为研究竖直上升管内气液两相流通过90° 弯管后的流动演化特性,分别采用流体体积多相流模型以及Realizable k-ε湍流模型对其进行数值模拟,重点分析气液两相流通过90° 弯管后的速度变化、压力分布、截面含气率及流型演化规律.结果表明:不同气液两相流流型通过 90° 弯管后会产生不同程度的二次流现象,并且切向速度呈现双峰分布,随着流动发展最终耗散成为单峰分布;气液两相流入口速度越大,则弯管外壁面所受压力越大.截面含气率的变化与流型转化相关,泡状流流过弯管后演化成为细长段塞流,截面含气率减小;段塞流、搅动流及环状流通过弯管后演化成为分层-波浪流,截面含气率变化较小.研究结果可为气液两相流输送弯管设计开发及诱导应力预测提供一定的理论支持.

In order to investigate the evolution characteristics of gas-liquid two-phase flow passing through a 90° pipe bend, the volume of fluid (VOF) multiphase flow model and the Realizable k-ε turbulence model are used to conduct numerical simulations. The evolution of velocity, pressure distribution, gas void fraction, and flow pattern passing through a 90° pipe bend is studied in detail. The results show that different gas-liquid two-phase flow patterns will produce different degrees of secondary flow phenomenon after passing through the 90° pipe bend, and the tangential velocity presents a bimodal distribution, which eventually dissipates into a unimodal distribution in the horizontal pipe. The pressure on the outer wall of the pipe bend increases as the inlet velocity increases. The change of gas void fraction is related to the transformation of the flow pattern, the bubbly flow evolves into a slender slug flow in the horizontal pipe after passing through the 90° pipe bend, and the gas void fraction will decrease. The slug flow, the churn flow, and the annular flow evolve into the stratified-wave flow in the horizontal pipe after passing through the pipe bend, and the variation of the gas void fraction is relatively low. The research results can provide certain theoretical support for the design and development of gas-liquid two-phase flow conveying elbows and the prediction of induced stress.