Rub-Groove Width and Depth Effects on Flow Predictions for Straight-Through Labyrinth Seals

Abstract

A fully compressible, two-dimensional axisymmetric, turbulent Navier-Stokes code using the finite-volume discretization approach was utilized to obtain an enhanced understanding of the effects of rub-grooves in straight-through, abradable labyrinth seals. The high-Re form of the k-ε turbulence model was used. The code was first validated against measurements of straight-through honeycomb labyrinths, and accurate results were obtained. It was found that in most of the cases considered (tooth tip outside of its rub groove), the presence of rub-grooves increases the leakage, except for the case of the large pre-rub clearance and narrow rub-groove width. The presence of the large- or the intermediate-width rub-grooves allows the rub-groove depth to exert a fairly large effect on the leakage, especially for the smallest pre-rub radial clearance. Further, the presence of a narrow rub-groove with the smallest pre-rub radial clearance gives a dramatic effect on the streamwise (i.e., cavity-to-cavity) variation in overall flow patten.