钝锥表面脉动压力风洞试验研究

目的获得钝锥在风洞实验连续变雷诺数过程中表面脉动压力的变化规律。方法基于利用超声速风洞,研究Ma=6、α=0°工况下,单位长度雷诺数从4.5×10⁷ m^-1连续变化为1.0×10⁷m^-1过程中钝锥表面脉动压力时域、频域的变化规律。结果在雷诺数从高到低变化过程中,钝锥表面测点脉动压力时域信号幅值出现了瞬间下降现象。基于自由来流动压归一化脉动压力时域信号显示,转捩过程中归一化脉动压力较层流、湍流状态更高。从频域特性上看,10kHz范围内,转捩过程中6k Hz附近能量优先增长,并且逐渐往整个低频段扩展,整个频段归一化功率谱密度较湍流状态更高。结论在给定的马赫数与攻角工况下,湍流状态钝锥表面脉动压力归一化功率谱密度特性与来流雷诺数无关。边界层转捩时,基于来流动压归一化脉动压力功率谱密度较湍流更高,归一化脉动压力均方根系数约为湍流状态的2倍。环境工程及结构设计工程师在开展再入环境研究以及结构设计时应该对再入过程中出现的转捩现象予以关注。

Wind Tunnel Test Research on Surface Pressure Fluctuations of a Blunt Cone

Characteristics of surface pressure fluctuations for a blunt cone on sequent variable Reynolds numbers are analyzed in this study.A wind tunnel test with variable Reynolds numbers ranging from 4.5×10⁷m^?1 to 1.0×10⁷ m^?1 at Ma=6 andα=0°in FD-07 hypersonic wind tunnel.Detailed information of the characteristics of surface pressure fluctuations has been obtained in time domain and frequency domain,respectively.With the decrease of the Reynolds number,there exists a sudden reduction of the surface pressure fluctuations in time domain.The surface pressure fluctuations,which are normalized by the freestream dynamic pressure,reveals that the pressure fluctuations’magnitude of transition is higher than that of turbulence or laminar.Moreover,from the perspective of frequency analysis(<10 kHz),the increase of the pressure fluctuation energy at 6 kHz occurs prior to that at the lower frequency range during transition.The PSD of pressure fluctuations during transition is higher than that of turbulence.The surface pressure fluctuation characteristics have been obtained with the variation of Reynolds numbers in time and frequency domain.With specific Mach numbers and angles of attack of the test,the normalized PSD of surface pressure fluctuations is independent of the Reynolds number.The PSD of surface pressure fluctuations,which are normalized by the freestream dynamic pressure during transition,is higher than that in turbulence.Its root mean square is two times than that in turbulence.More attentions should be paid to the transition in reentry when dealing with the reentry environment analysis or architectural design by the environment engineers and architectural designers.