可压缩转捩/湍流边界层内多物理量场同步测量与时空解析方法

可压缩边界层——尤其是高超声速边界层——的转捩和湍流问题具有深刻的科学意义以及对太空探索、国防科技的重要价值，近年来备受关注。然而，受限于现有的近壁物理量场测量方法的不足，该领域的实验研究一直是难点。对此，本项目拟将激光光谱学、信号处理等学科的前沿技术引入测量中，探索可压缩边界层内的激光诱导磷光与荧光测量等新方法，通过光谱分析同步提取多个物理量场的时空信息。本项目将在磷光粒子示踪/图像测速的基础上，一是利用激光诱导磷光信号与流体局部温度、密度的定量关系，实现主要物理量场的同步测量；二是将磷光与荧光方法融合，提高测量的准确度和时空分辨率；三是通过发展近壁流动的多光谱测量技术，在法向小尺度几何限制下以及可变折射率环境中实现精确成像。本项目将针对可压缩边界层测量建立一套新型方法，实现多物理量场的同步量化与时空解析，并将新方法应用于超声速/高超声速边界层转捩实验中。

Due to its scientific significance and important value to space exploration and defense technology, the study of compressible transitional and turbulent boundary layers (especially hypersonic boundary layers) has attracted much attention in recent years. However, experimental research in this area has always been difficult, particularly due to limitations in the existing near-wall physical field measurement methods. This project aims to address this problem by introducing cutting-edge technologies in laser spectroscopy, signal processing and other disciplines to compressible boundary layer measurements, and by exploring laser-induced phosphorescence and fluorescence measurement in the compressible boundary layers to extract spatiotemporal information of multiple physical fields simultaneously via spectral analysis. This project will exploit the quantitative relationship between the laser-induced phosphorescence signal and the local temperature and density of the fluid, in conjunction with phosphorescent particle tracing/image velocimetry to achieve simultaneous multi-field measurement. It will then integrate the phosphorescence and fluorescence methods to improve the measurement accuracy and resolution. In addition, by developing multi-spectral measurement techniques for near-wall flows, accurate imaging can be also achieved even under challenges of small-scale wall-normal geometry and in environments of variable refractive index. Based on laser-induced phosphorescence and fluorescence, this project will establish a new method for simultaneous quantification and spatiotemporally resolved measurement of multiple fields in compressible boundary layers, and apply this new method to experimental studies of supersonic/hypersonic boundary layer transition.