• Title, Summary, Keyword: Longitudinal baffle

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Evaluation of the Effects of the Longitudinal Baffle on Settling Efficiency within Rectangular-shaped Sedimentation Basin (장방형 침전지내 도류벽의 침전효율에 대한 영향 평가)

  • Park, No-Suk;Kim, Seong-Su;Seo, In-Seok;Min, Kyong-En
    • Journal of Korean Society of Water and Wastewater
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    • v.23 no.5
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    • pp.573-581
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    • 2009
  • In the case that the average velocity within rectangular-shaped sedimentation basin is less than 1.5cm/sec, and Froude number less than $10^{-6}$, it can not be expected that the longitudinal baffle improves the sedimentation efficiency. Also, since relatively lower velocity increases the effect of geostrophic body force, asymmetric flow pattern on a plane occurs within the basin. From the results of CFD (Computational Fluid Dynamics) simulation, in the case that the highest velocity within rectangular-shaped sedimentation basin is over 1.5cm/sec, and Froude number over $10^{-6}$, it can be expected that the longitudinal baffle installed within rectangular-shaped sedimentation basin improves the sedimentation efficiency.

Evaluation of the Effect of Sedimentation Basin Structure on Hydrodynamic Behavior using CFD(I): The Effect of Longitudinal Baffle (CFD를 이용한 침전지 구조가 수리거동에 미치는 영향 평가(I): 도류벽의 영향)

  • Park, Se-Jin;Park, No-Suk;Lim, Jae-Lim;Kim, Sun-Kyu;Kim, Sug-Goo;Mun, Yong-Taek;Bang, Ki-Woong
    • Journal of Korean Society of Water and Wastewater
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    • v.20 no.5
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    • pp.667-676
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    • 2006
  • This study was conducted to evaluate the effect of longitudinal baffle on hydrodynamic behavior within a certain full-scale sedimentation basin (flow rate per basin; $1,000m^3/d$). Comparative experimental investigations have been carried out on the sediment removal efficiencies and the sludge deposit distribution in the baffled and un-baffled sedimentation basin, respectively. From the results derived in the baffled and un-baffled sedimentation, the turbidity removal rate in the baffled sedimentation basin is about 38% higher than that in un-baffled. Also, the height of sludge deposit in the baffled sedimentation basin is approximately 20% lower, and the sludge concentration is 10% higher than those in un-baffled sedimentation basin. In order to explain the experimental results and investigate the effect of longitudinal baffle in more detail, we conducted Computational Fluid Dynamics (CFD) simulation. From the results of CFD simulation, the flow, especially in the near of outlet orifice, was more stable in the case of longitudinal baffled sedimentation basin than that in un-baffled basin. Also, it could be concluded that the longitudinal baffle made a fully developed flow more effective for sedimentation.

The Remodelling of Hydraulic Structure in a Distribution Channel for Improving the Equality of the Flow Distribution (II): Optimization through Wet Tests (수리구조 개선을 통한 분배수로 균등분배 성능 향상에 관한 연구(II): Pilot plant 실험을 통한 최적화)

  • Park, No-Suk;Kim, Seong-Su;Hwang, Jun-Sick;Im, Jae-Rim;Kim, Chung-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.5
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    • pp.581-587
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    • 2007
  • In order to suggest the methodology for improving the equality of flow distribution in a distribution channel, wet tests were carried out for pilot plant which was scaled down to 1/8 of full scale distribution channel being operated in domestic K_water treatment plant. The correlation between various hydraulic variables and their effects on the equality of flow distribution was evaluated through wet tests using pilot plant. From the results of wet tests, the longitudinal baffle with orifices was installed in the distribution channel, the equality of flow distribution was improved on the condition that the Froude number in pilot plant was similar with that in the full scale channel. Also, the opening ratio of the orifices on the longitudinal baffled did not have influence on the performance of the equality of flow distribution when the average flow velocity and Froud number were relatively low (Froude number ${\fallingdotseq} 0.01$). In the other hand, the performance of the equality of flow distribution was improved with increasing the opening ration of on the longitudinal baffle under conditions of relatively high average flow velocity and high Froud number(${\gtrsim}0.1$)

Finite Element Analysis of Sloshing Eigen Behavior in Horizontal Baffled Fuel Tank (수평으로 놓인 배플형 연료탱크의 슬로싱 고유거동에 관한 유한요소 해석)

  • 조진래;하세윤;이홍우;박태학;이우용
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.15 no.4
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    • pp.619-628
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    • 2002
  • This paper deals with the FE analysis for the free vibration of sloshing in horizontal cylindrical tank with baffles. We use Laplace equation based on potential theory as governing equation. This problem is solved by FEM using lineal isoparametric elements. We assume that the tank as well as baffles is rigid body and by separating nodes into two at the baffle location, baffle effect is obtained by separating nodes into two at the baffle location. For the calculation of natural frequencies and mode shapes, we introduce Lanczos transformation and Jacobi iteration methods. Numerical results of the first longitudinal and transverse modes, while comparing with literature cited, are very good. In order for the baffle effects on the free vibration of sloshing, various combinations of baffle parameters, which are location, inner diameter and number, are examined.

Numerical Analysis of Performance and Combustion Characteristics in a liquid Propellant Rocket Engine with baffle (배플을 장착한 액체 추진제 로켓엔진의 성능 및 연소 특성 해석)

  • 문윤완;김영목
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.4-5
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    • 2002
  • 로켓 엔진의 개발에 있어 성능과 수명(life time)에 가장 문제가 되는 것은 연소 안정성에 있다. 일반적으로 연소 불안정을 야기시키는 것은 3가지로서 축방향(longitudinal), 반경방향(radial)과 접선방향(longitudinal) 모드(mode)가 있다. 이와 같은 모드를 제어하는 방법에는 수동적 제어방법으로 음향공(acoustic cavity)과 배플(baffle)이 있으며, 음향공은 모드에 관계없이 특정한 주파수에 맞추어 체적을 조절하여 음향파(acoustic wave)를 감쇄시키는 것이고 배플은 주파수에 관계없이 접선방향 모드를 제어하는 것이 기본 목적이나 허브(hub)를 설치하여 반경방향 모드까지 제어할 수 있다. 음향공은 엔진의 성능 또는 연소장에는 영향을 주지 않고 작동하는 반면, 배플은 초기 엔진설계를 할 때 고려하지 않으면 후에 배플을 장착하였을 때는 초기 설계의 제한 때문에 장착의 어려움과 성능 및 연소장에 영향을 미쳐 원하지 않는 엔진의 시험 결과를 야기할 수 있다. 본 연구에서는 KSR-III와 동일한 조건의 연소기에서 다양한 배플을 장착하였을 경우에 대하여 성능과 연소장에 대하여 예측하였다.

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Evaluation of the Effect of Sedimentation Basin Structure on Hydrodynamic Behavior Using CFD (II): The Effect of Trough (CFD를 이용한 침전지 구조가 수리거동에 미치는 영향 평가(II): 트라프의 영향 중심으로)

  • Park, No-Suk;Lim, Jae-Lim;Lee, Sun-Ju;Kwon, Soon-Bum;Min, Jin-Hui
    • Journal of Korean Society of Water and Wastewater
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    • v.19 no.6
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    • pp.758-766
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    • 2005
  • This study was conducted to evaluate the effect of the transverse troughs on hydrodynamic behavior within the a certain full-scale sedimentation basin (flow rate/one basin; $10,000m^3/d$) using CFD simulation and ADV technique. In order to verify the CFD simulation, we measured the factual velocity at 36 points in the full-scale sedimentation basin, whose outlet structure is inadequate, with ADV technique. Both the CFD simulation and the ADV measurement results were in good accordance with each other. From the CFD simulation results of the existing basin, it was investigated that extreme upward flow occurs in the near of two transverse troughs. It was suspected that since the transverse troughs converted the open channel flow into the local closed pipe flow, the increased pressure in this local closed pipe flow region made the extreme upward flow. For solving this problems, it was suggested to modify transverse-typed launder into finger-typed launder and to install a longitudinal baffle in the center in this study. The CFD simulation results of all suggested amendments told us that the extreme upward flow, had occurred especially in the beneath of transverse troughs, was much less in the case of finger typed launder basin than that in the existing basin. Also, it was predicted that installing a longitudinal baffle made the fully developed flow which is more effective for sedimentation.

The Remodelling of Hydraulic Structure in a Distribution Channel for Improving the Equality of the Flow Distribution (I): Design Using CFD Simulation (수리구조 개선을 통한 분배수로 균등분배 성능 향상에 관한 연구(I) : CFD를 이용한 설계 중심으로)

  • Park, No-Suk;Kim, Seong-Su;Park, Jong-Yoon;Yoon, Cheol-Hwan;Kim, Chung-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.21 no.5
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    • pp.571-579
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    • 2007
  • This study was conducted to qualify the equality of the flow distribution from open channel between rapid mixing basin and flocculation basins in a domestic full-scale water treatment plant, and suggest a remedy for improving the equality. In order to evaluate the feasibility of the suggested remedy, computational fluid dynamics (CFD) technique are used, and for verifying the CFD simulation results wet tests were carried out for the pilot scale channel based on geometric similarity. From the results of CFD simulation and wet tests, it was investigated that the modification of hydraulic structure in the distribution channel, which is to install the longitudinal orifice baffle in flow direction, could improve the equality of the flow distribution. Also, in the case that Froude number is relatively small (Froude number <<0.03), the open ratio of orifices on the installed baffle hardly affects the equality of flow distribution.

Examining the Equality of Multi-Outlet Flow Rates within a Dual Open Channel (이중 수로 구조의 분배수로 내 다지점 유출 유량의 균등성 평가에 관한 연구)

  • Kim, Seong-Su;Park, No-Suk;Jeong, Woo-Chang;Wang, Chang-Keun
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.3
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    • pp.423-430
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    • 2012
  • This study was conducted to qualify the equality of the flow distribution from open channel between rapid mixing basin and flocculation basins in a domestic S_ water treatment plant, and to suggest a remedy for improving the equality. In order to evaluate the feasibility of the suggested remedy, computational fluid dynamics (CFD) technique are used, and for verifying the CFD simulation results tracer tests were carried out. From the results of CFD simulation and tracer tests, it was investigated that the modification of hydraulic structure in the distribution channel, which is to install the longitudinal orifice baffle in flow direction, could improve the equality of the flow distribution over 75%.

Study for Flow Phenomenon in the Circulation Water Pump Chamber using the Flow-3D Model (Flow-3D 모형을 이용한 순환수취수펌프장 내 흐름현상 연구)

  • Ha, Sung-Won;Kim, Tae-Won;Choi, Joo-Hwan;Park, Young-Jin
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.4
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    • pp.580-589
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    • 2019
  • Indonesia has a very short supply of electricity. As a solution to this problem, plans for construction of thermal power plants are increasing. Thermal power plant require the cooling water system to cool the overheated engine and equipment that accompany power generation, and the circulation water pump chamber among the cooling water system are generally designed according to the ANSI (1998) standard. In this study, the design criterion $20^{\circ}$ for the spreading angle of the ANSI (1998) of the layout of the circulating water pump chamber can not be satisfied on the K-coal thermal power plant site condition in Indonesia. Therefore, 3-D numerical model experiment was carried out to obtain a hydraulically stable flow and stable structure. The Flow-3D model was used as numerical model. In order to examine the applicability of the Flow-3D model, the flow study results around the rectangular structure of Rodi (1997) and the numerical analysis results were compared around the rectangular structures. The longitudinal velocity distribution derived from numerical analysis show good agreement. In order to satisfy the design velocity in the circulating water pump chamber, a rectangular baffle favoring velocity reduction was applied. When the approach velocity into the circulating water pump chamber was occurred 1.5 m/s ~ 2.5 m/s, the angle of the separation flow on the baffle was occurred about $15^{\circ}{\sim}20^{\circ}$. By placing the baffle below the separation flow angle downstream, the design velocity of less than 0.5 m/s was satisfied at inlet bay.

The Experimental Study on the Heat Transfer Characteristics (가스보일러 코일형 열교환기의 열전달 특성에 관한 실험적 연구)

  • Hong, S.H.;Kim, Y.K.;Kim, I.G.;Kim, D.C.;Lee, C.E.;Yim, C.S.
    • Solar Energy
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    • v.17 no.4
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    • pp.57-66
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    • 1997
  • The performance of gas-fired boilers were experimentally investigated. The heat exchanger used for the experiments consisted of circular tube with longitudinal fins for the gas side and a spiral coil for the water side. The burner was located at the top of the heat exchanger, and the burned gas flowed down to the exit. The experiments carried out for different water flow rates, the heat capacities of the boiler and the number of baffle. The thermal efficiency of the upward flow was higher than that of the downward flow of the water in the heat exchanger. As the boiler capacity increased, the thermal efficiency decreased. As the number of the baffles increase, the thermal efficiency increased and the increasing rate of the efficiency decreased. The gas-side overall heat transfer coefficient was independent of the flow rate of the water. The effect of the number of the baffles on the heat transfer coefficient was greater than that of the boiler capacity.

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