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本文对卧式V型管高压汽水两相流的传热特性进行了试验研究。根据试验得到了计算临界热负荷的关系式。该式可用来预测卧式V型管弯头上、下游部分的传热恶化条件,为沸腾燃烧锅炉中卧式V型坦管、锅炉炉膛出口凝渣管等的设计与运行提供了可靠依据。 相似文献
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采用一维均相流模型,运用Clausse和Lahey提出的非线性两相流垂直上升单管分析法,考虑倾斜角度、内螺纹管因素,发展了多管道系统不稳定性理论模型;对超临界锅炉并联倾斜内螺纹双管汽-水两相流密度波型脉动进行了理论分析和求解.采用时域法求得密度波型脉动发生时,试验段进口质量流量在各个时间点的数值.根据流量随时间发散或收敛的趋势,判断得到发生脉动的阈值.对脉动时的周期、振幅等特征值进行分析,得到进口质量流量随时间的变化规律.计算得到的各工况下的脉动周期范围大多在5~16 s之间,与实验所得的7~19 s 基本吻合.比较可得,该模型的计算结果与试验数据符合较好,可用于判定是否发生密度波型脉动,为确定锅炉安全运行时的水冷壁参数提供参考. 相似文献
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基于壁面汽泡壅塞理论,针对近临界压力区两相流动沸腾的偏离泡核沸腾(DNB)现象,对垂直上升内螺纹管的DNB型临界热流密度(CHF)进行了数值计算研究。以内螺纹管为分析对象改进已有的汽泡壅塞模型,计算了汽泡层区与主流区的极限传递质量流量、湍流速度分布、汽泡层区临界截面含气率等本构关系,汽泡脱离直径的计算考虑了汽泡接触角的影响。本文模型还根据大量CHF实验数据拟合得到了新的αb关联式。最后,基于Fortran语言编制了CHF的理论预测数值模型程序,研究分析了压力、质量流速、热平衡干度及进口欠焓对CHF的影响,并根据CHF查表值对本文模型进行评估,同时将实验得到的内螺纹管CHF数据与采用Bowring模型、Katto模型、Shah模型和本文模型计算的CHF进行比较,发现本文模型的误差最小,与实验值吻合结果较好,说明本文模型能较好地对垂直上升内螺纹管DNB型CHF进行预测。 相似文献
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针对直流蒸汽发生器(OTSG)中全流型沸腾传热及一、二次侧耦合换热等复杂物理现象,计算流体动力学(CFD)数值分析普遍面临计算难度大、计算效率低及不确定性大等问题。基于欧拉两流体多相流模型与临界热流密度(CHF)壁面沸腾模型,建立了管内全流型流动沸腾传热数值分析模型,并验证了模型的有效性。基于所验证的模型,开展了数值模型在多管耦合传热下的应用特性研究,明确了该数值模拟方法在多管耦合下的可靠性,并对温度与相分布计算结果对相间作用力模型的敏感性进行了数值分析。研究结果表明:基于欧拉两流体多相流模型与CHF壁面沸腾模型,能够较准确地预测管内水介质由过冷到过热的全流型流动沸腾传热过程,计算的“干涸”点位置及壁面峰值温度与实验值符合较好,最大误差小于10%;基于欧拉两流体多相流模型与CHF壁面沸腾模型的数值方法对多管耦合工况有较好的适用性,计算的二次侧温度与实验结果吻合良好;两相间曳力对壁面温度及空泡份额的计算结果有较明显的影响,但非曳力对壁面温度的影响较小,因此对于大规模工程应用计算,可在分析中不考虑部分相间非曳力的影响。本文研究结果可为OSTG的三维精细化数值分析的模型选择提供有益参考。 相似文献
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采用辐射接枝共聚法在微粒聚四氟乙烯表面键合适当单体,已制得具有良好性能的新型气相色谱固定相。本文叙述用蒸气相共辐照接枝法制备微粒聚四氟乙烯—醋酸乙烯酯(PTFE—VAC)接枝物的工艺特点,对产物的色谱效果作了初步讨论。 相似文献
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《IEEE transactions on nuclear science》1979,26(4):4399-4404
The Holifield Heavy Ion Research Facility is a national resource which will serve a large number of nuclear and atomic physicists who expect to perform experiments which vary widely in type and complexity. Although much consideration must be given to the problem of rapid acquisition and processing of many-parameter data, an equal emphasis will be placed on operational simplicity and the standardization of hardware and software. Two "active" experimental counting areas and two or more "setup" areas are served by three remotely located Perkin-Elmer 8/32 computers which are interfaced to the user equipment by means of three CAMAC branch highways. Other equipment includes a large disk system, alphanumeric/graphic terminals and printer-plotters located in each of the counting areas. The system operation as well as techniques for the rapid sorting of data into large (~ 10 million channels) histograms on disk are discussed. 相似文献
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The temperature dependent Fe Mossbauer and X-ray diffraction measurement on Bi-system 2:2:2:3 phase have been carried out from 77 K to 300 K. It was found that there are two anomalous behaviors of lattice vibrational modes near 125 K and 220 K. This phenomena of lattice softening above Tc is taken as a precursor effect of superconductivity. 相似文献
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本文介绍了一种事故早期可防止剂量的计算方法,分析讨论了时间,空间,环境和不同防护行动之间相互作用等对防护行动实施效果有主要影响的因素;通过计算不采取任何防护行为时所受到的剂量与采取防护行动后的剂量之差得到可防止剂量,将其与国际原子能机构建议采用的通用干预水平进行比较,可得到应采取紧急防护行为的区域,同时也可以为进一步的防护决策最优化提供剂量数据。该方法已经应用在广东省核事故场外后果预测评价系统(GNARD2.0)和秦山地区环境核事故后果评价系统(QS-NUCAS1.0)之中。 相似文献
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A data acquisition system for high energy physics experiments is described here, which is in accordance with the specifications of EUR 4100e and EUR 4600e. This is a multicrate system using branch highway and type A crate controllers. Most of the components are now commercially available. 相似文献
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S. V. Akulinichev G. N. Vyalov M. I. Grachev S. K. Esin E. S. Konobeevskii É. A. Koptelov L. V. Kravchuk S. G. Lebedev V. A. Matveev A. D. Perekrestenko V. N. Sazanov V. L. Serov S. F. Sidorkin V. M. Skorkin Yu. V. Ryabov A. V. Feshchenko 《Atomic Energy》2003,94(1):45-49
The current status and prospects of work on the Moscow meson factory are described. The maximum energy obtained at the present time is limited by the existing powerful klystrons and is 247 MeV. The maximum beam intensity is 150 A. The accelerator beam is used for fundamental research and for solving applied problems. The average duration of the sessions is 2000 h per year. Three of the five branches of the proton channel which are provided in the design are in operation in the experimental complex. This includes the branch on the multifunctional neutron complex, which is to be used for, among other things, research on nuclear transmutation of long-lived fission products, Np, Am, Cm, and the electronuclear method of generating electricity. The first phase of the proton therapy complex is under construction. 相似文献
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A data acquisition system that provides real-time data acquisition and control, and on-line data analysis facilities has been recently installed. A PDP-11/44 is interfaced to CAMAC via a MBD-11 microprogrammable parallel branch driver. Both system and user software has been implemented in the structured high level "C" language in the UNIX time-sharing environment. Implementation of the system is discussed. 相似文献
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《等离子体科学和技术》2016,18(3):305-310
One of the main problems in the Ultra High Voltage(UHV) transmission project is to choose the external insulation distance,which requires a deep understanding of the long air gap discharge mechanism.The leader-streamer propagation is one of most important stages in long air gap discharge.In the conductor-tower lattice configuration,we have measured the voltage,the current on the high voltage side and the electric field in the gap.While the streamer in the leader-streamer system presented a conical or hyperboloid diffuse shape,the clear branch structure streamer in front of the leader was firstly observed by a high speed camera in the experiment.Besides,it is found that the leader velocity,width and injected charge for the branch type streamer are greater than those of a diffuse type.We propose that the phenomenon results from the high humidity,which was 15.5-16.5 g/m~3 in our experiment. 相似文献
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T型三通管内热分层流动3D数值模拟 总被引:4,自引:0,他引:4
针对主管和支管流体温度不同的等径三通管,利用AQUA程序,对该三通管内的热分层流动进行了三维数值流场模拟。模拟结果显示,高流速的支管流体自上部射入,深入到主管的主流内部,迫使主管内上游来流贴着主管下壁面流动。在支管人流的背流面有一涡存在,主支流在此涡下部的狭窄通道内被加速到较支流速度更高的速度。对三通管内的温度分布计算表明,支流人流的迎流面存在着很大的温度梯度,两种流体的混合主要存在于远离支流人流的下游地区。 相似文献
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Jae Young Lee Soo Hyun Hwang Manwoong Kim Goon Cherl Park 《Nuclear Engineering and Design》2007,237(10):1046-1054
An experimental and analytical investigation of onset condition of gas pull through and liquid entrainment in a single inclined branch to the arbitrary direction was performed in the present study. Since previous studies have been made only for specific angles of 0° and ±90°, it is hard to apply them to the case of branch off to the arbitrary direction. In the present study, series of experimental works was made with a horizontal header of 184 mm inner diameter with a single branch pipe which can be attached in nine different orientations of 0°, ±30°, ±45°, ±60°, ±90° angles and with two different diameters of 16.0 and 24.8 mm, respectively. Also, a simple mechanistic model is developed here based on the force balance at the top of the vortex on the surface of the stratified water. The onset condition due to the vortex breakup for the branch oriented with angle of θ was determined as and the onset condition due to the ascending film was which is similar to that of side branch. It was found that the present model predicted experimental data well in terms of the direction and diameter of the branch pipe. The present model and data may be useful in determination of the quality of flow through the inclined branch which is one of key parameter in the safety study of hypothetic small break loss of coolant accident in the nuclear power plant. 相似文献