水力空化改质对重质原油沥青质及性质的影响

利用水力空化过程产生局部的高温、高压、高射流以及强大的剪切力等极端化学物理条件改质处理沙特重质原油,试验结果表明：沙特重质原油经过水力空化改质后粘度由13.61降低至7.22mm2/s,残碳由7.16%降低至6.48%,实沸点蒸馏后减压渣油降低1个百分点。进一步采用APPI FT-IR MS、XRD、FT-IR、SEM和粒度分布等技术研究了水力空化改质对沙重原油分子组成,沥青质团聚体微晶结构、沥青质胶束粒径分布、沥青质官能团、沥青质形貌等方面的影响,从分子角度阐述空化改质重油的机理。研究结果表明：水力空化改质后沙重原油分子量分布、芳烃类化合物缔合作用变小;沥青质对低DBE化合物吸附性能降低;沥青质团聚体微晶结构更加松散;沥青质胶束粒度分布降低;沥青质分子相互团聚作用力减弱。进一步考察了水力空化改质前后减压渣油延迟焦化性能,改质处理后焦炭产率降低1.85个百分点,液体收率和气体产率分别增加1.52和0.33个百分点,水力空化改质对沥青质性质、结构特点的改善能够有效的提高其加工性能。     

一种定性评估同系列聚合物水动力学半径大小的方法

水动力学半径是衡量聚合物注入能力的重要参数.通过统计同系列的普通聚合物(部分水解聚丙烯酰胺)和疏水缔合聚合物的产品质量检测结果,并测量相应聚合物的水动力学半径,分析聚合物Huggins常数与性能参数关系,得到一种定性评估同系列聚合物水动力学半径大小的方法.Huggins常数变化与聚合物分子结构、官能团有关,一定条件下,...     

HYDRODYNAMIC FORCE ON SMOOTH HORIZONTAL CYLINDER IN UNIFORM OSCILLATORY FLOW

ＨＹＤＲＯＤＹＮＡＭＩＣ　ＦＯＲＣＥ　ＯＮ　ＳＭＯＯＴＨ　ＨＯＲＩＺＯＮＴＡＬ　ＣＹＬＩＮＤＥＲ　ＩＮ　ＵＮＩＦＯＲＭ　ＯＳＣＩＬＬＡＴＯＲＹ　ＦＬＯＷＨＹＤＲＯＤＹＮＡＭＩＣＦＯＲＣＥＯＮＳＭＯＯＴＨＨＯＲＩＺＯＮＴＡＬＣＹＬＩＮＤＥＲＩＮＵＮＩＦ...     

不同雷诺数下水平桩柱的水动力待征

本文介绍了均匀振荡流中光滑水平桩柱上水动力特征的试验研究.试验中,雷诺数Re=20000～260000(该区域为亚临界区与临界区),Kc=5～40.分析中,利用最小二乘法来确定Morison方程中的速度力系数C_(?)及惯性力系数C_M;还利用最大值法及均方根值法对合力系数C_F与升力系数C_L进行分析,所有的正向力与升力系数都作为Re及Kc数的函数给出,并且各系数相对于其平均值的均方差值也在图中示出.其主要研究成果如下:当Re≥80000时,所有的水动力系数(包括C_D、C_M,C_F与C_L),几乎与雷诺数Re无关,且各系数均随Kc数的逐渐增加而趋向于不同的常数;当Re<80000时,速度力系数C_D随Re数的增大而减小,而惯性力系数C_M随Re数的增大而增大.     

文丘里管中空化流场的数值模拟

基于FLUENT软件,采用标准k-ε模型和空化泡动力学模型,对三种不同几何形状的文丘里管内空化流场进行数值模拟,计算了文丘里管内空化区的空化数、压力分布和汽含率分布,研究了操作条件、文丘里管的结构形式对空化效果的影响。结果表明,理论计算的空化区汽含率分布与实验拍摄的空化云雾区图像有较好的吻合性;水力空化装置的操作条件,以及文丘里管的结构形式对空化效果有着明显的影响。     

A hydrodynamic lubrication model for the deep-drawing process

A steady hydrodynamic lubrication model that includes the pressure viscosity factor has been developed for the deep-drawing process. Equations for lubricant film thickness, radial and drawing stresses are presented. Analysis reveals that the pressure viscosity factor has a significant influence on estimating lubricant film thickness and radial and drawing stresses.     

考虑弹性变形的不同综合曲率下的滑动副油膜计算

本文介绍了考虑滑动副中较软元件弹性变形及贫油状态的滑动副承载能力计算,其中变形计算采用了半无限体法,并参照联邦德国Bernd Schaude著作采用了简化的处理方法,大大简化了计算过程,且便于利用油压分布计算中的差分格式。为了保证计算精度,减少计算时间,采用了合理划分网格,合理选定计算顺序和设法加速收敛等措施。     

Developments in engine bearing design

Some of the important recent developments in engine bearing design techniques are highlighted. The availability of increased computing power has enabled more realistic assumptions about bearing conditions to be considered; these include oil feed features, oil film history, non-circular bearings, inertia effects due to journal centre movement, improved prediction of main bearing loads, flexible housings and special bearings. References to these advances are made, together with illustrations of how they affect predicted bearing performance. Experimental evidence is also being obtained, which helps to verify and give confidence in the analytical predictions     

Quasielastic scattering from dilute polymer solutions

The initial slope $\text{Ω(q)}$ of the time-dependent scattering function and the static structure factor S(q) of macromolecules in good solvents are calculated without using the Gaussian assumption. For S(q), the scaling relation S(q)～q^?1.7 is confirmed in the intermediate q range, whereas no q dependent cross-over behaviour can be observed. The calculation of $\text{Ω(q)}$ reveals a q³ dependence in this range and no evidence is seen for an exponent apart from 3. The time-dependent scattering function S(q,t) is treated within the framework of the Gaussian assumption. Hydrodynamic as well as excluded volume interactions are incorporated. It has been found that excluded volume effects decrease the decay of the scattering function in comparison with the Gaussian chain.     

IMPROVED HYDRODYNAMIC MODEL OF TWO-PHASE SLUG FLOW IN VERTICAL TUBES

Merits of the Fernandes model(Fernandes et al.1983)for two-phase slug flow in verticaltubes are reviewed in this paper.While predicting many macroscopic parameters of slug flow in verti-cal tubes,it fails to present correctly the trend that the average voidage in liquid slugs increases asthe rising velocity of Taylor bubbles is increased.It is also desirable to extend its application toelectrolyte systems, and to churn flow conditions.Based on the diagnostic analysis,the model equa-tion for gas entrainment by falling liquid film is reformulated and the influence of surface tension isalso accounted for.Development of the falling liquid film is recognized in the revised model in or-der to suit the case of short Taylor bubbles as well.The modified model predicts the variation of av-erage voidage in liquid slugs in good agreement with available experimental data.