Experimental Investigation of an Innovative Cooling System (ICS) for High Temperature Transonic Turbine Stages

Abstract

Gas turbine design technology requires the development of transonic turbine stages capable of carrying high stage load and of handling hot gas temperatures at turbine inlet. A reliable cooling system is necessary to cope with the shock system in the main flow field especially in the leading edge region of the rotor blades. These requirements are fulfilled by the Innovative Cooling System (ICS) developed at the Institute for Thermal Turbomachinery and Machine Dynamics, Graz University of Technology. The ICS is also able to cover large areas of the blade surface with an effective cooling film and to reduce the metal temperature. In this paper the authors present results on the flow measurements giving the aerodynamic behavior of these cooling films and on the investigation of their cooling effectiveness. The measurements were done on an industrial turbine blade in a linear cascade arrangement. In addition to conventional measurement methods optical methods (Schlieren visualization, Laser Doppler Velocimetry) were employed to investigate and visualize the transonic flow through the linear blade cascade. An infrared (IR) camera system was used to determine the effectiveness of this newly designed cooling system by measuring the temperature distribution on the blade surface. Experimental results concerning aerodynamic flow behavior and cooling effectiveness are presented.