Heat Transfer Augmentation in Gas Turbine Blade Passages

In general gas turbine cooling is achieved by bleeding some relatively cool air from the compressor and using it inside the gas turbine blades to remove heat transferred into the blade from the hot mainstream. The cooling air flows through internal cooling passages inside the blade. These passages are specifically designed to maximize the heat transfer. In modern gas turbine blades this is usually done by the use of contact area enhancers and turbulence promoters such as ribs and pin-fins in the passages. Some of this cooling air is ejected onto the surface of the turbine blade to form an insulating film - with the goal of reducing contact of the blade with the hot mainstream gas.