垂直管内气液螺旋流的衰减特性研究

Study on Decay Characteristics of Gas-liquid Swirling Flow in Vertical Pipe

气液两相旋流在工业中应用广泛,为了研究螺旋流的维持距离,从而提高气井的携液能力,本文通过数值模拟研究了叶片式起旋器引发的气液两相螺旋流衰减特性,获得了预测螺旋流维持距离的关系式。研究发现:起旋器下游气液相分布变化,环状液膜沿管周向分布逐渐变均匀,气相切向速度相对于轴向和径向速度,衰减最明显;然后基于模拟结果,通过气液两相旋流数和绝对涡通量定量研究了旋流强度和涡强度的衰减规律:随着表观气速增大和表观液速减小,旋流数减小,涡通量增大,但涡强度的衰减程度较小;最后提出了预测气液螺旋流中旋流强度和涡强度衰减的关系式,为气液螺旋流的作用距离提供参考。

Gas-liquid two-phase swirling flow has been widely used in industry.In order to study the maintenance distance of swirl flow,improving the liquid carrying capacity of gas wells.In this work,decay characteristics of the two-phase swirl flow induced by a vane-type swirler were studied by numerical simulation,a relationship formula was obtained to predict the maintained distance of the swirl flow.It was found that the gas-liquid distribution changes downstream of the swirler,the annular liquid film gradually becomes uneven distributed along the circumference of the pipe,the tangential velocity decreased significantly along the streamwise direction,compared with decay of axial and radial velocity.Based on simulation results,the swirl intensity and vortex decay of the gas-liquid swirl flow was quantitatively described by the swirl number and absolute vortex flux of the gas-liquid two-phase flow:with the increase of superficial gas velocity and decrease of superficial liquid velocity,the swirl number of the gas-liquid two-phase decreases,and the absolute vortex flux increases,but the decay degree is lower than that of the swirl number.Based on above results,two models were proposed to quantitative predict the decay of swirl intensity and vortex strength in gas-liquid swirl flow,providing a guide to predict the operating distance of gas-liquid swirl flow.