Aerodynamic Performance Measurements of a Film-Cooled Turbine Stage: Experimental Results

Modern high performance gas turbine engines utilize film cooling to reduce the heat load on high-pressure turbine stage components, thereby increasing the maximum turbine inlet temperature at which the cycle can operate. However, increased turbine inlet temperature comes at the expense of a reduction in turbine efficiency. The objective of this research is to measure the aerodynamic performance of a film cooled turbine stage and to quantify the loss caused by film cooling. An un-cooled turbine stage was first fabricated with solid blading and tested using a newly developed short duration measurement technique. The stage was then modified to incorporate vane, blade and rotor casing film cooling. The film-cooled stage was then tested over a range of coolant-to-mainstream mass flow and temperature ratios for the same range of operating conditions (pressure ratios and corrected speeds) as the un-cooled turbine. This paper presents the experimental results for these two series of tests.