Influence of combined blade design–end wall modeling on secondary flow in a wide-operating-condition turbine

This study investigates the stator of a single-stage high-pressure turbine, focusing on the control of secondary flow in the end wall region through a combination of three-dimensional blade design and non-axisymmetric end wall modeling. The prototype blade was modified using curved blade technology to obtain a positive compound lean blade. Accordingly, the upper wall was shaped using non-axisymmetric end wall technology. The original and modified turbine stators were then evaluated in a full turbine stage environment. The results show that the positive compound lean blade reduces the flow losses within the turbine. When combined with non-axisymmetric end wall modeling at the upper end wall, the losses are further reduced. However, the modified blade exhibits a larger area of underturning at the outlet airflow angle, resulting in an increase in the mass flow rate. By adjusting the throat width and the geometric angle at the blade root, the radial distribution of the outlet airflow angle can be aligned with that of the original blade, thereby reducing the mass flow rate to a level similar to that of the original blade. Following these refinements, the modified blade demonstrates higher efficiency than the original blade. The application of non-axisymmetric end wall modeling on the upper end wall further enhances efficiency. Within a pressure ratio range of 1.2–2.0 and a relative rotational speed range of 0.75–1.40, the efficiency increases by an average of 0.17% and 0.22%, respectively. These results highlight the turbine's excellent adaptability over a wide range of operating conditions.