• 제목/요약/키워드: Sloshing effect

검색결과 105건 처리시간 0.024초

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

  • 김동현;최재원
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2000년도 추계학술대회논문집A
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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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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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    • 제7권4호
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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.

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

  • 김동현;최재원
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 2000년도 제15차 학술회의논문집
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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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Experimental study and numerical modeling of liquid sloshing damping in a cylindrical container with annular and sectorial baffles

  • Mohammadi, Mohammad Mahdi;Moosazadeh, Hamid
    • 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.

Numerical investigation on the effect of baffles on liquid sloshing in 3D rectangular tanks based on nonlinear boundary element method

  • Guan, Yanmin;Yang, Caihong;Chen, Ping;Zhou, Li
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제12권1호
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    • pp.399-413
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    • 2020
  • The numerical simulation of liquid sloshing in the three-dimensional tanks under horizontal excitation and roll excitation was carried out, and the inhibition effect of different baffles on the sloshing phenomenon was investigated. The numerical calculations were carried out by the nonlinear Boundary Element Method (BEM) with Green's theorem based on the potential flow, which was conducted with the governing equation corresponding to the boundaries of each region. The validity of the method was verified by comparing with experimental values and published literatures. The horizontal baffle, the vertical baffle and the T-shaped baffle in the sloshing tanks were investigated respectively, and the baffles' position, dimension and the liquid depth were provided and discussed in detail. It is drawn that the baffle shape plays a non-negligible role in the tank sloshing. The vertical baffle is a more effective way to reduce the sloshing amplitude when the tank is under a horizontal harmonic excitation while the horizontal baffle is a more effective way when the tank is under a roll excitation. The amplitude of free surface elevation at right tank wall decreases with the increasing of the horizontal baffle length and the vertical baffle height. Although the T-shaped baffle has the best suppression effect on tank sloshing under horizontal excitation, it has limited suppression effect under roll excitation and will complicate the sloshing phenomenon when changing baffle height.

얼리지 압력이 2차원 슬로싱 실험에 미치는 영향에 관한 연구 (A Study on Ullage Effect in 2-D Sloshing Experiment)

  • 최후인;권순홍;이상범;이기현;박정호
    • 한국해양공학회지
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    • 제26권1호
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    • pp.54-59
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    • 2012
  • This study presents investigation on ullage effect in sloshing experiment. The experiment was done with two dimensional tank. Sloshing experiments were carried out in the tank with 6 different ullage pressures. The tested filling ratio was 30% of the tank height. The flow field was recorded with high speed camera. The sloshing impact pressure were measured at 18 locations. It was shown that the variation of ullage pressures influences the magnitude of pressure and flow field. This study demonstrated the importance of ullage pressure in sloshing test.

선수파 중 슬로싱을 고려한 병렬배치된 두 부유체의 거동 특성에 관한 실험 연구 (Experimental Study of Motion Behavior of Side-by-Side Moored Two Floating Bodies Including Sloshing in Head Sea)

  • 조석규;성홍근;홍장표;홍사영;홍석원
    • 한국해양공학회지
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    • 제26권6호
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    • pp.46-52
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    • 2012
  • The motions and drift forces of side-by-side moored FSRU and LNGC including the sloshing effect, were studied using experiments. The FSRU and LNGC contained LNG cargo tanks and the LNG sloshing could affect the motions and drift forces of the structures due to its coupling with floating body motion. The effect of coupling can vary with the LNG filling level, and the effect of the filling level was investigated. The coupling effect was stronger at lower filling level. It was confirmed that longitudinal sloshing influenced the surge and surge mean drift force in head sea. In addition, gap flow affected the sway and mean drift forces. Sloshing attenuated the sway and yaw excited by gap flow in side-by-side configuration.

유체 슬로싱모드가 탱크의 진동에 미치는 영향에 대한 연구 (A Study on Vibration Characteristics with Sloshing Mode Effect in Water Tank Structure)

  • 배성용
    • 대한조선학회논문집
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    • 제40권6호
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    • pp.88-95
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    • 2003
  • Liquid storage rectangular tank structures are used in many fields of airplane and marine engineering. Fatigue damages are sometimes observed in these tanks which seem to be caused by resonance. Therefore it is essentially important to estimate vibration characteristics of tank structures. Many Investigators studied the vibration of cylindrical and rectangular tank structures containing still fluid. In general, the eigenbehavior of interior liquid is characterized by the sloshing mode while that of the structure by the bulging mode. However, the structure deformation to the sloshing mode and the liquid free-surface fluctuation to the bulging mode have been neglected in the classical added-mass computation. in the present paper, we study the vibration characteristics with sloshing mode effect.

사각통에서의 슬로싱에 대한 전산유체역학적 연구 (A Computational Fluid Dynamics Analysis on Sloshing in Rectangular Tank)

  • 곽영균;이영신;고성호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2002년도 학술대회지
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    • pp.99-102
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    • 2002
  • The present study describes a numerical analysis for simulation of the sloshing of flows with free-surface which contained in a rectangular tank The SOLA-VOF (Volume of fluid) method uses a fixed mesh for calculating the motion of flow and the free-surface. This Eulerian approach enables the VOF method to use only a small amount of computer memory for simulating sloshing problems with complicated free-surface contours. The VOF function, representing the volume fraction of a cell occupied by the fluid, is calculated for each cells, which gives the locating of the free-surface filling any some fraction of cells with fluid. Using SOLA-VOF method, the study describes visualization about simulation of the sloshing of flows and damping effect by baffle. Translation and pitching motion of the forms have been investigated The time-dependent changes of free-surface height are used for visualization subject to several conditions such as fluid height horizontal acceleration, sinusoidal motion, and viscosity. The free-surface heights were used for comparing wall-force, which is caused by sloshing of flows. Baffle was Installed to reduce the force on the wall by sloshing of flows. Damping effects was extensively expressed under the conditions such as baffle shape and position.

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Study on sloshing simulation in the independent tank for an ice-breaking LNG carrier

  • Ding, Shifeng;Wang, Gang;Luo, Qiuming
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제12권1호
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    • pp.667-679
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    • 2020
  • As the LNG carrier operates in ice covered waters, it is key to ensure the overall safety, which is related to the coupling effect of ice-breaking process and internal liquid sloshing. This paper focuses on the sloshing simulation of the ice-breaking LNG carrier, and the numerical method is proposed using Circumferential Crack Method (CCM) and Volume of Vluid (VOF) with two main key factors (velocity νx and force Fx). The ship motion analysis is carried out by CCM when the ship navigates in the ice-covered waters with a constant propulsion power. The velocity νx is gained, which is the initial excitation condition for the calculation of internal sloshing force Fx. Then, the ship motion is modified based on iterative computations under the union action of ice-breaking force and liquid sloshing load. The sloshing simulation under the LNG tank is studied with the modified ship motion. Moreover, an ice-breaking LNG ship with three-leaf type tank is used for case study. The internal LNG sloshing is simulated with three different liquid heights, including free surface shape and sloshing pressure distribution at a given moment, pressure curves at monitoring points on the bulkhead. This present method is effective to solve the sloshing simulation during ice-breaking process, which could be a good reference for the design of the polar ice-breaking LNG carrier.