The Strength And Modal Analysis Of Turbo-expander Impeller

Turbo-expander is such a machine which can output external work through gas expansion and produce refrigeration through gas expansion. As the sources of refrigeration, turbo-expander is the key component of air separation equipment, natural gas (petroleum gas) liquefaction separation equipment, low temperature comminution equipment, and also the heart to guarantee the stable operation of the whole equipment. The key part of turbo-expander are impellers, but owing to some characteristics of turbo-expander such as large changes of operating temperature and high speed running, some problems as insufficient strength or heavy vibration of impellers can easily arise, so the research of impellers strength and natural vibration characteristic in order to remove the malfunction is a major concern all the time. And it is also an issue with importantly theoretical and high practical significance engineering application.Based on the general finite element method platform ANSYS, the strength and vibration characteristic of turbo-expander impellers were analyzed in this paper.Temperature distribution of turbo-expander impellers was analyzed first. Coupling theory of thermal and structure dynamics were adopted to calculate the thermal stress of expansion impeller and booster impeller with the boundary conditions of temperature_distribution, this laid the groundwork for strength analysis.And then took the results of thermal field as boundary conditions, meanwhile, the combined action of centrifugal force, thermal stress and aerodynamic force were considered. Based on these, the stress distribution and displacement deformation of impellers were carried out and strength and security of expansion impeller and booster impeller were checked as well.Furthermore, in working condition, modal analyses with prestressed structure of turbo-expander impellers were made, and then the vibration characteristic and vibration form under inertia force action were obtained, the modal characteristic of turbo-expander impellers were included and the influences of impeller structure on natural frequency were discussed. The vibration characteristics of impellers were analyzed in this paper shows that the vibration security allowances can meet the requirement, and then the security of impellers resonance was checked.