Axial flow rotating machinery

An axial flow rotating machinery, comprising:

• a rotor configured to rotate about an axis;
• a casing accommodating the rotor so as to be rotatable;
• a rotating-blade stage including rotating blades fixed to the rotor at intervals in a circumferential direction and a radially-outer side rotating blade ring continuing to radially outer ends of the rotating blades;
• and
• a rotating-blade side seal device configured to seal a gap between the radially-outer side rotating blade ring and the casing,
• wherein the rotating-blade side seal device includes:
• a seal fin having an annular shape and extending toward an outer peripheral surface of the radially-outer side rotating blade ring from the casing;
• and
• a swirl brake fixed to the casing in a cavity formed at an upstream side of the seal fin, and
• wherein the swirl brake includes:
• a first plate-shaped member having a surface along a radial direction of the rotor, the first plate-shaped member extending along the axis or extending in a direction which interests with the axis such that a leading edge of the first plate-shaped member is positioned upstream of a trailing edge of the first plate-shaped member in a rotational direction of the rotor;
• and
• a second plate-shaped member or a third plate-shaped member having a surface oblique to the radial direction of the rotor, the second plate-shaped member extending from an inner end of the first plate-shaped member toward a downstream side in the rotational direction of the rotor and the third plate-shaped member extending from the inner end of the first plate-shaped member toward an upstream side in the rotational direction of the rotor.