Analysis On The Non-axisymmetric Coupled Vibrations Of A Cylindrical Shell Containing Sand/Water Double Layer Liquids

The shell equipment is often used to store or transport various fluids or special structures,such as outer shell of aircraft and missiles in the field of aerospace,submarine ship body in deep sea,oil pipelines,sand-removing cylinders in the petroleum industry and so on.They are widely concerned due to the problems of coupling vibration among the shell,internal and external fluids and even the built-in structure.Especially in the petroleum industry,the sand-removing cylinder is filled with sand/water mixture.In order to understand the height of the sand layer in the cylinder and remove it at an appropriate time,it is necessary to monitor the accumulation of sand in the cylinder in real time from the outside without damage.It is noted that the mixing rate directly affects the dynamic performance of the shell system,due to the two mixed media,i.e.the sand layer and the water layer in the sand-removing cylinder.Therefore,the further study of the non-axisymmetric coupled vibration characteristics of the cylindrical shell containing two mixed media is carried out based on the Flügge thin shell theory.Finally,some meaningful conclusions have been obtained:1)The non-axisymmetric vibration modes of the system are obtained for the non-axisymmetric vibration of the liquid-filled cylindrical shell.Besides,the characteristics of the inertial effect of fluid on the system resonance frequency are revealed.In addition,the effect of the circumferential mode order on the resonance frequency and non-axisymmetrical vibration modes of the coupled system is clarified.2)By introducing the interface effect of the sand layer and the water layer,the problem of non-axisymmetric vibration of the cylindrical shell filled with sand/water mixture is solved.The non-axisymmetric coupled vibration model of the sand/water mixed fluid medium and the cylindrical shell is established through the interface continuity conditions.It is clarified that the characteristic of the interface effect on the dynamic performance of the system's non-axisymmetric vibration.Besides,the influence law of interface movement on the resonance frequency and displacement amplitude of the system is further revealed.3)The dynamic model of the coupled vibration of the viscous fluid medium and the cylindrical shell is established by introducing the viscous effect of the internal fluid medium in the shell.Moreover,the influence law of the viscous effect on the system resonance frequency is clarified.In a word,the problem of non-axisymmetric coupled vibration of the cylindrical shell filled with sand/water mixture is deeply studied in this paper.Thus,the effect of the sand layer height on the resonance frequency and vibration mode of the non-axisymmetric vibration of the system is obtained.It is noted that this study not only provides a simple and effective method for the non-destructive real-time monitoring of the sand-removing cylinder in the petroleum industry,but also has a reference value for studying the coupled vibration between the multi-phase fluid media and the cylindrical shell.