Patent ID: 8757967

Claim:
An axial flow turbine comprising: a low pressure turbine section; and a turbine exhaust system in axial flow series with the low pressure turbine section, the low pressure turbine section comprising: a final low pressure turbine stage having a circumferential row of static aerofoil blades followed in axial succession by a circumferential row of rotating aerofoil blades, each aerofoil blade having a radially inner hub region and a radially outer tip region, wherein a K value, being equal to a ratio of a throat dimension (t) to a pitch dimension (p), of each static aerofoil blade varies along a height of the static aerofoil blade, between the hub region and the tip region, according to a substantially W-shaped distribution; and wherein the K value of each static aerofoil blade varies along the height of the static aerofoil blade between values K stat min and K stat max according to the substantially W-shaped distributions as follows: Fractional Minimum Maximum height of fixed K value K value aerofoil blade (K stat min ) (K stat max ) 0 0.423985906 0.623985906 0.080855998 0.36638664 0.56638664 0.165294716 0.303545296 0.503545296 0.255880075 0.250207381 0.450207381 0.34182611 0.292337117 0.492337117 0.4154889 0.327357863 0.527357863 0.480483625 0.358649554 0.558649554 0.541802843 0.343071191 0.543071191 0.604115243 0.311514359 0.511514359 0.669284849 0.276224263 0.476224263 0.738563225 0.24037955 0.44037955 0.808859552 0.245298199 0.445298199 0.875782568 0.256737999 0.456737999 0.939306658 0.268124553 0.468124553 1 0.27945616 0.47945616.