Abstract: A rotor blade for a gas turbine engine has an airfoil, a base integrally joined to the airfoil, and a root integrally joined to the base and mountable in a slot in a rotor hub of the gas turbine engine. The root has a dovetail including at least one contact face that, when mounted, contacts a surface of the slot to retain the rotor blade in the hub. The root includes a neck between the base and the dovetail, and a groove in the neck for redirecting stress in the rotor blade. In certain embodiments, the groove is at a distance from the at least one contact face, has a length less than a length of the dovetail, and/or has an initial non-zero depth at the side of a trailing edge of the airfoil and tapers to a zero depth in the direction of the leading edge of the airfoil.

Abstract: A rotor blade for a gas turbine engine has an airfoil, a base integrally joined to the airfoil, and a root integrally joined to the base and mountable in a slot in a rotor hub of the gas turbine engine. The root has a dovetail including at least one contact face that, when mounted, contacts a surface of the slot to retain the rotor blade in the hub. The root includes a neck between the base and the dovetail, and a groove in the neck for redirecting stress in the rotor blade. In certain embodiments, the groove is at a distance from the at least one contact face, has a length less than a length of the dovetail, and/or has an initial non-zero depth at the side of a trailing edge of the airfoil and tapers to a zero depth in the direction of the leading edge of the airfoil.

Abstract: A tuning rib is added preferably in the aft cavity of a cored turbine bucket to alter the bucket's natural frequencies. The tuning rib may be a solid rib or a segmented rib and is particularly suited for altering high order frequency modes such as 2T, 4F and 1-3S. As such, detrimental crossings of natural bucket frequencies and gas turbine stimuli can be avoided to thereby improve the reliability of a gas turbine without impacting other features of the bucket that are important to the performance of the gas turbine.

Abstract: The first-stage buckets have airfoil profiles substantially in accordance with Cartesian coordinate values of X, Y and Z set forth in Table I wherein Z is a perpendicular distance from a plane normal to a radius of the turbine centerline and containing the X and Y values with the Z value commencing at zero in the X, Y plane at the radially innermost aerodynamic section of the airfoil and X and Y are coordinates defining the airfoil profile at each distance Z. The X, Y and Z values may be scaled as a function of the same constant or number to provide a scaled-up or scaled-down airfoil section for the bucket.

Abstract: A tuning rib is added preferably in the aft cavity of a cored turbine bucket to alter the bucket's natural frequencies. The tuning rib may be a solid rib or a segmented rib and is particularly suited for altering high order frequency modes such as 2T, 4F and 1-3S. As such, detrimental crossings of natural bucket frequencies and gas turbine stimuli can be avoided to thereby improve the reliability of a gas turbine without impacting other features of the bucket that are important to the performance of the gas turbine.