化工学报
化工學報
화공학보
JOURNAL OF CHEMICAL INDUSY AND ENGINEERING (CHINA)
2015年
3期
942-948
,共7页
Taylor气泡%气液两相流%数值模拟%毛细管%相对坐标系
Taylor氣泡%氣液兩相流%數值模擬%毛細管%相對坐標繫
Taylor기포%기액량상류%수치모의%모세관%상대좌표계
Taylor bubble%gas-liquid flow%numerical simulation%capillary tubes%relative coordinate
采用相对坐标系方法，研究毛细管（d=2mm）内充分发展垂直上升气液 Taylor 流动，分析两种工作介质下Taylor气泡的形状、上升速度、液膜厚度以及压降特性。结果表明：随着两相表观速度（Vtp）增大，Taylor气泡长度增大，气泡尾部曲率半径增大。气泡长度及内部回流区随着气泡体积分数（ξg）增大而增大，量纲1液膜厚度与气泡上升速度与毛细数（Ca）正相关，模拟结果与经验公式吻合较好。摩擦阻力因子（fc）随Vtp与ξg的增大而降低，N2/乙二醇为工质的Taylor流动fc低于单相情况，而N2/水为工质的Taylor流动fc高于单相情况。Kreutzer等的流型依赖公式以及Lockhart等的分离模型可较好预测本文的两相压降，模拟结果与预测值的误差在±10%以内，常规通道所推荐C=5仍然适用于本文毛细管情况。
採用相對坐標繫方法，研究毛細管（d=2mm）內充分髮展垂直上升氣液 Taylor 流動，分析兩種工作介質下Taylor氣泡的形狀、上升速度、液膜厚度以及壓降特性。結果錶明：隨著兩相錶觀速度（Vtp）增大，Taylor氣泡長度增大，氣泡尾部麯率半徑增大。氣泡長度及內部迴流區隨著氣泡體積分數（ξg）增大而增大，量綱1液膜厚度與氣泡上升速度與毛細數（Ca）正相關，模擬結果與經驗公式吻閤較好。摩抆阻力因子（fc）隨Vtp與ξg的增大而降低，N2/乙二醇為工質的Taylor流動fc低于單相情況，而N2/水為工質的Taylor流動fc高于單相情況。Kreutzer等的流型依賴公式以及Lockhart等的分離模型可較好預測本文的兩相壓降，模擬結果與預測值的誤差在±10%以內，常規通道所推薦C=5仍然適用于本文毛細管情況。
채용상대좌표계방법，연구모세관（d=2mm）내충분발전수직상승기액 Taylor 류동，분석량충공작개질하Taylor기포적형상、상승속도、액막후도이급압강특성。결과표명：수착량상표관속도（Vtp）증대，Taylor기포장도증대，기포미부곡솔반경증대。기포장도급내부회류구수착기포체적분수（ξg）증대이증대，량강1액막후도여기포상승속도여모세수（Ca）정상관，모의결과여경험공식문합교호。마찰조력인자（fc）수Vtp여ξg적증대이강저，N2/을이순위공질적Taylor류동fc저우단상정황，이N2/수위공질적Taylor류동fc고우단상정황。Kreutzer등적류형의뢰공식이급Lockhart등적분리모형가교호예측본문적량상압강，모의결과여예측치적오차재±10%이내，상규통도소추천C=5잉연괄용우본문모세관정황。
In order to obtain the frictional characteristics of fully developed Taylor flow in the vertical capillary tube, numerical simulations of the flow in the capillary tube with diameter of 2 mm were conducted by using the moving frame reference method. The shape, rising velocity of Taylor bubble, liquid film thickness and pressure drop were obtained using two different working fluids and analyzed. Simulation results showed that the length of Taylor bubble and the radius of curvature increased with increasing two-phase superficial velocity Vtp. The length of Taylor bubble also increased with increasing gas void ξg, while the nose and tail of Taylor bubble were independent ofξg. Dimensionless thickness of liquid film and rising velocity of Taylor bubbles were proportional to capillary number Ca. Friction factor fc decreased with increasing Vtp andξg. The fc of Taylor flow with N2/(CH2OH)2 as working fluid was lower than that of single phase with the same Vtp, while the fc for N2/H2O was higher than that of single phase. The model proposed by Lockhart and Martinelli, and the flow pattern dependent model proposed by Kreutzer et al. could predict the pressure drop obtained from simulation with an error of ±10%. The Chisholm number C=5 which was recommended for conventional tube when both phases were laminar was also reasonable for the capillary tube in the simulation work.
