螺旋槽管强化传热研究及其在锅炉中的应用

论述了螺旋槽管管内外单相流体传热研究的试验结果,并将试验数据按流动参数、物性参数和几何参数采用无量纲准则数进行整理.给出了在雷诺数Rei=104～105范围内管内无量纲换热系数Nui的关联式,和在Re.=3×103～6×104及Re.=3.3×103～105范围内气流横掠螺旋槽管错列和顺列管束的管外无量纲换热系数Nu.的关联式,该关联式可以作为螺旋槽管换热器的设计依据.介绍了螺旋槽管作为空气预热器在电站煤粉锅炉中的广泛应用,给出了几个应用螺旋槽管空气预热器解决锅炉具体问题的实例,表明了螺旋槽管空气预热器的显著优越性.     

气体在螺旋槽管内强制湍流传热时N_u与R_e的关联

本文通过单头螺旋槽纹管进行蒸汽加热空气的实验研究,对实验结果进行了线性回归处理,确立了N_u与R_e的关联式。通过作图和误差分析表明:本关联式可应用于气体在螺旋槽纹管内强制湍流时的传热计算。     

针翅套管传热元件阻力特性实验研究

针翅套管式强化传热元件是一种新开发的传热管,传热效果好.以润滑油与水作为实验介质,对多根针翅高度与节距不同的针翅套管进行单管实验.根据实验结果,分析了油侧通道中针翅高度、节距、针翅管管径等参数对针翅套管阻力的影响,总结了适用于针翅套管阻力计算的实验关联式.应用该实验关联式对其他不同参数的针翅套管进行阻力计算,计算结果与实验结果符合较好,证实了实验关联式的可靠性.     

太阳能螺旋槽管相变蓄热器强化传热性能研究

针对太阳能利用过程中的蓄热储能问题及螺旋槽管换热器的优点,将螺旋槽管引入太阳能相变蓄热器中,并对蓄热器的蓄热过程进行了数值模拟。首先以光滑管蓄热器为例实验验证了该模拟方法和所用模型的可靠性,进而以螺旋槽管为水流管道、相变材料为蓄热介质,利用Gambit 建立三维蓄热器模型,应用ICEM对几何模型进行网格划分,运用流体计算软件Fluent模拟计算螺旋槽管和光滑管相变蓄热器的蓄热过程,考察螺旋槽管的强化传热效果。模拟计算螺旋槽管蓄热器不同槽纹节距和槽深等结构参数对蓄热器蓄热过程的影响,并对其影响规律进行了分析。结果表明,螺旋槽管代替光滑管用于太阳能相变蓄热器,可有效提高相变蓄热过程中的对流换热强度和传热能力,缩短蓄热时间,在模拟范围内,得到的最佳螺旋槽管结构参数为节距p=7 mm,槽深e=0.4 mm。螺旋槽管传热性能良好,对其深入研究有望进一步改进相变蓄热器的设计方案。     

内外螺旋三角翅片管管外冷凝传热建模与优化(Ⅱ)--数值分析与优化

为优化ＩＯＳＦ管的管外几何参数,根据所建数学物理模型,对不同换热工况和不同结构参数进行数值分析与模拟优化．研究结果表明：当管长Ｌ＝０．７ｍ、螺旋角β＝１８°、管外径Ｄｏ＝０．０１６ｍ,Ｈ＝０．００１ｍ时,φ＝７６°与Ｎ＝３２是最佳匹配参数,此时有最大平均冷凝换热系数;ＩＯＳＦ管管外螺旋角在β＜２７°的范围内,其管外传热特性与纵槽管基本相当;翅片夹角φ和螺旋槽头数Ｎ是对ＩＯＳＦ管管外冷凝换热产生主要影响的结构参数;局部冷凝换热系数沿管长跌落主要集中在开始的０．５ｍ内,因此排液盘的间距应不大于０．５ｍ,才能更有助于平均冷凝换热系数的提高     

单头“W”形螺旋槽管强化传热机理研究

单头“W”形螺旋槽管是在螺旋槽管的基础上开发出的一种新型强化管。本文研究了各种结构参数对流动和紊流换热特性的影响,从理论上探讨了其强化传热机理,并和实验结果进行了比较,结果表明此管的性能明显优于光滑管,在p/e=10～14范围内且具有小螺距和适当槽深的单头“W”形螺旋槽管的综合性能是最优的。     

恒速滴重法测定动态界面张力

建立了文题的测定装置，能检测０．５ｍＮ／ｍ以上，液滴表面寿命大于０．０５ｓ的动态界面张力。从液滴形成的过程中，考虑运动摩擦力和环流摩擦力在液滴分离的力平衡中所起的作用，提出了恒速滴重法测定σ１计算式，并用实验数据关联了相对运动度Ｕ０的计算式。用纯物质的油－水系统的实验数据对公式加以验算，一般误差在０．５＾以内，用上述两式计算ＳＤＳ，ＣＴＡＢ，Ｔｒｉｔｏｎ Ｘ－１００等油－水系统的σｔ，并推算各表面     

内螺纹管高压汽水两相流摩擦阻力特性的研究

对内螺纹管两相流摩擦阻力在高压汽水试验台上进行了试验研究，试验用管为我国６００ＭＷ超临界变压运行直流锅炉所采用的Φ２８ｍｍ×５．４１ｍｍ的１２ＣｒＩＭｏＶ四头内螺纹管，试验压力为：１３～２２ＭＰａ，质量流达为：４００～１８００ｋｓ／ｍ２ｓ，蒸汽干度为：０～１．０．对试验结果进行了分析，给出了计算内螺纹管摩擦压降的关联式。     

螺旋折流板波槽管换热器换热与阻力实验研究

以水为工质，对螺旋折流板波槽管换热器、螺旋折流板光管换热器及传统弓形折流板光管换热器进行了壳程和管程的传热及阻力对比实验研究．结果表明，相比弓形折流板光管换热器，螺旋折流板光管换热器总传热系数和壳程换热系数分别提高50％～80％和90％，壳程阻力减少15％～20％；螺旋折流板与波槽管结合使用，换热能力进一步加强，总传热系数是弓形折流板光管换热器的2．01～2．11倍，是螺旋折流板光管换热器的1．15～1．6倍．     

螺旋槽纹管管内紊流流动与换热数值研究

系统地研究管内径Di,节距P,槽深e,槽宽B,螺旋角β和头数N等各因素对管内流动和换热的影响及管内各种不同工质的换热和流动情况,以优化螺旋槽纹管的管型结构参数,完全依靠实验很难达到此目的,因此有必要用数值模拟的方法来研究。本文对前人在单头和多头螺旋槽纹管管内紊流流动与换热的数值研究中,所采用的方法、模型、网格的划分以及计算结果做了简要的介绍,并认为采用周期性充分发展换热的概念,螺旋坐标变换的方法,修正的K-ε模型与应用其他计算方法是解决该问题的关键。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

Perspherical Approaches for Electrons in Atoms and Charged Excitons in Quantum Wells

Instead of following Fock’s expansion,we solve the Schrodinger equation for some quantum mechanical manybody systems such as electrons in atoms and charged excitons in quantum wells in a similar way in hyperspherical coordinates by expanding the wave functions into orthonormal complete basis sets of the hyperspherical hannonics(HHs)of hyperangles and generalized Laguerre polynomials(GLPs)of the hyperradius.This leads the equation to     

Advances in broadband wireless communications under high-mobility scenarios

Future mobile communication systems aim at providing very high data transmission rates, even in high-mobility scenarios such as high-speed wheel-track trains, maglev trains, highway vehicles, airplanes, guided missiles or spacecraft. A particularly important commercial application is the strong and increasing worldwide demand for high- speed broadband wireless communications （up to 574.8 km/ h test speeds or 380 km/h commercial speeds） in railways, providing data, voice and video services for applications such as onboard entertainment services to passengers, train control, train dispatch, train sensor status handling and sur- veillance. In such high-mobility scenarios, there are a number of communication challenges, including fast hand- over, location updating, high-speed channel modeling, estimation and equalization, anti-Doppler spreading tech- niques, fast power control, and dedicated network architec- ture. Because signal transmission in very high-speed scenarios will inevitably experience serious deterioration, it is imperative to develop key broadband mobile communi- cation techniques for such high-speed vehicles.     

Wuhan University Journal of Natural Sciences TOTAL CONTENTS

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海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

Scale-based spatial data model for GIS

Being the primary media of geographical information and the elementary objects manipulated, almost all of maps adopt the layer-based model to represent geographic information in the existent GIS. However, it is difficult to extend the map represented in layer-based model. Furthermore, in Web-Based GIS, It is slow to transmit the spatial data for map viewing. In this paper, for solving the questions above, we have proposed a new method for representing the spatial data. That is scale-based model. In this model we represent maps in three levels: scale-view, block, and spatial object, and organize the maps in a set of map layers, named Scale-View, which associates some given scales.Lastly, a prototype Web-Based GIS using the proposed spatial data representation is described briefly.     

Exciton Seebeck in Molecular Systems

Various applications relevant to the exciton dynamics,such as the organic solar cell,the large-area organic light-emitting diodes and the thermoelectricity,are operating under temperature gradient.The potential abnormal behavior of the exicton dynamics driven by the temperature difference may affect the efficiency and performance of the corresponding devices.In the above situations,the exciton dynamics under temperature difference is mixed with     

Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to