Blade outer air seal with improved thermomechanical fatigue life

摘要

A blade outer air seal (20) for a gas turbine has an abradable coating (22) with a substantially uniform thickness during service use. Prior to being placed in service, the abradable coating has a central portion (34C) with a greater thickness (t 2 ) than leading and trailing portions (34L; 34T). When placed in service, the blade outer air seal is positioned so that the central portion of the abradable coating with the greater thickness is located in a blade rub path of the turbine blades. As a result of abrasion in the blade rub path, the thickness of the central portion of the abradable coating is reduced so that it becomes substantially similar to the thickness (t 1 ) of the leading and trailing portions.