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.

Abstract: An axial-flow gas turbine engine includes a plurality of inlet guide vanes (V) which are radially disposed in an annular gas passage defined between an inner peripheral wall (Ch) and an outer peripheral wall (Ct) of a turbine. The inner peripheral wall (Ch) of the gas passage includes inner peripheral concave portions (Cc1 and Cc3) on an upstream side, and inner peripheral convex portions (Cv1 and Cv3) on a downstream side. The outer peripheral wall (Ct) of the gas passage includes outer peripheral convex portions (Cv2 and Cv4) on an upstream side, and outer peripheral concave portions (Cc2 and Cc4) on a downstream side. Therefore, a pressure difference in a radial direction of the inlet guide vane V is reduced or partially reversed, and a secondary flow toward an inner side in the radial direction can be suppressed to reduce pressure loss.

Abstract: In a transonic region with a Reynolds number not more than a critical Reynolds number, a flow velocity distribution on an extrados of an airfoil has a single supersonic maximum value within a range of up to 6% from a leading edge on a chord, or a shape factor has a maximum value in a region of 6 to 15% from the leading edge on the chord, the value being nearly constant in a region of 30 to 60% and gradually can increase up to 2.5 in a region downstream of 60% of chord. A pressure loss in a low Reynolds number region can be drastically reduced, while conventionally keeping low the pressure loss in a high Reynolds number region. Moreover, this pressure-loss reduction effect in the low Reynolds number region is exerted even if an inflow angle is changed in a wide range.

Abstract: A first bent portion bent toward an intrados and a second bent portion located in the rear of the first bent portion and bent toward an extrados are provided on a camber line on a trailing edge in the rear of 90% of a chord length of a turbine blade having an extremely low aspect ratio for an axial-flow turbine. The inclination of the camber line immediately in the rear of the second bent portion on the side of a blade root is substantially equal to the inclination of the camber line immediately in front of the first bent portion, and the curvature of the second bent portion is decreased from the side of the blade root toward a blade tip. As a result, a higher-pressure portion on the intrados which is a pressure surface of the turbine blade is displaced toward the trailing edge, and thus a secondary flow from the side of the blade tip toward the blade root can be suppressed, whereby a pressure loss particularly in the vicinity of the blade root can be suppressed to the minimum.

Abstract: An axial-flow gas turbine engine includes a plurality of inlet guide vanes (V) which are radially disposed in an annular gas passage defined between an inner peripheral wall (Ch) and an outer peripheral wall (Ct) of a turbine. The inner peripheral wall (Ch) of the gas passage includes inner peripheral concave portions (Cc1 and Cc3) on an upstream side, and inner peripheral convex portions (Cv1 and Cv3) on a downstream side. The outer peripheral wall (Ct) of the gas passage includes outer peripheral convex portions (Cv2 and Cv4) on an upstream side, and outer peripheral concave portions (Cc2 and Cc4) on a downstream side. Therefore, a pressure difference in a radial direction of the inlet guide vane V is reduced or partially reversed, and a secondary flow toward an inner side in the radial direction can be suppressed to reduce pressure loss.

Abstract: In a transonic region with a Reynolds number not more than a critical Reynolds number, a flow velocity distribution on an extrados of an airfoil has a single supersonic maximum value within a range of up to 6% from a leading edge on a chord, or a shape factor has a maximum value in a region of 6 to 15% from the leading edge on the chord, the value being nearly constant in a region of 30 to 60% and gradually can increase up to 2.5 in a region downstream of 60% of chord. A pressure loss in a low Reynolds number region can be drastically reduced, while conventionally keeping low the pressure loss in a high Reynolds number region. Moreover, this pressure-loss reduction effect in the low Reynolds number region is exerted even if an inflow angle is changed in a wide range.

Abstract: A first bent portion bent toward an intrados and a second bent portion located in the rear of the first bent portion and bent toward an extrados are provided on a camber line on a trailing edge in the rear of 90% of a chord length of a turbine blade having an extremely low aspect ratio for an axial-flow turbine. The inclination of the camber line immediately in the rear of the second bent portion on the side of a blade root is substantially equal to the inclination of the camber line immediately in front of the first bent portion, and the curvature of the second bent portion is decreased from the side of the blade root toward a blade tip. As a result, a higher-pressure portion on the intrados which is a pressure surface of the turbine blade is displaced toward the trailing edge, and thus a secondary flow from the side of the blade tip toward the blade root can be suppressed, whereby a pressure loss particularly in the vicinity of the blade root can be suppressed to the minimum.

Abstract: A high-turning and high-transonic blade for use in a blade cascade of an axial-flow compressor, wherein a distribution of flow speed on an extrados at a leading edge of the blade has a supersonic region of a substantially constant flow speed in the rear of a first large value of the flow speed and inside a position corresponding to 15% of a chord length from the leading edge. The supersonic region is established so that a value obtained by the division of a difference between Mach numbers at front and rear ends of the supersonic region by a chord-wise length of the supersonic region is smaller than 1, and the maximum Mach number in the supersonic region is smaller than 1.4. A first large shock wave is positively generated at a position where the flow speed assumes a first maximum value, whereby a second shock wave generated in the supersonic region of the substantially constant flow speed in the rear of such a position can be weakened.

Abstract: A gas turbine engine has, in a cross section in the axial direction of an annular inner peripheral wall connected to a blade main body of a turbine blade, a concave part and a convex part on the front edge side and the rear edge side. The concave part has a negative curvature and is concave toward the axis, and the convex part has a positive curvature and is convex away from the axis. The flow rate on the upper face of the blade main body can be reduced in the concave part on the front edge side, thus suppressing generation of a shock wave, and the flow rate can be increased in the convex part on the rear edge side following the concave part, thus smoothly changing the flow rate on the upper face of the blade main body and thereby minimizing the pressure loss. In this way, the thickness of the blade main body can be reduced while ensuring the performance of the gas turbine engine, thereby contributing to a reduction in weight.

Abstract: A high-turning and high-transonic blade for use in a blade cascade of an axial-flow compressor, wherein a distribution of flow speed on an extrados at a leading edge of the blade has a supersonic region of a substantially constant flow speed in the rear of a first large value of the flow speed and inside a position corresponding to 15% of a chord length from the leading edge. The supersonic region is established so that a value obtained by the division of a difference between Mach numbers at front and rear ends of the supersonic region by a chord-wise length of the supersonic region is smaller than 1, and the maximum Mach number in the supersonic region is smaller than 1.4. A first large shock wave is positively generated at a position where the flow speed assumes a first maximum value, whereby a second shock wave generated in the supersonic region of the substantially constant flow speed in the rear of such a position can be weakened.

Abstract: In a high turning airfoil capable of being suitably applied to each of blades constituting a blade row of an axial flow-type compressor, both of an intrados generating a positive pressure and an extrados generating a negative pressure exist on one side of a chord line, and the curvature of the extrados made non-dimensional by a chord length has a maximum value between a position corresponding to 10% of the chord length and a position corresponding to 35% of the chord length, and a minimum value in the rear of the position of the maximum value and between a position corresponding to 30% of the chord length and a position corresponding to 50% of the chord length. Preferably, a difference between the maximum value and the minimum value of the curvature is equal to or larger than 0.5, and a turning angle is equal to or larger than 40°.

Abstract: In a high turning airfoil capable of being suitably applied to each of blades constituting a blade row of an axial flow-type compressor, both of an intrados generating a positive pressure and an extrados generating a negative pressure exist on one side of a chord line, and the curvature of the extrados made non-dimensional by a chord length has a maximum value between a position corresponding to 10% of the chord length and a position corresponding to 35% of the chord length, and a minimum value in the rear of the position of the maximum value and between a position corresponding to 30% of the chord length and a position corresponding to 50% of the chord length. Preferably, a difference between the maximum value and the minimum value of the curvature is equal to or larger than 0.5, and a turning angle is equal to or larger than 40°.

Abstract: In a stator vane arrangement including a plurality of stator vanes axially opposing a plurality of rotor vanes in rotating machinery, each stator vane is tilted with respect to a radial line so that the load acting on the hub end of each stator vane is reduced and a secondary flow is minimized. This allows the aspect ratio of each stator vane to be reduced, and the number of stator vanes to be reduced without impairing the efficiency of the rotating machinery. This in turn allows the frequency of the oscillator force produced by the stator vane in relation with the motion of the rotor vanes to be lowered so that a resonant condition of the stator vanes can be avoided relatively easily.

Abstract: A blade for an axial-flow turbine includes an intrados producing a positive pressure between a leading edge and a trailing edge, and an extrados producing a negative pressure. The intrados is formed at its rear portion with a flat surface portion connected to the trailing edge, and the extrados has a curved surface portion formed at least at a portion corresponding to the flat surface portion. The trailing edge of the turbine blade is pointed at its end. The angle of intersection between the intrados and the extrados at the trailing edge is a right angle or an acute angle. Thus, it is possible to inhibit the flowing of a gas from the intrados at the trailing edge toward the extrados and to decrease the degree of curvature of the extrados at the trailing edge portion to reduce the flow speed, thereby minimizing a shock wave generated at the trailing edge portion to reduce the pressure loss and enhance the performance of the turbine.

Abstract: A turbine blade for an axial-flow turbine includes an intrados generating a positive pressure, and an extrados generating a negative pressure, wherein the intrados and the extrados are provided between a leading edge and a trailing edge. An inflection point is provided between a concave portion on an upstream side and a convex portion on a downstream side in a region extending from a position of 80% on the intrados to a rear throat, and the length of a normal line drawn downwards from the intrados of one of the turbine blades to an extrados of the other turbine blade has at least one maximum value in a region extending from a front throat of the one turbine blade to a rear throat. Thus, it is possible to disperse a shock wave generated from the intrados at the trailing edge to prevent the generation of a strong shock wave, thereby reducing the pressure loss caused by the shock wave.

Abstract: A blade for an axial-flow turbine includes an intrados producing a positive pressure between a leading edge and a trailing edge, and an extrados producing a negative pressure. The intrados is formed at its rear portion with a flat surface portion connected to the trailing edge, and the extrados has a curved surface portion formed at least at a portion corresponding to the flat surface portion. The trailing edge of the turbine blade is pointed at its end. The angle of intersection between the intrados and the extrados at the trailing edge is a right angle or an acute angle. Thus, it is possible to inhibit the flowing of a gas from the intrados at the trailing edge toward the extrados and to decrease the degree of curvature of the extrados at the trailing edge portion to reduce the flow speed, thereby minimizing a shock wave generated at the trailing edge portion to reduce the pressure loss and enhance the performance of the turbine.