| Wave propagation in fluid widely exists in astronautical and aeronautical engineering,ship transportation and fluid machinery engineering.Gravitational wave and mechanical wave are two important forms of wave in fluid.Theoretical analysis and experimental study on liquid sloshing in an open elastic cylindrical tank and micro vibration damping mechanism of fluid isolator are conducted in this thesis.Patterns of gravitational wave propagation and the influence it impose on structure are preliminary studied under specific external dynamic conditions including sudden stop,oscillation,sudden start and harmonic micro vibration.Theoretical and experimental studies show that in liquid sloshing case,the power spectrum of one spot on liquid surface contains "multi peaks".Typical nonlinear sloshing phenomenon of gravitational wave,i.e.double frequency relationship,is discovered in experiments.Elasticity of storage tank does not significantly affect propagation of gravitational wave in fluid.The strain of one spot on container side wall will fluctuate,but the power spectral of it does not have multiple peaks,whose frequency mainly distribute in the section below 10 Hz,which indicates that liquid sloshing "fuzz" the frequency response of elastic container;In the study of damping mechanism of liquid isolator,wave equations are derived according to the propagation theory of mechanical wave in variable cross-section tube.Pass ratio of vibration intensity in two-dimensional bellows are calculated.The influence of geometry coefficient including wave-spacing,wavelength,wave height,wave number and expansion ratio on the pass ratio are analyzed.Experiment shows that wavy tube does not affect the frequency of input vibration,but it will attenuate the amplitude of input vibration by 1.0-1.1d B,which means it has a certain isolation effect.This attenuation effect is 17% lower compared with theoretical analysis.Its reason may come from the fact that plane wave assumption is not critically satisfied in this case. |
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