新型气液旋流分离器的模拟研究

为了分离气液喷射反应器的产物,开发了一种新型气液旋流分离器。分别采用Muschelknautz模型、改进的Muschelknautz模型和计算流体力学(CFD)离散相模型对新型气液旋流分离器进行了模拟计算,对新型气液旋流分离器的压力场、分离效率、液滴运行轨迹进行了考察。结果表明:相对于传统Muschelknautz模型,改进的Muschelknautz模型与CFD的模拟结果更为接近,能更加准确地对旋流分离器的分离性能和压降进行预测:在设计条件下,液滴直径越小,颗粒在旋流分离器中的运动轨迹就越紊乱,>3μm的液滴颗粒的分离效率超过80%:颗粒的入口位置会影响颗粒的运动轨迹。     

进气型式对并联旋风分离器流场的影响

采用FLUENT软件模拟催化裂化三旋中并联旋风分离器进气型式的不同对内部流场的影响，主要对比了不同进气型式下入口处的流场分布、分离空间内的切向速度与压降的差异。研究结果表明，采用U型进气型式，分离器压降与速度略大，且比较容易引起环形空间内不利于分离器的二次流动；采用D型进气型式，分离器芯管下口处向内的径向速度较大，容易形成“短路流”。2种进气型式均会造成入口处的涡流，在气固分离过程导致颗粒的沉积以及管道的磨损，其对分离效率的影响有待试验进一步测量。     

颗粒混合过程DEM模拟中搜索网格尺寸的优化

随着计算机技术的迅猛发展,离散单元法(DEM)模拟已成为颗粒体系研究中普遍采用的方法。该方法一般采用网格划分技术来搜索邻近颗粒,以达到O(N)水平的计算复杂性。其中,网格的大小是影响模拟速度的重要因素。本研究对280 mm×1060 mm挡板式混合器中半径分别为R和r的2种颗粒物料的混合进行了模拟(运行在配置Intel(R)Xeon(R)E5430 2.66GHz处理器的工作站上),颗粒分别从混合器顶端两侧给入,汇聚成颗粒流,与挡板发生撞击并沿着挡板流动,从而达到混合的目的。研究分别考察了R=r=1 mm、R=r=2 mm、及R=2～3 mm而r=1～2 mm的3种条件和不同浓度颗粒在不同搜索网格尺寸下的运行速度。模拟结果发现,在当前的模拟体系下,单粒径颗粒及不同粒径颗粒的模拟速度由网格总数及网格内的颗粒数决定。在相同条件下,当搜索网格尺寸约为相应粒径的3倍时,计算速度较快;当颗粒的质量流量相同时,颗粒数密度与粒径的3次方成反比,因此对小颗粒的模拟计算耗时较多;另外,对颗粒质量流量在(1～10)t/h之间变化时的模拟结果表明,高流量会增加混合器中的物料浓度,从而导致模拟时间的增加。这些发现对提高颗粒物料混合的DEM模拟的效率有重要参考价值。     

窄进料旋风分离器分级性能的研究

为了探索新型清晰切割分级方法,本文以Stairmand型旋风分离器为对象进行了窄进料分级性能的模拟与实验研究.模拟软件采用FLUENT6.2,气相流场选用后k-εRealizable模型,颗粒相采用随机轨道模型.实验设备直径0.1 m,进口风速10 m/s,颗粒粒径在0.1 μm～36 μm之间.模拟与实验结果表明:与全进料相比,窄进料能够得到更高的分级效率与更好的分级精度,但提高不大.颗粒轨迹模拟结果表明,这种情况是由旋风分离器本身固有的"短路流"与"下灰环"夹带造成.     

基于FLUENT的两种油气分离器分离效率分析

针对某型发动机的2种不同结构的油气分离器,采用FLUENT对流场进行数值模拟.使用RNG k ε模型计算连续相气体,得到油气分离器内部的流场速度分布.使用离散相模型（Discrete Phase Model,DPM）计算液态油滴,追踪离散项的运动轨迹,从而计算得到分离效率.探讨影响油气分离效率的因素,同时进行试验验证.结果可为油气分离器的后续优化设计提供参考.     

气力输砂试验系统惯性分离元件性能研究

为研究气力输砂系统中惯性分离元件的性能,采用欧拉-拉格朗日方法数值模拟了平面形底边、三角形底边和半圆形底边3种分离元件的流场和颗粒撞击特性,并对比分析了不同风速时,3种分离元件的分离效率和阻力特性。研究结果表明,分离元件底边形状对气流阻力、颗粒运动轨迹及其与壁面碰撞次数有很大影响,平面底边分离元件的分离效率随风速的提高下降幅度较大,因而仅适用于低速情况;三角形底边元件分离效率及其对风速的适应性均有很大改善;而半圆形底边分离元件分离效率最佳,并且基本不受来流速度影响。因此,当风速较高时应考虑优先采用三角形底边或半圆形底边分离元件。研究结果对类似气力输砂系统分离器的设计及优化具有指导意义。     

基于Aspen Plus的循环流化床锅炉效率的计算

以150T/H中温分离、低循环倍率循环流化床锅炉为背景,采用Aspen Plus建立了循环流化床锅炉模型。将循环流化床锅炉分解为煤裂解、碳及挥发分的燃烧、气固分离、烟气能量回收4个子过程,由以上过程构成完整的循环流化床锅炉模型。用装置现场测得烟气组成检验模型的可靠性,模型计算结果与现场数据吻合良好。通过对循环流化床锅炉的模拟,本文提供了一种基于Aspen Plus模型的方法计算循环流化床锅炉的效率,充分利用装置现场数据,包括各级换热器进出口流股的温度,蒸汽温度、压力、流量等数据,计算出锅炉各项热损失而计算锅炉的效率而得到锅炉效率,也可以直接计算锅炉的有效吸收热量,计算出锅炉的效率。并与采用标准算法的结果进行比较,两者吻合良好。验证了采用Aspen Plus模型计算循环流化床锅炉效率的可行性。与常规法相比,该方法简单易行,不必测定飞灰含碳量、灰渣含碳量、排渣量等数据,能够及时的计算锅炉工况改变后的效率,并得到各项热损失的具体数据,为装置的优化提供指导意见。     

聚碳酸酯液液分离器进料构件的流体力学模拟

测定了聚碳酸酯(PC)物料电导率随水油相体积比的变化,确定生产中物料为水包油型乳液,即分散相为PC胶液,连续相为水。采用F1uent商用软件对液液分离器内部流场进行了数值模拟,通过得到的分离器内部流线分布和轴向速度标准偏差分布,考察了不同进料口位置、挡板位置以及不同整流构件尺寸对液液分离器内部流场的影响。研究发现,进料口位置为中部,挡板位置距离进料口为50mm,整流构件开孔率为40%,长度为150mm时,分离器内的流场质量最佳,为液液分离器进料构件的进一步优化研究提供了参考。     

螺旋分离器单相流动的数值模拟

利用PHOENICS数值模拟软件,分析不同质量浓度、不同流量、不同工作介质的螺旋分离器螺旋流流场分布、压力场分布.结果表明:在螺旋分离器螺旋流中,其切向速度占速度优势;随着流量、聚合物浓度的增加,压力下降速度也增大;在螺旋分离器内部压力变化并不均匀.该结果可为分离器内部的螺旋流动的进一步研究与应用提供参考.     

多管束管柱式气液旋流分离器的数值仿真

研究一种多管束管柱式气液旋流分离器的设计,并对性能进行研究.根据流体力学方法,采用雷诺应力输运模型(RSM)和大涡仿真相结合的方式进行数值仿真,得到不同进口速度工况下分离效率的变化情况和湍流流动情况.结果显示:流体总流量一定时,分离效率与各个管进口的流量分配有关,处理量与竖直管的数目有关.分离效率在仿真中给定的速度工况条件下可调范围在44.93％-87.12％,证明三根管气液旋流分离器的处理能力是一根管的3倍,大大增强了分离效率.     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

Call for Papers The 6^th International Conference on Grid and Cooperative Computing

Recent years have seen rapid advances in various grid-related technologies, middleware, and applications. The GCC conference has become one of the largest scientific events worldwide in grid and cooperative computing. The 6th international conference on grid and cooperative computing (GCC2007) Sponsored by China Computer Federation (CCF),Institute of Computing Technology, Chinese Academy of Sciences (ICT) and Xinjiang University ,and in Cooperation with IEEE Computer Soceity ,is to be held from August 16 to 18, 2007 in Urumchi, Xinjiang, China.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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