Rotordynamic performance prediction for surface-roughened seal using transient computational fluid dynamics and elliptical orbit model

Abstract

This article presents a transient computational fluid dynamics method based on the elliptical orbit model to solve the rotordynamic coefficients of the non-axisymmetric rotating turbomachinery. To validate the numerical approach, an arbitrary stator roughened seal, named hole-pattern seal, is taken as an object to investigate the rotordynamic performance at different excitation frequencies. For each case, the transient fluid force is computed by integrating the unsteady pressure on the off-centered rotor surface. The rotordynamic coefficients are obtained by solving the frequency dependent reaction force/seal motion equations. The transient pressure distributions on the rotor and stator are plotted to analyze the influence of the rotor precession on the pressure fluctuation during a period. It shows that the computed leakage rate and rotordynamic coefficients for the hole-pattern seal agree well with the experimental data. Compared to the previous circular orbit model, the present numerical approach for the elliptical orbit model has equivalently high accuracy, but the consumed transient solution time is reduced by 50%.