Abstract:

A new annular supersonic nozzle was designed for natural gas dehydration based on the principle of conservation of angular momentum. Corresponding mathematical and physical models were established. The flow characteristics of natural gas in the annular supersonic nozzle were numerically simulated with the RNG k-εturbulence model. The results showed that natural gas expanded to supersonic velocity，resulting in a low temperature in the annular nozzles. The Mach number could reach 1.85 at a low temperature of －70 ℃ at the nozzle exit. The swirling motion was generated by the vanes located at the entrance of the nozzle，leading to a centrifugal field of about 640 000g. Water could be condensed and removed from natural gas under the combined effects of low temperature and strong centrifugal field. The strong swirling flow could be obtained in the annular nozzle as a result of the central body. When the swirling flow passed through the nozzle，the expansion characteristics of the nozzle was weakened，which was different from the common Laval nozzle.

摘要：

依据角动量守恒原理设计了一种用于天然气脱水的环形超声速喷管，建立了相应的物理和数学模型，并采用RNG k-ε湍流模型对喷管内天然气流场特性进行了数值计算。结果表明，天然气进入环形超声速喷管后发生膨胀降温，在喷管出口处马赫数可达1.85，温度低达－70 ℃，天然气经旋流叶片产生旋流，离心加速度最大可达640 000g，在低温和旋流场的联合作用下，天然气中的水凝结成液滴并被甩向管壁，实现天然气脱水。与传统的拉法尔喷管不同的是，中心体的存在可以有效地加强旋流，但同时旋流效应会降低喷管的膨胀制冷性能。