GB1207873A - Axial-flow fluid-handling machines having centre-rotating blade-carrying annular discs - Google Patents

Abstract

1,207,873. Axial-flow compressors; turbines. SOC. NATIONALE D'ETUDE ET DE CONSTRUCTION DE MOTEURS D'AVIATION. July 5, 1968 [July 10, 1967], No.32274/68. Headings F1C, F1G and F1T. An axial-flow compressor or turbine having contra-rotating blade carrying annular discs comprises a first set of annular discs each with a free outer periphery to which the blades are fixed and an inner periphery attached to a driving member, and a second set of annular discs each with an outer periphery to which the blades are fixed and which is connected to an oppositely rotating driving member, each disc of the second set having a free inner periphery, and the contrarotating discs are provided near their outer peripheries with annular seals for isolating a main annular flow duct occupied by the blades from an inner annular space within which the major part of the surface area of the discs is located, the discs of the first set being provided within the inner annular space with openings spaced radially away from the free internal peripheries of the discs of the second set, the openings co-operating with the discs of the second set to define an auxiliary flow duct of serpentine nature displaced alternately towards and away from the axis of the machine through which a cooling fluid can flow. The compressor shown comprises rotor discs 1a, 3a, 5a...... 11a connected together by an annular shroud 16 and driven from a shaft 17, and rotor discs 2a, 4a.... 10a connected together by partitions 19, 20, 21 and driven in the opposite direction by a shaft 22. Labyrinth seals 1b-2b, 2b-3b, ....... are provided between adjacent rotor discs, and labyrinth seals 1b and 11b are provided between the end discs and stationary structure. Cooling fluid, which may be air taken from a preceding L. P. compressor or from a fan mounted in a by-pass if the compressor is part of a dualflow turbojet engine, flows through radial ducts 14 and thence through openings 1c, 2c, 4c.....10c, finally leaving via radial ducts 15 which may open into the atmosphere. The cooling fluid takes the serpentine course shown by the arrows, passing over the downstream face of the disc 2a and over both faces of each of the subsequent discs. Preferably, the pressure of the cooling fluid at entry to the compressor is made lower than or at the most equal to that of the air being compressed, to avoid leakage of cooling fluid into the main flow duct.