TURBINE ABRADABLE LAYER WITH PROGRESSIVE WEAR ZONE TERRACED RIDGES

摘要

Turbine and compressor casing abradable component embodiments for turbine engines, with composite grooves and vertically projecting rows of stepped first ridges in planform patterns, to reduce, redirect and/or block blade tip airflow leakage downstream into the grooves rather than from turbine blade airfoil high to low pressure sides. Each stepped first ridge has a first portion (332B) proximal the substrate surface with a pair of first opposed lateral walls (335B, 336B) terminating in a plateau (334B) having a first cross sectional width, and a second portion (332A) with a pair of second opposed lateral walls (335A, 336A) terminating in a ridge tip (334A) having a second cross sectional width smaller than the first cross sectional width. These ridge or rib embodiments have first lower and second upper wear zones. The lower zone, which at and below first portion height, optimizes engine airflow characteristics, while the upper zone, between the plateau and the second portion ridge is optimized to minimize blade tip gap and wear by being more easily abradable than the lower zone.