• Structural Engineering and Mechanics
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• 제60권1호
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• pp.131-148
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• 2016

Tuned Liquid Dampers (TLDs) provide low damping when it comes to deep water condition, and that not all water depth is mobilized in energy dissipation. This research focussed on a method to improve the efficiency of TLDs with deep water condition. Several bottom-mounted baffles were installed inside a TLD and the dynamic characteristics of modified TLDs together with their effect on the vibration control of a SDOF structure were studied experimentally. A series of free vibration and harmonic forced vibration tests were carried out. The controlling parameter in the conducted tests was the Vertical Blocking Ratio (VBR) of baffles. Results indicated that increase in VBR decreases the natural frequency of TLD and increases its damping ratio. It was found that the VBR range of 10% to 30% reduced response of the structure significantly. The modified TLD with the VBR of 30% showed the best performance when reduction in structural responses under harmonic excitations were compared.

• 동력기계공학회지
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• 제13권2호
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• pp.36-41
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• 2009

An experimental investigation was conducted to examine the fluid flow resistance in the rectangular channel with two inclined wire screen baffles. Two different types of wire screens; dutch weave and plain weave, were used as baffle devices in this experiment. Three kinds of baffles with different mesh specifications were made up of dutch type and four different kinds of baffles were made up of plain weave type. The stainless steel wire screen baffles were mounted on the bottom wall with varied angle inclination. Reynolds numbers were varied from 23,000 to 57,000. Results show that the mesh number of baffles plays an important role on friction factor behaviour. It is found that the baffle with the most number of meshes (type SA) has the highest fluid flow resistance.

• Advances in aircraft and spacecraft science
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• 제9권4호
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• pp.349-366
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• 2022

The ability of baffles in increasing the sloshing damping is investigated in this study by theoretical, numerical, and experimental methods. Baffles Installed as separators in containers, can change the dynamic properties of sloshing. The main purpose of this study is to investigate the effect of baffle placement.The main purpose of this study is to investigate the effect of placing baffles in order to provide appropriate frequencies and damping and to present a practical baffle arrangement in the design ofsloshing. In this regard, an experimental setup is designed to study the fluid sloshing behavior and damping properties in cylindrical tanks filled up to an arbitrary depth. A new combination of annular and sectorial baffles is employed to evaluate fluid sloshing in the tank. The results show that the proposed baffle arrangement has a desired effect on the damping and fluid sloshing frequencies and optimally satisfies the anticipated design requirements. In addition, the theoretical frequencies exceed empirical frequencies at the points far from baffles, while at the points close to baffles, the empirical ones are higher than theoretical ones. Also, at the depths near the bottom of container sloshing frequencies are not affected by sectorial baffles, although the theoretical curve predicts a reduction in the fundamental frequency of sloshing. Finally, the results of finite volume and finite element methods which compared with experimental data, indicated a good agreement between different approaches.

• Korean Chemical Engineering Research
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• 제48권3호
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• pp.337-341
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• 2010

직경 1 m, 높이 1 m의 교반탱크 내 유체흐름 패턴을 상용 전산유체역학 프로그램의 하나인 CFX를 사용하여 해석함으로써 교반속도, 임펠러 회전날개의 경사각, 방해판의 존재 유무, 탱크바닥 형태가 흐름패턴에 미치는 영향을 알아보았다. 방해판이 없을 경우 탱크 중심에서 와류가 관찰되었으며 교반속도가 증가함에 따라 탱크 중심의 와류 현상이 증가하였으나, 방해판 설치에 의해 와류가 감소하였다. 임펠러 날개의 경사각을 증가시킴으로써 교반탱크 상하로의 유체흐름이 증가하였고 와류도 감소하였다. 탱크바닥을 수평으로 하는 것 보다 둥글게 함으로써 탱크 바닥 구석에서 유체흐름이 원활하게 변화하였다.

• Structural Engineering and Mechanics
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• 제63권4호
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• pp.567-574
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• 2017

Sedimentation tanks are essential structures to filter the suspended sediments in the inlet flow which are constructed at the inlet of the basins forked from rivers and irrigation canals. The larger the constructed tank, the better the sedimentation process is conducted. However, the construction and dredging costs increase. In this regard, improving the performance and sedimentation efficiency seem necessary by alternative methods. One of these effective methods is using baffle plates. Most of the studies carried out in this field are on the use of these baffles in the primary and secondary sedimentation tanks. Hence, this study is carrier out with the objective of increasing the retention efficiency in the irrigation sedimentation tanks using baffles. To reach this goal, the experiments were carried out in a flume with length 8 meters, width 0.3 meters, and height 0.5 meters, considering a sedimentation tanks with a length of 3 meters, in three different inlet concentration, three flow rates and three Froude numbers. The baffles were mounted at the bottom of the tank and the effects of the angle, height and position in the tanks were investigated. The results showed that on average, employing the baffles increased the sedimentation efficiency 5 to 6% and the highest value was obtained for angle 60 with respect to the flow direction. According to the results of this study, the most favorable height and position of these baffles were obtained to be in 40% of the depth of the flow and 50% of the length of the sedimentation tank, respectively. Also, by increasing the number of baffles, the sedimentation efficiency decreased. Regarding the sedimentation regions in this case, more than 80% of the settled sediments were observed in the middle of the tank measured from the inlet.

• 동력기계공학회지
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• 제13권2호
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• pp.11-17
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• 2009

The heat transfer characteristics of flow through two inclined wire-mesh baffles in a rectangular channel were investigated experimentally with varying the mesh number of wire screens and inclination angle of the baffles. Two different types of wire meshes such as dutch and plain weaves, were used in this experiment. Three kinds of baffle plates with different mesh specifications in the dutch weave and four different kinds in the plain weave were manufactured. Baffles were mounted on bottom wall with varied angles of inclination. Reynolds number was varied from 23,000 to 57,000. It is found that the placement of inclined wire-mesh baffles in the channel affects the heat transfer characteristics by combining both jet impingement and flow disturbance. The wire screen modified the flow structure leading to a change in the heat transfer characteristics. The results show that the baffle plate with the most number of mesh (type SA) has the highest heat transfer rate.

• 한국마린엔지니어링학회:학술대회논문집
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• 한국마린엔지니어링학회 2006년도 전기학술대회논문집
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• pp.45-46
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• 2006

Experimental and numerical analysis on the heat transfer behaviors and the associated frictional loss in a rectangular channel with two inclined perforated baffles($\;5^{\circ}$) mounted on the bottom plate has been systematically performed. The parametric effects of perforated baffles (3, 6, 9 holes) and flow Reynolds number on heat transfer characteristics of the heated target surface are explored. A combination of two baffles of same overall size was considered and the flow Reynolds number for this study is varied between 28,900 and 61,800. Comparisons of the experimental data with the numerical results by commercial code CFX 5.7 are made. As for the investigation of heat transfer behaviors on local Nusselt number with the two baffles installed at $x/D_h=0.8\;and\;x/D_h=8.0$, it is evident that there exist an optimum perforation density to maximize heat transfer coefficients; i.e., the maximum Nusselt number decreases with increasing number of holes.

• 한국전산유체공학회지
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• 제11권4호
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• pp.101-106
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• 2006

In the microfluidic devices the most important thing is mixing efficiency ol various fluids. In this study a newly designed miler is proposed to enhance the mixing effect with the purpose to apply it to microchannel mixing in a short future. This design is composed of a channel with cross baffles periodically arranged on the both bottom and top surfaces ol the channel. To obtain the yow patterns, the numerical computation was performed by using a commercial code, ANSYS CFX 10.0. To evaluate the mixing performance, we computed Lyapunov exponent and obtained Poincare sections. it was shown that our design provides the excellent mixing effect.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2006년도 추계 학술대회논문집
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• pp.159-162
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• 2006

In the microfluidics devices the most important thing is mixing efficiency of various fluids. In this study a newly designed mixer is proposed to enhance the mixing effect with the purpose to apply it to microchannel mixing in a short future. This design is composed of a channel with cross baffles periodically arranged on the both bottom and top surfaces of the channel. To obtain the flow patterns, the numerical computation was performed by using a commercial code, ANSYS CFX 10.0. To evaluate the mixing performance, we computed Lyapunov exponent and obtained Poincare sections.