Curved turbulator configuration for airfoils and method and electrode for machining the configuration

An airfoil comprising:

• a tip including at least one exit hole;
• a root;
• a body extending between said tip and said root, said body including a pressure side and a suction side and a leading wall on said suction side and a trailing wall on said pressure side;
• at least one radial cooling passage extending through said body between said tip and said root, said radial cooling passage being defined by at least an inner surface of said leading wall and an inner surface of said trailing wall;
• a curved turbulator configuration integrated with the inner surfaces of said leading and trailing walls, said curved turbulator configuration comprising:
• a plurality of spaced curved turbulator pairs positioned along a center-line on the inner surface of said leading wall, wherein said curved turbulator pairs are curved facing away from the center-line of said leading wall and facing said tip;
• and
• a plurality of spaced complementary curved turbulator pairs positioned along a center-line on the inner surface of said trailing wall, wherein said complementary curved turbulator pairs are curved facing the center line of said trailing wall and facing said tip,
• wherein said exit hole is connected to said radial cooling passage and is configured to vent coolant from said airfoil after the coolant flows through said radial cooling passage.

A rotor blade comprising:

• a shank;
• an airfoil attached to said shank, said airfoil comprising:
• a tip including at least one exit hole;
• a root;
• a body extending between said tip and said root, said body including a pressure side and a suction side and a leading wall on said suction side and a trailing wall on said pressure side;
• at least one radial cooling passage extending through said body between said tip and said root, said radial cooling passage being defined by at least an inner surface of said leading wall and an inner surface of said trailing wall;
• a curved turbulator configuration integrated with the inner surfaces of said leading and trailing walls, said curved turbulator configuration comprising:
• a plurality of spaced curved turbulator pairs positioned along a center-line on the inner surface of said leading wall, wherein said curved turbulator pairs are curved facing away from the center-line of said leading wall and facing said tip;
• and
• a plurality of spaced complementary curved turbulator pairs positioned along a center-line on the inner surface of said trailing wall, wherein said complementary curved turbulator pairs are curved facing the center line of said trailing wall and facing said tip,
• wherein said exit hole is connected to said radial cooling passage and is configured to vent coolant from the airfoil after the coolant flows through said cooling passage.

An electrochemical machining method for forming a curved turbulator configuration on an inner surface of a leading wall of an airfoil and on an inner surface of a trailing wall of the airfoil, the inner surfaces defining a radial cooling passage extending between a tip and a root of the airfoil, said electrochemical machining method comprising:

• positioning an electrode in a predrilled hole in the airfoil, the electrode comprising a conductive core and an insulating coating, the electrode having a leading face and a trailing face, wherein the insulating coating provides a curved turbulator pattern on the leading face and a complementary curved turbulator pattern on the trailing face;
• machining at least one pair of curved turbulators on the inner surface of the leading wall using the curved turbulator pattern and at least one pair of complementary curved turbulators on the inner surface of the trailing wall using the complementary curved turbulator pattern, the pairs of curved turbulators and complementary curved turbulators being machined simultaneously by passing an electric current between the electrode and the airfoil while circulating an electrolyte solution through the predrilled hole, wherein a plurality of curved turbulators pairs spaced along a center-line of the inner surface of the leading wall are simultaneously machined with a plurality of complementary curved turbulator pairs spaced along a center-line of the inner surface of the trailing wall, said simultaneous machining comprising passing the electric current between the electrode and the airfoil while circulating the electrolyte solution through the predrilled hole, wherein the curved turbulator pairs are curved facing away from the center-line of the leading wall and facing the tip of the airfoil, wherein the complementary curved turbulator pairs are curved facing the center line of the trailing wall and facing the tip of the airfoil.

An electrode for forming a curved turbulator configuration in a radial cooling passage within an airfoil, said electrode comprising:

• a tip,
• a leading face having a curved turbulator pattern;
• a trailing face having a complementary curved turbulator pattern;
• a conductive core;
• and
• an insulating coating disposed on said conductive core, said insulating coating being partly removed,
• wherein said curved turbulator pattern comprises a plurality of pairs of curved exposed portions of the conductive core wherein said curved exposed portions of said conductive core are curved facing away from a center-line of said leading face of said electrode and towards said tip, and said complementary curved turbulator pattern comprises a plurality of pairs of complementary curved exposed portions of the conductive core, wherein said complementary curved exposed portions of said conductive core are curved facing a center-line of said trailing face of the electrode and towards said tip.

An electrode for forming a curved turbulator configuration in a radial cooling passage within an airfoil, said electrode comprising:

• a tip,
• a leading face having a curved turbulator pattern;
• a trailing face having a complementary curved turbulator pattern;
• a conductive core;
• and
• an insulating coating disposed on said conductive core, said insulating coating being partly removed to include a plurality of pairs of curved portions of said insulating coating on said leading face and a plurality of pairs of complementary curved portions of said insulating coating on said trailing face, each of said curved portions and said complementary curved portions being surrounded by an exposed region of said conductive core,
• wherein said curved turbulator pattern comprises said pairs of curved portions of said insulating coating wherein said curved portions of said insulating coating are curved facing away from a center-line of said leading face of said electrode and towards said tip, and said complementary curved turbulator pattern comprises said pairs of complementary curved portions of said insulating coating, wherein said complementary curved portions of said insulating coating are curved facing a center-line of said trailing face of said electrode and towards said tip.