Aerothermal Performance Evaluation and Separation Flow Control Investigation of High-Lift Low Pressure Turbine Blades

This thesis presents an investigation into the aerodynamic performance and one separation flow control method relevant to highly loaded low pressure turbine (LPT) blades. First, the aerodynamic performance and Reynolds lapse characteristics of a new class of highly loaded LPT blades was investigated by quantifying the loss coefficient at on- and off-design Reynolds numbers. This characterization is done experimentally with an annular cascade test section in a pressure-driven wind tunnel capable of decoupling Mach and Reynolds with a downstream sonic valve and vacuum tank. The blade inlet flow-conditioning gauze is also characterized experimentally to fully define the inlet and outlet flow of the blades for performance evaluation. The Reynolds lapse characteristics of these blades proved to meet expectations with an average 40% increase in loss coefficient at a Reynolds less than half the design condition. Additionally, a passive acoustic flow-control method was experimentally investigated in a linear test section of a suction-driven wind tunnel. This investigation first characterized the separation bubble over a hump geometry, quantifying its length and identifying key other flow features, all at multiple operating conditions. A modular shallow Rossiter cavity system was designed and tested first independently, which verified the production of distinct modal frequencies at sound pressure levels above 125 dB. The cavity system was tested with the separated hump geometry, resulting in a modest impact on the separation bubble, including a maximum 15% reduction in separation bubble length.