Passive Shroud Cooling Concepts for HP Turbines: Experimental Investigations

The cooling of rotor shrouds in the first stage of a high-pressure turbine requires special attention as flatter turbine inlet temperature profiles and more highly loaded blades result in increased thermal and mechanical stresses. The use of film cooling and/or internal convective cooling makes the rotor shroud heavier and oversized, restricting the maximum rotational speed. Alternative methods are, therefore, sought to achieve improved cooling of the shroud. This paper discusses the low-speed experimental investigation of two “passive” cooling concepts known as “rail cooling” and “platform cooling.” It has been shown experimentally that the modified cooling method, namely, the platform cooling, substantially improves the rotor shroud coolant distribution in the critical areas while employing significantly lower amounts of coolant.