Rotordynamic Coefficients for a Tooth-on-Stator Labyrinth Seal at 70 Bar Supply Pressures: Measurements Versus Theory and Comparisons to a Hole-Pattern Stator Seal

Rotor dynamic and leakage coefficients are presented for a labyrinth seal that was tested at a supply pressure of 70 bar-a and speeds up to 20,200 rpm. Tests were conducted at clearances of 0.1 mm and 0.2 mm, pressure ratios of 0.10, 0.31, and 0.52, and three preswirls ratios. Comparisons are made between test data and predictions from one-control-volume and two-control-volume bulk-flow models. Generally, theoretical predictions agree poorly with the test results, with the one-control volume model giving better predictions. The one-control-volume model provides a conservative prediction for effective damping; i.e., this parameter is underestimated. Both models under predict leakage rates. Comparisons are also made between rotordynamic coefficients of labyrinth and hole-pattern seals.