高超音速湍流分离表面热流率的脉动特性

本文给出高超音速湍流分离不稳定特性的实验研究结果。试验条件是:自由流马赫数为 7.8,单位长度雷诺数为 3.5×10~7/米。分离流场由有限展长前向台阶产生,并用有高空间分辨率和快速响应的一列平齐安装的铂膜电阻温度计和多通道系统测量其表面热流率脉动。信号的条件采样分析结果表明:分离激波的根部由一束压缩波构成,流向展长约二分之一来流边界层厚度,在边界层外汇聚成单一主激波。这种激波结构极其不稳定,出现大尺度运动,流向运动的尺度约为分离激波上游影响区域长度的22％。激波振荡频率为一宽频带,主要集中在 1～3 千赫。在分离激波运动区域,热流脉动呈间歇性,在无扰动和激波扰动间跳跃。可以认为这种间歇性是分离激波系统大尺度振荡的结果。在激波运动区域的下游为分离区,流体继续压缩,热流脉动无间歇。

NATURE OF THE SURFACE HEAT TRANSFER FLUCTUATION IN A HYPERSONIC SEPARATED TURBULENT FLOW

This paper presents the results of an experimental study of the unsteady nature of a hypersonic separated turbulent flow. The nominal test conditions were a freestream Mach number of 7.8 and a unit Reynolds number of 3.5×107/m. The separated flow was generated using finite span forward facing steps. An array of flush mounted high spatial resolution and fast response platinum film resistance thermometers was used to make multi-channel measurements of the fluctuating surface heat transfer within the separated...