致密油藏液测应力敏感性计算模型

综合成藏地质学、岩石力学和渗流力学,建立准确可靠的致密油藏考虑边界层、临界喉道和孔喉分布的液测应力敏感性计算模型.由于大庆油田致密油藏孔喉分布范围比长庆油田更窄,导致大庆油田应力敏感性更强,因此大庆油田产能更低.本文从微观角度定量表征了真实油藏中应力敏感性的作用机理.     

分子层次的金纳米棒-表面活性剂-磷脂自组装复合体形貌

金纳米粒子表面修饰剂的组分和形貌影响其物理化学性质.本文采用隐式溶剂耗散粒子动力学模拟的方法,研究了金纳米棒、溴化十六烷基三甲基铵和二肉豆蔻酰磷脂酰胆碱的自组装形貌.结果表明,复合体组装形貌主要与溴化十六烷基三甲基铵和二肉豆蔻酰磷脂酰胆碱这两种修饰剂的摩尔比有关,而金纳米棒与修饰剂的相互作用强度以及金纳米棒的直径对形貌的影响不明显.当作用强度和直径一定时,随着摩尔比增加,修饰剂在金纳米棒表面会形成完整的双层膜、有裂痕的双层膜、长片状胶束、以及以螺旋形式缠绕在金纳米棒上的蠕虫状胶束.进一步分析发现,金纳米棒直径越小、摩尔比越大、或作用强度越大时,金纳米棒两端的覆盖程度越高,同时修饰剂吸附层的厚度越薄.这些结果直接表征了溴化十六烷基三甲基铵和二肉豆蔻酰磷脂酰胆碱混合物在金纳米棒表面的形态,在分子水平上加深了对金纳米棒自组装行为的理解,有助于实现金纳米棒的可控自组装.     

声波测井技术在非常规致密油藏储层评价中的应用

本文应用声波测井技术,针对松辽盆地齐家-古龙地区,非常规致密油储层有效性评价方法进行研究,即评价可能的裂缝发育段、可能的含油层段和可压裂改造的层段等。针对研究区非常规致密油藏特征及勘探实践,采用声波时差等效深度法建立超压层识别方法,通过计算岩石脆性指数建立岩石易压裂性评价技术。该技术较好的解决了非常规致密油藏储层有效性评价的关键问题,在老井压裂改造和新钻水平井、大斜度井测井评价中发挥雷要作用,见到很好的应用效果。     

微纳米加工技术在纳米物理与器件研究中的应用

物质在纳米尺度下可能呈现出与体材料不同的物理特件，这正是纳米科技发展的基础之一。要想探索在纳米尺度下材料物埋性质的变化规律及可能的应用领域，离不开相应的技术手段，微纳米加工技术作为当今高技术发展的重要技术领域之一，是实现功能人工纳米结构与器件微纳米化的基础。本文根据几个不同的应用领域，介绍了微纳米加工技术在纳米物理与器件研究领域的应用。     

微纳米加工技术在纳米物理与器件研究中的应用

物质在纳米尺度下可能呈现出与体材料不同的物理特性,这正是纳米科技发展的基础之一.要想探索在纳米尺度下材料物理性质的变化规律及可能的应用领域,离不开相应的技术手段.微纳米加工技术作为当今高技术发展的重要技术领域之一,是实现功能人工纳米结构与器件微纳米化的基础.本文根据几个不同的应用领域,介绍了微纳米加工技术在纳米物理与器件研究领域的应用.     

纳米粒子在亚浓高分子溶液中的扩散: 多粒子碰撞动力学

The diffusion of nanoparticles immersed in semidilute polymer solutions is investigated by a hybrid mesoscopic multiparticle collision dynamics method. Effects of polymer concentration and hydrodynamic interactions among polymer monomers are focused. Extensive simulations show that the dependence of diffusion coefficient D on the polymer concentration c agrees with Phillies equation D-exp (-αc^δ) with a scaling exponent δ≈0.97 which coincides with the experimental one in literature. For increasing nanoparticle size, the scaling prefactor α increases monotonically while the scaling exponent always keeps fixed. Moreover, we also study the diffusion of nanoparticle without hydrodynamic interactions and find that mobility of the nanoparticle slows down, and the scaling exponent is obviously different from the one in experiments, implying that hydrodynamic interactions play a crucial role in the diffusion of a nanoparticle in semidilute polymer solutions.     

星形两嵌段共聚高分子薄膜微相分离的耗散粒子动力学模拟

利用耗散粒子动力学模拟研究了两类典型的星形两嵌段共聚高分子薄膜的微相分离行为. 结果表明,(A_x)₄(B_y)₄体系的相图较(A_xB_y)₄体系具有明显的对称性,且前者比后者更易发生相分离,与体相中的情况相近,并可归因于两类星形高分子在结构上的差异;组成相同的星形共聚高分子体系在体相与薄膜中所形成的介观结构之间存在对应关系;减小薄膜厚度与加大A-B组分间排斥强度均有利于增强所形成结构的有序性. 同样是缘于分子结构差异,两类星形高分 子薄膜中的均方回旋半径随体系组分分率的变化规律几乎相反.     

微液滴动力学特性的耗散粒子动力学模拟

对传统的耗散粒子动力学方法进行了改进.改进的耗散粒子动力学方法采用了包含远程吸引力和近距排斥力的保守力势函数,从而使得用耗散粒子动力学方法模拟多相流动成为可能.应用改进的耗散粒子动力学方法,对微尺度下液滴的形成及液滴在微重力下的大幅度振荡变形进行了数值模拟.计算结果表明,改进的耗散粒子动力学(DPD)方法能够有效地描述微尺度下液滴的动力学特性,对研究复杂流体多相流动有着重要的意义. 关键词： 多相流 微液滴 耗散粒子动力学(DPD)方法 保守力势函数     

基于回音壁微腔拉曼激光的纳米粒子探测

回音壁模式光学微腔由于其品质因子高、模式体积小等优点, 近年来在非标记性的纳米粒子探测方面得到了广泛的重视, 开展了大量的研究, 取得了重要的进展. 利用回音壁微腔的拉曼激光, 通过测量纳米粒子造成的模式劈裂的拍频, 可以实现不同环境下纳米粒子的实时探测. 与传统的稀土离子掺杂法不同, 这种方法采用腔的内禀增益, 不仅提高了应用回音壁模式微腔进行纳米粒子探测的极限, 而且避免了传统方法中稀土离子能级对泵浦光的限制, 拓展了应用范围. 这种方法还可以应用于其他材料的回音壁微腔, 如硅基微环腔等, 以及光子晶体结构、超材料等受损耗限制的系统中. 本文简单介绍了回音壁模式光学微腔进行纳米粒子探测的基本原理以及最新研究进展.     

有结构壁面上液滴运动特征的耗散粒子动力学模拟

本文采用耗散粒子动力学方法, 研究了恒定外力驱动下液滴在有结构壁面上的运动过程. 通过研究液滴在通过壁面结构时前缘接触点和前进角的变化, 分析了液滴的运动特征. 研究结果表明, 在不同润湿性或不同外力驱动下, 存在使液滴运动最快的“最优”壁面结构, 并对其机理进行了讨论. 本文还探讨了壁面润湿性、热涨落以及外力对液滴运动状态的影响. 关键词： 微流体 有结构壁面 润湿性 耗散粒子动力学(DPD)     

Combined Flow Control Strategy Investigation for Corner Separation and Mid-Span Boundary Layer Separation in a High-Turning Compressor Cascade

To comprehensively control the corner separation and mid-span boundary layer (BL) separation, this study proposed and evaluated two new flow control configurations. One is a slotted configuration composed of blade-end and whole-span slots, and the other is a combined configuration with end-wall BL suction and whole-span slot. Additionally, the adaptability of the combined configuration to the lower blade solidity (c/t) condition was verified. The results indicate that both the slotted configuration and combined configuration can eliminate the mid-span BL separation, but a better reduction in the corner separation can be observed in the combined configuration. The two configurations can remove the concentrated shedding vortex and reduce the passage vortex (PV) for the datum cascade, but the wall vortex (WV) will be generated. By contrast, the combined configuration has weaker WV and PV than the slotted configuration, which contributes to further reducing the corner separation. In the combined configuration with a c/t of 1.66 and 1.36, the total pressure loss is reduced by 38.4% and 42.1%, respectively, on average, while the averaged static pressure rise coefficient is increased by 16.2% and 17.6%, respectively. This is advantageous for enhancing the working stability and pressure diffusion capacity for compressors. Besides this, the combined configuration with lower c/t can achieve a stronger pressure diffusion capacity and smaller loss than the higher c/t datum cascade. Therefore, the combined configuration is advantageous to the improvement of the aero-engine thrust-to-weight ratio through decreasing the compressor single-stage blade number.     

Kinetic theory of point vortices in two dimensions: analytical results and numerical simulations

We develop the kinetic theory of point vortices in two-dimensional hydrodynamics and illustrate the main results of the theory with numerical simulations. We first consider the evolution of the system “as a whole” and show that the evolution of the vorticity profile is due to resonances between different orbits of the point vortices. The evolution stops when the profile of angular velocity becomes monotonic even if the system has not reached the statistical equilibrium state (Boltzmann distribution). In that case, the system remains blocked in a quasi stationary state with a non standard distribution. We also study the relaxation of a test vortex in a steady bath of field vortices. The relaxation of the test vortex is described by a Fokker-Planck equation involving a diffusion term and a drift term. The diffusion coefficient, which is proportional to the density of field vortices and inversely proportional to the shear, usually decreases rapidly with the distance. The drift is proportional to the gradient of the density profile of the field vortices and is connected to the diffusion coefficient by a generalized Einstein relation. We study the evolution of the tail of the distribution function of the test vortex and show that it has a front structure. We also study how the temporal auto-correlation function of the position of the test vortex decreases with time and find that it usually exhibits an algebraic behavior with an exponent that we compute analytically. We mention analogies with other systems with long-range interactions.