• 동력기계공학회지
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• 제4권2호
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• pp.11-16
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• 2000

Simultaneous quantitative measurements are made of the velocity fields for two-dimensional natural convection in a rectangular enclosure using PIV(Particle Image Velocimetry). The experiments are performed at a Prandtl number of 6.62, an aspect ratio of 1.0, Rayleigh numbers from $1.294{\times}10^6\;to\;3.8841{\times}10^6$, and angles of inclination of $0^{\circ},\;30^{\circ}\;and\;60^{\circ}$ inside a $30mm{\times}30mm{\times}8mm$ cavity made of an acrylic glass 10mm, with two isothermal copper walls kept at a prescribed temperature. The experimental results agreed very well with the numerical results. It was found that the flow consisted of a large double convection cell at angle of inclination of $60^{\circ}$.

• Journal of Advanced Marine Engineering and Technology
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• 제22권3호
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• pp.294-302
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• 1998

The charateristics of the convective mass transfer in horizontal rectangular enclosure with horizontal concentration gradients are analyzed. The effect of Grashof number(Gr) and aspect ratio(L/H) is investigated numerically using the control-volume method. Numerical results are obtained for Grashof numbers between $10^4$ and $10^6$ aspect ratios from 1 to 100 and results are compared with existing andlytical results. It is found that there exists a well defined aspect ratio for which the mean Sherwood number is maximum and the core flow changes from parallel to non-parallel at $Gr^2{Sc^2}(A^{-3}}{\geq}{10^5}$ and in the Ralongrightarrow0 regime the numerical results agreed very well with correlation derived from analytical results.

• 한국음향학회지
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• 제16권3호
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• pp.26-32
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• 1997

본 연구에서는 직각형의 밀폐함 내부 음장이 임피던스와 음압응답에 미치는 효과를 유한요소법을 직각형의 밀폐함에 적용하여 연구하였다. 이론 및 실험결과가 비교적 잘 일치하여 유한요소법이 다양한 모드를 나타내는 스피커 시스템의 개발에 유용한 방법임을 확인하였다.

• 한국정밀공학회지
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• 제23권4호
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• pp.60-66
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• 2006

For the purpose of finding out the sound field characteristics in a rectangular cavity, analytical and experimental studies are performed with white noise input. Two-microphone impedance tube method is used to measure the impedances of foamed aluminum. Foamed aluminum is well known metallic porous material which has excellent properties of light weight and high absorbing performance. And predicted impedances of foamed aluminum are compared with measured impedances. The predicted acoustical parameters are applied to the theoretical analysis to predict sound pressure field in the cavity. The measured sound absorption effects are compared with the predicted values for both cases with and without foamed aluminum lining in the cavity of the rectangular enclosure.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집B
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• pp.296-303
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• 2000

Study on natural convection in a rectangular enclosure with a heating point has been studied by numerical and experimental methods. The governing equations were solved by a finite volume method, and for pressure term was used a SIMPLE algorithm. The parameters considered for numerical study are positions and surface temperature of a heating point i.e. Y/H = 0.25. 0.5. 0.75 and $11^{\circ}C{\leq}{\Delta}T{\leq}59^{\circ}C$. The results of isotherms and velocity vectors have been represented for various parameters. Based on the numerical data. the mean Nusselt number in the space can be expressed as a function of Grashof number

• 태양에너지
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• 제6권2호
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• pp.54-61
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• 1986

The influence on natural convection was studied by solving the partial differential equations within a rectangular enclosure which have a cooling strip at the right side wall of the space, a isothermally heated bottom plate and adiabatic two other walls. Computation was carried out for the range of Grashof number from $5*10^3$ to $2.5*10^5$ with Plandtl number of 0.73. The results have been obtained in cases of four aspect ratios and various strip sizes. Temperature and Stream function distributions have been plotted using explicit finite difference method in two dimensional, laminar flow, and also mean Nusselt number and Local Nusselt number have been obtained.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 춘계학술대회논문집; 경주코오롱호텔; 22-23 May 1997
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• pp.681-686
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• 1997

Foamed aluminum is well known metallic porous sound absorption material which has excellent properties of light weight and high absorbing performance. For the purpose of finding out the sound field characteristics within a simple closed cubic enclosure with foamed aluminum, analytic and experimental studies are performed. For the first time, the standing wave apparatus is used to measure absorption coefficient and impedance of the foamed aluminum. Next, the sound effects of absorption material in acoustically loaded rectangular enclosure are identified according as the foamed aluminim is to be or not.

• 대한기계학회논문집
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• 제16권3호
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• pp.555-568
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• 1992

본 연구에서는 상기 연구의 연장으로서 내부 Rayleigh수가 1*$10^{4}$~1.5 *$10^{5}$ 범위 일때 Prandtl수가 6.05인 내부발열유체에 의해 자연대류가 일어나는 밀폐공간에서 종회비가 1/2, 1/3, 및 1/4로 변화할 때 유동, 온도분포 및 열전달특성 을 수치적인 방법 및 실험적인 방법으로 연구하였다.

• 대한설비공학회지:설비저널
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• 제12권4호
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• pp.264-274
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• 1983

Two-dimensional jet flows into a couple of confined rectangular enclosures such as an Ondol flue channel and their flow distributions were analyzed by numerical graphics : rectangular space in one enclosure is vacated and the other has 8 rectangular small posts. Both enclosures have a protruded inlet nozzle and on outlet on its center line. Steady state incompressible laminar viscous flow was assumed. The primitive forms of Navier-Stokes equations and continuity equation in a cartesian coordinate system were solved numerically by the Marker and Cell method for Reynolds numbers of 5, 10, 20, 30 and 40. From the numerical graphics it was found that the flow regions in both enclosures were devided into tow parts ; one part was the jet flow localized in a narrow center region of the enclosure and the other part was the very slow recirculating flow occupying the rest of the flow region in the enclosures. However there were a little differences in the shapes of jet flow in both enclosures for Reynolds numbers of 5 and 10 and also in the shapes of recirculating flows in both enclosures for all Reynolds number. Also it was found that waving flow appeared right before the outlet at Reynolds number of 20 and more.

• 대한기계학회논문집B
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• 제40권11호
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• pp.717-726
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• 2016

본 연구는 밀폐계 내부에 고온의 원형 실린더가 존재할 때, 밀폐계의 종횡비 변화에 따른 밀폐계 내부의 3차원 자연대류 현상에 대해 수치해석을 수행하였다. 밀폐계 내부의 원형 실린더는 유한체적법(FVM)에 기초한 가상 경계법(IBM)을 사용하여 구현하였다. 본 연구에서 고려한 Rayleigh 수의 범위는 $10^5{\leq}Ra{\leq}10^6$이며, Prandtl 수는 0.7이다. 밀폐계의 폭을 변화하여 밀폐계의 종횡비를 증가시켰으며, 밀폐계의 종횡비는 $1{\leq}W/L{\leq}4$ 범위에서 1 간격으로 고려하였다. 본 연구에서 고려한 모든 Rayleigh 수와 밀폐계의 종횡비 범위에서 열유동장은 x=0 단면을 기준으로 좌우 대칭을 이루며 정상상태에 도달하였다. 또한 밀폐계의 종횡비가 증가할수록 원형 실린더의 표면 평균 Nusselt수는 증가하는 반면, 밀폐계 벽면의 표면 평균 Nusselt수는 감소하였다.