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1.
Li Guang Jun Guo Lie Jin Chen Xue JunNational Laboratory of Multiphase Flow in Power Engineering Xi''''an Jiaotong University Xi''''an ) 《核技术(英文版)》1998,9(1):39-44
The interfacial wave patterns and their transition characteristics in gas-liquid two-phase flow through rectangular and circular horizontal conduits are investigated.The interfacial waves were traced and recorded by using conductance probes.With the experimental observation and the analysis,some kinds of different interfacial waves were distinguished and dfined,and then the interfacial wave patterns were given,which were compared with previous results.The interfacial wave transition mechanism between each interfacial wave pattern was discussed and a set of transition equations were presented to predict the interfacial wave pattern transitions.The repdictive results are in good agreement with the experimental data. 相似文献
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摇摆状态下气液两相流流型转变的实验研究 总被引:2,自引:0,他引:2
通过可视化观察和数码照片对摇摆状态下光滑有机玻璃管内气液两相流流型进行分类和定义,并分析了不同管径、摇摆角度以及摇摆周期对流型之间转变的影响.结果表明:在液相折算流速一样的情况下,管径增加、摇摆周期缩短或摇摆角度减小会使得环状流形成需要更高的气体折算流速;弹状流向搅混流转变所需气相流量则随着管径的减小、摇摆周期的增加或摇摆角度的减小而增加.而在气相折算流速一样的条件下,管径增加、摇摆周期缩短或摇摆角度增大会使泡状流产生需要更高的液相流量. 相似文献
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1IntroductionTwo-phasebubblyflowisencounteredinawidevaxietyofindustrialapplications;Suchasintheproductionofelectricalpowerandpetrochendcajsindustry.Oneofthemosttwortantandyetleastunderstandingaspectsoftwo-phaseflowislateralphasedistribution.Theinformationonphasedistributionisarequiredparameterforhydrodynalincandthermalcalculationsinmanypracticalapplications.Considerableexperimentalandseal-theoreticalresearchhasbeenconductedbymanyresearchersinverticalupwaxdsordownwaxdsbubblynow.[1-7]However,L… 相似文献
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摇摆产生的惯性力以及水平管路发生向上和向下倾斜,会使管道内两相流的流动型式发生变化.本文对直径25mm管内气-水两相流在摇摆周期为15s、摇摆角度为10°状态下的流型进行了实验,研究了气-水两相流在摇摆状态下的流动型式,并给出了流型图.实验结果表明,在一些气-水流量区域,两相流体在一个摇摆周期内存在两种流动型式. 相似文献
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Flow patterns in upstream and downstream straight tubes of suddenchanged areas in a horizontal straight pipe were experimentally examined.Both sudden-expansion cross-section(SECS)and sudden-contraction cross-section(SCCS) were inverstigated.The flow pattern maps upstream and downstream were delineated and compared with those in straight tubes with uniform cross-sections.The effects of the SECS and SCCS on flow patterns were discussed and analyzed.Furthermore.flow pattern transition mechanisms resulting in occurrences of different flow patterns were simply discussed and some transition criteria for the flow pattern transitions were deduced by using the non-dimensionlized analysis method. 相似文献
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本文以空气和水为工质,对竖直向上矩形通道(40 mm ×1.41 mm ,40 mm ×10 mm )和圆形通道(D=25 mm )内的两相流流型特性进行了可视化研究。气液两相的表观速度分别为:0.03~24.71 m /s和0.03~3.73 m /s。3个实验段内均出现了泡状流、弹状流、搅混流和环状流4种流型,40 mm ×10 mm 和圆形通道中流型特征较为接近,与40 mm ×1.41 mm 通道中流型相比存在明显差别。此外,绘制出了3种通道详细的流型图。对比结果显示,矩形通道窄边宽度对流型转变有显著的影响,随着矩形通道窄边宽度的增加,其流型转变边界更加趋近于圆形通道。 相似文献
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本文研究不同边界条件及物理模型对两相流不稳定性边界的影响。采用RELAP5程序模拟直流蒸发管内的两相流不稳定性实验工况,对计算程序和模型进行验证,分析恒定流量及恒定压降两种边界条件、并联管数量、轴向功率分布形式和传热管热容等不同边界条件和物理模型对不稳定性边界的影响。结果表明:恒定压降边界条件下,单根管、2根并联管和多根并联管的不稳定性边界差别小于5%;恒定流量边界条件下,多根并联管不稳定性边界和2根并联管相比差别小于5%,而与单根管不稳定性边界的差别则超过100%;并联管根数相同时,恒定流量边界条件的稳定性好于恒定压降边界条件;沿流动方向(轴向)功率递增分布时,系统稳定性好于沿流动方向功率均匀分布,沿流动方向功率均匀分布时,系统稳定性好于沿流动方向功率递减分布;当管壁厚度为0~20 mm时,管壁热容对不稳定性边界几乎没有影响。 相似文献
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An experimental and theoretical study on the bubble shape of intermittent flow in the horizontal and inclined pipes has been carried out. The experiment results show that the bubble shape depends on the Froude number, bubble length and pipe inclination. The bubble with staircase pattern tail is observed at low Froude numbers, which is corresponding to plug flow. A model for the prediction of the bubble shape in horizontal and inclined pipes is proposed. The model is able to predict the bubble shape, flow pattern transition between plug and slug flow regimes as well as nose-tail inversion phenomenon observed in the downwardly inclined pipe. Validation shows the model can well predict the bubble shapes in horizontal and inclined pipes. The model discloses that the transition between plug and slug flow regimes occurs within a region. The Froude number range for plug flow regime in the downwardly inclined pipe is much wider than that in the horizontal or upwardly inclined pipe. The assumption of fully developed liquid film under the long bubbles tends to under-estimate the liquid fraction in this part of the slug structure, especially, for the intermittent flow in the upwardly inclined pipe with high Froude numbers. 相似文献
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棒束通道内气液两相流流型的实验研究 总被引:2,自引:2,他引:0
常温、常压条件下,在7×7矩形截面棒束通道内进行了垂直向上气液两相流动实验,气液两相折算速度的变化范围分别为0.04~14 m/s和0.238~1.860 m/s。实验中用高速摄像仪对流型进行记录,观察到了泡状流、泡状-搅混流、搅混流和搅混-环状流4种流型,发现搅混流是主要流型,并对Hewitt流型图的界限进行了修正。分析实验数据发现,摩擦压降在泡状流和搅混流区域的变化是相反的。根据实验数据,参考前人的研究得到棒束通道中泡状流向搅混流转变的边界。 相似文献
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《Journal of Nuclear Science and Technology》2013,50(2):180-189
An experimental study of upward air-water bubbly two-phase flow in an entry region was performed with various rough wall test tubes. The objective of the work is to clarify the effects of wall roughness and entry length on void profile. The fluid flows in the vertical circular test tube of 25 mm I.D. under nearly atmospheric pressure, at room temperature. The void profile changes from a pattern similar in appearance to the saddle shape which has local void peaks near the wall, into the power law shape whose curve is approximated by a power law formula, with increasing wall roughness and/or entry length. That is, wall roughness and entry length have a similar effect upon void profile. There are two patterns in the power law shape, a pattern with sharp center peak and a pattern with obtuse center peak. As wall roughness and/or entry length increase, the void profile changes from the former pattern to the latter pattern. At enough long entry length (L/D ? 150), every void profile has almost the same power law shape independent of wall roughness. Some void profiles are asymmetric to the axis. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(11):1013-1022
Following Part (I) of the present paper, which presented the experimental results obtained on the void distribution and average void fraction shown by nearly fully-developed, vertically downward two-phase flow of air-water mixture, this Part (?) covers the flow regime transition criteria among the three basic flow regimes : bubbly, slug and annular flows. The annular flow further was divided into two subregions of falling film flow and annular drop flow. The general situation of the transition criteria is as follows : (1) bubbly-to-slug flow transition occurs when the local void fraction in the central region of the tube is 0.3; (2) slug-to-annular drop flow transition criterion is given as a case which equations giving average void fraction for the slug flow and the annular flow are simultaneously satisfied; (3) slug-to-falling film flow transition occurs when the pressure difference between the crest of large wave and the bottom overcomes the surface tension; (4) the occurrence of liquid droplets from wave crests gives the transition criterion between the falling film flow and the annular drop flow. These criteria were correlated to predict each flow regime boundary respectively considering flow mechanisms or from experimental results. The correlations obtained were compared with published flow regime maps for atmospheric air-water flow and showed satisfactory agreement. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(9):868-879
The interfacial friction was investigated for high-pressure (3 to 9 MPa) steam/water stratified-wavy flow, using the TPTF experimental data for 4 and 8-inch diameter horizontal pipe test sections. The interfacial waves observed in the stratified-wavy flow regime with void fractions typically <–0.6, became larger in r.m.s. amplitude and more irregular in both amplitude and wave length, as the transition boundary to slug flow was approached. A correlation to predict the interfacial friction factor has been obtained for the stratified-wavy flows including the vicinity of the transition boundary to slug flow. The correlation is based on two non-dimensional parameters related to the interfacial wave generation by the Kelvin-Helmholtz instability, and correlates the TPTF data taken under different pipe diameters and pressures. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(5):321-327
Flow patterns for cocurrent and countercurrent air-water flows in vertical tubes (40 and 80mm I.D.) at volumetric flux densities of air and water in the ranges ?115–158 and ?100–102 cm/s were observed. A flow pattern map presenting the entire data of the observed flow patterns, i.e. bubbly, slug and annular flow for each mode of flow operation (upflow, countercurrent flow and downflow) were presented on the jl vs. jg plane. The flow pattern maps showed significant difference of flow pattern transition boundaries with upflow, countercurrent flow and downflow. Flow pattern transition curves were smoothly continuous with the change of the direction of water flow, on the other hand the change of flow direction of air showed complicated effect on flow pattern transition near zero jg . Comparison of the present flow pattern data with the reported general flow pattern maps for upflow showed that the correlation of Taitel et al. for bubble-slug flow transition is applicable to both cocurrent and countercurrent air-water flows. 相似文献
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《Journal of Nuclear Science and Technology》2013,50(12):903-914
A model is developed to describe the transition from annular flow to intermittent flow in a vertical two-phase flow system. Since the instability of the disturbance wave, which is a dominant wave shape at the boundary between annular flow and intermittent flow, is considered as a governing mechanism, this instability described by the concept of hyperbolicity breaking in the characteristic equation is included in the model. The developed model is validated by comparing its predictions of gas superficial velocity for the transition with experimental data available in the literature, and comparing those with the predictions of the other correlations. The comparison results show that the model gives better predictions for the transition condition than existing correlations, and the effects of fluid properties, geometry and liquid flow rate on the transition are well considered by the developed model. The average of prediction errors is 3% for the present model. The standard deviation of the prediction errors of the model reaches 28%, which is the smallest among the models compared here. 相似文献
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倾斜管内气液两相流流型的实验研究 总被引:4,自引:1,他引:3
对空气-水形成的两相流同向通过管径15mm、管长6m,倾斜角为15°和30°两种不同的倾斜角有机玻璃管的流型进行了实验研究。通过可视化观察和压差波动特性对流型进行分类,结合实验数据绘制出不同倾角下的流型图。另外,通过与相同管径下的水平管流型图进行对比以及不同倾角下流型产生范围的比较,发现试验段倾角对流型区间有显著的影响。 相似文献