Abstract: It is known there is ingestion of hot gas flow 35 from an annular flow 36 in gas turbine engines. This flow 35 is prevented from attaching to the disc by coolant flow 32 passing through gaps in lock plates 28, 29 by creation of a barrier layer. In order to regulate and enhance this effect spacer protrusions 31 are provided between ends of lock plates 28, 29. In such circumstances the gap 30 is controlled and therefore the rate of leakage flow 32 regulated for best cooling effect. This cooling effect and cooling flow 32 can be further enhanced by providing chutes 39 for presentation of the coolant flow 32.

Abstract: Assembly of segmented seals can be problematic in areas of limited space for an introductory tapered mandrel and where there are the problems with damage to the seal surfaces 23, 24. By the present method and arrangement, a seal formed from segments 22 is expanded to an expanded state and then retained at that state by the use of a sacrificial material 26 in the gaps 25 between the segments 22 opened by expansion. The sacrificial material 26 is typically a low melting temperature wax and so is removed when the seal arrangement reaches its operating temperature.

Abstract: In gas turbine engines it is found that leaked coolant flow through the lock plates 28, 29, 50, 60 can be used to insulate the rotor surfaces 33, 34 from the effects of hot gas ingestion. In order to enhance this effect chutes 39, 59, 69 are provided to guide the leakage airflow adjacent to the lock plate such that the ingested hot gas flow is prevented from coming into contact with the surfaces of the lock plate and other cavity surfaces 33, 34 to improve cooling effect. The chutes 39, 59, 69 create apertures 40, 53 which can be of dimensions to ensure that there is a high ratio between width and depth of the coolant flow 32 again facilitating heat exchange and cooling efficiency.

Abstract: Efficient cooling of a stage of gas turbine engine turbine blades (36) is achieved by first reducing the pressure of the cooling air after it has been bled from the annulus of the compressor (12) by passing it through a diffuser (30), to a pressure magnitude lower than is required at entry to the turbine blades, then re-pressurising the bled air up to the required entry pressure, by passing it through a radial compressor defined by a cowl (44) positioned in close spaced, co- rotational relationship with the downstream face of the associated turbine disk (34).