共查询到20条相似文献,搜索用时 15 毫秒
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在城市天然气管道的输送中,管道建筑用户相连,中途有流量分出,从途泄流量和输转流量的角度研究,利用计算公式来计算管段的计算流量,确定其压力降,并进行了举例说明,为输气管道的设计工作提供了参考。 相似文献
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Subhashini Ghorai 《Chemical engineering science》2005,60(23):6637-6648
The simultaneous flow of water, oil and gas is of practical importance for the oil and gas industry. These three phases are present in varying degrees of concentration in many oil and gas pipelines. In this work, a model has been developed to predict the values of the hold-up and pressure gradient for three-phase stratified flow prevailing in a horizontal pipeline. This information is usually the first step for analyzing the stability of stratified flow and developing transition criteria. The concept of extended velocity has been applied to compute the wall shear stresses in three-phase flow. The effect of process variables such as gas to liquid ratio, pipe diameter, oil viscosity and non-Newtonian character of oil on hold-up and pressure gradient has been studied to simulate the oil well conditions. Structural stability analysis was also carried out to check for the sensitivity of the model. 相似文献
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ABSTRACT This work presents a complete improved mathematical model of drying in cyclone. The slip condition of the particles on the wall, the heat transfer wall-panicle and the shrinkage of the panicles during the drying process were considered. The mathematical model considers a two-dimensional turbulent gas-particle flow where the panicle phase is treated as a continuum. The momentum equations of both particle and gas phases were written in cylindrical coordinates. The discretized equations were solved by the SIMPLE algorithm. Considering the slip condition to the panicle phase and the shrinkage of the material during the drying process it was revealed a better fitness between numerical and experimental results than the previous model. 相似文献
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This work presents a complete improved mathematical model of drying in cyclone. The slip condition of the particles on the wall, the heat transfer wall-panicle and the shrinkage of the panicles during the drying process were considered. The mathematical model considers a two-dimensional turbulent gas-particle flow where the panicle phase is treated as a continuum. The momentum equations of both particle and gas phases were written in cylindrical coordinates. The discretized equations were solved by the SIMPLE algorithm. Considering the slip condition to the panicle phase and the shrinkage of the material during the drying process it was revealed a better fitness between numerical and experimental results than the previous model. 相似文献
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Hongkai Wang Meng Tang Dewu Wang Yan Liu Yishuo Zhang Baisong Hu Ruojin Wang Shaofeng Zhang 《American Institute of Chemical Engineers》2020,66(9):e16454
The flow characteristics of the blade unit of a tridimensional rotational flow sieve tray were investigated. First, the flow patterns are defined under different liquid arrangement methods. They are bilateral film flow, continuous perforated flow, and dispersion-mixing flow in overflow distribution, film and jet flow and jet and mixed flow in spray distribution. Second, the time and frequency domain analysis of the differential pressure pulsation signal in the blade unit is carried out, the main frequencies range is 2.0−5.5 Hz. The influence of perforation and mixing intensity on the flow pattern transition is clarified. Third, the rotational flow ratio of the gas–liquid phase is measured, the gas phase rotational flow range is 0.55–0.78, and the liquid phase range is 0.15–0.42. The influence of the operating conditions on the distribution of the rotational and perforated flow is investigated. Finally, a prediction model for the rotational flow ratio is proposed. 相似文献
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利用气液二相流一维波模型和段塞稳定性模型,对直径2.54 cm水平管内空气-水二相流出现段塞流时的各相临界表观速度和临界液层高度进行了理论预测。计算中发现,2种模型分别适用于不同的流速区域,在较低的气相流速下,一维波模型的预测结果比较理想,但是在较高的气速条件下不太适合,而利用段塞稳定性模型可以较好地获得高流速下分层流向段塞流的流型转变条件。因此,结合这2种模型对发生流型转变时的临界参数作了分析,并且应用于40 mm和50 mm水平管道的油气二相流实验。将理论计算的结果和实验测得的流型数据进行了对比,并且对影响流型的管径、流速等因素作了分析,结果表明计算得到的特征参数和实验数据比较吻合。 相似文献
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A quantitative criterion distinguishing stable from unstable transitional packed bed flow in standpipes is presented. This criterion can be used as an working guideline in actual standpipe operation. A fundamental and simple model based on stress free surface (SFS) theory has been developed. This model also provides a quantitative prediction method for the standpipe voidage. 相似文献
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<正>在流动沸腾传热两相流研究中,流型研究一直是众多研究者的兴趣所在。目前有关流型研究的报道均为低粘物系,但高粘流体两相流流型研究,对高聚物生产、食品、轻工等工业有重要应用价值。 浅尾芳久等在透明玻璃管中研究了流动沸腾的流型,表明Mishima等提出的流型划分判据可以较好地区分泡状流、弹状流、环状流。Kamiel等分析比较了大量低粘物系两相流实验数据和几种流型判别式,表明Weisman等提出的判别式可以较好地区分弹状流与环状流。 相似文献
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总结气液两相流流量测量方法的研究进展。介绍节流法、直接法、速度法和分离法的测量原理,并指出对两相流的物性进行全面、详细的实验研究和理论计算将是后续研究工作的重点。 相似文献
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基于文献中提出的针对常规管中气液两相流分层流稳定性的分析,考虑管壁入流对流型的影响,通过公式推导和分析得出了水平管中气液两相变质量流流型从分层流向非分层流转变的准则。通过室内实验研究和预测计算,分析了3种不同的流型转变准则中多个入流流量下管壁入流对流型转变的影响。研究结果表明,实际水平井筒的单位入流流量通常较小,对本地管道单元流型预测的影响可以忽略不计,但是通过不断累积,使得下游管道中流动参数发生变化,从而影响了下游管道单元中气液流动的流型。因此水平孔缝管中气液两相变质量流的流型判别可以采用常规管流型判别准则,但要分段进行。 相似文献
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A generalized model to predict minimum particle transport velocities in multiphase air–water horizontal pipes 下载免费PDF全文
Kamyar Najmi Brenton S. McLaury Siamack A. Shirazi Alan L. Hill Selen Cremaschi 《American Institute of Chemical Engineers》2015,61(8):2634-2646
A new model is proposed to predict minimum flow rates required to constantly move particles in both intermittent and stratified flow regimes. The new model consists of a single‐phase flow model along with an appropriate length scale to be extended to multiphase flow regime. A comparison of the new model with experimental data in a multiphase air–water flow shows that the new model is able to predict minimum flow rates well for a wide range of operating conditions. The new model can capture the effects of particle size, particle concentration, and pipe size as confirmed by experimental data. A comparison of the new model with previously proposed models in the literature shows that the new model improves critical velocity predictions significantly. Moreover, the new model is the only model that takes into account the effect of particle concentration and can predict critical velocity in both intermittent and stratified flow regimes. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2634–2646, 2015 相似文献
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Measurements of granular flows in two-dimensional hoppers by particle image velocimetry. Part I: experimental method and results 总被引:1,自引:0,他引:1
Daniel A. Steingart 《Chemical engineering science》2005,60(4):1043-1051
The objective of the present investigation was to test the applicability of particle image velocimetry (PIV), which is normally used for measuring velocities in liquids or gases, to measurement of velocities in granular flow. A second objective was to use PIV to provide experimental data for comparison with mathematical models. The flow of zinc particles, of size 0.4, 0.61 and 0.76 mm size, in a flat-bottomed two-dimensional hopper was measured by PIV. The particles were characterized using ASTM procedures for angle of repose, packing density and flow rate through a funnel. Through PIV, velocities and mass flow rates were determined for exit apertures 5 and 7.5 mm in width and 10, 30 and 50 mm long. The bed of particles in the hopper showed the expected stagnant zones on either side of the aperture. There was a continual avalanche of particles at the “V’’ which forms at the surface of the bed and some images of this avalanche, obtained with a boroscope, are included. 相似文献
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贫化电炉气液顶吹喷枪是一种独特的垂直下降管,其一端Y形通入气液两相,一端直接通入熔池中进行喷吹作业。本文采用多相流水模型模拟仿真的实验手段进行了定量分析,结果表明:不同于传统的垂直下降管,这种顶吹喷枪的管内流型受气液相间压差的影响,产生了一种由环状流过渡为泡状流的流型,不同流型的分布区域与压差的大小有关并且稳定存在;在支管与主管的交叉区域,对于不同的气液比存在3种气液混合相分界面,并各自产生不同的流型;浸没式顶吹气泡群形态在不同的管内流型驱动下有较大差异,表现在深度及宽度两个方面,并证明了气液比为2~5间的生产效果是最佳的。 相似文献
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The behavior of a relief valve with a short throat has been studied. Measurements of discharge rates when the unit was fed with a two-phase mixture have been made at moderate pressure differentials. These experiments show that the valve behavior is similar to that of an orifice and that flashing does not occur until downstream of the flow restriction. Design techniques which enable valve discharge rates to be computed under these conditions are developed
Other data show that, when fed with a two-phase mixture and subject to high pressure differentials, relief valves with longer throats exhibit critical flow rates close to these preducted by the homogeneous-equilibrium model (HEM). Additional data are needed in order to define the transition between orifice-like and HEM choking behavior. 相似文献
Other data show that, when fed with a two-phase mixture and subject to high pressure differentials, relief valves with longer throats exhibit critical flow rates close to these preducted by the homogeneous-equilibrium model (HEM). Additional data are needed in order to define the transition between orifice-like and HEM choking behavior. 相似文献
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根据气液两相流段塞稳定性理论,结合分层流理想化模型,对直径2.54 cm水平管内空气-水两相流出现段塞流时的各相临界表观速度和临界液层高度进行了理论预测,并且分析了气液两相界面的摩擦因子对于预测流型转变的影响.由于在不同的气相流速范围内,段塞流由不同形式的界面波形成,当气相表观速度小于 4 m(s(1时,由大振幅波形成段塞流,而当气相表观速度大于 4 m(s(1,段塞流由小波长的滚动波合并而成,因而根据实测数据对界面摩擦因子的计算进行了补充修正,并且应用到对应的气相流速范围.基于所给出的计算方法解得发生分层流向段塞流转变的临界表观速度和临界液层高度,并和实验数据进行了比较. 结果表明所做的修正可以避免以往理论预测中出现的低估情况,求得的各临界特征参数值和实验结果吻合得较好. 相似文献
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An alternative correlation for the flow of purely viscous non-Newtonian fluids in ducts of arbitrary cross-section is proposed. It involves two dimensionless groups which are Unique relationships exist between ? and Re*G for both laminar and turbulent flows which enable direct predictions of pressure drop from flow rate results or vice-versa. Excellent agreement between the new correlations and available experimental data for purely viscous non-Newtonian fluids flowing in circular tubes and square ducts is demonstrated. 相似文献
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研究了去离子水在3种规格矩形微槽内竖直向上流动沸腾的流阻特性,着重考察了出口干度、质量流速、进口过冷度和微槽尺寸对沸腾流动压降的影响.试验结果表明,两相摩擦压降随出口干度增大而增大,在相同出口干度下,入口质量流速越大摩擦压降越大,摩擦压降与入口过冷度无关;随着微槽道尺寸减小,摩擦压降增大. 相似文献