Sealing device, rotary machine, and design method for sealing device

A rotary machine, comprising:

• a sealing device including a sealing main body surrounding a rotor shaft rotating about an axis from an outer periphery side;
• the rotor shaft;
• and
• a casing surrounding the rotor shaft from an outer periphery side and supporting the sealing device that separates a high-pressure-side space on one side in the direction of the axis from a low-pressure-side space on another side in the direction of the axis,
• the sealing main body including:
• an inside surface facing an outside surface of the rotor shaft with clearance;
• and
• a plurality of hole parts formed recessed to an outer side in a radial direction from the inside surface and arrayed in a circumferential direction of the inside surface and in a direction of the axis,
• the plurality of hole parts including:
• a plurality of holes with a groove having an inner peripheral wall in which a spiral groove extending twisting toward the outer side in a radial direction is formed;
• and
• a plurality of holes without a groove having an inner peripheral wall in which the spiral groove is not formed, wherein
• a proportion of the plurality of holes with a groove to the plurality of hole parts arrayed in the circumferential direction of the inside surface increases toward the high-pressure-side space side.

A design method for a sealing device including a sealing main body that surrounds a rotor shaft rotating about an axis from an outer periphery side and includes an inside surface facing an outside surface of the rotor shaft with clearance and a plurality of hole parts formed recessed to an outer side in a radial direction from the inside surface and arrayed in a circumferential direction of the inside surface and in a direction of the axis, the design method comprising:

• a fluid force distribution acquiring step of acquiring a fluid force distribution of fluid flowing into the clearance from the direction of the axis;
• a groove forming region determining step of dividing the inside surface into a groove forming region and a non-groove forming region in accordance with the fluid force distribution;
• a first hole part setting step of disposing, in the groove forming region, the plurality of hole parts having an inner peripheral wall in which a spiral groove extending twisting toward the outer side in a radial direction is formed;
• and
• a second hole part setting step of disposing, in the non-groove forming region, the plurality of hole parts having an inner peripheral wall in which the spiral groove is not formed.