| CPC F03B 13/08 (2013.01) [F03B 11/02 (2013.01)] | 5 Claims |
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1. A hydraulic machine comprising:
a casing; and
a runner rotatably disposed in a central portion of the casing, wherein
the casing internally includes a main flow path and a fixed flow path, the main flow path being a flow path disposed outward and having a spiral shape and an inner diameter that decreases toward a center of the spiral, the fixed flow path being disposed inward and introducing water from the main flow path into the runner,
the runner is connected to a main shaft along a rotation axis of the runner and includes a plurality of runner vanes disposed apart from each other in a circumferential direction, and
at least one of the plurality of runner vanes has a pressure surface that receives pressure in an inflow direction from the water flowing into the runner through the fixed flow path, and, in a cross section of the runner vane perpendicular to a direction of the rotation axis, an outlet angle is 0° or more and less than 20°, the outlet angle being formed between a tangent at a tip portion on an outlet side of the water of the pressure surface and a line segment connecting the rotation axis and the tip portion on the outlet side of the pressure surface,
wherein the fixed flow path is formed by a plurality of stay vanes disposed apart from each other on a concentric circle,
a flow path width sequentially changes toward the center of the spiral of the main flow path, the flow path width being a length of an arc on an inner peripheral side of the fixed flow path disposed between the adjacent stay vanes among the plurality of stay vanes,
wherein the main flow path includes an inflow portion having an inner diameter that is largest in the main flow path and a terminal end portion having an inner diameter that is smallest in the main flow path,
the flow path width sequentially decreases toward the center of the spiral of the main flow path, and
a reduction rate D1 of the flow path width is expressed by the following formula (1),
 where, N is the number of the stay vanes,
Y is a first flow path width disposed between a first stay vane extending from the inflow portion and a second stay vane adjacent to the first stay vane in a water-flowing direction,
D1 is a reduction rate of the flow path widths adjacent to each other,
S is a length of an arc on an inner peripheral side of the stay vane, and
L is a length of an inner periphery of a surface of the casing in sliding contact with the runner.
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