水蒸汽亚毫秒级凝结实验研究

Experimental Research on Sub-Millisecond Condensation of Water Vapor

关键词:  燃烧加热风洞  水蒸汽  小时间尺度  非平衡凝结  凝结规律  吸收光谱技术

Key words:  Combustion heating wind tunnel  Water vapor  Small time scale  Non-equilibrium condensation  Condensation law  Absorption spectroscopy

摘要:

为模拟高超声速风洞中水蒸汽凝结现象，设计了一种基于稀疏波反射原理的凝结实验系统，采用“空间等效时间”思想，在固定位置测量流场随时间的变化，实现了0.14~1.4ms亚毫秒时间尺度的凝结。通过吸收光谱测量方法实现了凝结过程中流场温度、水蒸汽含量的高时间分辨率（100kHz）测量，对小时间尺度凝结现象的影响因素进行了分析。结果表明：不同亚毫秒时间尺度下凝结规律相同；水蒸汽含量或试验段初始压力增加，凝结发生越快，即喷管中的凝结位置越靠前，而发生凝结时的拐点温度越高；初始压力与水蒸汽含量不变时，压力下降速度越快，发生凝结位置越靠前，发生凝结时拐点温度相同。

Abstract:

To simulate the condensation phenomenon of water vapor in a hypersonic wind tunnel， a condensation experiment system based on the principle of sparse wave reflection was designed. With the idea of “space equivalent time”， the change of airflow over time was measured at a fixed position， and condensation on sub-millisecond time scales from 0.14ms to 1.4ms was achieved. Also， with the absorption spectrum measurement method， the temperature and water vapor content in the condensation process of the flow field were measured with high time resolution （100kHz）， and the influence factors of condensation phenomenon on small time scales were analysed. The results show that： the condensation laws keep the same at different sub-millisecond time scales. The condensation occurs faster when the water vapor content increases or the initial pressure in the test section increases， which means the more forward the condensation position in the nozzle， the higher the inflection point temperature is when condensation occurs. When the initial pressure and water vapor content are constant， the faster the pressure drops， the earlier the condensation occurs， and the temperature at the inflection point remains unchanged when condensation occurs.