不同倾斜角叶尖小翼水平轴风力机气动性能

为研究不同倾斜角的叶尖小翼对叶片气动性能的影响,设计了5种不同倾斜角的叶尖小翼,并采用结构化网格技术与CFD数值计算方法对比分析其气动性能。研究结果表明:与原始风力机相比,5种不同小翼对风力机输出功率及风能利用率均明显提升,最大输出功率增长16.73%,风能利用率增长4.41%;倾斜角较大的叶尖小翼能更多地增大叶片的上、下翼面压差,且翼根弯矩更小;大倾斜角小翼能明显改善叶尖绕流,打散叶尖拽拖强涡量,降低叶尖能耗损失。     

一种新型结构叶片对风力机气动性能的影响

针对风力机在旋转过程中产生的叶尖涡影响风力机本身以及下游风力机气动性能的问题,提出了一种控制叶尖涡的策略,以减小叶尖涡对风力机本身及下游风力机气动性能的影响.以PhaseⅥ叶片的1/8模型为原始模型,在叶尖处和轮毂处同时开洞,用管道将洞连接的模型称作新模型.采用数值模拟的方法对来流风速从6 m/s到20 m/s的15个工况下原始模型和新模型风力机进行了对比分析,结果表明:在低风速下原始模型和新模型气动性能几乎一样,即新模型对叶片气动性能影响很小,尾流扩散速度也相近;但随着来流风速的增大新模型对风力机气动性能的影响也随之增大,新模型风轮功率比原始模型风轮功率有明显提高,尾流在风轮旋转平面内扩散速度变快,在来流方向传播距离变短.新模型尾流可以减小对下游风力机的影响,提升了风电场风能的利用效率.     

基于遗传算法的风力机叶片气动外形抗台风优化设计

为了研究风力机叶片抗台风优化设计方法,分析了常规风力机叶片在设计工况下的风能利用系数及极端风况下的气动载荷沿展向的变化特征。并以此为根据,选取极限载荷指标变化显著的挥舞剪力和风能利用系数作为协调两种工况的综合优化目标,提出风力机叶片气动外形抗台风设计优化模型。基于遗传算法,并沿风力机叶片展向,通过使用不同加权系数策略,对某1.5 MW风力机叶片气动外形进行优化设计。研究结果表明,优化后的叶片在具有较高气动效率的基础上能够获得较好的降载效果。     

1.5MW风力机叶片设计与气动性能分析

叶片是风力机中最关键的部件,其气动性能决定风力机的风能利用效率。本文通过Glauert法设计1.5 MW水平轴风力机叶片,并利用FLuENT中的k-ωSST湍流模型,采用周期性边界,对叶片进行气动性能进行数值模拟。分析叶片桨距角固定的风力机在不同来流时风轮的转矩和轴向推力。研究表明:风轮在额定工况下,输出功率1 602 kW,风能利用系数达到0.325,满足设计要求;风速大于12 m/s时,可通过适当降低转速来维持风力机输出功率。     

叶片失速延迟控制垂直轴风力机气动性能

以麦克马斯特大学H型垂直轴风力机为基础,在叶片上加设射流管,设计一种叶片失速延迟控制垂直轴风力机。基于CFD方法计算典型工况下叶片失速延迟控制垂直轴风力机的功率,分析风场的涡强和风速分布特性。研究结果表明:在相同几何尺寸和工况下叶片失速延迟控制风力机的风能利用系数比麦克马斯特大学H型垂直轴风力机的高,在尖速比为1.3时,最大风能利用系数达到0.33。在叶片上加设射流管对于延迟层流分离具有显著作用。     

叶尖小翼对轴流风机气动性能及噪声特性影响的数值研究

为了控制轴流风机叶顶泄漏流造成的气动损失和噪声,在轴流风机叶片顶部添加了融合式叶尖小翼结构,并对风机的气动性能及噪声特性进行了数值研究。采用大涡模拟结合声类比方程的数值方法,研究了叶尖小翼对轴流风机流场和声场的影响。通过对风机叶尖流场和声场进行分析,对比不同外倾角的融合式叶尖小翼周围的涡场结构以及表面声压脉动,分析了不同外倾角小翼对叶尖泄漏流的控制作用以及叶尖小翼对风机气动性能和噪声特性产生的影响。结果显示:叶尖小翼结构可以有效抑制叶尖泄漏涡以及叶尖分离涡的发展,降低轴流风机的气动噪声,提高轴流风机静压效率;使用20°外倾角的叶尖小翼,风机静压效率提高了1.1%,噪声降低了5.0dB;叶尖泄漏流造成的气动噪声主要是宽频噪声,叶尖小翼可以明显降低轴流风机的宽频噪声;通过优化叶尖小翼的外倾角可以在不损害风机气动性能的同时实现较好的降噪效果。     

基于预条件技术的风力机叶片计算方法研究

风力机叶片气动性能对风电机组功率输出具有重要意义和价值,正确的评估叶片性能有利于风力机选型设计工作。为此研究一种基于预条件技术的CFD计算方法用以风力机叶片气动性能评估。研究内容包括预条件处理、S-A一方程湍流模型等内容。利用C++语言开发气动计算程序,采用所开发的程序对某型风力机叶片算例进行气动模拟,获取流场及叶片表面压力系数分布。计算结果与实验吻合良好,所开发的程序可用于工程风力机叶片气动分析,有利于风力机设计工作开展。     

叶片旋转方向对NREL Phase Ⅵ风力机功率特性的影响分析

风力机叶片旋转方向影响风力机流场特性,并改变风力机之间的气动干扰,从而影响风力机功率特性。为掌握风力机叶片旋转方向对风力机功率特性的影响规律,基于CATIA软件建立NREL PhaseⅥ风力机模型,并基于三维计算流体力学(CFD)软件(Fluent)建立风力机气动特性分析模型。通过计算各风速下的风力机叶片表面压力分布和功率特性,并与美国国家能源部可再生能源实验室的NREL PhaseⅥ风洞实验数据对比,验证本文风力机分析模型准确性。随后,计算分析2台相同叶片旋转方向的NREL PhaseⅥ风力机功率特性随风力机间距的变化。分析表明,在不同风力机间距下,上游风力机输出功率基本保持不变,而下游风力机输出功率随风力机间距增大而增大;当两风力机间距为12倍直径时,下游风力机输出功率恢复至正常水平的92.1%。最后,计算分析2台相反叶片旋转方向的NREL PhaseⅥ风力机功率特性随风力机间距的变化。相比于相同的叶片旋转方向,叶片旋转反向将增加下游风力机输出功率,且功率增幅随着间距增大而逐渐减小;风力机间距为4倍直径时,功率增幅达到最大值,约为4.4%。     

考虑气动弹性的风力机叶片分析

运用修正的叶素-动量理论和有限元方法,建立了一种全新的考虑气动弹性的风力机叶片性能分析方法.运用该方法,在多种风速工况下对某850 k W风力机叶片的性能进行了计算,结果表明:对于大功率风力机,在大风速大载荷工况下,气动弹性对风轮性能有明显的影响,使叶片偏离原设计值.该方法的运用对于叶片的气动设计、载荷计算和结构设计有实际指导意义.     

振荡射流提高风力机叶型升力的实验研究

如何有效地提高风力机叶片叶型的气动性能是风力发电技术面临的重要问题。为验证在风力机叶片叶型上表面头部加入一定频率的振荡射流可以对叶型的气动特性产生有利的影响,对实际的风力机叶片叶型进行实验研究,得到叶片的表面压力分布并进行了分析。对NACA4418叶型,当弦长Re为6.0×105时,在上表面距离头部弦长7.8%的位置加入50～500Hz频率的振荡射流都可以有效的提高叶型的升力因数,对升力因数增加射流的大小和频率存在最佳值。这一特性为提高变工况下叶片的气动效率指出了一种有益的途径。     

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…     

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.     

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。     

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     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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An on-line scaling method for improving scalability of a database cluster

The explosive growth of the Internet and database applications has driven database to be more scalable and available, and able to support on-line scaling without interrupting service. To support more client's queries without downtime and degrading the response time, more nodes have to be scaled up while the database is running. This paper presents the overview of scalable and available database that satisfies the above characteristics. And we propose a novel on-line scaling method. Our method improves the existing on-line scaling method for fast response time and higher throughputs. Our proposed method reduces unnecessary network use, i.e. , we decrease the number of data copy by reusing the backup data. Also, our on-line scaling operation can be processed parallel by selecting adequate nodes as new node. Our performance study shows that our method results in significant reduction in data copy time.     

An improved R-tree based on childnode''s probability

R-Tree is a good structure for spatial searching. But in this indexing structure,either the sequence of nodes in the same level or sequence of traveling these nodes when queries are made is random. Since the possibility that the object appears in different MBR which have the same parents node is different, if we make the subnode who has the most possibility be traveled first, the time cost will be decreased in most of the cases. In some case, the possibility of a point belong to a rectangle will shows direct proportion with the size of the rectangle. But this conclusion is based on an assumption that the objects are symmetrically distributing in the area and this assumption is not always coming into existence. Now we found a more direct parameter to scale the possibility and made a little change on the structure of R-tree, to increase the possibility of founding the satisfying answer in the front sub trees. We names this structure probability based arranged R-tree (PBAR-tree).     

Integrating GIS Web services based on mediating architecture

The geographic information service is enabled by the advancements in general Web service technology and the focused efforts of the OGC in defining XML-based Web GIS service. Based on these models, this paper addresses the issue of services chaining,the process of combining or pipelining results from several interoperable GIS Web Services to create a customized solution. This paper presents a mediated chaining architecture in which a specific service takes responsibility for performing the process that describes a service chain. We designed the Spatial Information Process Language (SIPL) for dynamic modeling and describing the service chain, also a prototype of the Spatial Information Process Execution Engine (SIPEE) is implemented for executing processes written in SIPL. Discussion of measures to improve the functionality and performance of such system will be included.