气-液两相垂直管流中液膜反转的数值模拟

气液两相环状流动时,气体流速的降低可能导致液膜流动方向在重力作用下反转,进而引发流型的过渡。本文对垂直管中的液膜反转现象进行瞬态数值模拟,对气-液相分布、速度、压力、壁面剪应力等参数进行动态追踪,得到液膜反转的临界气速,使用已公开的实验数据对模拟结果进行验证。模拟垂直管高1.5m,直径76mm,假设流场在二维剖面上轴对称,采用商业软件Fluent的Multi-Fluid VOF模型进行计算。结果表明,模拟的临界气速、持液率和前人实验数据吻合较好,但压力梯度偏差较大。随着气速降低,液体入口附液膜厚度和液滴夹带量显著增加。通过监测相速度和壁面剪力的动态变化,获得了携液临界气速,发现此时液膜出现间歇性的反转行为,而在大部分时间内,液膜会在界面波的带动下继续向上流动

Three-dimensional interface structures and characteristics in a stratified gas-liquid pipe flow

In this study, the air-water flow in a pipe with a diameter of 100 mm was tested to investigate the threedimensional (3D) interfacial characteristics of gas-liquid stratified flow in horizontal and slightly inclined pipes. The gas-liquid stratified flow interface exhibited a nonflat phenomenon (concave or convex). In particular, this phenomenon was verified by the transformation of the interface shape when the gas-liquid ratio exceeded 200 and 5 in the horizontal and inclined pipes, respectively. Compared with the flow in the horizontal pipe, the liquid holdup gradually decreased with an increase in the inclination angle in the downward stratified flow, and liquid height changes at the center was slight; however, the convex interface shape was obvious. In addition, the interface exhibited regular fluctuations in the flow direction under fixed operating conditions. Therefore, the hypothesis of a nonflat interface for stratified flow was proposed based on the experimental phenomena, and the interface shape function and flow equations were constructed to predict the degree of interface bending and critical conditions for gas-liquid stratified flow by analyzing the theoretical and influencing factors. The acceleration pressure drop was introduced to quantitatively characterize interfacial fluctuations in the flow direction; therefore, a modified model for nonflat stratified flow was developed. The proposed model could characterize the interface features in both the cross-sectional and flow directions of the pipe and provided a solution for the 3D interface of stratified flow. A comparison with the experimental results revealed that the proposed model performed the prediction satisfactorily. By solving the proposed model, the interfacial information in the pipe cross section and flow direction can be effectively predicted

导流式脱气设备分离特性测试

油田生产领域,采出液在举升至地面过程中,会因泄压造成溶解气析出,形成气-液两相流,影响后续处理环节。因此在进行后续处理前需经历脱气环节去除游离态气体。本文提出了一种基于导流式气-液分离原理设计的除气设备,并展开了系统的测试工作。研究发现气相在旋流场中以气柱形式存在。给定入口条件下,气柱尺寸随分流比增加而变小。在分离效率方面,给定入口条件,分离效率随分流比增加而逐渐增加,超过临界分流比后分离效率接近100%并保持不变。临界分流比受入口条件影响,与入口液相流量呈负相关关系;与入口含气率呈正相关关系。这些成果有助于导流式除气设备的改进和优化

江西鄱阳湖湖口水域船舶通行对长江江豚发声行为的影响

江西鄱阳湖是长江江豚（Neophocaena phocaenoides）的重要栖息地, 湖中栖息着约 400 头江豚。多年

江西鄱阳湖湖口水域船舶通行对长江江豚发声行为的影响

江西鄱阳湖是长江江豚(Neophocaena phocaenoides)的重要栖息地,湖中栖息着约400头江豚。多年的观察表明,船舶交通是鄱阳湖中江豚面临的重要威胁之一。为了评估船舶通行对长江江豚发声行为的影响,尤其是了解船舶通行期间及其前后江豚的发声和行为特征,作者于2007年6月27日—7月1日在江西鄱阳湖湖口水域采用固定被动声学系统,即安装在监测点(29°42′38″N,116°11′11″E)的一套水下声学数据记录系统,对周边通行船舶的水下噪声及江豚声纳信号脉冲事件进行了定点监测和记录,并对所记录的数据进行了定量和统计分析。在整个监测的109h中,声学记录仪共记录到船舶494艘,江豚声纳脉冲串信号13413个。船舶出现与江豚出现存在弱的负相关关系(r=0.029,N=6550,P0.05);当有船舶经过时,江豚的发声频次显著降低(Z=10.050,P0.05;Z=0.119,P>0.05);船舶通行之前和之后,江豚的发声频次、脉冲串持续时间、脉冲间间隔的差异性均不显著(χ2=5.255,P>0.05;χ2=3.511,P>0.05;χ2=5.155,P>0.05);在船舶经过时,江豚对游动方向没有明显的选择性(χ2=0.861,P>0.05)。基于分析结果推测,在狭窄水域中江豚躲避船舶干扰通常采取"临时性"策略,而非长距离逃避。由于鄱阳湖湖口水域水道相对狭窄,尽管研究的结果表明江豚对船舶有一定的敏感反应,但是在相对狭窄的水域中,江豚躲避船舶的行为难以充分表现。另外,江豚对该水域中高密度航行船舶的噪声可能存在一定的"适应性",导致当遭遇船舶时,江豚的声行为反应不十分强烈。因此,建议有必要在不同尺度的水体中采用声学数据记录仪继续开展类似的观察,以进一步了解江豚对船舶的行为响应,尤其是观察江豚躲避船舶的行为及发声特征

赫歇尔-伯克利流体气液分层管流持液率特性研究

以牛顿流体、幂率流体和宾汉流体建立的气-液流动理论模型不能准确应用于非常规石油领域。为此,基于赫歇尔-伯克利流体本构,借助双流体理论和流动控制方程,推导了两相分层管流中持液率预测模型。综合考虑非牛顿流体流变特性参数,流动条件及管道倾斜角度对赫歇尔-伯克利流体气-液分层流动的影响。结果表明,非牛顿流变特性(如幂律指数和屈服应力)对两相流动中持液率具有显著影响,具体表现为液体屈服性和剪切稀化特性的增强将导致持液率的增加。对比实验数据,持液率计算模型显示出较好的预测效果。该预测模型的主要特征是,即使液体具有复杂的流变性或包含固体颗粒,也可以通过气体/非牛顿流体行为描述两相分层流动。该模型为倾斜管中复杂流体的气-液流动特性研究提供了新的见解

管道式气液旋流器分离特性研究

随着油田采出液高含水逐年升高,管道式气液分离设备越发凸显出优势。本文结合实验和数值模拟对气液在管道式气液旋流器中的相分布和分离性能进行了研究。通过研究发现,管式分离设备可以在较大的分流比范围内保持接近100%的分离效率;出口和入口液相雷诺数比值与分流比呈现近似呈现线性关系。在实验研究的基础上对管式分离设备进行了数值模拟验证,并通过数值模拟揭示了不同位置气芯形状及相分布规律等。这些成果为管道式导流片型分离设备的设计和应用提供了重要参考

Experimental investigation of film reversal evolution characteristics in gas liquid annular flow

In natural gas wells, liquid loading is a severe problem threatening production safety. Published studies have verified that liquid loading is closely related to film reversal in gas liquid annular flow, but the evolution of the film reversal is still unclear. This article reports on experiments conducted to reveal the film reversal evolution characteristics. Experiments were conducted in a 50 mm diameter vertical pipe with superficial gas velocities ranging from 5.66 to 22.64 m/s and superficial liquid velocities ranging from 0.014 to 0.170 m/s. A camera and electrical resistance tomography were used to obtain qualitative and quantitative results, and an error analysis verified the experiments' repeatability and reliability. The evolution process is divided objectively into three stages to clarify the film reversal: no film reversal (No FR), the onset of film reversal (Onset FR), and complete film reversal (Complete FR). The three stages occur successively with decreasing gas velocity. The characteristics of the individual stages are elaborated, including the interfacial structures, morphological features, and motion trajectories. The void fractions are analyzed in both the time and frequency domains, where the statistical parameters of the probability density function, average value, and standard deviation are presented. The results show that the Onset FR stage exhibits characteristics similar to both the No FR and Complete FR stages, indicating that it plays an intermediate role in the gradual evolutionary process. The current experimental results also achieve excellent agreement with published datasets and correlations

一种模拟深水环境的循环式油气水多相流动测试装置

本发明涉及模拟深水环境测试装置技术领域,提供了一种模拟深水环境的循环式油气水多相流动测试装置,包括储水单元和储油单元；储水单元的出口端和储油单元的出口端同时连接有油水混合单元,油水混合单元的出口端连接有气液混合单元,储水单元和储油单元的入口端同时连接有油气水分相回收单元；气液混合单元的出口端和油气水分相回收单元的入口端之间连接有测试单元；储水单元、储油单元、油水混合单元、气液混合单元、油气水分相回收单元和测试单元均电性连接至控制系统；采用本技术方案既能够实现分相流动模拟循环,同时又能够模拟极端环境下的温度和压力等参数,使实验测试条件与实际现场应用相同,为相关环境下的多相流动机理研究提供依据