Abstract: In a gas turbine engine the clearance between the tips of a row of rotor blades and the surrounding casing is maintained in a pre-determined range by providing supplies of relatively hot and cold air to passages in the casing. The amount of hot or cold air which is allowed to pass through the passages is controlled by exhausting the flow from the passages through a control clearance which varies in proportion to the size of the clearance to be controlled.

Abstract: A blade for a turbomachine having an aerofoil portion and a root portion. The blade is provided with a vibration damper for damping a predetermined vibration of the blade. The damper comprises a closed chamber 14 within the aerofoil portion 13 adjacent the tip of the blade, and liquid 15 within the chamber 14. The volume of liquid 15 is less than the volume of the chamber 14. The chamber 14 is shaped, positioned, and aligned relative to the blade, so that in use the liquid 15 is constrained to form a column which oscillates in the chamber 14 in radial directions and in the same directions as the vibration to be damped. The volume, mass, and viscosity of the liquid are all chosen in relation to the frequency vibration (W.sub.B) of the vibration to be damped and the rotor speed (W.sub.E) so that, in use, the length (L) of the column of liquid is such that ##EQU1## where R=the blade tip radius.

Abstract: A turbine disc for a bladed rotor assembly includes a rim, a plurality of generally axially extending slots in the rim adapted to receive the roots of rotor blades, the radially innermost surfaces of all of said slots lying at a first radius, a continuous circumferential flange projecting axially from the rim of the disc on at least one side face thereof, said flange providing a continuous circumferentially extending surface at a radius less than said first radius and being connected to the disc at a radius greater than said first radius, and a continuous circumferentially extending cooling air channel open towards the radially inner side of the flange, and extending radially outwardly between the flange and the side face of the disc to an extent sufficient to intersect the bottom and a portion of at least one of the flanks of each of the blade root-receiving slots.