Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. An axial distance Sr from an upstream end face of the suction ring groove 1 to an impeller full blade leading edge 4 or a width br of the suction ring groove 1 is represented as A·sin(?+?0)+A0 and is distributed in a sinusoidal shape in a circumferential direction, an initial phase angle ?0 is in a range of 0°??0?360°, and a circumferential angle ? of the casing 10 has a definition range of ?0????0+360°. In the expression, A denotes amplitude of distribution of the axial distance Sr or the width br, and A0 denotes an average of the axial distance Sr or the width br.

Abstract: The centrifugal compressor (1) includes: an impeller (3); and a casing (2) accommodating the impeller (3). The casing (2) includes: an inlet (6); an impeller-accommodating portion (14) in which the impeller (3) is disposed; an annular flow passageway (5) formed around the impeller (3); an outlet (9) communicating with the annular flow passageway (5); and an annular chamber (11) formed around at least one of the inlet (6) and the impeller-accommodating portion (14). An inner circumferential surface (2a) of the casing (2) facing the impeller-accommodating portion (14) is provided with a groove (12) which communicates the impeller-accommodating portion (14) and the annular chamber (11) with each other and which is formed over the entire circumference of the inner circumferential surface (2a). In addition, the annular chamber (11) communicates with another space only through the groove (12).

Abstract: The centrifugal compressor (1) includes: an impeller (3); and a casing (2) accommodating the impeller (3). The casing (2) includes: an inlet (6); an impeller-accommodating portion (14) in which the impeller (3) is disposed; an annular chamber (11) formed around the inlet (6); a downstream groove (13) communicating a downstream end portion of the annular chamber (11) with the impeller-accommodating portion (14); and an upstream groove (12) communicating an upstream end portion of the annular chamber (11) with the inlet (6). In addition, the downstream groove (13) is provided in a predetermined range in a circumferential direction of the impeller (3) so as to communicate with a high-pressure part to occur in part of the impeller-accommodating portion (14), and the upstream groove (12) is provided over the entire circumference of the inlet (6).

Abstract: A centrifugal compressor has a casing 7. In the casing 7 is formed a back-flow channel 9 to return fluid from a downstream position of an impeller full blade leading edge 6a to an upstream position of the impeller full blade leading edge 6a. The back-flow channel 9 includes a suction ring groove 9a and a back-flow ring groove 9b. The suction ring groove opens at the downstream position on the inner face 7a of the casing 7, and extends in the circumferential direction. The back-flow ring groove opens at the upstream position on the inner face 7a, and extends in the circumferential direction. Distribution in the circumferential direction of the axial-direction position of the suction ring groove 9a or a width of the suction ring groove 9a is asymmetric with reference to the rotation axis.

Abstract: A centrifugal compressor includes: a volute casing including a first casing and a second casing that are mutually coupled, the first casing including a volute chamber therein and the second casing including an impeller installation space therein; an impeller provided in the impeller installation space so as to be rotatable around a rotation axis; and a vaneless diffuser that has an inlet that communicates with an inside of the second casing and has an outlet that communicates with an inside of the first casing. The vaneless diffuser has a width having a non-axisymmetric distribution in the circumferential direction.

Abstract: A centrifugal compressor includes an impeller, a casing, an impeller housing portion, an inlet port, an annular flow passage provided around the impeller, a discharge port communicated with the annular flow passage, an annular chamber provided around the inlet port, a downstream slot communicating a downstream end of the annular chamber with the impeller housing portion, and an upstream slot communicating an upstream end of the annular chamber with the inlet port. The downstream slot draws a one-cycle curved line pulsating in an axial direction of the inlet port. A most upstream point of the downstream slot is located at an upstream end portion of impeller blades of the impeller when seen along a direction perpendicular to a rotary shaft of the impeller. According to the centrifugal compressor, it becomes possible to expand its operating range by improving a surging restriction effect brought by more effective casing treatment.

Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. An axial-direction position Sr from an upstream end face of the suction ring groove to an impeller full blade leading edge 4 or a width br of the suction ring groove 1 is represented as A(?·D??·D)2+A0 and is distributed in a parabolic shape in a circumferential direction. An initial phase angle ?0 is in a range of 0??0?2?. A circumferential angle ? of the casing has a definition range of ?0????0+2?. In the expression, A denotes a parameter of the parabola in the axial-direction position Sr or the width br, and A0 denotes an extreme of the axial-direction position Sr or the width br when corresponding circumferential angle ? and the ? are equal at an extreme point of distribution of the parabola.

Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. A position or a width of the suction ring groove 1 is distributed in an arc shape in a circumferential direction, and the arc has a center angle ? in a range of 0<??30°.

Abstract: The centrifugal compressor (1) includes: an impeller (3); and a casing (2) accommodating the impeller (3). The casing (2) includes: an inlet (6); an impeller-accommodating portion (14) in which the impeller (3) is disposed; an annular chamber (11) formed around the inlet (6); a downstream groove (13) communicating a downstream end portion of the annular chamber (11) with the impeller-accommodating portion (14); and an upstream groove (12) communicating an upstream end portion of the annular chamber (11) with the inlet (6). In addition, the downstream groove (13) is provided in a predetermined range in a circumferential direction of the impeller (3) so as to communicate with a high-pressure part to occur in part of the impeller-accommodating portion (14), and the upstream groove (12) is provided over the entire circumference of the inlet (6).

Abstract: The centrifugal compressor (1) includes: an impeller (3); and a casing (2) accommodating the impeller (3). The casing (2) includes: an inlet (6); an impeller-accommodating portion (14) in which the impeller (3) is disposed; an annular flow passageway (5) formed around the impeller (3); an outlet (9) communicating with the annular flow passageway (5); and an annular chamber (11) formed around at least one of the inlet (6) and the impeller-accommodating portion (14). An inner circumferential surface (2a) of the casing (2) facing the impeller-accommodating portion (14) is provided with a groove (12) which communicates the impeller-accommodating portion (14) and the annular chamber (11) with each other and which is formed over the entire circumference of the inner circumferential surface (2a). In addition, the annular chamber (11) communicates with another space only through the groove (12).

Abstract: A centrifugal compressor includes: a volute casing including a first casing and a second casing that are mutually coupled, the first casing including a volute chamber therein and the second casing including an impeller installation space therein; an impeller provided in the impeller installation space so as to be rotatable around a rotation axis; and a vaneless diffuser that has an inlet that communicates with an inside of the second casing and has an outlet that communicates with an inside of the first casing. The vaneless diffuser has a width having a non-axisymmetric distribution in the circumferential direction.

Abstract: A centrifugal compressor includes an impeller, a casing, an impeller housing portion, an inlet port, an annular flow passage provided around the impeller, a discharge port communicated with the annular flow passage, an annular chamber provided around the inlet port, a downstream slot communicating a downstream end of the annular chamber with the impeller housing portion, and an upstream slot communicating an upstream end of the annular chamber with the inlet port. The downstream slot draws a one-cycle curved line pulsating in an axial direction of the inlet port. A most upstream point of the downstream slot is located at an upstream end portion of impeller blades of the impeller when seen along a direction perpendicular to a rotary shaft of the impeller. According to the centrifugal compressor, it becomes possible to expand its operating range by improving a surging restriction effect brought by more effective casing treatment.

Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. An axial distance Sr from an upstream end face of the suction ring groove 1 to an impeller full blade leading edge 4 or a width br of the suction ring groove 1 is represented as A·sin(?+?0)+A0 and is distributed in a sinusoidal shape in a circumferential direction, an initial phase angle ?0 is in a range of 0°??0?360°, and a circumferential angle ? of the casing 10 has a definition range of ?0????0+360°. In the expression, A denotes amplitude of distribution of the axial distance Sr or the width br, and A0 denotes an average of the axial distance Sr or the width br.

Abstract: A centrifugal compressor has a casing 7. In the casing 7 is formed a back-flow channel 9 to return fluid from a downstream position of an impeller full blade leading edge 6a to an upstream position of the impeller full blade leading edge 6a. The back-flow channel 9 includes a suction ring groove 9a and a back-flow ring groove 9b. The suction ring groove opens at the downstream position on the inner face 7a of the casing 7, and extends in the circumferential direction. The back-flow ring groove opens at the upstream position on the inner face 7a, and extends in the circumferential direction. Distribution in the circumferential direction of the axial-direction position of the suction ring groove 9a or a width of the suction ring groove 9a is asymmetric with reference to the rotation axis.

Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. A position or a width of the suction ring groove 1 is distributed in an arc shape in a circumferential direction, and the arc has a center angle a in a range of 0<?30°.

Abstract: A centrifugal compressor includes an asymmetric self-recirculating casing treatment that includes, on an inner face of a casing 10, a suction ring groove 1, a ring guide channel 2 and a back-flow ring groove 3 to form a self-recirculating channel. An axial-direction position Sr from an upstream end face of the suction ring groove to an impeller full blade leading edge 4 or a width br of the suction ring groove 1 is represented as A(?·D??·D)2+A0 and is distributed in a parabolic shape in a circumferential direction. An initial phase angle ?0 is in a range of 0??0?2?. A circumferential angle ? of the casing has a definition range of ?0????0+2?. In the expression, A denotes a parameter of the parabola in the axial-direction position Sr or the width br, and A0 denotes an extreme of the axial-direction position Sr or the width br when corresponding circumferential angle ? and the ? are equal at an extreme point of distribution of the parabola.