Abstract: A suction surface of a blade forming a blade row of an axial compressor includes a concave region having a negative curvature at a leading edge part, and a flat region having substantially zero curvature continued rearwardly of the concave region, so that multiple compression waves are generated, enabling moderation of magnitude of a 1st passage shock to reduce pressure loss and suppress boundary layer separation on the suction surface. Providing a concave region having a negative curvature in a frontal part on a pressure surface of the blade suppresses an increase in the airflow velocity in the frontal part, thus weakening a 2nd passage shock generated on the pressure surface to enable reduction of pressure loss. The concave region of the pressure surface may be extended from a position having a chord length of no greater than 10% to a position having at least 20%.

Abstract: A vane for an axial-flow compressor has a pressure surface generating positive pressure and a suction surface generating negative pressure, and both are located on one side of the chord line. The pressure surface includes a bulging portion, having a maximum curvature of 1.5 or more between a chordal position of 70% and 95%, in a central section of the vane's span. This configuration increases the flow velocity around the bulging portion of the pressure surface to locally decrease the static pressure. By flow continuity the flow velocity on the suction surface that faces the pressure surface is decreased, and thus locally the static pressure on the suction surface is increased. Secondary flow from the pressure surface with positive pressure to the suction surface with negative pressure from the hub region, is suppressed due to the locally increased static pressure on the suction surface.

Abstract: A suction surface of a blade forming a blade row of an axial compressor includes a concave region having a negative curvature at a leading edge part, and a flat region having substantially zero curvature continued rearwardly of the concave region, so that multiple compression waves are generated, enabling moderation of magnitude of a 1st passage shock to reduce pressure loss and suppress boundary layer separation on the suction surface. Providing a concave region having a negative curvature in a frontal part on a pressure surface of the blade suppresses an increase in the airflow velocity in the frontal part, thus weakening a 2nd passage shock generated on the pressure surface to enable reduction of pressure loss. The concave region of the pressure surface may be extended from a position having a chord length of no greater than 10% to a position having at least 20%.

Abstract: A vane for an axial-flow compressor has a pressure surface generating positive pressure and a suction surface generating negative pressure, and both are located on one side of the chord line. The pressure surface includes a bulging portion, having a maximum curvature of 1.5 or more between a chordal position of 70% and 95%, in a central section of the vane's span. This configuration increases the flow velocity around the bulging portion of the pressure surface to locally decrease the static pressure. By flow continuity the flow velocity on the suction surface that faces the pressure surface is decreased, and thus locally the static pressure on the suction surface is increased. Secondary flow from the pressure surface with positive pressure to the suction surface with negative pressure from the hub region, is suppressed due to the locally increased static pressure on the suction surface.

Abstract: A generating line of a casing surrounding an outer periphery of vanes of a stator disposed downstream of a rotor of the axial-flow compressor includes: a recessed region recessed outward in a radial direction from a position forward of a front edge of each of the vanes to a position rearward of a rear edge of the vane; and a protruding region bulging inward in the radial direction at an intermediate position of the recessed region in a front-rear direction thereof. Thus, a distribution of static pressure in the radial direction on a surface of the vane is improved by a first recessed portion forward of the protruding region, and the static pressure on the tip side is raised by a second recessed portion rearward of the protruding region.