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该文在分析和计算水轮机运转时轮轮与座环迷宫止漏环径向间隙不均匀引起水力不平衡的基础上,提出机组水力振动的原因和处理措施,并给出漳平大坂电站振动问题的处理效果,可供参考。 相似文献
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采用 S1、S2两类相对流面理论的准三元流动计算方法,研究了混流式水轮机固定导叶和动导叶的流场。在 S1流面上建立势函数方程,S2流面上建立流函数方程,通过两个流面的叠代计算得到该流场的流动状态。这一成果可以用来分析混流式水轮机座环和导水机构区域的水流情况。 相似文献
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大型混流式水轮机座环一般设计为平板式结构,具有结构尺寸大、质量大、环板钢板厚度大的特点。锦屏二级水电站水轮机座环组装后最大外径Φ10558mm,总重量为338t;座环上/下环板板厚分别为260/220mm,材质选为牌号为S355J2-Z35的进口钢材,其结构尺寸、质量与环板板厚均为国内大型水轮机座环中较大的。通过锦屏二级水电站座环的实践、总结、研究和创新,重点论述大型混流式水轮机座环"快速"现场组焊、安装的技术,以期对后续大型混流式水轮机座环现场组焊与安装提供借鉴。 相似文献
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该文建立了一个新的结构-与尾流振子流固耦合模型.采用具有非线性阻尼的振子来模化、van der pol方程来描述流场近尾迹动力学.以结构与流体的受力互为反作用力的关系,建立了新的流固耦合模型.使用该文的模型对二维结构涡激振动问题进行研究,能很好地预计结构涡激共振的特性.计算结果表明,结构共振的最大振幅随着结构的数和质量阻尼参数的增大而减小,与实验结果规律一致、数值吻合.根据该文的模型计算结果给出了预测共振振幅值的拟合公式,并给出了共振情况下升力、相位等的变化规律. 相似文献
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一、引言 水轮发电机组随着单机容量的增大,座环尺寸也随之增大。为了解决运输问题,大型座环均分瓣运至工地,在现场组合施焊。 水轮机座环作为承重和基准部件,其高程、中心、水平度应严格按照国家标准《GB8564—88》所规定的质量标准进行调整,尤其是座环的水平度,它直接影响座环,顶盖及水导轴承的水平度与垂直度,严重时将影响水轮机转轮的止漏环配合间隙和导叶端部间隙。 相似文献
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排架式渡槽流 固耦合动力特性分析 总被引:6,自引:0,他引:6
本文分析了排架式渡槽横向流 固耦合动力特性,计算结果表明:排架式渡槽流 固耦合系统的模态可分为两类:一类为“流体振荡模态”,以流体的晃动为主,反映了流体固有晃动模态在耦合系统中的影响;另一类为“结构振荡模态”,以结构的振动为主,反映了结构固有振动模态在耦合系统中的影响。提出了两种特征值问题的计算方法,将其应用于实例计算,讨论了两种方法的优缺点。 相似文献
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排架式渡槽流一固耦合动力特性分析 总被引:6,自引:0,他引:6
本文分析了排架式渡槽横向流一固耦合动力特性,计算结果表明排架式渡槽流一固耦合系统的模态可分为两类一类为“流体振荡模态”,以流体的晃动为主,反映了流体固有晃动模态在耦合系统中的影响;另一类为“结构振荡模态”,以结构的振动为主,反映了结构固有振动模态在耦合系统中的影响.提出了两种特征值问题的计算方法,将其应用于实例计算,讨论了两种方法的优缺点. 相似文献
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引起水轮发电机组振摆的原因有机械、水力、电气及其他等方面的因素。在水力因素方面有转轮叶片数与导叶数组合不当;转轮叶片进口边与导叶出水边的距离过短;转轮止漏环迷宫间隙不当或偏心、或止漏环不圆造成间隙不对称;转轮叶片出口边缘开口不均匀;转轮上冠背水压力脉动;转轮叶片汽蚀严重;转轮叶片出口旋回流形成涡带;转轮叶片卡门涡流;转轮泄水锥形状不当:涡壳和座环引水不对称以及轴流式水轮机尾水管偏矮等等。 混流式水轮机中由于转轮过流部件制造偏差引起水流不平衡而造成摆动大致有下述两种情况。 相似文献
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座环是水轮机安装的基准,是水轮机埋设件安装中的关键项目,座环水平的优劣将直接影响底环、顶盖、水导轴承、导叶等部件的水平度和垂直度,直接影响到导叶的端部间隙。综合考查座环安装的中心、标高、水平度和圆度等质量标准,水平度是不可忽视的环节。 相似文献
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根据冗各电站地下厂房开挖支护的施工顺序,以隐式杆单元模拟锚杆,以壳单元模拟混凝土喷层,采用三维非线性有限元技术,对洞室群的开挖支护动态过程进行了模拟计算。通过三维非线性有限元计算分析得到:洞室群动态开挖过程中围岩应力变形的分布规律,围岩塑性区的发展规律,锚杆受力变化情况。计算结果表明:整个开挖过程中,洞周围岩位移变化规律正常,量值较小,塑性区主要分布在洞室周边,围岩稳定性较好;但在洞室交叉口处围岩的变形较大,出现较大范围的塑性区,在此基础上提出了支护措施优化方案,并对优化方案的效果进行了评价。 相似文献
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The relocation of unionacean mussels is commonly used as a conservation and management tool in large rivers and streams. Relocation has been used to recolonize areas where mussel populations have been eliminated by prior pollution events, to remove mussels from construction zones and to re-establish populations of endangered species. More recently, relocation has been used to protect native freshwater mussels from colonization by the exotic zebra mussel Dreissena polymorpha. We conducted a literature review of mussel relocations and evaluated their relative success as a conservation and management strategy. We found that 43% of all relocations were conducted because of construction projects that were forced to comply with the Endangered Species Act 1973 and that only 16% were monitored for five or more consecutive years. Most (43%) relocation projects were conducted from July to September, presumably a period when reproductive stress is relatively low for most species and the metabolic rate is sufficient for reburrowing in the substrate. The mortality of relocated mussels was unreported in 27% of projects; reported mortality varied widely among projects and species and was difficult to assess. The mean mortality of relocated mussels was 49% based on an average recovery rate of 43%. There is little guidance on the methods for relocation or for monitoring the subsequent long-term status of relocated mussels. Based on this evaluation, research is needed to develop criteria for selecting a suitable relocation site and to establish appropriate methods and guidelines for conducting relocation projects. 相似文献
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In the lower River Murray, Australia, populations of gastropods have declined markedly over the past 40 years. Of the native fauna of about 18 species, only the ancylid Ferrissia petterdi remains common (but in patches), and another five species feature in sporadic local resurgences. Until recently the viviparid Notopala was thought to be extinct. The introduced physid Physa acuta is widespread, but in low numbers. The decline probably is associated with flow regulation, high turbidity and the introduction of common carp. Snail populations have persisted, however, in irrigation pipelines fed from the river, where they periodically cause blockages. This paper reports the discovery of the only known populaion of Notopala hanleyi in a pipeline where the inner wall accumulates microbial and other organic matter, providing high quality food for snails. In the Murray before regulation most of the periphytic biomass was probably microbial, as fluctuating water levels would have maintained littoral communities in a highly productive, early state of succession his postulated that, by stabilizing seasonal water levels, regulation has promoted the production of filamentous green algae, an inferior food source, and so displaced snail populations from the open aquatic environment. 相似文献
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V. K. Konovalov O. V. Yashkin V. V. Ermakov 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2008,42(2):105-109
A system for removal and pneumatic transport of fly ash is examined, in which air pulses act on batches (pistons) of ash formed
in a duct. Studies are made of the effect of several physical parameters on the force required to displace a piston of ash
and these serve as a basis for choosing a system for removal and pneumatic transport of ash simultaneously from several hoppers
of an electric precipitator. This makes it possible to separate the ash particles according to size without introducing additional
components. Formulas are given for calculating the structural and dynamic parameters of this system and measurements of indirect
dynamic parameters are used to calculate the input-output characteristics of the system. In order to optimize the system,
configurations for summing several ducts into a single transport duct for pneumatic ash transport are proposed. Some variants
of dry ash utilization and the advantages of producing of size-separated particles are considered.
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Translated from élektricheskie Stantsii, No. 2, pp. 26–30 (2008). 相似文献
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Peter B. Bayley 《河流研究与利用》1991,6(2):75-86
The ‘flood pulse advantage’ is the amount by which fish yield per unit mean water area is increased by a natural, predictable flood pulse. Evidence for this increase is presented from tropical and temperate fisheries. It is argued that increasing multispecies fish yield by restoring the natural hydrological regime is consistent with increasing production of other trophic levels and with restoration from ecological and aesthetic viewpoints. When applied to a river-floodplain system, this restoration would provide a large, self-sustaining potential for recreation, commercial exploitation, and flood control. An interim ‘natural flood pulse’ restoration approach is proposed for systems modified for navigation. This approach approximates the natural hydrological regime in a river reach and is intended as a first step in the long process of restoring the watershed. 相似文献
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简述天湖水电站投运以来各种故障的表现形式,分析其原因,提出了相应的处理方法及措施,并对合理利用国内外设备提出建议。 相似文献