A compressor which includes: an inner casing arranged so as to cover a rotor shaft; an outer casing arranged so as to cover the inner casing and forming a fluid flow path around the rotor shaft; and a plurality of struts mounted in the entrance of the fluid flow path and between the inner casing and the outer casing; in which the plurality of struts are arranged in a radial pattern centered on the rotor shaft, and the spacings between the adjacent struts in the circumferential direction of the rotor shaft are unequal.
1. A compressor comprising:
an inner casing arranged to cover a rotor shaft;
an outer casing arranged to cover the inner casing and forming a fluid flow path around the rotor shaft; and
a plurality of struts mounted in the entrance of the fluid flow path and between the inner casing and the outer casing, wherein the plurality of struts are arranged in a radial pattern centered on the rotor shaft, and the spacings between the adjacent struts in the circumferential direction of the rotor shaft are unequal;
a first casing connected to the inner casing at the entrance end of the fluid flow path;
a second casing connected to the outer casing at the entrance end of the fluid flow path,
wherein a curved portion that curves to project toward the first casing is formed at the connection portion of the outer casing with the second casing;
a flat portion that is adjacent to the second casing and consists of a surface that is approximately parallel with the peripheral surface of the rotor shaft;
a curved surface that smoothly curves inward in the radial direction of the rotor shaft from the distal end of the flat portion;
a cross-section of the curved portion forms an approximate U-shape that projects toward the first casing;
the connection portions of the struts with the outer casing are positioned further to the downstream in the axial direction of the rotor shaft than the distal end of the curved portion; and
in the flat portion that is formed in an annular shape along the circumferential direction of the rotor shaft, the length in the axial direction of a portion adjacent to an open air suction port that is formed at the distal end of the first casing and the second casing is longer than the length in the axial direction of another portion that is positioned further from the suction port than the portion.
2. The compressor according to claim 1 , wherein n struts are arranged in the circumferential direction of the rotor shaft (n being an integer of 2 or more); and
the difference between the maximum value and the minimum value of the angle expressing the spacings of the adjacent struts when centered on the rotor shaft is at least 120 degrees/n.
3. The compressor according to claim 1 , wherein the connection portions of the struts with the outer casing are positioned further to the downstream in the axial direction of the rotor shaft than the distal end of the curved portion.
4. The compressor according to claim 1 , wherein in the curved portion that is formed in an annular shape along the circumferential direction of the rotor shaft, the distal end of a portion that is adjacent to an open air suction port that is formed at the distal end of the first casing and the second casing projects further toward the first casing than the distal end of another portion that is positioned further from the suction port than the portion.
5. The compressor according to claim 1 , wherein the connection portions of the struts with the outer casing are positioned further downstream in the axial direction of the rotor shaft than the connection portions of the struts with the inner casing.
6. The compressor according to claim 5 , wherein the distance in the axial direction of the connection portion between the struts with the outer casing and the distance in the axial direction of the connection portion between the struts with the inner casing are longer the closer the struts are to the suction port.
7. The compressor according to claim 3 , wherein in the curved portion formed in an annular shape along the circumferential direction of the rotor shaft, the distal end of a portion that is adjacent to an open air suction port formed at the distal end of the first casing and the second casing projects further toward the first casing than the distal end of another portion that is positioned further from the suction port than the portion.
8. The compressor according to claim 3 , wherein the connection portions of the struts with the outer casing are positioned further downstream in the axial direction of the rotor shaft than the connection portions of the struts with the inner casing.
9. The compressor according to claim 4 , wherein the connection portions of the struts with the outer casing are positioned further downstream in the axial direction of the rotor shaft than the connection portions of the struts with the inner casing.
10. The compressor according to claim 7 , wherein the connection portions of the struts with the outer casing are positioned further downstream in the axial direction of the rotor shaft than the connection portions of the struts with the inner casing.
11. The compressor according to claim 8 , wherein the distance in the axial direction of the connection portion between the struts with the outer casing and the distance in the axial direction of the connection portion between the struts with the inner casing are longer the closer the struts are to the suction port.
12. The compressor according to claim 9 , wherein the distance in the axial direction of the connection portion between the struts with the outer casing and the distance in the axial direction of the connection portion between the struts with the inner casing are longer the closer the struts are to the suction port.
13. The compressor according to claim 10 , wherein the distance in the axial direction of the connection portion between the struts with the outer casing and the distance in the axial direction of the connection portion between the struts with the inner casing are longer the closer the struts are to the suction port.