进口预旋下一体式超紧凑高低压涡轮过渡段流场重构机理研究

The application of aggressive inter-turbine duce (AITD) can improve the aerodynamic performance of turbine, shorten the axial length of ITD, and reduce the weight of the turbofan engine. While some characteristic of AITD, which contains large curvature and high diffusion, can induce the formation of secondary vortex, and reduce the total pressure recovery performance of ITD. To shorten the length of ITD, this project will study the complicated internal flow in the AITD on a low-speed annular tunnel rig, in which a series of annular cascade will be used to simulate the inlet swirl, and the measurement technique includes the seven-hole probe, hot-wire and surface oil-flow visualization. In the first phase, by detailed measuring the complicated secondary flow in this AITD under various inlet swirl conditions, it will be discussed how the inlet swirl interacts with the secondary flow in AITD, i.e. the counter-rotating streamwise vortices in mainstream and the three-dimensional boundary layer separation, and evaluate the effect of inlet swirl on the performance (total pressure loss & flow distortion) of this AITD. Based on the conclusions of the first phase, it will be explored to use the inlet swirl with the certain radial distribution to rebuild the flow field in this AITD in the second phase. The counter-rotating streamwise vortices and the three-dimensional boundary layer separation will be inhibited furthest by retarding the direction reversal of the radial pressure gradient. The achievement of this project will supplies the foundational theory of the AITD design for coupling its flowfield with HP and LP turbines.

超紧凑过渡段的采用能够有效提升膨胀系统气动性能，显著缩短民用航空发动机过渡段轴向长度、减轻发动机重量。然而，超紧凑过渡段的大曲率、高扩压度特征使得过渡段内很容易诱导出很强的二次流动，降低过渡段的总压恢复性能。为了有效缩短高低压涡轮过渡段长度，本项目提出了将宽弦长低压涡轮导向器置入高扩压度S型过渡段的耦合设计思路，以带导流叶栅的环形风洞试验台为研究载体，以七孔探针、热线及油流显示为主要测试手段，研究不同进口预旋条件下过渡段内部的复杂二次流动，深入探索进口预旋对主流涡系结构及环壁附面层三维分离的作用机理，定量分析不同进口预旋条件对过渡段性能的影响，在此基础上寻求利用上游预旋角度的径向布局重构过渡段内部流场的有效途径，最大限度地抑制过渡段三维分离，为现代大涵道比涡扇发动机超紧凑过渡段与高低压涡轮的耦合设计提供基础性的理论支撑。

超紧凑过渡段的采用能够有效提升膨胀系统气动性能，显著缩短民用航空发动机过渡段轴向长度、减轻发动机重量。然而，超紧凑过渡段的大曲率、高扩压度特征使得过渡段内很容易诱导出很强的二次流动，降低过渡段的总压恢复性能。为了有效缩短高低压涡轮过渡段长度，本项目提出了将宽弦长低压涡轮导向器置入高扩压度S型过渡段的耦合设计思路，以带导流叶栅的环形风洞试验台为研究载体，以三孔探针、七孔探针及油流显示为主要测试手段，研究不同进口预旋条件下过渡段内部的复杂二次流动，深入探索进口预旋对主流涡系结构及环壁附面层三维分离的作用机理，定量分析不同进口预旋条件对过渡段性能的影响，在此基础上寻求对过渡段内部流场重构的有效途径，最大限度地抑制过渡段三维分离。通过项目组近三年的努力，深入理解高扩压度S型过渡段内部的压力梯度变化特点、三维强剪切流动分离机制及向低压涡轮导向器动态迁移变化特性，诠释了一体式超紧凑过渡段内部二次流发展演化规律，形成进口预旋对一体式超紧凑过渡段性能影响规律，建立进口预旋下一体式超紧凑过渡段设计准则，完成了实验验证。.本项目中总结形成的一体式超紧凑过渡段复杂三维流场分析技术和结合涡轮上下游条件的超紧凑过渡段设计方法可应用于先进发动机涡轮过渡段研制。为先进发动机高低压涡轮过渡段气动、结构设计奠定良好基础，目前已用于中国科学院工程热物理研究所研制的XXX用1000公斤推力等级涡扇发动机，在气动性能未衰减条件下，实现过渡段组件重量减轻20%以上，为整机推重比提升做出贡献。并为现代大涵道比涡扇发动机超紧凑过渡段与高低压涡轮的耦合设计提供基础性的理论支撑。