The Research On Dynamic Characteristics Of High Pressure Cylinder Based On Finite Element Method

As a key component of natural gas compressor,high-pressure cylinder is the work place to complete the gas compression.During the working process,the cylinder is loaded in various forms,including dynamic mechanical and thermal load,which leads to the cylinder being in the harsh environment of high temperature and high pressure,and the failures,such as deformation,crack and fracture,often occur,and it may cause serious mechanical troubles or even personal safety threats.Therefore,it is a very important task to have a research on the high pressure cylinder.This paper takes the working cylinder of the first 52 MPa ultra-high-pressure natural gas compressor in China as the research object,combines load coupling analysis with dynamic response analysis to study its dynamic characteristics by finite element method with the relevant theories of material mechanics,heat transfer,gas dynamics,mechanical vibration and fatigue damage,for the purpose of mastering its internal dynamic operation laws and the factors of affecting reliability,which provides a reference for the development in technology of natural gas compressor.This paper studies the structure and working principle of the high-pressure-cylinder of 52 MPa natural gas compressor,and establishes its finite element model.On this basis,combined with the actual working conditions,the main dynamic and static loads in the working process of high-pressure cylinder are studied in detail,including alternating gas pressure load,dynamic thermal load,bolt preload load and interference fit pressure load of cylinder block and cylinder liner,and their accurate time history curves or load change nephograms are obtained.The dynamic response of cylinder structure under the coupling of single load and thermal-mechanical load is a pivotal characteristic,which is studied by finite element method,to explore the influence degree and law of each load on structural response;analyze the dynamic changes of response parameters such as deformation,stress and strain of the whole cylinder and the time-history curves of each node,also finish the fatigue strength check and life prediction,to find the dangerous areas of the cylinder.Structural improvements are made on the parts with high stress and low life,through simulation comparison,structures with high safety factor are adopted.Another aspect of dynamic characteristics is modal analysis.Based on the theory of modal analysis,the free and constrained modals of high-pressure cylinder are analyzed.Through modal parameters,such as mode shape and frequency,of the first 10 order,the inherent vibration law of high-pressure cylinder is mastered.The resonance check of high-pressure cylinder under the actual rated speed is done,and the improvements of structural anti-vibration ability are put forward.