Rotordynamic properties of high-pressure seals--an experimental approach.

摘要

An experimental facility for extracting the twelve coefficients of the linear anisotropic rotordynamic model for seals and journal bearings has been developed and constructed as part of this work. A double-spool-shaft spindle design is the heart of the test facility, allowing independent control over the shaft spin speed and circular orbit frequency for both forward and backward whirls. The static and dynamic eccentricities of the shaft can be adjusted. By accurately measuring the fluid interaction forces and the shaft dynamic displacements over a wide range of orbit frequencies, the rotordynamic stiffness, damping and inertia coefficients can be evaluated using an assumed linear mechanical impedance model. The implementation of two independent force measuring systems permits self-checking of the critical force measurements and thus the experimental results. A high-speed data acquisition system has been developed and implemented specifically for this test facility. Software (DAAS) was developed for the high speed data acquisition (A/D), data reduction, and the calculation of the rotordynamic coefficients using the assumed linear model. Rotordynamic coefficients obtained show an expected isotropic trend for deep grooved seals, and their values are within the expected orders of magnitude. A finite element based computational analysis was used to demonstrate the overall influence of seals on vibration of a typical high energy multistage centrifugal pump that utilizes several rotordynamically influential interstage seals.