Measured Comparison of Leakage and Rotordynamic Characteristics for a Slanted-Tooth and a Straight-Tooth Labyrinth Seal

Measured results are presented to compare rotordynamic coefficients and leakage of a slanted-tooth labyrinth seal and a straight-tooth labyrinth seal. Both seals had identical pitch, depth, and number of teeth. The teeth inclination angle of the teeth on the slanted-tooth labyrinth was 65deg from the normal axis. Experiments were carried out at an inlet pressure of 70bar-a (1015psi-a), pressure ratios of 0.4, 0.5, and 0.6, rotor speeds of 10.2, 15.35, and 20.2 krpm, and a radial clearance of 0.2mm (8 mils). One zero and two positive inlet preswirl ratios were used. The results show only minute difference in the rotordynamic coefficients between the two seals. The slanted-tooth labyrinth seal consistently leaked approximately 10% less at all conditions. Predictions were made using a one control volume bulk-flow model (1CVM) which was developed for a straight-tooth labyrinth seal design. 1CVM under-predicted the rotordynamic coefficients and the leakage.

Measured Comparison of Leakage and Rotordynamic Characteristics for a Slanted-Tooth and a Straight-Tooth Labyrinth Seal Academic Article