NUMERICAL MODELLING OF THREE DIMENSIONAL HONEYCOMB LABYRINTH SEALS EMPLOYING A SIMPLIFIED APPROACH

摘要

This paper numerically analyses the flow through abrad-able honeycomb labyrinth seals using CFD. Three-dimensional CFD simulations using a single tooth have been compared to representative two-dimensional simulations. Two sizes of honeycomb (1.60mm and 3.20mm) have been analysed at pressure ratios from 1.20 up to 1.60. The seal geometry was kept constant throughout with a running clearance of 1.00mm. The honeycomb has been oriented in two planes with respect to the labyrinth teeth. The two-dimensional planes show equivalence both in terms of overall performance and inter-cavity pressure profiles. Comparisons of C_d typically agree within 2.5%, having an average variation of 1.3%. Total pressure profiles at the middle of the upstream and downstream cavity have been compared. These reveal typical average RMS variations of less than 3% between 3-D and 2-D profiles. It has also been shown that the honeycomb surface causes velocity effects in 3-D that propagate into the seal cavity. The technique used has achieved significant reductions in modelling times.