Liquid Sloshing Experiment And Equivalent Mechanical Model Parameter Identification Research In Spherical Tank

With the rapid development of Chinese industry,the demand for liquid fuel and raw materials is increasing,and the problem of liquid sloshing in the storage tank is widespread in aerospace,oil and gas transportation on road,nuclear power engineering and other fields.From the perspective of engineering,the complex non-linear motion presented by the liquid sloshing in the tank and the resulting unbalanced slosh force and the slosh moment have an important influence on the stability and safety of the tank and its related structures.This paper focuses on the liquid sloshing problem in a spherical tank,and the effect of horizontal and lateral external excitation on the liquid sloshing in the tank is mainly considered.An liquid sloshing experimental platform was built in order to accurately measure the sloshing force and the sloshing moment and the calculation method of data processing was deduced.Through analysing a large number data of sloshing experiments,the liquid sloshing behavior characteristics under different working conditions are studied.Based on the experimental data,the CFD simulation software was used to simulate the results,and the results were compared with the experiment to further verify the accuracy and reliability of the experiment.The specific work is as follows:(1)Based on the fluid dynamics theory,the basic equations of liquid sloshing and the governing equations of the boundary surface are given.Based on the principle of equivalence,the liquid sloshing in the liquid storage tank is equivalent to a first-order pendulum model.Finally,the identification principle of least square method is deduced,which lays a foundation for the parameter identification of liquid sloshing system in the following parts.(2)Considering the lateral external excitation effect on the liquid sloshing in the spherical tank,taking the efficient and accurate measurement of sloshing force and sloshing moment as a technical method,based on the basic theory of liquid sloshing dynamics,a real-time data acquisition and analysis for liquid sloshing force and sloshing moment of experimental platform was designed and experiments data processing and calculating method for sloshing force and sloshing moment is also deduced according to the design principle;A large number of liquid sloshing experiments under different working conditions are carried out to study the sloshing behavior characteristics through the experimental phenomena and experimental data,which provides reliable experimental data and research basis for the further study of the real-time online measurement of liquid sloshing dynamic characteristics,sloshing state identification,sloshing suppression and other related issues.(3)Based on the actual experimental data,the commercial finite element CFD software was used for simulation analysis.At the same time,the simulation results of various working conditions are compared with the experimental results,so as to further verify the accuracy and reliability of the experimental results.In this paper,the characteristics of liquid slosh in a spherical tank are analyzed,and the liquid slosh prevention simulation with different area anti-wobble plates is carried out by using CFD software.(4)Based on the parameterized equivalent pendulum model,the dynamic equation of liquid sloshing in a spherical tank was established and transformed into a state space expression.A large number of free attenuation shaking experiments were carried out.After de-noising the experimental data,the gray box identification method was used to identify the system parameters in MATLAB software.The natural frequency and damping ratio were calculated by theoretical method,and the spectrum diagram was obtained by FFT transformation.The identification effect of the identification method is further verified by comparing and analyzing the identification value of natural frequency,theoretical calculation value,spectrum analysis value and experimental value.