Abstract:

Experiments with liquid nitrogen and the vapor (LN₂/VN₂) in an inclined tube were conducted to investigate the flooding mechanisms. The flow patterns during flooding were analyzed and compared with those of water/air. The results showed that the interfacial waves kept their shape and the slug flow was formed with water/air when flooding occurred. As a comparison, the interfacial waves were crushed and the mist flow was formed with LN₂/VN₂. The Fast Fourier Transform (FFT) of pressure drops between the two ends of the tube was carried out to evaluate the frequencies of interfacial waves and the flooding intensity. The influence of inclination on the critical gas superficial velocities was investigated. It was indicated that the frequencies of the biggest waves triggering flooding were almost the same between the two working fluid pairs,and the inclination angles had little effects on the flooding intensity but had great influence on the critical gas superficial velocities.

Key words: gas-liquid flow, flow regimes, flooding, cryogenics, pressure drop, instability

摘要：

为探究低温流体液泛发生机理,采用液氮/饱和氮蒸汽(LN₂/VN₂)为工质开展了倾斜圆管内液泛实验研究。分析了液泛发生过程两相流流型变化,并对比了水/空气工质对的液泛特性,发现水/空气液泛时,界面波保持完整,两相流为塞状流的情形,LN₂/VN₂液泛时,界面波被气相击碎,形成雾状流。对倾斜管两端压差变化作傅里叶变换(FFT),分析了液泛发生时界面波频率变化规律以及液泛强度的影响因素。探究了倾斜角对液泛发生时临界气体速度的影响。发现对于低温流体和常温流体,液泛发生时最大界面波的频率并没有明显区别;角度对液泛强度影响很小,但是对液泛临界速度影响明显。

关键词: 气液两相流, 流态, 液泛, 深低温, 压降, 不稳定性