Homogenization of hardness distribution and distortion in high pressure gas quenching

Quenching with gases rather than oil or other liquid media has the advantages of reducing the risks concerning health and environment, while simultaneously homogenizing the quenching results and minimizing distortion due to a wide range of possible process parameter variations and the pure convective heat transfer. In this contribution, a coupled solution for increasing homogenization of quenching results within high pressure gas quenching will be presented. In the first stage, an experimental test facility was set up for flow investigations and in the second stage a numerical simulation model was generated. The numerical and experimental results of the flow through the chamber were compared for several boundary conditions. Finally, after complete verification of the simulation, the model may be used to assist in parameter variation for optimization of homogeneous high pressure gas quenching.     

缝洞型碳酸盐岩油藏流动单元概念和研究方法探讨

流动单元对于提高油田采收率具有很大的实际意义,该项研究在砂岩油藏研究中已取得较大进展。对于缝洞型碳酸盐岩油藏,由于岩石结构构造、成岩后生作用、构造断裂作用、溶蚀作用等多因素对储集空间的影响,已有的流动单元概念及研究技术方法难于应用。以塔河油田为例,针对缝洞型碳酸盐岩地质特征,论证了碳酸盐岩储层渗流屏障的存在及其类型,探索性提出区别于砂岩油藏的缝洞型碳酸盐岩储层流动单元的概念。提出的研究思路和方法包括;油藏压力趋势分析法、井间生产干扰分析法、流体性质差异分析法、井间干扰试井法。结合储层发育特征,初步建立了缝洞型碳酸盐岩流动单元的划分标准。     

Cellular automata model of gravity-driven granular flows

A cellular automata model is used to simulate a variety of granular chute flows. The model is tested against several case studies: flow down a chute, flow past an obstacle, chute flow in which complex, counter-rotating vortices result in streamwise surface stripes and flow near a boundary. The model successfully reproduces experimental observations in all of these cases. These results lead us to propose that simple, rule-based, models such as this can improve our detailed understanding of dynamics and flow within an opaque granular bed.     

EXPERIMENTAL RESEARCH ON EFFECT OF MAIN-FLOW SWING ON FLOW TURBULENCE STRUCTURE

It is mentioned in this paper that the adjustment of flow structure occurs when themain-flow swings.The changes of turbulence structure and flow energy loss in the indoor rivermodel are measured.The experimental data are presented for the first time for the further studyof complicated river flow structure.     

Flow stress of high density polyethylene and nylon 66 at high rates of strain

Measurement of the flow stress of high density polyethylene (HDPE) and nylon 66 at strain rates of 10³ s^?1 using a split Hopkinson pressure bar technique is discussed. The flow stress at a strain of 10% has been determined for both polymers at 20°C. The intrinsic errors involved in this technique are briefly reviewed. The results indicate that the flow stress of HDPE and nylon 66 were 50MPa and 150MPa, respectively, at strain rates of about 10³s^?1.     

Adhesive Dispensing Process Analysis: Steady-State Dispensing of One-Component Adhesives

The process of dispensing one-component heat-cure adhesives was investigated in order to understand current application processes and to guide new process development. Typical one-component adhesives exhibit non-Newtonian rheological behavior, and hence Newtonian fluid mechanics does not adequately describe the dispensing process. In the present study, the adhesives were modeled as Bingham fluids possessing a yield stress and a steady state viscosity. The model of the dispensing apparatus includes four major flow sections connected in a serial configuration. The fluid mechanics equations derived for Bingham fluids in the individual flow sections were solved by numerical methods in order to understand the interrelationships between the material variables (e.g. yield stress, viscosity, temperature dependencies) and process variables (e.g. pressure, flow geometry, temperature, output). The concept of the model is generic and the details of the model can be modified for any forced-flow adhesive application process.

The adhesive flow properties significantly influence the process output. Dispensing temperature, among the process variables, has the strongest effect on process output. A ± 1.0·C perturbation in the dispensing temperature can cause as much as a 14% variation in the bead size for the range of adhesives studied. Differences in flow characteristics result in differences in processability and non-linear temperature/pressure sensitivity. The non-linear sensitivity can be eliminated by operating the dispensing process isothermally. Finally, the process limits for one-component adhesives, which are susceptible to chemical instability induced by viscous heating during processing, are defined and discussed in terms of a modified Brinkman number that takes into account viscous dissipation, heat conduction and convection, and chemical stability of the material during processing.     

垂直井两相流动生产测井解释滑动模型

在两相流动模拟实验数据分析的基础上 ,提出油水两相和气液两相流动的滑脱速度的实验关系 ,进而确定垂直井两相流动生产测井解释的滑动模型。现场实际测井资料处理结果表明该模型有很好的应用效果     

Hydrodynamic force between two hard spheres tangentially translating in a power-law fluid

The hydrodynamic interaction between two hard spheres tangentially translating in a power-law fluid is investigated. By considering the gap between the two spheres being sufficiently small such that the Reynolds’ lubrication theory applies, an analytical equation to the pressure in the gap is obtained using truncated Fourier series. To a good approximation, the pressure equation can be further simplified. The simplified approximate equation over-predicts the pressure for shear thickening fluid (n>1) but under-predicts the pressure for shear-thinning fluid (n<1). However, the errors in the predicted tangential force and moment are relatively small. In particular, for a Newtonian fluid, the accurate solution and the simplified approximate solution degenerate to the asymptotic solution of Goldman et al. [1967. Slow viscous motion of a sphere parallel to a plane wall-motion through a quiescent fluid. Chemical Engineering Science 22, 637-651.] and O’Neill and Stewartson [1967. On the slow motion of a sphere parallel to a nearby plane wall. Journal of Fluid Mechanics 27, 705-724.]. Both solutions predict that for shear thickening fluid (n>1), the hydrodynamic force converged in the inner region of the gap between the two spheres and the contribution from the outer region is sufficiently small. For shear thinning fluid (n<1), the contribution from the outer region is also significant.     

A novel direct aerodynamically assisted threading methodology for generating biologically viable microthreads encapsulating living primary cells

In a recent discovery, coaxial electrospinning was explored to encapsulate living organisms within a continuous bio‐polymeric microthread from which active biological scaffolds were fabricated (Townsend‐Nicholson and Jayasinghe, Biomacromolecules 2006, 7, 3364). The cells were demonstrated to have gone through all expected cellular activity without their viability being compromised. These biologically active threads and scaffolds have direct and tremendous applicability from regenerative to therapeutic medicine. Currently these post‐processed cells as composite threads and scaffolds are being investigated in‐depth at a cellular level to establish if the processing methodology has any affect on the cellular make‐up. We now demonstrate a competing non‐electric field driven approach for fabricating composite threads and scaffolds influenced only by a differential pressure. We refer to this novel composite thread to scaffold fabrication methodology as coaxial aerodynamically assisted bio‐threading (CAABT). Our investigations firstly, demonstrate that this technique can process handle living organisms without biologically perturbing them in anyway. Secondly the process is elucidated as possessing the ability to form composite active threads from which biologically viable scaffolds are formed. Finally our study employs florescent activated cell sorting (FACScan), a method by which the cellular dynamics and viability are quantified on control and threaded cellular samples at two prescribed time points. In parallel with FACScan, optical comparison of cellular morphology at three time points within a period of three weeks is carried out to photographically observe any changes in the post‐processed cellular phenotype. Our developmental investigations into this novel aerodynamically assisted threading methodology has unearthed a unique biomicrofabrication approach, which joins cell electrospinning in the cell threading to scaffold fabrication endeavor. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008