Non-contacting gas seal for relatively rotating parts

摘要

In a non-contacting gas seal between static and rotatable components of a gas turbine engine, a seal ring (12) (FIG. 4) is composed of a plurality of overlapping segments (16) which co-operate to define a sealing face (15). The segments are located in a housing (14) preferably on the static component with the sealing face (15) confronting a sealing face (10) on the rotating component the arrangement being such that in operation the segments lift away from the rotating component to ride on a gas film leaving a very small sealing clearance therebetween. A secondary seal must be formed between the seal ring and the housing to avoid leakage around the seal ring and this is achieved by a narrow sealing land (23) on the low pressure side-face of each segment being urged into contact with a side-face (22) of the housing by the higher pressure fluid on the opposite side-faces of the segments. The narrow land provides a fulcrum on each segment which allows the segments to tilt so that contact of each land with the side-face of the housing does not put any constraint on the alignment of the confronting sealing faces even where the sealing face and the side-face of the segment may not be exactly at right angles. At least one of the overlapping surfaces of the segments is also contoured to provide a second fulcrum to facilitate tilting of the segments.