Critical Speed Analysis of an Eight-Stage Centrifugal Pump. K. E. Atkins/J. D. Tison/J. C. Wachel, 2nd International Pump Symposium, Texas A&M University, April 1985.

A critical speed and unbalance response analysis of an eight-stage centrifugal pump was performed, considering the variation of stiffness and damping coefficients with speed for both the oil film bearings and the fluid seals (interstage, neck ring and balance piston). The rotor response to unbalance was predicted and compared to measured test stand data, utilizing four different methods to estimate the fluid seal effects. The comparison showed that correlation was best when using the latest finite length seal procedures. The wide variation in predicted critical speeds and response amplitudes indicates the need for additional research in this area, to define the exact stiffness and damping values for fluid film seals.