Rotor Bearing Loads With Honeycomb Seals And Volute Forces In Reinjection Compressors.

Italy. He is responsible for all requisition, standardization, and CAD automation activities as well as for detailed design of new products for centrifugal compressors both in Florence (Nuovo Pignone) and Le Creusot (Thermodyn). Dr. Baldassarre began his career with General Electric Nuovo Pignone in 1997. He has worked as Design Engineer, R&D Team Leader for centrifugal compressors in Florence, Product Leader for centrifugal and axial compressors, and Requisition Manager for centrifugal compressors both for Florence and Le Creusot teams. Dr. Baldassarre received a B.S. degree (Mechanical Engineering, 1993) and Ph.D. degree (Mechanical Engineering/Turbomachinery Fluid Dynamics, 1998) from the University of Florence. He has authored or coauthored 20 technical papers, mostly in the area of fluid dynamic design of 3D transonic impellers, rotating stall, and rotordynamics. He presently holds three patents. In his 35 years with Exxon, he has worked in all phases of machinery engineering and in research and development. ABSTRACT The calculation for unbalance response of a rotor starts by calculating the bearing load to provide the basis for the bearing stiffness and damping characteristics. Measurements in test rigs at a major Texas university laboratory have shown that honeycomb-stator/drum-rotor annular seals can produce negative stiffness, in particular at zero to low whirl frequencies, which tends to pull the rotor off-center. Data given in this paper, from high-pressure factory tests of compressors using a honeycomb seal at the balance piston, have shown the rotor can be displaced from the usual position in the lower part of its journal bearing, degrading the unbalance response. In this paper the authors show that the honeycomb seal can produce a large disturbance in the equilibrium position of the rotor for certain values of negative stiffness, resulting in high bearing loads in unusual directions. It is also shown that aerodynamic forces on the rotor from the volute need to be considered.