Labyrinth seals for gas turbine engine

Abstract

A labyrinth seal for a gas turbine engine of the type having a high pressure compressor and high pressure turbine, an outer shaft interconnecting the high pressure compressor and turbine, a low pressure compressor and turbine, and an inner shaft interconnecting the low pressure compressor and turbine in which the shafts are concentric and are separated by the seal. The labyrinth seal includes a cylindrical sleeve which is discrete from and attached to the outer shaft, and which includes a plurality of annular seal teeth extending radially inwardly to the inner shaft. By placing the seal teeth on a sleeve which is discrete from the outer shaft and is easily replaceable, stress cracks created in the region of the seal teeth are prevented from propagating to the outer shaft and maintenance of the shafts is facilitated. Further, by configuring the seal teeth to extend, radially inwardly between two relatively rotating components, the fluid trapped by the seal is forced to take a tortuous path along the inner shaft; as a result, the seal of the present invention is more efficient at high temperatures and rotational speeds. The sleeve is captured between an annular rabbet at an aft end and radial slots formed on a seal tube the latter of which engage spaced, axially-extending fingers on the sleeve at the forward end of the sleeve. The sleeve is at a relatively low radius where mechanical deflections due to centrifugal loads of the two concentric shafts are similar. Deflection of the seal teeth is away from the inner shaft due to thermal effects in the concentric shafts.