共查询到20条相似文献,搜索用时 125 毫秒
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对机组的润滑油系统进行了介绍,在此基础上,对因主油箱油位测量引发的一起误停机事故进行了分析,对故障进行了检查,提出了处理方案,避免了事故再次发生。 相似文献
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从概率法出发对给水设计秒流量计算公式进行推导,对该公式的特性进行了分析,用集体宿舍和住宅实测数据对推导公式进行了验证。最后对排水设计秒流量与给水设计秒流量的关系进行了分析。 相似文献
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高速列车气动噪声的计算研究 总被引:1,自引:0,他引:1
通过对高速列车气动噪声产生的关键部位进行简化抽象,对其产生的噪声进行了数值分析。该文着重讨论了两个主要的简化模型,即二维后台阶问题以及三维圆柱绕流问题。对后台阶问题进行数值模拟时采用了NLAS和LES两种不同的方法,并同实验值进行了比较。对三维圆柱绕流问题则直接采用NLAS方法耦合FW-H声音传播方程进行了数值模拟。以此对高速列车气动噪声的机理进行了分析,并对适合于高速列车气动噪声计算的方法进行了选择。 相似文献
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通过模型试验,对上下游水位、通气孔直径、水平洞洞长和起旋器收缩断面面积比对水平旋流泄洪洞的流态的影响进行了研究。结果表明,在竖井为有压流的条件下,水平旋流泄洪洞的流态可分为自由流、吸吮流和淹没流3种基本流态,流态的分类与转变受各种因素的影响;通气时,水平旋流洞内旋流的空腔直径大而均匀,水流旋转的强度增大;不同的洞长,流态从吸吮流向淹没流转变时过渡区的相对上下游水位差相同,但洞长越大,吸吮流的范围越大,转变为自由流流态时所需要的起旋器出口的水流弗劳德数也越大;起旋器出口面积比不同时,流态分区的临界水力条件是不同的。 相似文献
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作为新型基础,负压桶基础具有较好的技术经济性。针对负压桶施工关键控制指标土塞隆起率的控制,通过开展粉质黏土中的负压桶沉贯模型试验,研究不同负压加载模式对施工效率及土塞隆起率的影响。试验加载负压均位于DNV规范方法获得的所需负压和临界负压之间。相同贯入深度条件下,消散模式施加的负压值大于持荷模式,且较大单级荷载下的负压消散模式在保持一定施工效率的同时,对土塞隆起率的控制效果较优。理论分析表明,深度变化率越大内侧摩阻力越大,土塞越难以形成,并从超孔隙水压力结果解释了负压消散模式下的土塞隆起率降低机理。土压力分析结果表明:负压消散模式下桶内土体对桶壁的有效应力高于负压保持加载模式,前者的侧摩阻力也更大。 相似文献
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A New Method for Simultaneous Calibration of Demand Pattern and Hazen-Williams Coefficients in Water Distribution Systems 总被引:1,自引:0,他引:1
Water distribution systems, where flow in some pipes is not measured or storage tanks are connected together, calculation of demand pattern coefficients of the network is difficult. Since, Hazen-Williams coefficients of the network are also unknown; the problem is becoming unintelligible further. The present study proposes a new method for simultaneous calibration of demand pattern and Hazen-Williams coefficients that uses the Ant Colony Optimization (ACO) algorithms coupled with the hydraulic simulator (EPANET2) in a MATLAB code. In this paper demand pattern and Hazen-Williams coefficients are the calibration parameters and measured data consist of nodal pressure heads and pipe flows. The defined objective function minimizes the difference between the measured and simulated values. The new proposed method was tested on a two-loop test example and a real water distribution network. The results show that the new calibration model is able to calibrate demand pattern and Hazen-Williams coefficients simultaneously with high precision and accuracy. 相似文献
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张应亮 《中国农村水电及电气化》2011,(8):39-44,58
通过试验研究了桂花水电站拱坝掺气分流墩的体型、布置和水流流态,消力池和消力池中T型墩的体型和布置,掺气分流墩和消力池联合应用的水流流态和消能效果。试验表明,掺气分流墩与消力池联合应用明显改变了水流流态,具有显著的消能效果。 相似文献
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Hydrological Environmental Responses of LID and Approach for Rainfall Pattern Selection in Precipitation Data-Lacked Region 总被引:1,自引:0,他引:1
Jiake Li Chenning Deng Huaien Li Menghua Ma Yajiao Li 《Water Resources Management》2018,32(10):3271-3284
Global climate change and urbanization development have changed the hydrological environment dramatically. Flood control, non-point source pollution control, and comprehensive utilization of water resources are facing new challenges. On the basis of the Storm Water Management Model (SWMM), an approach for design rainfall pattern selection in precipitation data-lacked region containing model establishing, response analysis and design rainfall pattern screening was put forward. And the responses of the hydrologic, hydraulic and environmental of 2-commercial community mode are explored by using a simulation analysis under different rainfall patterns in this study. Based on the worst principle, the Chicago rainfall pattern was selected for the above-mentioned evaluation indexes at different reoccurrence periods. Results showed that, (1) in traditional development (TD), the values of surface runoff, peak flow and depth of outlet, and total pollution loading were at their maximum at the Chicago rainfall pattern; and in low-impact development (LID), the reduction rates of surface runoff and total pollution loading were at their minimum at the Huff4 rainfall pattern, and the reduction rate of peak flow was at its minimum at the P&C rainfall pattern; then design storm patterns at different simulation targets were obtained. (2) For the Chicago rainfall pattern, the reduction rates of various evaluation indexes decreased while the reoccurrence period increased, and the reduction rate of peak flow was more sensitive to high reoccurrence period rainfall than surface runoff. (3) After the setting of LID measures, the control effect of storm water and non-point source pollution gathered better results from the increase of permeable area and the change of microtopography, as well as from the physical and biological action. This study will provide a reference for the selection of design storm pattern at different simulation targets in regions with deficient rainfall data. 相似文献
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小流域氮流失特征及其影响因素 总被引:9,自引:1,他引:8
由非点源流失的氮是造成水体污染的主要因子之一,而土地利用方式往往对氮的流失产生重要影响。本课题在福建省九龙江流域遴选了4个不同土地利用方式的小流域,通过在自然降雨条件下现场采样与室内分析相结合,研究不同土地利用结构的小流域氮的流失特征和影响因素。研究结果表明:总氮、可溶态氮和泥沙结合态氮的浓度通常比径流先达到峰值,然后开始降低;氮的流失以可溶态氮为主(占73%~98.3%),因此其流失量主要受径流量的影响与雨强关系不大;土地利用方式对氮的流失有明显影响,一般植被覆盖度提高可以降低流失,而农业活动会加剧流失;此外,在高植被覆盖度的天然林地,氮的流失呈现出以泥沙结合态为主。通过本研究可以看出土地利用结构的调整和合理布置是九龙江流域非点源污染控制的重点。 相似文献