Analysis On The Coupled Vibrations Of A Cylindrical Shell Filled With Sand/miscible Liquids And The Computation Of The Natural Frequencies Of The Coupled System

In the use of the sand removing cylinder in the oil industry,inner side of the shell is filled with sand/miscible liquids which sands will gradual sink and the water will overflow the cylinder.With the development of the working process,the sand layer deposited at the bottom of the cylinder will be more and more high,and finally the sand removing machine can not work again.Therefore,it is necessary to clean the sand in the cylindrical shell without delay.However,due to environmental constraints,it is impossible to observe the height of the sand layer directly from the outside.Hence,we propose a simple and feasible way to calculate the height of the sand layer in the shell by measuring the change of the natural frequency of the cylindrical shell filled with sand/miscible liquids.Based on the coupled vibration analysis of sand / water mixture and cylindrical shell,the relationship between the change of natural frequency and the height of sand layer is obtained.In order to achieve the real time prediction of sand layer height.The main research achievements in the article are as follows:1?The sand/miscible liquids in the cylinder is simulated into sand seam and water layers.The dynamic model of coupled vibration of cylindrical shell and these two layers is established.The characteristics of the natural frequencies and mode shapes of the coupling system are analyzed in detail,and the variation of the natural frequency of the system with the increase of the height of the sand layer is obtained.2?Taking into account the existence of intermediate transition layer which its density is constant/linearly varying between sand layer and water layer.In this paper,the dynamic model of coupled vibration between three layers of fluid medium and cylindrical shell is established.The flow field and pressure distribution are solved.The effect of the thickness of the middle layer on the natural frequency of the system is obtained.In a word,the study of the vibration characteristics of the cylindrical shell filled with multilayer fluid medium is carried out in this paper.The variation law of the natural frequency of the coupled system with the height of the sand layer is obtained which have important guiding significance for the design and scientific application of the sand removing cylinder in petroleum system.