The angle compensation method is adopted to detect sloshing waves by laser diffraction, in the case that the wavelength of the sloshing waves is much greater than that of the incident light. The clear diffraction patt...The angle compensation method is adopted to detect sloshing waves by laser diffraction, in the case that the wavelength of the sloshing waves is much greater than that of the incident light. The clear diffraction pattern is observed to be of asymmetry, involving orders, position and interval of the diffraction spots that are discovered during the light grazing incidence. It is found that the larger the angle of incidence is, the more obvious the asymmetry is. The higher the negative diffraction orders are, the smaller the intervals between spots are. On the contrary~ in the positive region, the higher the diffraction orders are, the larger the spot intervals are. The positive interval is larger than that of the same negative diffraction order. If the incident angle reaches 1.558 rad in the experiment, all positive diffraction orders completely vanish. Based on the mechanism of phase modulation and with the Fourier transform method, the relations between the incident angle and position, interval spaces, and orders of diffraction spots are derived theoretically. The theoretical calculations are compared with the experimental data, and the comparison shows that the theoretical calculations are in good agreement with the experimental measurement.展开更多
Tank sloshing in ship cargo is excited by ship motions, which induces impact load on tank wall and then affects the ship motion. Wave forces acting on ship hull and the retardation function are solved by using three-d...Tank sloshing in ship cargo is excited by ship motions, which induces impact load on tank wall and then affects the ship motion. Wave forces acting on ship hull and the retardation function are solved by using three-dimensional frequency domain theory and an impulse response function method based on the potential flow theory, and global ship motion is examined coupling with nonlinear tank sloshing which is simulated by viscous flow theory. Based on the open source Computational Fluid Dynamics （CFD） development platform Open Field Operation and Manipulation （OpenFOAM）, numerical calculation of ship motion coupled with tank sloshing is achieved and the corresponding numerical simulation and validation are carried out. With this method, the interactions of wave, ship body and tank sloshing are completely taken into consideration. This method has quite high efficiency for it takes advantage of potential flow theory for outer flow field and viscous flow theory for inside tank sloshing respectively. The numerical and experimental results of the ship motion agree well with each other.展开更多
Liquid sloshing in tanks is a very complex nonlinear free surface fluid flow problem,which must be considered in most of the marine engineering problems such as naval architecture,offshore engineering and so on.Violen...Liquid sloshing in tanks is a very complex nonlinear free surface fluid flow problem,which must be considered in most of the marine engineering problems such as naval architecture,offshore engineering and so on.Violent liquid sloshing in large containers can damage the tank structure due to the direct liquid impacting action.Sloshing also affects the capsizing process of the liquid cargo ship.Some works on mitigating sloshing by using all kinds of the baffles were thus followed with interests.Oil layers with thinner thickness were shown to reduce the sloshing load of water in tanks.The sloshing characteristics in tanks with different sizes were different,therefore,scaling effect of sloshing should also be considered.Sloshing in a tank can also be used as tuned liquid dampers(TLDs)to dampen wind,wave and flow-induced motions of floating or fixed marine platforms.This paper present an overview on recent advances of liquid sloshing hydrodynamics including sloshing mitigation by using anti-sloshing baffle,layered fluids sloshing,scaling effect of sloshing and TLDs.展开更多
基金Supported by the Open Research Fund of State Key Laboratory of Transient Optics and Photonics of Chinese Academy of Sciences under Grant No SKLST201508the China Postdoctoral Science Foundation Funded Project under Grant No 2015M580945the Government of Chaoyang District Postdoctoral Research Foundation
文摘The angle compensation method is adopted to detect sloshing waves by laser diffraction, in the case that the wavelength of the sloshing waves is much greater than that of the incident light. The clear diffraction pattern is observed to be of asymmetry, involving orders, position and interval of the diffraction spots that are discovered during the light grazing incidence. It is found that the larger the angle of incidence is, the more obvious the asymmetry is. The higher the negative diffraction orders are, the smaller the intervals between spots are. On the contrary~ in the positive region, the higher the diffraction orders are, the larger the spot intervals are. The positive interval is larger than that of the same negative diffraction order. If the incident angle reaches 1.558 rad in the experiment, all positive diffraction orders completely vanish. Based on the mechanism of phase modulation and with the Fourier transform method, the relations between the incident angle and position, interval spaces, and orders of diffraction spots are derived theoretically. The theoretical calculations are compared with the experimental data, and the comparison shows that the theoretical calculations are in good agreement with the experimental measurement.
文摘Tank sloshing in ship cargo is excited by ship motions, which induces impact load on tank wall and then affects the ship motion. Wave forces acting on ship hull and the retardation function are solved by using three-dimensional frequency domain theory and an impulse response function method based on the potential flow theory, and global ship motion is examined coupling with nonlinear tank sloshing which is simulated by viscous flow theory. Based on the open source Computational Fluid Dynamics （CFD） development platform Open Field Operation and Manipulation （OpenFOAM）, numerical calculation of ship motion coupled with tank sloshing is achieved and the corresponding numerical simulation and validation are carried out. With this method, the interactions of wave, ship body and tank sloshing are completely taken into consideration. This method has quite high efficiency for it takes advantage of potential flow theory for outer flow field and viscous flow theory for inside tank sloshing respectively. The numerical and experimental results of the ship motion agree well with each other.
基金Projects supported by the National Natural Science Foundation of China(Grant No.52171256).
文摘Liquid sloshing in tanks is a very complex nonlinear free surface fluid flow problem,which must be considered in most of the marine engineering problems such as naval architecture,offshore engineering and so on.Violent liquid sloshing in large containers can damage the tank structure due to the direct liquid impacting action.Sloshing also affects the capsizing process of the liquid cargo ship.Some works on mitigating sloshing by using all kinds of the baffles were thus followed with interests.Oil layers with thinner thickness were shown to reduce the sloshing load of water in tanks.The sloshing characteristics in tanks with different sizes were different,therefore,scaling effect of sloshing should also be considered.Sloshing in a tank can also be used as tuned liquid dampers(TLDs)to dampen wind,wave and flow-induced motions of floating or fixed marine platforms.This paper present an overview on recent advances of liquid sloshing hydrodynamics including sloshing mitigation by using anti-sloshing baffle,layered fluids sloshing,scaling effect of sloshing and TLDs.
