EXPERIMENTAL CHARACTERIZATION OF HIGH LIFT TRANSONIC TURBINE ROTOR PERFORMANCE IN AN ANNULAR CASCADE

Improvements in modern jet engines to obtain lower specific fuel consumption and emission levels have pushed towards the optimization of every component in these machines. One current approach in minimizing engine weight is using high lift blading to reduce blade count and therefore the overall turbine weight while maintaining similar levels of efficiency. The goal of this work was to evaluate the performance of six different high pressure turbine geometries to assess the viability of using high lift designs. To do so, this study begins through the development of measurement techniques to aid the aerodynamic characterization of the flow field in a turbine environment: five-hole probe calibration maps were produced, hot wire sensors were calibrated, and an oil visualization technique was developed. The airfoils in this work were tested in a rainbow annular cascade in a stationary rig and a flow conditioning gauze was used to replicate the rotor inlet profile in the blade reference frame. The next step taken was characterizing and validating the flow field behind the gauze. Subsequently, the six turbine geometries were tested at two transonic Mach number conditions and at different Reynolds numbers. Continuous total pressure and flow angle traverses were carried out to evaluate the pressure and kinetic loss coefficients across the turbines; blade loading measurements and oil visualizations were used to quantify the power extraction of the different geometries and to study the flow structures within a turbine passage.