US Patent 7131818 Airfoil with three-pass serpentine cooling channel and microcircuit

An airfoil, and in a disclosed embodiment a rotor blade, has a serpentine cooling path. To best account for the Coriolis effect, the paths of the serpentine cooling channel have trapezoidal cross-sections. An area of the rotor blade between a smaller side of the trapezoidal-shaped paths, and a facing wall of the rotor blade has high thermal and mechanical stresses, and is a challenge to adequately cool. A microcircuit, which is a very thin cooling circuit having crossing pedestals, is embedded into the blade in this area. The microcircuit provides additional cooling, and addresses the challenges with regard to cooling these areas.