Variable geometry turbine (VGT) exists in turbocharged gas engines to solve the problems of insufficient low-speed torque and poor transient response. However, there is a performance penalty associated with the end-wall clearance required for the movement of the guide vanes. Aiming at suppressing the end-wall clearance leakage flow loss to improve turbine performance, a novel scheme of end-clearance sealed guide vane (ESGV) is proposed and the effect assessment of this configuration is studied numerically and experimentally in a real variable geometry turbine. The numerical predictions reveal the three-dimensional leakage flow characteristics associated with the sealed end-wall clearance that optimizes the mixing process between the clearance leakage flow and the main flow and further improve the design and off-design performance of the turbine. Results exhibit that the relative leakage flow in the ESGV turbine is reduced by 26.81%, 7.33%, and 0.99% for 10%, 50%, and 90% nozzle openings, respectively, compared to that of the original turbine. Moreover, most of the leakage loss is concentrated in the groove clearance of the disk. The efficiency advantage of 20% and 4.4% points for the ESGV turbine at the peak efficiency point under 10% and 50% opening conditions, respectively. Besides, an experimental investigation is carried out to further verify the ESGV turbine performance predictions and analytical assumptions. Overall, the ESGV is found to be the best choice for the variable turbine guide vanes. The present results can provide valuable references for the vane-end clearance design of variable geometry turbines.

可变几何涡轮（VGT）存在于涡轮增压燃气发动机中，以解决低速扭矩不足和瞬态响应差的问题。然而，存在与导向叶片移动所需的端壁间隙相关联的性能损失。为了抑制端壁间隙泄漏流动损失以提高涡轮性能，提出了一种新的端间隙密封导叶（ESGV）方案，并在实际变几何涡轮机中通过数值和实验研究了该配置的效果评估。数值预测揭示了与密封端壁间隙相关的三维泄漏流特性，优化了间隙泄漏流与主流之间的混合过程，进一步提高了涡轮的设计和非设计性能。结果表明，与原始涡轮机相比，ESGV 涡轮机中的相对泄漏流量在 10%、50% 和 90% 的喷嘴开口下分别减少了 26.81%、7.33% 和 0.99%。而且，大部分泄漏损失集中在盘的槽隙中。在10%和50%开度条件下，ESGV涡轮机在峰值效率点的效率优势分别为20%和4.4%。此外，还进行了一项实验研究，以进一步验证 ESGV 涡轮机性能预测和分析假设。总体而言，ESGV 被发现是可变涡轮导叶的最佳选择。研究结果可为变几何涡轮叶片端隙设计提供有价值的参考。