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.