Cooling passages and methods of fabrication

An electrochemical machining process for forming a plurality of concavities on a surface of at least one cooling passage disposed within a turbine engine component, comprising:

• positioning in the at least one cooling passage an electrode coated with an insulating material in a pattern defining the plurality of concavities to be formed on said surface of said at least one cooling passage, and
• machining the plurality of concavities on the surface of the at least one cooling passage by passing an electric current between the electrode positioned in the at least one cooling passage and the turbine engine component while circulating an electrolyte solution through the cooling passage, wherein said plurality of concavities are configured in an array pattern to create a spiral bulk fluid motion.

An electrode for use in an electrochemical machining process comprising an electrically conductive housing having an external surface partially coated with an insulating coating in a pattern defining concavities to be formed on an internal surface of a cooling passage, wherein said plurality of concavities, so defined and when formed, are configured in an array pattern to create a spiral bulk fluid motion.

A method of forming a plurality of dimples on a surface of at least one cooling passage of a turbine airfoil, said method comprising:

• positioning in said at least one cooling passage an electrode coated with an insulating material in a pattern defining the plurality of dimples to be formed on said surface of said at least one cooling passage, and
• machining the plurality of dimples on the surface of said at least one cooling passage by passing an electric current between the electrode positioned in said at least one cooling passage and the turbine airfoil while circulating an electrolyte solution through the cooling passage, wherein said plurality of dimples are configured in an array pattern to create a spiral bulk fluid motion.