• Title/Summary/Keyword: sloshing

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A NUMERICAL STUDY ON FLOWS IN A FUEL TANK WITH BAFFLES AND POROUS MEDIA TO REDUCE SLOSHING NOISE (연료탱크 슬로싱 소음 저감을 위한 배플 및 다공성 물질 설치에 따른 유동해석 연구)

  • Lee, Sang-Hyuk;Hur, Nahm-Keon
    • Journal of computational fluids engineering
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    • v.14 no.2
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    • pp.68-76
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    • 2009
  • The sloshing tank causes the instability of the fluid flows and the fluctuation of the impact pressure by the liquid on the tank. These flow characteristics inside the sloshing tank can generate the uncomfortable sloshing noise. In the present study, a numerical analysis for the reduction of a fuel tank sloshing noise was performed. To simulate the flow characteristics in a sloshing tank with partially filled liquid, a VOF method was used for interfacial flows by applying a momentum source term for the sloshing motion in a non-inertial reference frame. This numerical method was verified by comparing its results with the available experimental data. For the reduction of the sloshing noise, the horizontal and vertical baffles and porous media inside a sloshing tank were considered and numerically analyzed in the present study. For various installations of these baffles and porous media, the characteristics of the liquid behavior in the sloshing tank were obtained along with the impact pressure on the wall and the height of the free surface along the wall. These basic results can be used for the design of the actual vehicular fuel tank with the reduced sloshing noise.

Estimation of Sloshing Natural Periods in Liquid Cargo Tanks (액체 화물창내의 SLOSHING 고유주기 산정에 관한 연구)

  • 신장용;최경식;강신영;김현수
    • Journal of Ocean Engineering and Technology
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    • v.8 no.2
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    • pp.93-104
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    • 1994
  • Recently in the design of super tankers or LNG carriers which transport a large amount of liquid in the cargo holds, the structural damage due to liquid sloshing becomes an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a ship. In this paper the sloshing natural periods in liquid cargo tanks are estimated for partially filled tanks with various geometries. Especially the sloshing periods of baffled tanks which are often installed to reduce liquid motion and sloshing forces are calculated. A variational method is adopted to analyze the baffled tank of arbitrary filling depth of liquid. In this approach the liquid domain is divided into several subdomains in which the analytic solutions are potential energy are calculated from the velocity potentials in eachsubdomain. By minimizing the Hamilton's functional, the sloshing natural periods are estimated and the results are compared with experimental and numerical results.

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Study on Sloshing Behaviors in Liquid Storage Tank with Rectangular Cross Section (사각단면 액체저장탱크에서의 슬로싱 거동 연구)

  • 윤성호;이은동;박기진
    • Proceedings of the Korean Society of Precision Engineering Conference
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    • 2003.06a
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    • pp.1087-1090
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    • 2003
  • In this study, experimental procedures were suggested to investigate the sloshing behavior of a liquid storage tank subjected to inevitably external vibrating conditions. For this purpose. liquid storage tank with rectangular cross section was made of an acrylic resin for the visualization of liquid fluctuation. A specially designed vibrator was used to provide a specified vibrating condition to the liquid storage tank. Extrapolation technique was applied to determine sloshing natural frequency by using various sloshing frequencies at each vibrating displacement and liquid contents at a fixed vibrating frequency. Sloshing mode was also determined from continuous images or liquid fluctuation captured from a video camera. In addition, change in the height of the liquid free surface was measured by using a floating target and a laser displacement sensor. It is found that the suggested method can be applicable to identify the sloshing behavior of liquid storage tank with rectangular cross section.

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Design of Optimal Attitude Controller for a Launch Vehicle Using Sloshing Filter (슬로싱 필터를 이용한 발사체의 최적 자세제어기 설계)

  • Kim, Dong-Hyun;Choi, Jae-Weon
    • Proceedings of the KSME Conference
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    • 2000.11a
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    • pp.584-589
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    • 2000
  • When the liquid tanks only partially filled and under translational acceleration, large quantities of liquid move uncontrollably inside the tanks and generate the liquid sloshing effect. Liquid sloshing effect could be a severe problem in launch vehicle stability and control if the liquid modes of motion couple significantly with the launch vehicle's normal modes of motion. Several methods have been employed to reduce the effect of sloshing, such as introducing baffles inside the tanks or dividing a large tank into a number of smaller ones. These techniques, although helpful in some cases, do not succeed in canceling the sloshing effects. In this paper, An attitude controller is designed for a launch vehicle with liquid sloshing effect. Both PD controller and sloshing filter are designed for the objective. PD gains and design parameters are determined by optimal algorithm. The performance of the attitude controller is evaluated via computer simulations.

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Analysis of Natural Periods of Sloshing and Control of Sloshing Effect for a Launch Vehicle (슬로싱 고유주기 해석 및 발사체의 슬로싱 효과 제어)

  • 김동현;최재원
    • 제어로봇시스템학회:학술대회논문집
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    • 2000.10a
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    • pp.201-201
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    • 2000
  • Recently in the design of fuel tanks(launch vehicle, ship, automobile) which transport a large amount of liquid in the cargo holds, the structural damage due to liquid-sloshing becomes an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a system. In this paper, the sloshing natural periods in liquid tanks are estimated for partially filled tanks with various geometries. In addition to, controlled for a launch vehicle with liquid sloshing effect by PD controller and sloshing filter The PD gain and sloshing filter parameter arc determined by optimal algorithm.

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A NUMERICAL ANALYSIS OF THE SLOSHING IN A TANK WITH PLATE/POROUS BAFFLES (판형 및 다공형 배플을 포함한 탱크 내 슬로싱에 대한 유동해석)

  • Lee, Sang-Hyuk;Hur, Nahm-Keon
    • 한국전산유체공학회:학술대회논문집
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    • 2009.04a
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    • pp.215-222
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    • 2009
  • In the present study, a numerical analysis on the sloshing in a tank with the harmonic motion was investigated. A VOF method was used for two-phase flows inside the sloshing tank and a source term of the momentum equation was applied for the harmonic motion. This numerical method was verified by comparing its results with the available experimental data. The sloshing in a tank causes the instability of the fluid flows and the fluctuation of the impact pressure on the tank. By these phenomena of the tank sloshing, the sloshing problems such as the failure and the noise of system can be generated. For the reduction of these sloshing problems, the various baffles such as the horizontal/vertical plate baffles and the porous baffles inside the tank are installed. With the installations of these baffles, the characteristics of the liquid behavior in the sloshing tank, the impact pressure on the wall, the amplitude of the free surface near the wall and the sloshing noise were numerically analyzed.

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Effects of boundary layer and liquid viscosity and compressible air on sloshing characteristics

  • Zou, Chang-Fang;Wang, De-Yu;Cai, Zhong-Hua
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.7 no.4
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    • pp.670-690
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    • 2015
  • In this paper, numerical investigations for tank sloshing, based on commercial CFD package FLUENT, are performed to study effects of boundary layer grid, liquid viscosity and compressible air on sloshing pressure, wave height and rising time of impact pressure. Also, sloshing experiments for liquids of different viscosity are carried out to validate the numerical results. Through comparison of numerical and experimental results, a computational model including boundary layer grid can predict the sloshing pressure more accurately. Energy dissipation due to viscous friction leads to reduction of sloshing pressure and wave elevation. Sloshing pressure is also reduced because of cushion effect of compressible air. Due to high viscosity damping effect and compressible air effect, the rising time of impact pressure becomes longer. It is also found that liquid viscosity and compressible air influence distribution of dynamic pressure along the vertical tank wall.

An Analytic Solution to Sloshing Natural Periods for a Prismatic Liquid Cargo Tank with Baffles (내부재가 설치된 직육면체 화물창 내의 Sloshing 고유주기 산정)

  • Shin, Jang-Ryong;Choi, Kyung-Sik;Kang, Sin-Young
    • Journal of Ocean Engineering and Technology
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    • v.19 no.6 s.67
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    • pp.16-21
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    • 2005
  • In the design of super tankers or LNG carriers, which transport a large amount of liquid in the cargo tanks, the structural d11mage due to liquid sloshing is an important problem. The impact pressure from sloshing is most violent when the liquid motion of a partially filled tank is in resonance with the motion of a ship. In this study, the sloshing natural periods of a baffled tank, often installed to reduce liquid motion, is analyzed. A variational method is adopted to estimate the sloshing natural periods for a prismatic cargo tank with baffles of arbitrary filling depth of liquid; the results are compared with Lloyd's Register regulations on sloshing periods. In this study, using an effective liquid-fill-depth concept, sloshing periods for a baffled tank can be expressed by the same form as rectangular prismatic tanks without baffles. In contrast to Lloyd's Register regulations, which can be applicable only to cargo tanks with constant baffle size and distribution, the present results can be applicable to cases of variable baffle size and distribution.

Sloshing characteristics of an annular cylindrical tuned liquid damper for spar-type floating offshore wind turbine

  • Jeon, S.H.;Seo, M.W.;Cho, Y.U.;Park, W.G.;Jeong, W.B.
    • Structural Engineering and Mechanics
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    • v.47 no.3
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    • pp.331-343
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    • 2013
  • The natural sloshing frequencies of annular cylindrical TLD are parametrically investigated by experiment, aiming at the exploration of its successful use for suppressing the structural vibration of spar-type floating wind turbine subject to multidirectional wind, wave and current excitations. Five prototypes of annular cylindrical TLD are defined according to the inner and outer radii of acryl container, and eight different liquid fill heights are experimented for each TLD prototype. The apparent masses near the first and second natural sloshing frequencies are parametrically investigated by measuring the apparent mass of interior liquid sloshing to the acceleration excitation. It is observed from the parametric experiments that the first natural sloshing frequency shows the remarkable change with respect to the liquid fill height for each TLD model with different container dimensions. On the other hand, the second natural sloshing frequency is not sensitive to the liquid fill height but to the gap size, for all the TLD models, convincing that the annular cylindrical sloshing damper can effectively suppress the wave- and wind-induced tilting motion of the spar-type floating wind turbine.

Simple analytical method for predicting the sloshing motion in a rectangular pool

  • Park, Won Man;Choi, Dae Kyung;Kim, Kyungsoo;Son, Sung Man;Oh, Se Hong;Lee, Kang Hee;Kang, Heung Seok;Choi, Choengryul
    • Nuclear Engineering and Technology
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    • v.52 no.5
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    • pp.947-955
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    • 2020
  • Predicting the sloshing motion of a coolant during a seismic assessment of a rectangular spent fuel pool is of critical concern. Linear theory, which provides a simple analytical method, has been used to predict the sloshing motion in rectangular pools and tanks. However, this theory is not suitable for the high-frequency excitation problem. In this study, the authors developed a simple analytical method for predicting the sloshing motion in a rectangular pool for a wide range of excitation frequencies. The correlation among the linear theory parameters, influencing on excitation and convective waves, and the excitation frequency is investigated. Sloshing waves in a rectangular pool with several liquid heights are predicted using the original linear theory, a modified linear theory and computational fluid dynamics analysis. The results demonstrate that the developed method can predict sloshing motion over a wide range of excitation frequencies. However, the developed method has the limitations of linear solutions since it neglects the nonlinear features of sloshing motion. Despite these limitations, the authors believe that the developed method can be useful as a simple analytical method for predicting the sloshing motion in a rectangular pool under various external excitations.