Patent ID: 8439364

Claim:
A seal for sealing between a stator and a rotor including: a generally annular carrier having a longitudinal axis, said carrier defining an annular opening; an array of adjacent leaves mounted in the annular carrier for sealing between the stator and rotor with the major planes of the leaves lying parallel to the axis of the carrier; and front and back plates each defining an annular opening, said plates disposed on respective axial sides of the leaves characterised in that the front and back plates each have one or more fully enclosed apertures which extend from an axial outer surface of the plate to an axial inner surface of the plate, said apertures dimensioned for providing a substantially symmetric pressure distribution in an axial direction across the leaves; wherein the front and back plates each are spaced from the leaves so as to form a gap between each plate and the leaves, and said plates each extend to a free end spaced from the leaves; and wherein at least one of the fully enclosed apertures on the back plate is larger than a fully enclosed aperture on the front plate.