Airfoil with three-pass serpentine cooling channel and microcircuit

A turbine blade comprising:

• an airfoil extending outwardly of a platform, said airfoil being curved with a pressure wall and a suction wall spaced from each other;
• cooling channels formed between said suction and pressure walls and within said airfoil, said cooling channels including a serpentine channel, said serpentine channel having a first path extending from said platform outwardly of said platform and through said airfoil, a second path communicating with said first path and returning cooling fluid back toward said platform, and a third path communicating with said second path and returning cooling fluid back outwardly away from said platform, said first, second and third paths having a generally trapezoidal shape in cross-section, with each of said trapezoidal shapes defining a larger side and a smaller side, said larger sides of said first and third paths being positioned facing said pressure wall and said smaller sides of said first and third paths being positioned facing said suction wall, and said larger side of said second path being positioned facing said suction wall, with said smaller side of said second path being positioned facing said pressure wall;
• and
• a microcircuit cooling circuit positioned between said pressure wall and said smaller side of said second path, said microcircuit cooling circuit receiving cooling fluid to provide additional cooling in an area between said smaller side of said second path and said pressure wall, said microcircuit cooling circuit receiving said cooling fluid from one of said first and third paths, and said microcircuit cooling circuit communicating with a plurality of openings in said pressure wall to pass said cooling fluid onto said pressure wall to provide film cooling, said microcircuit cooling circuit being smaller in cross-section than said first, second and third paths.

A gas turbine engine comprising:

• a fan;
• a compressor;
• a combustion section;
• and
• a turbine having rotor blades, and vanes, at least one of said rotor blades and said vanes having an airfoil with a base and a tip, and said airfoil extending between a suction wall and a pressure wall, and cooling channels formed between said suction and pressure walls and within said airfoil, said cooling channels including a serpentine channel, said serpentine channel having a first path extending outwardly away from said base and through said airfoil towards said tip, a second path communicating with said first path and returning cooling fluid back toward said base, and a third path communicating with said second path and returning cooling fluid back outwardly away from said base, said first, second and third paths each having a generally trapezoidal shape in section, with each said trapezoidal shape defining a larger side and a smaller side, said larger sides of said first and third paths being positioned facing one of said pressure and suction walls and said smaller sides of said first and third paths being positioned facing the other of said pressure and suction walls, and said larger side of said second path being positioned facing said other of said pressure and suction walls, with said smaller side of said second path being positioned facing said one of said pressure and suction walls, a microcircuit embedded within said airfoil adjacent said smaller side of one of said first, second, and third paths and between said smaller side of said one of said first, second, and third paths and a facing one of said pressure and suction walls, said microcircuit cooling circuit receiving cooling fluid to provide additional cooling in an area between said smaller side of said one of said first, second, and third paths and said pressure wall.