A Novel Cooling Design and Improvement of a Radial-Inflow Turbine Rotor Blade

Abstract With the continuous increase in turbine inlet temperature, traditional uncooled radial-inflow turbines are becoming inadequate for operation in higher-temperature environments. This study investigates both the overall layout of internal cooling passages and the characteristics of local cooling structures for a radial-inflow turbine. Using a conjugate heat transfer numerical approach, four cooling schemes are evaluated from the perspectives of cooling efficiency, as well as turbine stage aerodynamic performance. To enhance the thermal protection of the wheel, a novel sunken-type disk cooling scheme is first proposed. In this design, a portion of the coolant after being used for blade cooling is redirected toward the disk region, resulting in a reduction in both disk temperature and the temperature in high-stress root regions of the blade. To reduce the aerodynamic efficiency losses caused by the conventional full-cut trailing-edge slot design, this study proposed a novel pressure-side slot near the trailing edge. This approach preserves the structural integrity of the trailing edge and significantly improves the aerodynamic performance of the turbine stage. Turbine stage efficiency assessments reveal that the commonly used full-cut trailing-edge cooling design provides the least structural retention at the trailing edge, resulting in a 15.5% drop in aerodynamic turbine stage efficiency compared to the uncooled baseline. In contrast, the pressure-side trailing-edge slot cooling configuration offers a minimal aerodynamic efficiency reduction of 2.7% relative to the uncooled blade. The study also analyzes the flow and heat transfer characteristics associated with leading-edge, blade-tip, and trailing-edge cooling designs, summarizing the underlying fluid-thermal interaction mechanisms.