双柱单锥型液-液旋流管内流场的激光诊断

应用激光测速仪，对一种双柱单锥型液 液旋流管内的流动结构，进行了全场范围内的多工况流动诊断研究．揭示出其切向速度由内旋流区和外旋流区构成，其中内旋流区中的速度分布符合准强制涡关系，外旋流区中的速度分布符合准自由涡关系；轴向速度由上行流动区和下行流动区构成，两者之间在直管段以零速点作分界，在锥体段则以零速区作过渡并伴随有一定的回流出现，且该过渡区或回流区的大小随锥体截面的收缩而减小，直到进入直管段后消失；各湍流量的分布以管芯处最大向外逐渐减小，沿轴向是直管段中的湍流度大于锥体段中的湍流度，而且湍流度在旋流管内具有各向异性的特性．     

Flow patterns and heat transfer in vertical upward air–water flow with surfactant

Flow patterns, the pressure drag reduction and the heat transfer in a vertical upward air–water flow with the surfactant having negligible environmental impact were studied experimentally in a tube of 2.5 cm in diameter. Visual observations showed that gas bubbles in the air–water solution with surfactant are smaller in size but much larger in number than in pure air–water mixture, at the all flow regimes. The transition lines in the flow regime map for the solution of air–water mixture with surfactant of the 300 ppm concentration are mainly consistent with the experimental data obtained in clear air–water mixture. An additive of surfactant to two-phase flow reduces the total pressure drop and decrease heat transfer, especially in the churn flow regime.     

岩体中非填实爆炸空腔壁振动状态分析

采用流体动力学模型研究了地下空腔中化学爆炸冲击波的传播过程及空腔壁的运动状态。计算中体现了空气冲击波与空腔壁作用后激发的强谱振幅高频冲击波。在实验中 ,解决了空腔内传感器的防护和抗干扰等技术难题 ,测到了空腔壁的地运动加速度波形。通过对所测波形的时频域分析得出了非填实爆炸在源区和近区激发高频应力波 ,其频率明显高于填实爆炸的频率。这些特征与数值计算相一致。最后简略讨论了数值计算与实验测量中需解决的问题。     

跳马项目的三维实时动态测量系统

为跳马项目研究的电测系统中引入数字信号处理的传递函数及频谱分析的方法,采集和处理了因人体冲击三维力对信号的耦合干扰造成的十分复杂的响应信号,具有较高的动态测试精度.可以获得跳马动作的全部运动生物力学参数.现已用于中国国家体操队进行计算机辅助训炼.     

盐岩储库区地面沉降预测与控制研究现状与展望

利用盐岩地层建设地下油气储库群已成为各国发展能源储备的重要方向,然而关于储库区地面沉降的研究至今仍处于探索阶段。由于地面沉降所造成的重大事故屡见不鲜,因此有必要集中力量研究盐岩库区地面沉降问题,为我国盐岩储库群的建设提供可靠的理论依据。本文主要从以下3个方面总结了近几十年来国内外学者在盐岩储库区地面沉降预测方面所做出的努力与成绩： （1）现场监测——法国、德国、美国先后建立了现场监测网络,获得了大量的长期监测数据;  （2）理论计算——我国学者于20世纪90年代末将随机介质理论引入到盐矿水溶开采地面沉降预测中,从而为储库区地面沉降预测提供了新的理论基础;  （3）数值模拟——欧洲学者利用FLAC2D 程序对盐岩储库区的地面稳定性进行了数值模拟,而我国学者则利用在新概率积分法的基础上建立起的预测模型成功进行了沉降预测模拟。此外,为了有效地控制库区地面变形,预留矿柱式水溶开采法在国外众多盐岩地下储库群建设中得以广泛应用。本文最后提出在后续研究中将重点着眼于地表变形随时间的发展过程,并对现有理论模型进行适当的修正以及利用现场实测数据进一步完善预测所需参数的选取方法,从而使预测结果更为准确可靠。     

Acoustics of a Bubbly Liquid with a Weak Chemical Reaction in the Gaseous Phase

The influence of the composition and thermophysical properties of gas-liquid bubbly systems with a dissociating component in the gaseous phase on the laws of small-disturbance propagation and attenuation is investigated. It is found that the reacting gas component in the bubbles significantly affects the sonic-wave attenuation coefficient in the bubbly liquid. This follows from the fact that when a gas bubble is compressed isothermally, a recombination reaction occurs which prevents pressure growth in the bubble.Small-disturbance propagation in bubbly liquids was investigated in a number of publications discussed in review [1]. The acoustics of a bubbly liquid with a gas phase containing active admixtures are of both methodical and practical interest. The dynamics of such multicomponent bubbles were investigated in [2].     

On the spatial localization of the laminar boundary layer in a non-Newtonian dilatant fluid

In dilatant fluids the shear perturbation propagation rate is finite, in contrast to Newtonian and pseudoplastic fluids in which it is infinite [1]. Therefore, in certain dilatant fluid flows, frontal surfaces separating regions with zero and nonzero shear perturbations may be formed. Since, in a sense, the boundary layer is a “time scan” of the nonstationary shear perturbation propagation process, in dilatant fluids the boundary layer should definitely be spatially localized. This was first mentioned in [2] where, however, it was mistakenly asserted that boundary layer spatial localization does not take place in all dilatant fluids and is absent in so-called “hardening” dilatant fluids. In [3], the solutions of the laminar boundary-layer equations for speudoplastic and “hardening” dilatant fluids were investigated qualitatively. The formation of frontal surfaces in dilatant fluid flows is usually mathematically related with the existence of singular solutions of the corresponding differential equations [4]. However, since the analysis performed in [3] was inaccurate, in that study singular solutions were not found and it was incorrectly concluded that in “hardening” dilatant fluids there is no spatial boundary layer localization. The investigation performed in [5] showed that in fact in “hardening” dilatant fluids boundary layers are spatially localized, since there exist singular solutions of the corresponding differential equations. Subsequently, this result was reproduced in [6], where an attempt was also made to carry out a qualitative investigation of the solutions of the laminar boundary-layer equations for other types of dilatant fluids. The author did not find singular solutions in this case and mistakenly concluded that in these fluids there is no spatial boundary layer localization. This misunderstanding was due to the fact that in [6] it was not understood that in dilatant fluid flows the formation of frontal surfaces can be mathematically described not only in relation to the existence of singular solutions.     

黄土构造节理研究及其应用

作者发现大量不同力学性质的黄土构造节理后，识别了它们的区域性、系统性特征；认定其两组扭裂面代表新构造应力场最大剪切应力方向，利用黄土构造节理系及由其控制的土层沟槽网络恢复了相应地区Q3-4构造应力场；提出构造节理是黄土区地下水运移的主要通道和赋存的场所；发现构造节理是黄土区地裂缝、滑坡、崩塌和水土流失等地质灾害的构造基础之一，证实构造节理是黄土地层的软弱面，风化和继之而来的应力侵蚀就由此开始，进而逐步塑造黄土碟、穴、井、桥、柱、墙、沟等潜蚀地貌和部分侵蚀地貌。研究黄土构造节理对恢复新构造应力场、帮助预测地裂乃至地震活动、控制水土流失和滑塌灾害、进行工程乃至区域稳定性评价、重新认识黄土潜蚀地貌发育规律、指导干旱半干旱黄土区找水，既有理论意义又有实际意义。     

环形腔内双层薄液层热毛细对毛细对流的渐近解

为了解水平温度梯度作用下环形腔内双层薄液层热毛细对流的基本特性,采用渐近线方法 获得了热毛细对流的近似解. 环形腔外壁被加热,内壁被冷却,上、下壁面绝热. 结果表明, 当环形腔宽度与内半径比趋于零时,环形腔退化为矩形腔,所得到的主流区速度场和温度场 的表达式演化为Nepomnyashchy 等得到的矩形腔内的结果;与数值模拟结果的比较 发现,在主流区渐近解与数值解吻合较好.     

High-Velocity Laminar and Turbulent Flow in Porous Media

We model high-velocity flow in porous media with the multiple scale homogenization technique and basic fluid mechanics. Momentum and mechanical energy theorems are derived. In idealized porous media inviscid irrotational flow in the pores and wall boundary layers give a pressure loss with a power of 3/2 in average velocity. This model has support from flow in simple model media. In complex media the flow separates from the solid surface. Pressure loss effects of flow separation, wall and free shear layers, pressure drag, flow tube velocity and developing flow are discussed by using phenomenological arguments. We propose that the square pressure loss in the laminar Forchheimer equation is caused by development of strong localized dissipation zones around flow separation, that is, in the viscous boundary layer in triple decks. For turbulent flow, the resulting pressure loss due to average dissipation is a power 2 term in velocity.     

微重力气液两相流动与池沸腾传热

综述了近年来中国科学院微重力重点实验室(国家微重力实验室)完成的一系列微重力气液两相流动与池沸腾传热方面的地基实验、飞行实验和理论研究等方面获得的主要成果.在微重力气液两相流动方面,提出了半理论Weber数模型用于预测微重力条件下气液两相弹-环状流转换,并采用Monte Carlo方法,针对气泡初始尺寸对泡-弹状流转换的影响进行数值研究.通过俄罗斯"和平号"空间站与IL-76失重飞机实验,获得了微重力下的气液两相流型图,与此同时在地面利用小尺度毛细管模型模拟了微重力气液两相流动特征.实验测量了微重力气液两相流压降,并基于微重力流动特性建立了一个泡状流压降关联模型.在微重力池沸腾传热方面,利用我国返回式卫星完成了两次空间实验,其中,第22颗返回式卫星搭载铂丝表面R113池沸腾实验采用控制温度的稳态加热方式,而实践8号育种卫星搭载平面FC-72池沸腾实验则采用控制加热电压的准稳态加热方式.同时,还进行了地面常重力和落塔短时微重力条件下的对比实验研究.观察到丝状加热表面微重力时轻微的传热强化现象,而平板加热表面微重力核态池沸腾低热流时传热强化、高热流时传热恶化.微重力实验中观察到气泡脱落前存在横向运动现象,据此分析了气泡行为与传热之间关系,并提出了一个预测丝状加热表面气泡脱落直径的半理论模型.旨在对相关领域的进一步发展和空间两相流系统的应用提供数据及理论支持.     

Galerkin finite element simulation of convection driven by rotation and gravitation

The performance of the Galerkin finite element method when applied to time-dependent convection involving rotation, self-gravitation and the normal gravity field in a horizontal cylinder is discussed in this paper. The governing equations, the parameters of the problem and our implementation of the numerical schemes are presented. The accuracy, spatial scale of resolution, flexibility and robustness of the resulting code show the element method as a valuable tool for research in this area or in related problems in astrophysical fluid dynamics. The numerical difficulties in large-amplitude flows are associated with an error-control scheme for time integration and the ‘short-time’ wiggles in transient Dirichlet problems. Coarse grids give the correct qualitative picture in most simulations, but the type of solution at short time (and hence grid refinement) presumably resolves the degeneracy in the azimuthal orientation of convection cells in flows driven by self-gravitation and (perhaps) centrifugal buoyancy. The final state in transient flows is a motionless isothermal fluid. However, residual motions can be nullified only in the limit of zero grid size in flows driven by centrifugal buoyancy (self-gravitation), while a fairly coarse grid is sufficient for this purpose in normal gravity-driven flows.     

半晶态聚合物拉伸变形的微观机理

应用大规模分子动力学方法,采用粗粒化聚乙烯醇模型,模拟了晶区与非晶区随机交杂的半晶态聚合物模型系统,研究了半晶态聚合物在单轴拉伸变形过程中的应力-应变行为和微观结构演变.应力-应变曲线表现出4个典型变形阶段:弹性变形、屈服、应变软化和应变强化.在拉伸变形过程中,主要存在晶区折叠链之间的滑移、晶区破坏、非晶区的解缠结,以及分子链沿拉伸方向重新取向等4种主要的微结构演变形式.在屈服点附近,晶区分子链之间排列紧密程度减小而发生滑移,之后晶区变化需要的应力变小,从而形成应变软化现象.随着应变的增大,经各分子链段协同作用使非晶区分子链的解缠结和重新取向行为扩展到相对宏观尺度,导致拉伸应力增大而形成应变强化现象.      

黑龙江省矿区生态破坏与地质灾害及其防治

黑龙江省矿产分布情况和开发概况以及矿业开发在经济发展中占有重要地位 ;在矿业开发过程中引起的诸多生态破坏和地质灾害及其引起的危害 ,已引起高度重视 ;本文在综合论述黑龙江省矿区发展所带来各项利弊后提出了具体的防治对策。     

同轴双方柱气动力载荷的相互干扰

本文研究了在大气边界层气流中同轴双方柱气动力载荷的相互干扰,讨论了这种干扰与风向角和间距比之间的关系.结果表明处于相邻方柱的干扰下,上游方柱的最大气动力载荷大于单体的载荷;而下游方柱则受到前柱明显的阻挡作用,不仅如此,当风向角为0°,小间距下的后柱,不但没有阻力,还会受到反向的摧力.还发现在串列情况下存在和双圆柱类似的临界间距,阻力和升力在临界间距附近有明显的突变.同时将本实验的结果和一些文献中的结果进行了比较.     

有效集法在数学规划加权残值法中的应用

本文研究有效集法在数学规划加权残值法求解微分方程问题中的应用。从理论上和实际应用方面 阐明，对于数学规划加权残值法和线性规划问题，有效集法比常用的单纯形法更简便、易程序化、计算速度更快，因此更适用于数学规划加权残值法求解微分方程问题。     

Characterization of Microvascular-Based Self-healing Coatings

A protocol is described to assess self-healing of crack damage in a polymer coating deposited on a substrate containing a microvascular network. The bio-inspired coating/substrate design delivers healing agent to cracks in the coating via a three-dimensional microvascular network embedded in the substrate. Through capillary action, monomer flows from the network channels into the crack plane where it is polymerized by a catalyst embedded in the coating. The healing efficiency of this materials system is assessed by the recovery of coating fracture toughness in a four-point beam bending experiment. Healing results for the microvascular networks are compared to data for a coating containing microencapsulated healing agents. A single crack in a brittle epoxy coating is healed as many as seven times in the microvascular systems, whereas microcapsule-based healing occurs for only one cycle. The ability to heal continuously with the microvascular networks is limited by the availability of catalyst in the coating.     

化学跑合对齿轮胶合的影响

选用了３ 种跑合剂在ＣＬ－１００ 型齿轮试验机上进行满载跑合能力对比试验和齿轮抗胶合载荷级对比试验．结果表明：材质为４５＃ 钢的试验齿轮副和材质为２０ＣｒＭｎＴｉ钢的试验齿轮副用含磨料跑合剂进行１ 次满载跑合试验时,发生严重胶合;而采用化学跑合剂可以实现１ 次满载跑合,且用化学跑合剂跑合后的齿面比用普通油跑合后的齿面抗胶合能力提高１ 个载荷级,显示化学跑合剂在齿轮中的应用很有潜力．     

On Cavitation, Configurational Forces and Implications for Fracture in a Nonlinearly Elastic Material

Experiments on polymers indicate that large tensile stress can induce cavitation, that is, the appearance of voids that were not previously evident in the material. This phenomenon can be viewed as either the growth of pre-existing infinitesimal holes in the material or, alternatively, as the spontaneous creation of new holes in an initially perfect body. In this paper our approach is to adopt both views concurrently within the framework of the variational theory of nonlinear elasticity. We model an elastomer on a macroscale as a void-free material and, on a microscale, as a material containing certain defects that are the only points at which hole formation can occur. Mathematically, this is accomplished by the use of deformations whose point singularities are constrained. One consequence of this viewpoint is that cavitation may then take place at a point that is not energetically optimal. We show that this disparity will generate configurational forces, a type of force identified previously in dislocations in crystals, in phase transitions in solids, in solidification, and in fracture mechanics. As an application of this approach we study the energetically optimal point for a solitary hole to form in a homogeneous and isotropic elastic ball subject to radial boundary displacements. We show, in particular, that the center of the ball is the unique optimal point. Finally, we speculate that the configurational force generated by cavitation at a non-optimal material point may be sufficient to result in the onset of fracture. The analysis utilizes the energy-momentum tensor, the asymptotics of an equilibrium solution with an isolated singularity, and the linear theory of elasticity at the stressed configuration that the body occupies immediately prior to cavitation. This revised version was published online in June 2006 with corrections to the Cover Date.     

The axisymmetric Rayleigh waves in a semi-infinite elastic solid

It is well-known that Rayleigh wave, also known as surface acoustic wave(SAW), solutions in semiinfinite solids are plane waves with signatory properties like the distinct velocity and exponentially decaying deformation in the depth. Applications of Rayleigh waves are focused on the deformation and energy in the vicinity of surface of solids and less loss in the propagation. A generalized model of Rayleigh waves in axisymmetric mode is established and solutions are obtained with cylindrical coordinates. It is found that the Rayleigh waves also propagate in the axisymmetric mode with slow decay in radius, confirming the existence of surface acoustic waves is irrelevant to coordinate system. On the other hand, the solutions can be treated as plane waves in regions far away from the source. Furthermore, the particle trajectory of axisymmetric SAW is a line with constant slope rather than the signatory ellipse in Cartesian coordinate case.