水蒸气在低膨胀率气流中的放热分析

EXPERIMENTAL STUDY ON THE PROCESS OF SPONTANEOUS NUCLEATION AND CONDENSATION OF WATER VAPOR BY USING A LASER SCATTERING SYSTEM AND A SHOCK TUBE

在激波管内产生的低膨胀率蒸气膨胀气流中，探测记录了水蒸气凝结相变的过程及压力曲线在非等墒膨胀阶段出现的两次压力突跳，分析了产生两次突跳的原因及影响因素。并通过对比压力曲线和散射光功率曲线，指出，在低膨胀率状态下，最大过饱和度对应的Ｗｉｌｓｏｎ，点并不是出现在按通常定义的散射光信号开始增大的时刻。

The processes of spontaneous nucleation and condensation of water vapor are measuredon a shock tube apparatus using a laser scattering determination system,The curves of pres-sure and light power scattered vs.time at various initial partial pressure and expansion rate ofwaters vapor have been obtained.These curves represent the relative change of nucleationrate and condensation mass during phase-change process of water vapor.The effects of ex-pansion rate and partial pressure of water vapor on the nucleation time and growth rate ofdroplets are analyzed accordingly.