Investigation Of Sloshing Impact Loads In Large Ship Tank

As the capacity of ship tank has been dramatically increased, liquid sloshing with partially filling level can result in significant impact loads on tank structure. Impact lodas induced by sloshing can cause high tank wall structure dynamic response. So sloshing impact loads is a key issue in the structure design of large voume liquid tank.The large-scale sloshing model experimental method which can truly reveal the process of liquid sloshing in tank is the most reliable approach to determine impact loads. A well-equipped experimental method was set up in order to estimate the loads accurately and reliably in this paper. Hexapod test rig, large-scale model tank, pressure measurement system and statistical post-processing method were employed. A series of model tests in both2D rectangular tank and2D prismatic tank subjected to regular and irregular excitation were performed on the hexapod test rig, respectively. There are two primary aspects of this paper:load mechanism study and engineering application.The load mechanism study focuse on the sloshing physical phenomenon, influence parameters (excitation amplitude, period and filling level of the tank), spatial and temporal distribution as well as statistical analysis of sloshing impact loads in mechanism study. Rise time,duration and skweness distribution of the impact loads are investigated in the statistical analysis. The experimental results show that different sloshing phenomenon in the tank can cause different impact loads pattern and the loads are sensitive to tank excitation amplitude, period and filling level; The impact loads perform linear correlation both in the vertical and horizontal direction below the impact areas; The rise time and duration of impact loads are milliseconds which show some certain properties.Design sloshing loads for membrane-type CCS (cargo contain system) tank structural design are also investigated. It focuse on the application of both impact loads impulse and rise time in structural design. An idealized triangular design loads and prototype pressure in a real tank by Froude scaling are presented. It is reported that a short rise time for high pressure peaks which can induce large structural dynamic response. The prototype pressure obetained by Froude scaling is conservative and some further investigation should be carried out.