US Patent 7641445 Large tapered rotor blade with near wall cooling

A turbine rotor blade for use in a gas turbine engine, the blade including a serpentine flow cooling circuit that includes a first leg forming a leading edge cooling channel, a second leg that includes an upper channel with trip strips and a lower portion with near wall cooling channels that split off from the upper portion of the second leg to form near wall cooling channels extending along the pressure side and the suction side of the blade, the near wall cooling channels being separated by a dead cavity, and a third leg formed along the trailing edge of the blade with a collecting cavity formed in the blade root and providing the fluid communication between the trailing edge third leg and the near wall cooling channels. The trailing edge channel is connected to a plurality of metering and diffusion holes spaced along the trailing edge. These exit holes include a metering hole, a first diffusion hole, and a diffusion slot located on the pressure side of the trailing edge of the blade. A plurality of the metering and diffusion holes opens into a single diffusion slot. The diffusion slots each include a second diffusion hole and a third diffuser arranged in series.