Aerodynamic Performance Enhancement of Ram Air Turbine Blades with Different Tip Configurations

A ram air turbine serves as a critical emergency power system for aircraft. To mitigate aerodynamic losses from tip vortices, this study proposes three blade tip enhancement configurations: a tip plate, tip contraction, and winglet. Numerical results indicate that the tip plate slightly improves the power at low tip speed ratios (TSRs); however, at medium and high TSRs—typical of turbine operation—power gains turn negative, and thrust loads increase significantly, failing to balance the gain and load. In contrast, the tip contraction—applied to the outer 5% span—enhances the power output at medium to high TSRs, with a maximum power increase of 2.05%, and consistently reduces thrust loads across all TSRs. Its highest power–thrust net gain coefficient reaches 3.85%, indicating strong potential for optimizing power efficiency and load mitigation. The winglet achieves the greatest power enhancement, increasing the power across all TSRs, with a maximum power increase of 7.59%. However, its thrust load also increases accordingly, resulting in a power–thrust net gain coefficient lower than the tip contraction. Further optimization of the winglet parameters using an orthogonal experimental design revealed that the optimized winglet increased the power output by 8.69% compared to the baseline configuration, thereby increasing the maximum power–thrust net benefit coefficient from 1.72% before optimization to 3.95%.