水平管束间气液两相流局部含气率分布的实验研究

在废热锅炉火管管束间的气液两相流中,局部含气率的分布直接影响管束间流场、温度场的均匀性以及火管壁温工况.使用单纤光纤探针对水平管束间含气率的分布进行测量.实验沿管周方向以5度的间隔布置测点,得出含气率随径向、角度、气量、液量等参数变化的分布规律.同时通过分析得到了平均截面含气率的计算式.     

下倾管内气-液两相流单气泡界面特征研究

本文对下倾管内气-液两相流单气泡的界面特征进行了实验和理论研究.实验采用双平行探针技术和摄像方法.结果发现,当弗劳德数Fr较小时存在单气泡的首尾倒置现象,气泡移动速度与这种倒置现象密切相关,单气泡的界面特征与气泡的长度无关而与流体的Fr数密切相关.基于双流体模型推导得到描述气泡尾部特征的计算模型,该模型对下倾管内气泡尾部界面特征的预测与实验结果吻合良好.进一步的理论分析表明,下倾管内气泡首尾倒置的临界Fr数随着管道下倾角和管道内径的增大而增大.     

卧式螺旋管内泡状流转变的研究

本文在对卧式螺旋管内气液两相泡状流动及其转变的特征进行详细的实验研究的基础上,以现象为根据建立了泡状流转变的模型,给出了全范围内泡状流转变的边界预报式,实验与理论结果符合得很好。模型考虑了离心力和重力联合作用下的机制,对于弯管和直管内流动,模型具有兼顾的性质。     

卧式螺旋管内流动沸腾传热研究

在较宽广的参数范围内对卧式螺旋管内水／水蒸汽两相流沸腾传热特性进行了详细的试验研究，螺旋管内径ｄ＝１１ｍｍ，曲率直径比Ｄ／ｄ为２３．２７。试验参数范围：压力０．５－３．０ＭＰａ：质量流速２００－２５００ｋｇ／ｍ２·ｓ；热负荷２３０－５００ｋＷ／ｍ２：出口干度０－０．８６。得到了沸腾传热系数的实验关联式，并深入分析了局部传热与壁温特性，沿流动方向，管截面平均传热系数在螺旋管的上升段最大，而在下降段最小；沿管截面内表面圆周方向上，局部传热系数在外侧最大，在内侧最小，在顶部和底部处的值居中。得到了管截面局部传热系数的分布实验关联式。同一管截面外表面圆周方向上，外侧壁温最低而内侧最高。     

段塞流的流量瞬变特性试验研究

An investigation of the characteristics of flowrate transients within slug flow was conducted in a largescale outdoor testing facility.The test section consisted of a 378m long,7.62cm diameter stainless steel pipe. Air and water were used as the test fluids.The response to a change of flowrate o either phase or two phases was measured using a series of pressure transducers and differential pressure transducers.An increase or decrease in gas flowrate caused a pressure overshoot above the value at new steady state or led to a pressure undershoot to form a temporary stratified flow.Pressure waves existed in the pipeline,spreading from the entrance to the exit.The magnitude of pressure overshoot in “up-gas”transient or of pressure undershoot and period of the temporary stratified flow in “Down-gas” transient are related to the change of gas flowrate and the distance away from the entrance.In contrast,the change in liquid flowrate was accommodated by smooth transitions between the corresponding steady states,and only one obvious change was found in the slug frequency.According to experimental results,the pressure overshoot,pressure undershoot and the pressure wave propagation were analyzed,and the phenomena were explained reasonably.Some correlations for the calculation of the pressure overshoot and undershoot were proposed.     

水平管内气液段塞流液塞长度发展规律的实验和模拟研究

In petroleum industry, the slug flow is a fre-quently encountered flow regime in multiphase flowpipeline. For pipeline designers, the liquid slug lengthdistribution is important for the proper design ofdownstream facilities, such as slug catcher and sepa-ration system. However, for its transient and unsteadynature, it is a great challenge for engineers to correctlypredict the flow parameters of slug flow, especiallythe maximum liquid slug length. The unit cell model for slug flow in horizontal…     

水平管内气液段塞流液塞发展特性实验研究

Slug initiation and subsequem evolution along a 5.0 cm ID, 16m long horizomal pipe are experimentally studied. The transient characteristics of interfacial structures are described by using simultaneous measuremeres of the liquid height at multiple locations along the pipe. Various effects of superficial gas and liquid velocities and pressure oscillation on the slug initiation and evolution along the pipe are illustrated. It is found that the slug is initiated by a deterministic orocess with reolenishmem and deoletion of liquid near the inlet for the superficial gas velocity USG〈3.0m·s^-1 and by a stochastic process with wave coalescence along the pipe for USG〉3.0m·s^-1.The evolution of the slugs is strongly attected by superhclal gas and liquid veloclties for USG〈3.0m·s^-1 but weakly affected by the superficial gas velocity for USG〉3.0 m·s . The suppression of pressure oscillation at the pipe inlet significantly delays the onset of slugging, with slugs forming postponed further downstream. The slug frequency at the outlet is, however, not affected by the variation in the pressure oscillation.     

N掺杂Ta2O5的制备及其光催化分解水制氢性能研究

通过对Ta2O5程序升温的氮化方法,制备了在可见区具有较强吸收的N掺杂Ta2O5光催化剂,并采用X射线衍射(XRD)、UV-Vis漫反射光谱、X射线荧光(XRF)、扫描电镜(SEM)等化学物理手段对其进行了表征,其吸收阈约为630nm,带隙约为2.0eV。在乙醇和Na2S-Na2SO3牺牲剂体系中,研究了N掺杂Ta2O5催化剂的可见光催化分解水制氢性能,并考察了采用光还原法在N掺杂Ta2O5表面上负载贵金属Ru对光催化剂的产氢活性影响,探讨了Ru的负载量与产氢速率的关系,结果表明在N掺杂Ta2O5表面上负载贵金属Ru可明显提高其产氢活性,Ru的最佳负载量约为0.1 wt.%。     

循环流化床锅炉旋风分离器内气固两相流动的数值模拟

为研究旋风分离器内部气固两相流动的特征，本文应用FLUENT5.4.8软件对某厂50MW级别的旋风分离器内部气固两相流动进行了数值模拟，在此基础上，本文又分别对中心筒长度减半，变梯形入口为弧形引导入口，增加筒径的三种改进模型重新进行了计算，并得出了有用的结论，这些数值模拟的结果对新型旋风分离器的设计、运行和改造等均具有指导意义。