Patent ID: 7785074

Claim:
A blade of a rotor of a second stage of a compressor, which can be defined by coordinates of a discreet combination of points, in a Cartesian reference system (X, Y, Z), wherein the axis (Z) is a radial axis intersecting the central axis of the compressor, said blade having an aerodynamic profile which can be identified by a series of closed intersection curves between the profile itself and planes (X, Y) lying at distances (Z) from the central axis, said blade comprising: a base portion fixable to the rotor, the aerodynamic profile identified by a first substantially concave surface, which is pressurized, and a second substantially convex surface which is in depression and which is opposite to the first concave surface, said two surfaces being continuous and joined to each other to form the aerodynamic profile of said blade extending from a foot at said base portion to a free end of said blade distal from said base portion, wherein each closed curve substantially parallel to said base portion has a maximum thickness determined by a maximum distance between said first surface and said second surface, said maximum thickness of each closed curve, along the height of the blade in the direction of the free end of the blade, having a non-linearly variable trend decreasing at a higher rate from said base portion to a first predetermined height, then at a lower rate from the first predetermined height to a second predetermined height, said variable trend of maximum thickness halfway up the blade being suitable for shifting one or more natural resonance frequencies of the blade itself outside a functioning velocity range of said rotor.