This paper presents an in-depth investigation of the unsteady flows through two-stage high-pressure (hp) axial turbine with analyses of the rotor-stator interaction effects on the aerothermodynamic performance. The unsteady flow structures are characterized by the formation and convection of the tip leakage vortex and the hub corner vortices from the first stage blade-row through the second stage nozzle guide vanes (NGV) and blade-row. The modal decomposition of the circumferential distributions of static pressure depicts the modulation of the potential effect in the form of lobed structure propagating in both sides. Moreover, the blade pressure field shows that the first blade-row is exposed to a periodic overpressure induced by the first NGV while in the second blade-row the linear combination of both potential effects is dominant and results in a complex unsteady blade loading. FFT analyses of unsteady turbine performance for two-stage and part stages reveal that the total-to-total isentropic efficiency, torque-based efficiency and pressure ratio of the first stage depend strongly on the first blade-row passing frequency (BPF), whereas the total-to-total isentropic efficiency in second stage and two-stage turbine is related to the second blade-row BPF while the pressure ratio and the torque-based efficiency depend on the two rotors BPFs. Finally, the torque oscillations are mainly associated with the combination of frequencies of first stage NGV with that of second stage NGV. Furthermore, the obtained results show that Unsteady Reynolds-Averaged Navier-Stokes (URANS) simulations are essential in analyzing the complex wakes and vortical structures through the two-stage turbine components and may produce better estimation of the performance.

本文对两级高压（hp）轴流式涡轮机的非稳态流动进行了深入研究，并分析了转子-定子相互作用对空气动力性能的影响。非稳态流动结构的特征在于，从第一级叶片行到第二级喷嘴导流叶片（NGV）和叶片行的尖端泄漏涡和轮毂角涡形成并对流。静压圆周分布的模态分解以两侧传播的叶状结构的形式描绘了潜在效应的调制。此外，叶片压力场显示，第一叶片行受到第一NGV引起的周期性超压，而在第二叶片行中，两种潜在影响的线性组合占主导，并导致复杂的不稳定叶片载荷。两阶段和部分阶段的非定常涡轮性能的FFT分析表明，第一阶段的总总等熵效率，基于转矩的效率和压力比很大程度上取决于第一叶片行通过频率（BPF），而第二级和两级涡轮的总等熵效率与第二叶片行BPF有关，而压力比和基于转矩的效率则取决于两个转子BPF。最后，扭矩振荡主要与第一级NGV和第二级NGV的频率组合有关。此外，获得的结果表明，非稳态雷诺平均Navier-Stokes（URANS）模拟对于通过两级涡轮机部件分析复杂的尾流和涡旋结构至关重要，并且可能会更好地评估性能。