气体非牛顿流体两相流动.docx

1、气体非牛顿流体两相流动气体非牛顿流体两相流动气体/非牛顿流体两相流动 与气/水两相流动阻力特性的比较 劳力云 吴应湘 郑之初 李东晖 石在虹 (中国科学院力学研究所应用流体力学研究室) 提 要 本文基于常用的均相流动模型主要针对油/气/水混输管道中经常遇到的气体/幂律液体水平管道两相流动对其阻力特性进行了阐述其中包括流动基本模型和方程、常用的经验估算方法等方面将它与气/水两相流动中对应的有关问题进行了比较。 Summary In this paper, the pressure loss characteristics of the gas and power-law liquid two-p

2、hase flow that was often met within oil/gas/water concurrent -one of the transportation pipeline were presented. Based the homogeneous modelfrequently adapted models, the issues of fundamental model and equations of the flow and the estimation methods of pressure losses were included. These results

3、were also compared with the correspondents related to gas/water two-phase flows. 关键词 均相模型 气液两相流 非牛顿流体 Key words homogeneous model, gas/liquid two-phase flow, non-Newtonian fluid 1 引 言 在海洋石油资源开发中，油气混输正在成为一种越来越重要的油气输运手段。为了了解油气混输管道中的能耗，进行混输管线与增压系统的合理设计，在油气混输过程中对油、气、水等介质进行有效准确的计量，以及对整个混输系统的运行状态进行监控等等，需要

4、深入了解油气混输管道的流动阻力特性。另一方面，油气混输问题实际上属于气液两相流动中的气体/非牛顿液体的流动问题。而目前在国内外，气液两相流研究主要集中于对气体/牛顿液体(尤其是气/水两相流)的流动特性上，对于气体/非牛顿液体流动问题的研究相对较少，尚无比较成熟的结果。因此，对气体/非牛顿液体的流动阻力特性进行研究，不但具有重要的工程价值，也具有较大的学术意义。 实际测试结果表明，我国油田所生产的原油，在常温输送时，其流变特性表现为幂率流ndu,K,dr1，2,体的特性流动剪应力与剪应变呈现为幂率关系(对于管流即)。其主edges should be cleaned, after making

5、sure that no defect shall be marked with a marker pen to write down welding near the weld, including the slogan of welding, welders, etc. (16) welding Qian Preheat and the welding Hou heat treatment pipe welding Qian Preheat and the welding Hou heat treatment process conditions welding Qian Preheat

6、and the welding Hou heat treatment temperature table project material welding Qian preheat temperature (?) welding Hou heat treatment and the insulation time (?/H) wall thick (mm) temperature (?) wall thick (mm) temperature (?) 20 ? 26 100200 36 600650/1-1.5 15CrMo ? 10 150200 10 670700/1.2-2 Prehea

7、t and the heat treatment process in the, Inner and outer wall temperature shall be kept uniform, in order to avoid internal stresses. Preheating before welding and post weld heat treatment, shall measure and record the temperature, temperature measurement locations and number of points are reasonabl

8、e. Prone to weld delayed crack of steel, post weld heat treatment after welding should be carried out promptly, when not conducting timely post weld heat treatment, should be uniformly heated to 200300? immediately after welding and insulation and slow cooling, . 26mm more than 20 steel pipe welding

9、 preheating before welding should be carried out, 36mm the above heat treatment after welding should be done. Before welding and heat treatment used oxyacetylene flame heating, heat treatment after welding using special heat treatment after welding equipment. Hardness after heat treatment of welds n

10、eeded testing. 6.5.4 sides of the dissimilar steel welding when were non-austenitic steel or austenitic steel, alloy content according to lower one side of the base metal or selecting welding material in between. When one of the sides of material when austenitic steels, should select the 要的参数为稠度系数K和

11、幂率指数n。本文中的非牛顿液体即指这一类流体。下面根据两相流的均相流动模型和基本方程，针对油/气/水混输管道中经常遇到的气体/幂律液体水平两相流动的阻力特性进行了阐述，并讨论了对摩擦系数的经验估算方法，将它与气/水两相流动中对应的有关问题进行了比较。 2 均相流动模型 在某些两相流态中，如果一相均匀地弥散在另一相中，两相间的动量传递和能量传递足够快，两相的局部平均速度和温度就基本相同。此时，可以应用均相模型对两相流的流动特性进行研究。均相模型的基本思路是用一等效可压缩流体代替两相流体。一般，在研究气泡流、雾状流等流态下的流动特性时，常采用均相流模型。均相模型的基本假设为: u,u,uLHG(1

12、)(1)气液两相具有相同的线速度，即 (式中u表示介质线速度，下标G, L和H分别表示气相、液相和均相，下同); (2)(2)两相间处于热平衡状态。 对于两相管流，设其轴线方向为z，根据连续性、动量守恒和能量守恒原理以及上述假设，可以得到: ,ddu1dAHHu，,，,u,0HHHHdzdzAdz (1) Pdvdp2rH,，G，,gsin,H0dzAdz (2) dvdpdF2H,，G，,gsin,HHdzdzdz (3) ,0上列式中，为介质密度，A为流道截面积，p为管道中的压力，P为流道周长，为管r1v,G,u,HH道壁面剪应力，为质量流速，为介质比容，g为重力加速度，, 为管道轴线的倾

13、角，F为管道中摩擦力所引起的能量损失。 比较(2)、(3)两式，易知由摩擦力引起的管道压降 2,dp4f,uFPdFTPHH,r,H0dz2D,dzAe (4) 式中f两相摩擦系数，D为两相流动水力直径。 TPe,dpFP,r,0dz,A实际上，(2)式反映了这样一个事实，管道的总压降由管道摩擦压降、edges should be cleaned, after making sure that no defect shall be marked with a marker pen to write down welding near the weld, including the slogan

14、 of welding, welders, etc. (16) welding Qian Preheat and the welding Hou heat treatment pipe welding Qian Preheat and the welding Hou heat treatment process conditions welding Qian Preheat and the welding Hou heat treatment temperature table project material welding Qian preheat temperature (?) weld

15、ing Hou heat treatment and the insulation time (?/H) wall thick (mm) temperature (?) wall thick (mm) temperature (?) 20 ? 26 100200 36 600650/1-1.5 15CrMo ? 10 150200 10 670700/1.2-2 Preheat and the heat treatment process in the, Inner and outer wall temperature shall be kept uniform, in order to av

16、oid internal stresses. Preheating before welding and post weld heat treatment, shall measure and record the temperature, temperature measurement locations and number of points are reasonable. Prone to weld delayed crack of steel, post weld heat treatment after welding should be carried out promptly,

17、 when not conducting timely post weld heat treatment, should be uniformly heated to 200300? immediately after welding and insulation and slow cooling, . 26mm more than 20 steel pipe welding preheating before welding should be carried out, 36mm the above heat treatment after welding should be done. B

18、efore welding and heat treatment used oxyacetylene flame heating, heat treatment after welding using special heat treatment after welding equipment. Hardness after heat treatment of welds needed testing. 6.5.4 sides of the dissimilar steel welding when were non-austenitic steel or austenitic steel,

19、alloy content according to lower one side of the base metal or selecting welding material in between. When one of the sides of material when austenitic steels, should select the ,dpdpFAdv2,H,G,dzdz,gsin,dzH管道加速压降和管道重力压降三部分构成的。流体的流变特性不影响其中的加速压降和重力压降，但将通过影响两相摩擦系数而直接影响摩擦压降。 3 气/水两相流的摩擦系数计算 均相模型在本质上将两相流

20、动视为单相流动，其摩擦系数的确定方法与单相流动类似。在单相流动的摩擦阻力计算中，摩擦系数f与流体介质动力粘度, 的关系比较简单，主要决GDRe,定于流动的Reynolds数(式中D为单相流动的水力直径)。当Re低于2000时(层流)，摩擦系数为 f,16/Re (5) 当Re高于2000时(湍流)，则应用Blasius公式: ,0.25f,0.079，Re (6) 3 对于气体/牛顿液体的气液两相流，常采用以下三种方法计算粘度: (1)取两相粘度为单相粘度。 当含气率较低时，取两相粘度为液相粘度 ,TPL (7) 当含液率较低时，取两相粘度为气相粘度 ,TPL (8) (2)低浓度悬浮小球粘度

21、计算式。 对于空隙率, 低于0.05的气泡流，取两相粘度为 ,(1，,)TPL (9) (3)经验拟合关系式。 常用下列几种 1x1,x,，,TPGL McAdams: (10) ,(1,x)，,xTPLG Cicchitti: (11) ,(1,)，,TPLG Dukler: (12) 上列式中，x为质量含气率(干度)，,为体积含气率。 edges should be cleaned, after making sure that no defect shall be marked with a marker pen to write down welding near the weld,

22、including the slogan of welding, welders, etc. (16) welding Qian Preheat and the welding Hou heat treatment pipe welding Qian Preheat and the welding Hou heat treatment process conditions welding Qian Preheat and the welding Hou heat treatment temperature table project material welding Qian preheat

23、temperature (?) welding Hou heat treatment and the insulation time (?/H) wall thick (mm) temperature (?) wall thick (mm) temperature (?) 20 ? 26 100200 36 600650/1-1.5 15CrMo ? 10 150200 10 670700/1.2-2 Preheat and the heat treatment process in the, Inner and outer wall temperature shall be kept uni

24、form, in order to avoid internal stresses. Preheating before welding and post weld heat treatment, shall measure and record the temperature, temperature measurement locations and number of points are reasonable. Prone to weld delayed crack of steel, post weld heat treatment after welding should be c

25、arried out promptly, when not conducting timely post weld heat treatment, should be uniformly heated to 200300? immediately after welding and insulation and slow cooling, . 26mm more than 20 steel pipe welding preheating before welding should be carried out, 36mm the above heat treatment after weldi

26、ng should be done. Before welding and heat treatment used oxyacetylene flame heating, heat treatment after welding using special heat treatment after welding equipment. Hardness after heat treatment of welds needed testing. 6.5.4 sides of the dissimilar steel welding when were non-austenitic steel o

27、r austenitic steel, alloy content according to lower one side of the base metal or selecting welding material in between. When one of the sides of material when austenitic steels, should select the 4 气体/幂率流体流动的摩擦系数计算 对于气体/幂率流体两相流，在进行摩擦系数的计算时，其基本思路类似于气/牛顿液体，但是应根据液相的流变特性进行必要的修正。 4幂率液相的Renoalds数可以采用下式计

28、算: n2,n,DuLLRe,Ln3n，1,n,18K,4n, (13) (Re)c其临界Renoalds数也与幂率指数有关: 610(2n，1)(3n，2)(4n，3)(Re),c3(3n，1) (14) 在气相层流、气相紊流和液相层流时，可以参照牛顿流体的Blasius公式计算单相状态摩擦系数;对于液相紊流时，则采用修正的Blasius公式计算液相摩擦系数: af,Lb，ReL (15) 0.133,0.217a,0.3164n,b,0.25n其中。 f,f(1,x)，fxTPLG 获得气、液两相的摩擦系数后，可以根据 计算出两相流摩擦系数f。而实际的均相摩擦系数还应进行修正。文献2根据三

29、种管径的泡状流提出以下TP的修正公式: Bf,Af TPTP (16) 参数A、B仅与幂率指数有关， ,2.0255A,0.3804n (17) ,0.8448B,0.8911n (18) 需要指出，上述计算中，涉及介质的速度时应取介质的表观速度。 5 结论 在气体/幂率液体两相流各种流态中，气泡流和雾状流流态表现出较好的介质均布性，如各参数沿流道的变化率不大，可以采用均相流模型。对于流动阻力中的重力分量和加速分量，可以通过管道尺寸以及流动工况进行直接计算;对于流动摩擦阻力，需要根据实际数据回归出经验关系进行估算。与气/水两相流相比较，需要进一步考虑液相引起流动摩擦系数edges should

30、 be cleaned, after making sure that no defect shall be marked with a marker pen to write down welding near the weld, including the slogan of welding, welders, etc. (16) welding Qian Preheat and the welding Hou heat treatment pipe welding Qian Preheat and the welding Hou heat treatment process condit

31、ions welding Qian Preheat and the welding Hou heat treatment temperature table project material welding Qian preheat temperature (?) welding Hou heat treatment and the insulation time (?/H) wall thick (mm) temperature (?) wall thick (mm) temperature (?) 20 ? 26 100200 36 600650/1-1.5 15CrMo ? 10 150

32、200 10 670700/1.2-2 Preheat and the heat treatment process in the, Inner and outer wall temperature shall be kept uniform, in order to avoid internal stresses. Preheating before welding and post weld heat treatment, shall measure and record the temperature, temperature measurement locations and number of points are reasonable. Prone to weld delayed crack of steel, post weld heat treatment after welding should