Abradeable labyrinth stator seal

Abstract

In a gas turbine engine having a laybrinth seal between an annular rotor and stator therein, in which the stator is surmounted by a honeycomb structure and the rotor has a knife edge which is mounted to rotate in close annular proximity with said honeycomb structure, an improvement is provided wherein such labyrinth seal has a layer of abradeable coating atop the honeycomb structure for the rotor knife edge to rotate proximate thereto and to rub in, without substantially damaging the knife edge nor the honeycomb structure. In one embodiment the layer of abradeable coating is mounted on a metalic foil which is mounted in turn, atop the honeycomb structure. The abradeable coating thus provided, is more yieldable and less damaging to a rotor knife edge than is the honeycomb structure of the prior art, to better preserve rotor and stator and thus the labryrinth seal. Because of such protection, the rotor knife edge can be thinner and of lighter weight and the honeycomb structure can be made of larger cell sizes, again resulting in weight savings for each lab seal, which can have one or a plurality of rotor (knife edge)-stator pairs. Further, the abradable coating seals the top of the honeycomb structure and thus blocks air flow into the honeycomb cells beneath and behind the knife edge and thus reduces losses in seal efficiency.

Dependencies are inferred from the claim text.