HL—1装置水平杂散场的优化补偿

本文描述HL-1装置的水平杂散场及其动态优化补偿的实验研究和理论计算。理论和实验结果符合很好。     

Effect of secondary flow on droplet distribution and deposition in horizontal annular pipe flow

In horizontal annular dispersed pipe flow the liquid film at the bottom is thicker and rougher than at the top of the pipe. A turbulent pipe flow experiencing a variation of roughness along the pipe wall will show a secondary flow. Such secondary flow, consisting of two counter-rotating cells in the cross-section of the tube, can change the distribution of the droplets inside the pipe and their deposition at the wall. Here, we compare the behaviour of the droplets (dispersed phase) with and without secondary flow, using large-eddy simulations. It is shown that the presence of secondary flow increases the droplet concentration in the core of the pipe and the droplet deposition-rate at the top of the pipe.     

Critical friction factor modeling of horizontal annular base film thickness

Measurements of liquid base film thickness distribution have been obtained for 206 horizontal annular two-phase (air–water) flow conditions in 8.8 mm, 15.1 mm, and 26.3 mm ID tubes. It is found that the trends in base film thickness measurement do not match trends in the literature for average film thickness, which considers waves and base film together. An iterative critical friction factor model is used to model circumferentially-averaged base film thickness; an explicit, empirical correlation is also provided. Asymmetry is well-correlated by a modified Froude number based on the correlated base film thickness and the gas mass flux. The iterative model is also extended to estimate the critical film flow rate.     

Wave behavior in horizontal annular air–water flow

In this study, non-intrusive pressure drop, liquid base film thickness distribution, and wave behavior measurements have been obtained for 206 horizontal annular two-phase (air–water) flow conditions in 8.8, 15.1, and 26.3 mm ID tubes. Reliable wave velocity measurements are available for 185 of these flow conditions, while 131 flow conditions allow for reliable wave frequency measurements. The wave velocity is found to be predicted to within 9% by gas friction velocity and 6% by an optimized correlation of similar structure. Wave frequency can also be predicted with a simple correlation to within 5% for the 8.8 and 15.1 mm tubes, but a separate relation is required to explain 26.3 mm frequency data. The differences in wave behavior between the annular and wavy-annular/wavy regimes are also discussed.     

土工格栅路堤加筋效果的影响因素分析

土工格栅作为一种新型的土工合成材料,由于具有高强度、低延伸率等特点而被选作主要的路堤加筋材料,在路堤中适当位置加入土工格栅能有效地减少路堤的沉降和侧向变形。本文采用通用非线性有限元程序ABAQUS分析了加筋前后的路堤底部的竖向位移、堤址点垂线下地基深度的水平位移和地表的水平位移,计算中采用D rucker-Prager模型和C lay p las-tic ity模型模拟土体的非线性,土工格栅采用一维杆单元来模拟。通过对加筋层数、筋材模量、软基模量、填土高度和软土层厚度等影响加筋效果的因素进行对比分析,从计算结果分析可知,路堤加筋虽然对软土地基的竖向位移影响不大,但加筋能有效抑制侧向位移的发展,这样增大了路堤边坡的稳定性,分析结果与大多数实际工程的实测资料相吻合。     

FINITE ELEMENT METHOD ON NUMERICAL SIMULATION OF STRATUM CORNEUM''''S PENETRATION PROPERTY

How the outer substance could penetrate through the skin lies in the stratum corneum, because it is the main barrier in the multi-layers of the skin. Supposing the keratin cell with a special geometry as tetrakaidecahedron, the penetration property of stratum corneum was the key problem which was numerically simulated with finite element method. At first the discretization of the stratum corneum region was given in two steps: first, the discretization of the keratin cell; second, the discretization of fattiness that surrounds the keratin. Then there was the work of numerical simulation. In this procedure, the finite element method and the multi-grid method were used. The former was to obtain the discretization of basic elements; the latter was to decrease the high frequency error. At last the visualization of the numerical simulation was shown.     

套管-水泥环-地层应力分布的理论解

利用弹性力学理论研究地应力场中套管-水泥环-地层系统应力分布的理论解，在求解过程中，将原问题分解为两个相对简单的子问题．考虑到套管井系统是层状结构的特点，且各层受力情况具有相似性，进一步地，基于两个弹性力学平面应变基本问题的解，采用结构力学的求解思想，由位移连续条件分别求得了两个子问题的解，最后由叠加原理得到了原问题的理论解．     

Numerical analysis for slugging of steam-water stratified two-phase flow in horizontal duct

Thermalhydraulic transient phenomena of a steam-water two-phase flow was calculated numerically in order to investigate the onset of slugging from a stratified flow in a horizontal duct. Conservation equations were solved by the finite difference method using a two-phase flow analyzer ‘MINCS’. The analysis was performed to investigate the initiation of slugging with and without phase change, or condensation. The present instability criteria for the onset of slugging with no condensation agreed well with that of the Mishima–Ishii relation while it was much lower than that defined by the Kelvin–Helmholtz instability criteria. However, as the temperature difference between phases increased, steam velocity became higher for the onset of slugging condition. The characteristics of flow reversal and water hammering which were the consequences of slugging with condensation, were investigated and described. It is expected that this modeling could be well applied to complicated thermalhydraulic phenomena accompanied by flow reversal and water hammering in power plants.     

Stability for basic system of equations of atmospheric rhotion

The topological characteristics for the basic system of equations of atmo- spheric motion were analyzed with the help of method provided by stratification theory.It was proved that in the local rectangular coordinate system the basic system of equations of atmospheric motion is stable in infinitely differentiable function class.In the sense of local solution,the necessary and sufficient conditions by which the typical problem for determining solution is well posed were also given.Such problems as something about“speculating future from past”in atmospheric dynamics and how to amend the condi- tions for determining solution as well as the choice of underlying surface when involving the practical application were further discussed.It is also pointed out that under the usual conditions,three motion equations and continuity equation in the basic system of equations determine entirely the property of this system of equations.     

Friction factor improved correlations for laminar and turbulent gas–liquid flow in horizontal pipelines

We develop improved correlations for two-phase flow friction factor that consider the effect of the relative velocity of the phases, based on a database that includes 2560 gas–liquid flow experiments in horizontal pipes. The database includes a wide range of operational conditions and fluid properties for two-phase friction factor correlations. We classify the experiments by liquid holdup ranges to obtain composite analytical expressions for two-phase friction factor vs. the Reynolds number by fitting logistic dose curves to the experimental data with. We compute the liquid holdup values used to classify the experimental data using correlations proposed previously. The Reynolds number is based on the mixture velocity and the liquid kinematic viscosity. The Fanning friction factor for gas–liquid is defined in term of the mixture velocity and density. Additionally, we sort the experimental data by flow regime and obtain the two-phase friction factor improved correlations for dispersed bubble, slug, stratified and annular flow for different holdup ranges. We report error estimates for the predicted vs. measured friction factor together with standard deviation for each correlation. The accuracy of the correlations developed in this study is compared with that of other 21 correlations and models widely available in the specialized literature. Since different authors use different definitions for friction factors and Reynolds numbers, we present comparisons of the predicted pressure drop for each and every data point in the database. In most cases our correlations predict the pressure drop with much greater accuracy than those presented by previous authors.