Dynamics Research On The Packaged Integrally Geared Centrifugal Compressor

The packaged integrally geared centrifugal compressor is widely used in petrochemical, air separation, metallurgical and power station fields with its compact structure, high load capacity and high efficiency characteristics. However, because of its complex dynamics, China cannot independently product the compressor with six stages or more, mostly depend on imports. It is a typical rotor gear coupling system which has very complex coupling properties:the coupling of rotor-gear-bearing, lateral-torsional coupling vibration and the vibration transmission between rotors. Therefore, the traditional single-axis rotor dynamics analysis is barely difficult to meet the design criteria and project requirements. This paper focuses on the research of a six stages packaged compressor, establishing a complete gear-bearing rotor system model, combining the theory of rotor dynamics and gear dynamics. The main contents are as follows:(1) Expounding the theory of rotor dynamics and gear dynamics, establishing a gear-bearing-rotor system finite element model.Giving an overview of impeller vibration property, introducing the theory of impeller spectrum (SAFE). The modal analysis of uncoupling rotors on rigid support was made. And the unbalance response analysis of uncoupling rotors on flexible support was made, considering the impact of bearing stiffness and damping performance. After that, the unbalance response analysis and modal analysis of coupling rotors were made. Comparing to the uncoupling unbalance response curve, it was found that critical speed and resonance amplitude were increased, and because of the vibration transmission, some new critical speeds emerged.(2) Exploring the impact of gear and bearing parameters on the dynamic characteristics of the coupling shafts:the coupling shafts natural frequency remained unchanged when gear helix angle changed between8°-30°, the stability of shafts changed with the helix angle increased, the most stable value appeared at15°, the natural frequency and stability increased with the helix angle changed. Theoretical and simulation analysis of shafts under different forms of support were made, revealing the essential reason of vibration suppression of tilting pad bearing. Helix angle on15°could reduce the bending and axial vibration and improve system stability.(3) Carrying out the impeller modal simulation and experimental test, expounding the theory of impeller spectrum (SAFE), and drawing the impeller spectrum (SAFE) diagram. The failure mode was obtained when the impeller through the blade frequency and guide blade frequency, the result was coincident with its actual site of failure. SAFE diagram for the modified design was performed again showing a successfully operating in this field.