclosure was analyzed across the thermal and flow fields, and the distributions of the Nusselt numbers.

A Numerical Study on Effects of Flow Through Openings on Convection (개구부의 유동이 대류에 미치는 영향에 관한 수치연구)

  • 박외철;이경아
    • Journal of the Korean Society of Safety
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    • v.15 no.3
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    • pp.52-56
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    • 2000
  • The finite control volume method was utilized to investigate the effects of flow through openings on convection in an enclosure. Flow patterns and temperature distribution were compared for non-dimensional inflow velocity U=20, 40, 60 at Ra=$10^4$ and $5\times10^4$, respectively. The inflow velocity influenced temperature distribution in the enclosure significantly and lowered temperature on the top wall. The flow through openings forced the position of the highest temperature on the top wall to move toward the outflow opening.

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