Non-contact seal with axial engagement

1. An assembly for rotational equipment, comprising:

a stationary structure;

a rotating structure rotatable about an axial centerline; and

a non-contact seal assembly configured to substantially seal an annular gap between the stationary structure and the rotating structure, the non-contact seal assembly comprising a seal shoe configured to sealingly engage the rotating structure axially along the axial centerline;

the non-contact seal assembly further comprising a seal carrier and a seal element;

the seal carrier mounted to the stationary structure; and

the seal element projecting radially out from the seal carrier towards an axially extending surface of the seal shoe such that the seal element and a portion of the seal shoe with the axially extending surface form a knife-edge seal.

2. The assembly of claim 1 , wherein the non-contact seal assembly is configured as a hydrostatic seal assembly.

3. The assembly of claim 1 , wherein the seal shoe is a monolithic full hoop body.

4. The assembly of claim 1 , wherein the seal shoe includes a seal shoe base and a seal shoe projection that projects axially along the axial centerline out from the seal shoe base towards the rotating structure.

5. The assembly of claim 1 , wherein the seal shoe sealingly engages and is axially adjacent a radially extending surface of the rotating structure;

the radially extending surface of the rotating structure has a first radial height; and

the seal shoe has a second radial height that is less than or equal to the first radial height.

6. The assembly of claim 1 , wherein

the non-contact seal assembly further comprises a spring structure; and

the spring structure flexibly connects the seal shoe to the seal carrier.

7. The assembly of claim 6 , wherein

the non-contact seal assembly further comprises a second spring structure; and

the second spring structure further flexibly connects the seal shoe to the seal carrier.

8. The assembly of claim 6 , wherein

the spring structure comprises a plurality of ligaments arranged in an annular array about the axial centerline; and

each of the plurality of ligaments extends radially out from the seal shoe to the seal carrier.

9. The assembly of claim 8 , wherein a first of the plurality of ligaments is circumferentially tapered.

10. The assembly of claim 1 , wherein

the seal shoe is coupled to the seal carrier; and

the seal shoe is configured to axially and/or circumferentially shift relative to the seal carrier.

11. The assembly of claim 1 , wherein

the non-contact seal assembly further comprises a seal carrier and a second seal element; and

the second seal element projects axially along the axial centerline out from the seal carrier and into a groove in the seal shoe such that the second seal element and a portion of the seal shoe with the groove form a labyrinth seal.

12. The assembly of claim 1 , wherein the non-contact seal assembly further comprises a plurality of ligaments arranged in an annular array;

the plurality of ligaments extend between and couple the seal shoe and the seal carrier; and

the seal shoe projects axially along the axial centerline into a channel in the seal carrier.

13. The assembly of claim 1 , wherein

the non-contact seal assembly further comprises a seal carrier and a plurality of ligaments that extend radially between and couple the seal shoe and the seal carrier; and

a monolithic body includes at least the seal shoe, the seal carrier and the plurality of ligaments.

14. An assembly for rotational equipment, comprising:

a stationary structure;

a rotating structure rotatable about an axial centerline; and

a non-contact seal assembly configured to substantially seal an annular gap between the stationary structure and the rotating structure, the non-contact seal assembly comprising a seal shoe configured to sealingly engage the rotating structure axially along the axial centerline;

the non-contact seal assembly further comprising a seal carrier and a spring structure;

the seal carrier mounted to the stationary structure;

the spring structure flexibly connecting the seal shoe to the seal carrier;

the spring structure comprising a plurality of ligaments arranged in an annular array about the axial centerline; and

each of the plurality of ligaments extending radially out from the seal shoe to the seal carrier;

wherein a first of the plurality of ligaments is axially tapered.

15. An assembly for rotational equipment, comprising:

a seal carrier extending circumferentially around an axial centerline;

a seal shoe extending circumferentially around the axial centerline, the seal shoe projecting axially into an annular channel in the seal carrier, and the seal shoe configured to sealingly engage a radially extending surface axially along the axial centerline;

a plurality of flexible ligaments arranged in an annular array within the annular channel, each of the plurality of flexible ligaments extending radially between and connected to the seal shoe and the seal carrier, wherein the plurality of flexible ligaments enable axial and/or lateral shifting of the seal shoe relative to the seal carrier; and

a seal element projecting radially out from the seal carrier towards an axially extending surface of the seal shoe such that the seal element and a portion of the seal shoe with the axially extending surface form a knife-edge seal.

16. The assembly of claim 15 , wherein a first of the plurality of flexible ligaments is axially tapered.

17. The assembly of claim 15 , wherein a first of the plurality of flexible ligaments is laterally tapered.

18. The assembly of claim 15 , further comprising a second seal element projecting axially along the axial centerline out from the seal carrier and into a groove in the seal shoe such that the second seal element and a portion of the seal shoe with the groove form a labyrinth seal.