Abstract: A seal assembly (50) controls leakage of working fluid through an annular gap (G) between a static component (16) and a rotary component (28) in a turbomachine. The fixed and moving components (16, 28) each have stepped diameters including a plurality of circumferentially and axially extending lands (56, 58) that confront each other across the annular gap (G). They are complementarily formed such that the annular gap is maintained over the axial extent of the seal assembly. Both components (16, 18) are provided with rows of fins (60, 62) which extend circumferentially of the lands and project radially therefrom towards each other. The rows of fins 60 of the static component 16 are preferably unequally spaced apart with respect to the rows of fins 62 of the rotating component 16, so producing a vernier seal arrangement.

Abstract: A turbine blade has a shroud, a blade portion and a T-section root portion configured to lock into a T-section channel in a turbine rotor adjacent like blades in a ring. The blade portion is pre-twisted so that mutual alignment of the edges of the root and the shroud portion along the axis of the turbine in the final assembled condition provides a torsional bias which maintains the shroud in frictional contact with its neighbours to resist relative radial movement. The root portions have generally flat-sided surfaces occupying opposed substantially parallel radial planes of the T-section, but have circumferential abutments in the form of lands projecting from each side of the root portion at the same radius. When the circumferential abutments are radially aligned in the final assembled position, angular separation between adjacent blades is greater, by an amount related to the combined thickness of the abutments, than when the abutments are radially staggered.

Abstract: One turbine, e.g. a high pressure (HP) turbine, has a conventional diaphragm and disc structure with impulse turbine stages. A preceding or following turbine, e.g. an intermediate (IP) turbine, on a common axis and on the same steam path, has a rotor drum which carries an annular row of moving blades having root portions held within a slot in the periphery of the drum. A turbine casing surrounds the drum and carries a static blade assembly with an annular row of static blades which, together with the annular row of moving blades, constitutes a modified turbine stage. The static blade assembly has a radially inner static ring with a radially inner side confronting the periphery of the drum. A seal acts between the inner static ring and the rotor.

Abstract: A turbine, e.g., a high pressure (HP) turbine, has a conventional drum-type structure with reaction turbine stages. A preceding or following turbine, e.g. an intermediate pressure (IP) turbine, on a common axis and on the same steam path, has rotor drum which carries an annular row of moving blades having root portions held within a slot in the periphery of the drum. A turbine casing surrounds the drum and carries a static blade assembly with an annular row of static blades which, together with the annular row of moving blades, constitutes a modified turbine stage. The static blade assembly has a radially inner static ring with a radially inner side confronting the periphery of the drum. A seal acts between the inner static ring and the rotor.

Abstract: In order to provide a turbine in which fir tree root or similar types of turbine blades can be inserted into the turbine shaft at an angle close to the axial direction without frictional blocking of shroud sections, each blade comprising a root for insertion into the shaft, along an insertion axis which is at an angle of not more than 30° the axial direction, an aerofoil section and a shroud section, each shroud having lateral surface sections comprising a contact surface section and a free surface section, the contact surface sections of adjacent shroud sections contacting one another, the free surface sections of adjacent shroud sections being spaced from one another. Each contact surface section lies at an angle of from 20° to 50° to the axial direction and each free surface section lies at an angle of not more than 30° to the axial direction, each contact surface section lies at a greater angle to the axial direction of the shaft than the corresponding free surface section.

Abstract: A seal assembly (50) controls leakage of working fluid through an annular gap (G) between a static component (16) and a rotary component (28) in a turbomachine. The fixed and moving components (16, 28) each have stepped diameters including a plurality of circumferentially and axially extending lands (56, 58) that confront each other across the annular gap (G). They are complementarily formed such that the annular gap is maintained over the axial extent of the seal assembly. Both components (16, 18) are provided with rows of fins (60, 62) which extend circumferentially of the lands and project radially therefrom towards each other. The rows of fins 60 of the static component 16 are preferably unequally spaced apart with respect to the rows of fins 62 of the rotating component 16, so producing a vernier seal arrangement.