Three dimensional free convection couette flow with transpiration cooling

INTRODUCTION In recent years, the subject of free convection flow has attracted the attention of a number of scholars because of its possible applications to several geophysical problems. In view of these applications, a series of investigations were made to study the flow past a vertical wall. Transpiration cooling can very effectively pro-tect certain structural elements in turbojet and rocket engines, like combustion chamber walls, exhaust nozzles or gas turbine blades from hot gases. …     

Experimental investigation on mixing enhancement mechanism of turbulent jet flow with tabbed nozzle

Flow visualization and hot-wire measurement techniques were combined to investigate the influence of the size and number of tabs on jet flow field and vortex structure generation mechanism. Streamwise vortices generated by the tabs of different sizes and numbers were ob- served from the flow visualization images. Combined with flow visualization, hot-wire measurement gave a quantitative insight of the effect of various tabbed jet flows. Instantaneous two-component velocity signals （longitudinal and transverse velocity components） at different cross sections along radius direction and streamwise direction with different tabbed jet nozzles were measured using hot-wire anemometer. Average flow field parameters of tabbed jet flow such as mean velocity, turbulence intensity, vorticity were analyzed and the effects of tabs with different sizes and numbers were compared with that of circular no-tab jet flow. It is revealed that the generation of a series of counter-rotating quasi-streamwise vortices, azimuthal vortices and double-row azi-muthal vortex are the reasons for mixing enhancement of tabbed turbulent jet flow.     

150吨复吹转炉底部供气模拟研究

通过水模型实验,研究了复吹转炉底部供气流量、喷嘴数目及分布对熔池均混时间的影响.通过正交设计试验,测定了不同底气流量、喷嘴数目及不同的位置条件下的均混时间,根据水模试验优化的结果为本钢150吨复吹转炉底部供气元件的布置提供了依据.     

同向双螺杆端面内混合模拟

建立了同向自洁双螺杆端面内二维周期性流动的物理模型及数学模型。借助商用有限元软件POLYFLOW叠加网格技术求解得到速度场,基于具有4阶精度的RungeKutta数值积分方法自行开发了流体前锋追踪代码,并对对混合过程动力学进行了数值模拟表征。采用粒子群可视化模拟、Poincaré截面分析、界面演化及界面增长等探讨了混合过程动力学细节,揭示混沌混合作用的尺度。结果表明,传统的同向双螺杆端面内混沌混合与常规的层流混合共存,不同区域的混合效果相差很大。螺槽中部存在8字型准周期运动带,带内混合为常规的层流混合。     

GIS技术在新农村规划中的应用

从GIS的产生、含义、功能等方面出发,分析和探讨了GIS技术在新农村规划中的应用前景,以及对新农村规划在设计理念、技术方法、规划的实施与管理等方面所带来的影响.     

Three-dimensional transient numerical simulation for intake process in the engine intake port-valve-cylinder system

This paper presents a KIVA-3 code based numerical model for three-dimensional transient intake flow in the intake port-valve-cylinder system of internal combustion engine using body-fitted technique, which can be used in numerical study on internal combustion engine with vertical and inclined valves, and has higher calculation precision. A numerical simulation (on the intake process of a two-valve engine with a semi-sphere combustion chamber and a radial intake port) is provided for analysis of the velocity field and pressure field of different plane at different crank angles. The results revealed the formation of the tumble motion, the evolution of flow field parameters and the variation of tumble ratios as important information for the design of engine intake system.     

Design science research – a powerful tool for improving methods in engineering education research

ABSTRACT

Modelling is a central activity in practical engineering and something that is also useful in engineering education research (EER). Additionally, qualitative research methods have found important applications in engineering research, although their use in EER has not always been widely accepted. Design science research is a qualitative research approach in which the object of study is the design process, i.e. it simultaneously generates knowledge about the method used to design an artefact and the design or the artefact itself. This paper uses techniques from design science research to analyse the method used when deriving the ‘learning of a complex concept’ (LCC) model, which we developed while designing teaching sequences for a course on electrical engineering. Our results demonstrate the value of design science research in EER and suggest that the LCC model is generally applicable in this field.     

加磁场退火对铁基薄膜巨磁阻抗效应的影响

用射频溅射法制备了(Fe88zr7B5)0.97CU0.03软磁合金薄膜,研究了不同磁场退火方式对(Fe88Zr7B5)0.97 Cu0.03薄膜软磁性能和巨磁阻抗(GMI)效应的影响。结果表明,纵向和横向磁场退火方式都能有效地提高薄膜样品的巨磁阻抗效应,在13 MHz频率下纵向最大GMI比分别为18％和17％;纵向磁场退火能有效消除薄膜样品的磁各向异性,优化薄膜样品的软磁性能;横向磁场退火则能有效感应横向磁各向异性并提高巨磁阻抗效应的磁场响应灵敏度。     

Three-dimensional transient numerical simulation for intake process in the engine intake port-valve-cylinder system

INTRODUCTIONTheinternalcombustionengineisthemostwidelyusedpowermachineryinmodernsociety ,butisalsooneofthebiggestenvironmentalpol lutantsources.Tomeetmoreandmorestringentemissionrequirements,manyadvancedtech niques,suchastheleanburntechnique ,multi valvet…     

3D couette flow of dusty fluid with transpiration cooling

INTRODUCTION Transpiration cooling is a very effective process to protect certain structural elements like combustion chamber walls, exhaust nozzles, or gas turbine blades in turbojet and rocket engines, from the influence of hot gases. In view of this, Eckert (1958) obtained an exact solution of the plane couette flow with transpi-ration cooling. The problem remained 2D due to the uniform injection and suction applied at the porous plates. Flow and heat transfer along a plane wall with…     

硬质PVC干混料注塑成型要点分析

对影响硬质PVC干混料注塑成型产品质量的主要因素：硬质PVC干混料的配方、注塑机的选择、注塑产品的结构设计、模具设计以及注塑工艺等多方面进行了比较祥细地分析，总结了使用PVC干混料注塑产品时可能出现的产品缺陷及问题，结合实际给出了一般使用条件下PVC产品的干混料注塑成型的配方方法和注塑加工工艺参数。     

Mode transition process in a typical strut-based scramjet combustor based on a parametric study

The combustion performance of hydrogen fuel in a scramjet combustor has been a popular focus for scholars all over the world. In this study, the influence of the jet-to-crossflow pressure ratio on combustion performance in a scramjet combustor was investigated numerically, and the influence of a wall-mounted cavity was evaluated. The simulations were conducted using the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the renormalization group (RNG) k-ε turbulence model and the single-step chemical reaction mechanism. This numerical approach was validated by comparing predicted results with published experimental shadowgraphs and velocity and temperature measurements. When the pressure of the wall-injector increases, the performance of the combustor decreases. At the same inflow condition, this may lead to a scram-to-ram mode transition. The cavity adopted in this study would prevent pre-combustion shock waves from pushing out of the isolator and help to stabilize the flow field, but it would decrease the mixing and combustion efficiencies.     

板坯连铸机结晶器内流场的有限元分析

应用有限元分析软件ANSYS热一流场耦舍板块FLOTRAN CFD，模拟了武钢三炼钢板坯结晶器在相同浇铸温度下的流场分布情况。通过ANSYS模拟结果，分析了不同拉坯速度、浸入式水口的插入深度和水口出口张角对结晶器中钢液流场分布状况的影响，从而为提高钢液的清洁度和优化连铸工艺参数提供了依据。     

电力工程的地基处理

以实例说明电力工程地基处理的重要性。电力工程地基处理的常用方法有换填法、振冲法、搅拌桩法、桩基、注浆法、强夯法。用实例说明了尽可能从结构设计上采取加强措施,不作耗资巨大的地基处理。     

SK型静态混合器的数值模拟

利用专业的多物理场耦合软件COSMOLMultiphysics对sK型静态混合器内的不可压缩层流流场进行了仿真模拟,计算过程中采用软件中的层流流动和稀物质的传递内置模块,得到了静态混合物中流体的浓度场、速度场及压力场分布。由于螺旋混合元件的作用,流体做螺旋运动,通过对流体的剪切、旋转,使流体充分混合,结果在出口处几乎混合完全。利用后处理软件对计算结果进行分析,为其性能测试提供了理论依据。     

大型发酵机多层搅拌流固耦合仿真分析

基于有限元法对流固耦合作用下的刀具转速开展搅拌效果及受力变形分析。 在流体动力学分析中,采用示踪剂浓度法、多重参考系法研究转速对搅拌效果的影响。 将静力学和动力学模块进行连接搭建,研究不同转速下的刀具受力变形情况,获得搅拌叶片的安全转速取值范围。 结果表明:在达到临界转速前,所需混合时间对转速的变化敏感,搅拌桨的受力和变形也随转速的增加而增大;从流场、混合时间、应力和应变的角度综合考虑,搅拌转速设置为200 rpm 时综合指标更高。     

Electrical process tomography: seeing "without eyes" inside stirred vessels

Body-scanning exploiting 3-D imaging has revolutionised diagnostics and treatment in medicine. Process engineers would like to be similarly able to image chemical process units in 3-D, but without the ￡multi-million price tag. UMIST and Leeds University have together, through the Virtual Centre for Industrial Process Tomography (http://www. vcipt.org), pioneered several electrical process tomography techniques and used them in a variety of applications. Illustrations are presented to show how electrical resistance tomography (ERT) has been developed for typical stirred vessels widely encountered in batch process manufacturing. The technique is potentially fast and inexpensive and capable of imaging both dynamic and pseudo-stationary processes. Examples from UMIST's two-tonne vessel will be presented for miscible tracer mixing, as well as gas-liquid and solid-liquid mixing.     

浅谈水泥土搅拌桩在南水北调工程中的应用

水泥土搅拌桩是利用水泥（或石灰）等材料作为固化剂,通过特制的搅拌机械在地基中将软士和固化剂强制搅拌,使软士硬结成具有整体性、水稳性和一定强度的水泥加固士,从而提高地基士强度,增大变形模量。此方法适用于软基处理,效果显著。使用水泥士搅拌法加固地基也有其局限性,这点更应该引起设计单位的重视。当采用水泥士搅拌法用于处理无类似工程经验的地区或工程时,必须有针对性的进行地质勘探补探工作,按规范通过设计前期的现场试验确定其适用性。     

影响连续流动分析法测定烟草钾含量的因素

研究连续流动分析法检测烟草钾含量过程中火焰强度、进样速度、进样试剂、进样流量等因素对结果的影响,结果表明火焰强度、进样速度、进样试剂、进样流量对测试仪器的基线及峰形影响不大,但对结果的准确度、稳定性有一定的影响。     

Numerical Simulation of Unsteady-State Flowsin Bubble Column Reactors

Thebubblecolumnreactor (BCR) ,withbatchfeedandcontinuousgasaerated ,hasobtainedwideapplica tionsinbiochemicalengineering ,chemicalengineeringandwastewatertreatment ,etc .OneimportantfeatureofBCRisthattheconversionandtheyieldofthereactioncanbehighlyincreasedundertheunsteady stateopera tion .Sincethemassandtheheattransferpropertiesinaprocessmainlydependontheflowbehavior ,itisstronglydesirabletoinvestigatetheunsteady stateflowstructurebeforethedesignandscale upofBCRwithhighreactiveconversionsa…