Experimental and Numerical Characterization of Flow Through Highly Loaded Low-Pressure Turbine Cascade

An increase in loading of low-pressure turbine blades beyond the present state of the art will directly translate into lighter, smaller, and lower-cost turbine engines. Advances in aerodynamic modeling have permitted the design of highly loaded low-pressure turbine blades with good midspan loss performance. Earlier research has shown that forward loading can mitigate the low-Reynolds-number performance lapse at midspan but also results in increased secondary losses. Experiments and simulations were carried out to characterize the flow through a highly loaded linear cascade with front-loaded profiles at a Reynolds number based on axial chord and inflow velocity of 100,000. Endwall and suction surface oil-flow visualizations were obtained and particle image velocimetry measurements were taken in several axial planes inside and downstream of the cascade. Good agreement of the experimental and numerical data was achieved with respect to the trajectory of the passage vortex and the suction-side corner flow as well as the total pressure loss coefficient. A detailed analysis of the simulation data revealed a pronounced suction-side corner separation that can be characterized by streamwise vortices that have the same sense of rotation as the passage vortex.