Turbine blade

Abstract

An airfoil profile is formed such that a passage width ratio, represented in a dimensionless manner, of an inter-blade passage width of vane root cross-section to an outlet throat width substantially monotonously decreases from a blade inlet toward a blade outlet. The blade has a blade airfoil profile shape in an envelope within a range of ±2.0 mm in a direction normal to any surface location of an airfoil profile portion. The airfoil profile portion has a reference airfoil contour represented in Cartesian coordinates, wherein Z is a distance representing a sectional height from a root of the airfoil profile portion. The contours represented by X and Y at each section Z are joined smoothly with one another in a blade height direction to form a complete shape of the airfoil profile portion.

1 . A gas turbine comprising a turbine blade, the turbine blade having a blade airfoil profile portion,
 wherein the airfoil profile portion is formed such that a passage width ratio, represented in a dimensionless manner, of an inter-blade passage width of vane root cross-section to an outlet throat width monotonously decreases toward a blade outlet after monotone increasing from a blade inlet; and is formed such that a ratio of a peak passage width ratio to a passage width ratio at the blade inlet is set to 1.05 or less.   
     
     
         2 . The gas turbine according to  claim 1 ,
 wherein the blade is secured to an insertion groove by an axial entry method, the insertion groove being formed on a rotor disk and parallel to the rotor disk rotating shaft;   wherein a divisional plane of a platform of the blade is formed approximately parallel to a direction of turbine rotational axis; and   wherein a peak of the airfoil back-side profile of a blade-root cross-section and a lowest point of the airfoil ventral-side profile adjacent thereto are formed not to overlap each other.   
     
     
         3 . The gas turbine according to  claim 1 , wherein the blade is a first stage turbine blade.