Abstract: A pressure actuated tip clearance system for a shroud structure of a gas turbine engine rotary stage includes an annular plenum chamber formed between an annular arrangement of a plurality of shroud liners on the inner circumference of the chamber and a generally cylindrical casing on the radially outer side, and, in use, a hot gas stream radially inwards of the shroud liners. Each shroud liner comprises a hollow box section comprising upstream and downstream walls, radially inner and outer walls, and side walls, the downstream and radially inner and outer walls being closed, the upstream wall having an air inlet aperture, and at least one of the side walls having at least one outlet aperture. The inlet aperture is in flow communication with a source of high pressure air at a pressure higher than that of the gas stream.

Abstract: A casing arrangement (20) for surrounding a rotary component (16) of a gas turbine engine (10) especially a turbine is disclosed. The arrangement (20) comprises an annular casing member (22A) surrounding a bladed rotary section, such as a turbine stage. An array of gas path liner segments are suspended from the casing at a nominal clearance gap form the tips of the rotary blades. Running clearance is determined by expansion and contraction of the casing which, in turn, is controlled by a supply of heat transfer fluid passed through heat transfer holes in the casing. The casing arrangement described includes a passive pressure bleed effective during engine deceleration to reduce a pressure differential driving the fluid flow in order to avoid too rapid contraction of the casing as a result of overcooling.

Abstract: A sealing arrangement that can be employed to maintain a seal in any suitable pressure vessel including but not limited to a gas turbine engine. The sealing arrangement is forg sealing a leakage gap between at least two relatively moveable parts that are adjacent to each other in a flow path between a region of high fluid pressure and a region of low fluid pressure. The sealing arrangement comprises at least two resilient sealing strips, each strip having a portion formed along at least part of its width to locate in a groove provided along adjacent faces of the relatively moveable parts. The remaining portion of each of the sealing strips has a substantially flat surface which, in operation, abuts a corresponding flat surface of an adjacent sealing strip, thereby forming a seal.

Abstract: An annular seal plate for an interstage air riding seal arrangement for the internal cooling system of a gas turbine engine is mounted on a rotatable disc by means of an annular mortise and tenon mounting. The contact faces of the mortise and tenon are angled relative to a radial plane of the disc so that centrifugally generated forces are reacted by the faces in a sense to counter axial tilt so that a seal face of the plate lies exactly in a radial plane, at a design rotational speed, thereby to eliminate convergence or divergence between the seal faces of the air riding seal.

Abstract: A vectorable nozzle mounting for an engine installation in a VSTOL aircraft in which hot gas nozzles are mounted on the airframe is described. A swivelable nozzle is mounted by means of a bearing on an intermediate fixed member such as a mounting ring on the airframe. The hot exhaust gas is discharged into the nozzle through a stub duct carried by the engine casing. Misalignment and movement between the duct and the nozzle is accommodated by movable sealing rings carried in the intermediate member which engage the outer surface of the duct. The sealing rings are spaced apart to form an annular chamber which is supplied with cooling air at a higher pressure than the pressure in the exhaust duct. The cooling air is arranged to cool the nozzle bearing and leakage passed the seals is of cooling air into the nozzle thus excluding hot exhaust gas from the engine bay.