Turbine Passage Secondary Flow Dynamics and Endwall Heat Transfer Under Different Inflow Turbulence

This study presents endwall hydrodynamics and heat transfer in a linear turbine cascade at Re 5×10～5 at low and high intensities of turbulence. Results are numerically predicted using the standard SST model and Reθ-γ transition model as well as using the high-resolution LES separately. The major secondary flow components, comprising the horseshoe, corner, and passage vortices are recognized and the impact on heat or mass transfer is investigated. The complicated behavior of turbine passage secondary flow generation and establishment are impacted by the perspective of boundary layer attributes and inflow turbulence. The passage vortex concerning the latest big leading-edge vane is generated by the enlargement of the circulation developed at the first instance adjacent to the pressure side becomes powerful and mixes with other vortex systems during its migration towards the suction side. The study conclusions reveal that substantial enhancements are attained on the endwall surface, for the entire spanwise blade extension on the pressure surface, and in the highly 3-D region close to the endwall on the suction surface. The forecasted suction surface thermal exchange depicts great conformity with the measurement values and precisely reproduces the enhanced thermal exchange owing to the development and lateral distribution of the secondary flows along the midspan of the blade passage downstream. The impacts of the different secondary flow structures on the endwall thermal exchange are described in depth.