高压涡轮叶顶激波与冷却射流相互作用的机理研究

高压涡轮动叶尖部的冷却设计对延长涡轮寿命、提高整机效率至关重要。随着高推重比航空发动机中涡轮级负荷的增加，叶片设计工况进入跨音状态，叶顶间隙内产生激波，叶尖泄漏的流热特性较亚声速状态发生质变。然而，当前跨音涡轮叶顶冷却的传热测试误差较大，缺少可靠的实验数据，因此对叶顶激波与冷气相互作用的机理缺乏理解。针对上述问题，本项目利用红外热成像技术，提出基于斜坡加热的瞬态传热测量新方法，降低跨音涡轮叶顶冷却的传热测试误差。基于此，获取高精度高分辨率的跨音叶尖冷却实验数据，实现精确捕获叶顶激波传热特征的目标。进而结合计算流体力学仿真与实验验证，分析叶顶间隙中激波与冷却射流相互作用的流动机理，揭示冷却射流涡系对叶顶激波和泄漏流边界层的作用机制，及其与叶顶激波传热足迹的联系，阐明冷却参数对叶顶激波流动和传热特征的影响规律。本项目可促进传热测试方法的发展，为高负荷涡轮叶顶的冷却设计提供理论支撑。

Cooling design of high-pressure turbine rotor blade tip is crucial to prolong turbine life and improve aero-engine efficiency. As turbine stage loading increases with the rise of thrust-to-weight ratio in modern aero-engines, the working condition of turbine blades becomes transonic, producing shock waves in rotor blade tip clearance, which qualitatively change aerothermal characteristics of tip leakage flow compared to that in subsonic regime. However, high-quality experimental data on transonic blade tip cooling are quite limited due to the large uncertainty associated with heat transfer measurement techniques, thus physical understanding about the interaction between overtip shock wave and cooling injection is still lacking. To address these issues, this project proposes a novel transient thermal measurement technique based on ramp heating and infrared thermography to reduce the uncertainty of transonic tip cooling data. As such, high-accuracy and high-resolution heat transfer experimental data on transonic tip cooling are obtained, based on which heat transfer signature of overtip shock wave can be identified. Furthermore, computational fluid dynamics is implemented and validated against heat transfer experimental data, in order to analyze the aerodynamic interaction between overtip shock wave and cooling injection. Impact of cooling injection vortices on shock wave-boundary layer interaction mechanism within tip clearance is demonstrated, along with its implications on heat transfer features of overtip shock wave. Influence of cooling design parameters on overtip shock wave structure and its heat transfer signature is also revealed. This project will contribute to the advancement of heat transfer measurement technique, as well as cooling design wisdoms in highly-loaded turbine blade tips.