低雷诺数环境下一体化超紧凑过渡段非定常流动机理研究

The integrated aggressive inter-turbine duct (AITD) which can reduce the engine’s weight, improve the inter-turbine duct's flow field structure and enhance the low pressure rotor’s dynamic characteristics, is a promising technology. Under dual influence of low Reynolds number and unsteady inflow condition, the enhancement effect of unsteady wake on the integrated AITD is still to be explored. This project is based on a low-speed double-circulation wind tunnel test rig, with the help of dynamic measurement technology, for example, high-frequency response aerodynamic probe, surface hot film, three-dimensional hot wire anemometer, surface static pressure measurement and so on. Moreover, numerical simulation technology with predicting boundary layer transition model is adopted to assist analysis. Internal flow mechanisms of the integrated AITD in low Reynold number condition, especially the separation and transition mechanisms of LPT nozzle’s suction surface boundary layer is explored. The influence of incoming flow condition and wake feature on the integrated AITD’s unsteady flow performance and its downstream flow field is studied. Furthermore, the measurement criteria and optimization strategy of flow field’s non-uniformity at the integrated AITD’s exit is studied too. All the findings in the current project aim to provide prosperous key technology which can be used in the state-of-art aeroengine’s design.

一体化超紧凑高低压涡轮过渡段可以减轻发动机重量、改善过渡段内部流场组织、提升低压转子动力学特性，是一种极具前景的设计方法。在低雷诺数/非定常尾迹扫掠的入流条件下，一体化超紧凑过渡段内部非定常尾迹的增益效应尚有进一步挖掘的潜力。本申请项目以低速双环流风洞实验台为载体，借助高频响气动探针、表面热膜、三维热线风速仪及表面静压测量等动态实验测量技术以及液晶非接触测量技术，辅之以可预测边界层转捩的数值模拟技术，探索低雷诺数环境下，一体化超紧凑过渡段内部流动机理，尤其是低压涡轮导向器吸力面分离流动特性和转捩机制；研究来流条件和尾迹特征对一体化超紧凑过渡段内部及出口流场的影响，一体化过渡段出口流场不均匀性的衡量标准及优化策略。本项目研究为发动机研制提供基础性的关键技术支撑。

超紧凑高低压涡轮过渡段可以减轻发动机重量、提升低压转子动力学特性，因此在现代高性能航空发动机上得到了广泛应用。但超紧凑过渡段轴向长度的缩短、抬升角和面积比的增大，以及过渡段内部存在的各种复杂流动结构，致使超紧凑过渡段及其下游低压涡轮内部极易出现流动分离，尤其是在高空低雷诺数状况下，严重恶化过渡段及低压涡轮的气动性能。将低压涡轮导向器与过渡段耦合设计的一体化过渡段设计方案，可改善过渡段内部流场组织，是一种极具前景的过渡段设计方法。本项目利用上游高压转子尾迹“负射流”在过渡段中低压涡轮导向器吸力面产生的“寂静区”效应以抑制附面 层分离，在不增加发动机质量和复杂性的基础上，提高了一体化超紧凑过渡段的性能。