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: A cooling structure of a turbine airfoil cools a turbine airfoil (10) exposed to hot gas (1), using cooling air (2) of a temperature lower than that of the hot gas. The turbine airfoil (10) includes an external surface (11), an internal surface (12) opposite to the external surface, a plurality of film-cooling holes (13) blowing the cooling air from the internal surface toward the external surface to film-cool the external surface, and a plurality of heat-transfer promoting projections (14) integrally formed with the internal surface and protruding inwardly from the internal surface. The turbine airfoil further includes a hollow cylindrical insert (20) which is positioned inside the internal surface of the turbine airfoil and to which the cooling air is supplied. The insert has a plurality of impingement holes (21) for impingement-cooling the internal surface (12).

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. 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 a in a range of 0<?30°.

Abstract: A cooling structure of a turbine airfoil cools a turbine airfoil (10) exposed to hot gas (1), using cooling air (2) of a temperature lower than that of the hot gas. The turbine airfoil (10) includes an external surface (11), an internal surface (12) opposite to the external surface, a plurality of film-cooling holes (13) blowing the cooling air from the internal surface toward the external surface to film-cool the external surface, and a plurality of heat-transfer promoting projections (14) integrally formed with the internal surface and protruding inwardly from the internal surface. The turbine airfoil further includes a hollow cylindrical insert (20) which is positioned inside the internal surface of the turbine airfoil and to which the cooling air is supplied. The insert has a plurality of impingement holes (21) for impingement-cooling the internal surface (12).