低温液体输送系统间歇泉现象机理分析与消除措施

在低温液体输送系统的垂直管路中有可能发生间歇泉现象 ,对管路系统和液体储存都会产生不利影响。文中从气泡动力学、间歇泉循环过程、管路结构等方面对低温液体输送系统中出现的间歇泉现象进行了机理分析 ,介绍了几种消除间歇泉现象的措施 ,为进一步研究间歇泉现象提供了理论基础     

Hydro-mechanical aspects of the sand production problem

This paper examines the hydro-mechanical aspect of the sand production problem and sets the basic frame of the corresponding mathematical modelling. Accordingly, piping and surface erosion effects are studied on the basis of mass balance and particle transport considerations as well as Darcy's law. The results show that surface erosion is accompanied by high changes of porosity and permeability close to the free surface. Quantities which can be measured in experiment, like the amount of produced solids or fluid discharge, can be used in an inverse way to determine the constitutive parameters of the problem.Notation dV Volume element - dV _s Volume of solids pt - dV _v Volume of voids - dV _ff Volume of fluid phase - dV _fs Volume of fluidized-particles - Volume of mixture - dM _s Mass of solids - dM _ff Mass of fluid phase - d _{M fs} Mass of fluidized-particles - Mass of mixture - s Density of solids - f Density of fluid - ff Density of fluid phase - fs Density of fluidized-particles - Density of mixture - _i ^ff Velocity of fluid - _i ^fs Velocity of fluidized-particles - _i ^s Velocity of solids - Velocity of mixture - q ^ff Volume-discharge of fluid - q ^fs Volume-discharge of fluidized-particles - Volume-discharge of mixture - m ^ff Mass-discharge of fluid - m ^fs Mass-discharge of fluidized-particles - Mass-discharge of mixture - _er Rate of mass-eroded - _dep Rate of mass-deposited - Mass generation term - dS _i Surface element - Pore-surface element - D _IJ Tensor of mechanical dispersion - x _i Location - t Time - Porosity - c Transport concentration - c _cr Critical value ofc - p Fluid-pressure - k Permeability coefficient - _k Kinematic viscosity - Spatial frequency of erosion starter points     

Riccati传递矩阵法在流体动力学中的应用

传统的传递矩阵法在求解管内流体的固有频率时,因奇点干扰出现漏根现象.本文结合气体压缩机管道,运用转子动力学中的Riccati方法计算管内气体的固有频率及振型,从根本上消除了漏根现象.算例表明了本方法的可靠性.     

Determining creep ratio in buried pipes for applications without pressure. Accuracy of experimental results

A buried plastic pipe undergoes deformation, but it stabilizes at the end of a certain time not exceeding two years.Thus, there is an interest in determining the extrapolated creep of structured wall plastic pipes at 2 years.The main goal of this work is to present information regarding the assessment of results and their accuracy, based both on the requirements of the product standard [3] and on the uncertainty of the tests.     

ANALYSIS OF NONLINEAR DYNAMIC STABILITY OF LIQUID-CONVEYING PIPES

Nonlinearly dynamic stability of flexible liquid-conveying pipe in fluid structure interaction was analyzed by using modal disassembling technique . The effects of Poisson . Junction and Friction couplings in the wave-flowing-vibration system on the pipe dynamic stability were included in the analytical model constituted by four nonlinear differential equations . An analyzing example of cantilevered pipe was done to illustrate the dynamic stability characteristics of the pipe in the full coupling mechanisms , and the phase curves related to the first four modal motions were drawn . The results show that the dynamic stable characteristics of the pipe are very complicated in the complete coupling mechanisms, and the kinds of the singularity points corresponding to the various modal motions are different.     

Mineralogy, size, morphology and porosity of aggregates and their relationship with soil susceptibility to water erosion

Soil erosion has been considered as the main process related to losses of soil mass and decrease of productivity in cultivated lands as well as on e of the most important processes in landscape evolution. Attention has been paid to many pedological variables affecting intensity of erosion, but little to the influence of iron compounds on the type, size, shape and porosity of soil aggregates. In the present study, three lithopedodomains which were assumed to be closely related to the dominant lithology of the soil parent material, varying in the degree of water erosion intensity, were selected for further analysis which focused mainly on the influence of iron oxide mineralogy on the soil aggregation. Powder X-ray diffractometry, 80 K Mössbauer data and SEM images are used to correlate all these variables with observed erosion activity in the field. The present data indicate that the more the soil is rich in iron (hematite and/or goethite) or aluminium (gibbsite) (hydr)oxide, the smaller are its aggregates and is porous. Soils derived from metabasic rocks are much more susceptible to collapse under wetting than those from other lithologies. They have the highest iron and clay content. Schist-derived soil is richer in muscovite, has bigger aggregates and porous and are less prone to collapse, while the granite-derived soil presents relatively intermediate resistance, when humid.     

Wet steam flows in industrial large-diameter pipes: flowrate, moisture and pressure drop measurements

The flowrate, moisture and pressure drop were measured in a water-steam mixture flowing at a pressure of I MPa in pipes with 0.3 and 1.2 m dia. The results are presented here, along with an original method for assessing pressure drops in a water-steam mixture flowing in such industrial pipes.     

关于复杂管系气柱固有频率计算的若干问题

本文论述了复杂管道系统气柱固有频率计算中存在的若干问题，在模型简化、计算方法等方面提出一个基于频响函数改进措施，并增加了验根过程。通过和实验数据、以往传递矩阵法计算结果的比较和实际管系的应用计算，证明本文方法是令人满意和有效的。     

东莞南城区能源厂组合式挡土墙失稳分析及处理措施

挡土墙病害和破坏形式主要有:滑移、倾覆、墙身开裂等,并且主要考虑一级或单级挡墙的破坏。本文通过对东莞南城区能源厂重叠式组合挡土墙失稳观察,提出其破坏形式除了一般挡土墙具有的常见病害———倾覆之外,还伴随有该类挡土墙特有的灾害———流土的发生,本文从定量、定性两方面对该失稳挡墙进行了具体分析,最后,根据分析结果对该挡墙提出了具有针对性的处理措施。通过对该挡土墙的分析总结,为今后该类挡土墙的设计、施工提出了极具借鉴价值的建议。     

核反应堆管道和压力容器的LBB分析

管道和压力容器的破前漏（ＬＢＢ）分析是在近二十年里发展起来的保证核反应堆结构安全性和可靠性的一种重要分析方法．本文综述了ＬＢＢ分析的国内外研究和应用现状，介绍了一些典型的ＬＢＢ分析方法以及ＬＢＢ分析过程中遇到的一些主要问题，尤其是与断裂力学相关的问题，包括韧性裂纹扩展的稳定性分析、裂纹张开面积和泄漏率的计算等．ＬＢＢ问题的研究对于我国核能工业的发展具有重要的意义．