Dual impeller

1. A compressor comprising:

a dual impeller comprising:

a hub configured to rotate about a rotation axis;

a plurality of first blades which are disposed on a first surface of the hub along a circumferential direction of the hub;

a first shroud which is mounted on the plurality of first blades to cover the plurality of first blades;

a plurality of second blades which are disposed on a first surface of the first shroud along a circumferential direction of the first shroud;

a second shroud which is mounted on the plurality of second blades to cover the plurality of second blades;

a plurality of first flow paths defined by the hub, the plurality of first blades, and the first shroud; and

a plurality of second flow paths defined by the first shroud, the plurality of second blades, and the second shroud,

wherein a first angle formed between adjacent first blades, with the rotation axis as a vertex of the first angle, is smaller than a second angle formed between adjacent second blades, with the rotation axis as a vertex of the second angle,

wherein inlets of the plurality of first flow paths and inlets of the plurality of second flow paths are disposed at an end of the hub,

wherein outlets of the plurality of first flow paths and outlets of the plurality of second flow paths are open in a radial direction of the dual impeller,

wherein first ends of the plurality of first blades and the plurality of second blades are located at the inlets of the plurality of first flow paths and the inlets of the plurality of second flow paths, respectively,

wherein second ends of the plurality of first blades and the plurality of second blades, that are opposite the first ends, comprise tips that are located at the outlets of the plurality of first flow paths and the outlets of the plurality of second flow paths, respectively,

wherein the tips of the plurality of first blades and the plurality of second blades face the radial direction of the dual impeller, and

wherein the compressor further comprises:

a diffuser connected to the outlets of the plurality of first flow paths and the outlets of the plurality of second flow paths; and

a scroll connected to the diffuser such that fluid from the first flow paths and fluid from the second flow paths is discharged to the scroll through the diffuser.

2. The compressor of claim 1 , wherein the inlets of the plurality of first flow paths and the inlets of the plurality of second flow paths are open in a direction parallel to the rotation axis.

3. The compressor of claim 1 , wherein the outlets of the plurality of first flow paths and the outlets of the plurality of second flow paths are open radially along the circumferential direction of the hub.

4. The compressor of claim 1 , wherein the outlets of the plurality of first flow paths are disposed farther from the end of the hub than the outlets of the plurality of second flow paths along an axial direction of the dual impeller.

5. The compressor of claim 1 , wherein the inlets of the plurality of first flow paths surround the end of the hub.

6. The compressor of claim 5 , wherein the inlets of the plurality of second flow paths surround the plurality of first flow paths.

7. The compressor of claim 6 , wherein the inlets of the plurality of first flow paths and the inlets of the plurality of second flow paths form concentric circles.

8. The compressor of claim 1 , wherein the plurality of first flow paths have a first operation region, and the plurality of second flow paths have a second operation region.

9. The compressor of claim 8 , wherein the first operation region is a first speed operation region and the second operation region is a second speed operation region, the second speed operation region being faster than the first speed operation region.

10. The compressor of claim 1 , wherein a number of the plurality of first blades and a number of the plurality of second blades are different from each other.

11. The compressor of claim 10 , wherein the number of the plurality of first blades is greater than the number of the plurality of second blades.

12. The compressor of claim 1 , wherein the plurality of second blades are provided farther away from the rotation axis than the plurality of first blades.

13. The compressor of claim 1 , wherein the adjacent first blades are spaced apart from each other by a first predetermined distance, and

wherein the adjacent second blades are spaced apart from each other by a second predetermined distance different from the first predetermined distance.

14. The compressor of claim 1 , wherein in response to a surge occurring in the plurality of second flow paths, a fluid is compressed in the plurality of first flow paths for the dual impeller to operate without effects of the surge.

15. The compressor of claim 1 , wherein in response to a choke occurring in the plurality of first flow paths, a fluid is compressed in the plurality of second flow paths for the dual impeller to operate without effects of the choke.

16. The compressor of claim 1 , wherein each of the plurality of first blades is a same size as each other.