A turbine includes a blade, a structure installed at a tip section side of the blade via a gap and configured to relatively rotate with respect to the blade, a step section formed at the tip section of the blade, having at least one step surface, and protruding toward a portion opposite to the tip section of the structure, a seal fin formed at the portion opposite to the tip section of the structure, extending toward the step section, and configured to form a micro gap between the step section and the seal fin, and a cutout section formed at the step surface to be connected to an upper surface of the step section. The cutout section guides a separation vortex separated from a main stream of a fluid passing through the gap toward the seal fin on the upper surface of the step section.
1. A turbine comprising:
a blade;
a structure installed at a tip section side of the blade via a gap and configured to relatively rotate with respect to the blade;
a step section formed at one of sections, the tip section of the blade and a section of the structure opposite to the tip section, protruding toward the other sections such that protrusion heights are gradually increased from an upstream side toward a downstream side of the step section, and having a first step surface and a second step surface which is provided on a downstream side of the first step surface;
a seal fin formed at the other of sections, the tip section of the blade and a section of the structure opposite to the tip section, extending toward the step section, and configured to form a micro gap between the step section and the seal fin; and
a cutout section formed at each of the first step surface and the second step surface to be connected to an upper surface of the step section, wherein
a fluid flows through the gap,
the cutout sections guide a separation vortex separated from a main stream of the fluid toward the seal fin on the upper surface of the step section,
the cutout sections are inclined sections inclined from an upstream side toward a downstream side, and
an inclination angle of the inclined sections formed at the second step surface with respect to a radial direction of a rotary shaft is set to be larger than an inclined angle of the inclined section formed at the first step surface.
2. A turbine comprising:
a blade;
a structure installed at a tip section side of the blade via a gap and configured to relatively rotate with respect to the blade;
a step section formed at one of sections, the tip section of the blade and a section of the structure opposite to the tip section, protruding toward the other sections such that protrusion heights are gradually increased from an upstream side toward a downstream side of the step section, and having a first step surface and a second step surface which is provided on a downstream side of the first step surface;
a seal fin formed at the other of sections, the tip section of the blade and a section of the structure opposite to the tip section, extending toward the step section, and configured to form a micro gap between the step section and the seal fin; and
a cutout section formed at each of the first step surface and the second step surface to be connected to an upper surface of the step section, wherein
a fluid flows through the gap,
the cutout sections guide a separation vortex separated from a main stream of the fluid toward the seal fin on the upper surface of the step section,
the cutout sections each have an arc-shaped section smoothly connected to the upper surface from the upstream side toward the downstream side, and
an angle between a tangential direction of a portion of the arc-shaped section formed at the second step surface connected to the upper surface and a radial direction of a rotary shaft is set to be larger than an angle between a tangential direction of a portion of the arc-shaped section formed at the first step surface.