模拟突放水体问题的SPH方法

采用SPH方法数值模拟了二维方形水箱突放水体各时刻流动的情况,计算结果表明:模拟过程中,整个水体的密度和速度值变化不大,而压强值变化比较大。数值模拟粒子分布图可以显示出各时刻整个水体的流态、各时刻闸门开启情况及闸门对周围水体流态的影响等,闸门开启的1.460 3 s时刻,闸门左侧部分水体有相对下降缓慢的特殊流态。     

QT间期离散度与急性心肌梗死患者预后的关系

通过观察急性心肌梗死(AMI)患者QT间期离散度(QTd)变化,探讨其与临床关系。应用体表同步十二导联心电图对168例AMI患者进行心电图QTd和校正QT间期离散度(QTcd)测定,并与168例正常人做对照。结果表明:AMI患者入院后心电图的QTd、QTcd均明显长于对照组(P<0.01);室性心律失常组、心衰组、死亡组QTd、QTcd均明显长于非心律失常组、非心衰组、生存组(P<0.01);前壁组QTd、QTcd明显长于下后壁组(P<0.01);AMI组中QTmax存在于梗死或缺血区导联163例,占97%。AMI中发生室性心律失常组QTd增加均>60 ms,其中6例室颤QTd均>100 ms。综上得出结论:AMI患者QTd、QTcd明显延长,为AMI发生室性心律失常、心力衰竭和猝死简单而实用的重要预测指标。QTd>60 ms可以作为预测心肌梗死患者发生室性心律失常的指标,而QTd>100 ms是识别高危心律失常的敏感指标。     

大型汽轮发电机瞬态参数的计算

本文利用瞬态电磁场有限元法计算汽轮发电机空载时发生三相突然短路的绕组电流曲线,然后对电流曲线的数值结果进行分解,拟合,得到电机的瞬态参数,该方法有效地考虑了电机齿槽结构和饱和现象。     

近50年湖漫水库径流量与降雨量特征分析

依据湖漫水库1966—2012年间46a的年径流量和降雨量的实测资料,综合采用统计方法和Mann-Kendall检验法分析降雨量和径流量的历史变化趋势,及降雨量和径流量之间的相关性,为今后水库的运行管理提供技术支持．分析结果表明：对于降雨量,年际变化不均匀,各月间差异较大,呈明显下降趋势的为4—6月以及10月;对于径流量,月际变化呈下降趋势的月份为3～5月以及7月份;1980年以来,降雨量和径流量总体趋势呈现上升趋势,枯水年的频率减小,特大洪水发生频率呈增大趋势．     

A DEM‐based parallel computing hydrodynamic and transport model

The sudden and accidental water pollution response system (SAWPRS) for Yangtze River in central China required to develop a hydrodynamic and transport model, which is readily available and capable of simulating a large river system within GIS environment. This study facilitates such effort by developing a parallel computing method based on digital elevation model (DEM) using overlapping domain decomposition approach (ODDA) and message passing interface (MPI) protocol. The hydrodynamic and transport model was redesigned using finite volume method for hydrodynamic and transport model dispersion, the SIMPLEC method for solving the flow field, and the pressure weighted interpolating method for the flow field modification. This modelling approach was verified in two experiments using different sets of computer clusters. The model output was evaluated against the measured data collected for the year 1998 for Wanzhou, an upstream river segment of Yangtze River. The relative error was found to be less than 10%. The performance of parallel computation was found excellent as evident from the cost efficiency values greater than 0.81 in both experiments and increased computation speed while increasing the number of computer clusters. Overall, the parallel computing modelling system developed here was found to meet all requirements of SAWPRS. Copyright © 2010 John Wiley & Sons, Ltd.     

基于水库调度的河流突发水污染应急处置

天然河流水污染事件频发,如何运用水库应急调度降低污染损失具有重要意义。以突发水污染事件应急处置为目标,分别构建了水污染溯源、浓度预测和水库应急调度模型,并通过数值模拟的方式对水库调度方案进行优选,最终建立了一套完善的水库应急调度技术体系。将技术运用于贺江2013年水污染事件应急处置分析,结果表明,模型重构的监测断面污染物浓度过程与实测过程较为接近,优选的水库调度方案及其处置效果也与实际情况基本吻合。结果说明本文建立的水库应急调度关键技术体系可运用于指导河流突发水污染事件应急处置。     

汉江上游径流演变趋势及影响因素分析

为了研究汉江上游径流演变趋势并对影响因素进行分析,根据1950～2007年汉江上游安康水文站的实测径流资料,对汉江上游径流在年际、年代、汛期（5～10月）的演变进行了分析。用径流量的累积曲线对径流变化趋势及突变进行了研究,并使用非参数Mann-Kendall法(M-K法)来检验径流的趋势变化。趋势分析表明,20世纪90年代以前,汉江上游径流呈现增加的趋势,但到了1990年后径流量锐减,进入21世纪后径流量也在减少,但减少趋势有所缓解。重点分析了1990年后汉江上游径流量锐减的主要原因,结果表明,径流减少主要原因为降水量的减少、气温的增高、下垫面的变化、社会经济耗水的增加和水资源开发利用等方面。     

THREE-DIMENSIONAL NUMERICAL SIMULATION OF AERATED FLOWS DOWNSTREAM SUDDEN FALL AERATOR EXPANSION-IN A TUNNEL

Air entrainment is known to be one of efficient and inexpensive methods to prevent cavitation damages in hydropower projects.The shape of sudden expansion-fall is used as a common device for mitigating cavitation erosions.The complex flow patterns with cavitation are numerically simulated by using the realizable k-εturbulence model and the air-water mixture model.The calculated results are compared well with the experimental results as well as those obtained with the k-εturbulence model with the Volume Of Fluid(VOF)Model.The calculated results agree well with the experimental data for the aeration cavity and wall pressure.Moreover,the air concentration near sidewall is simulated by a mixture model.It is found that the mixture turbulence model is superior to the VOF turbulence model.     

刘家峡水电站坝基承压水水位突降原因分析

介绍了刘家峡坝基承压水力突降情况,分析了承压水变化规律,揭示了承压水位突降是由于裂隙突然张开或裂隙的某一部位突然与相邻的上部裂隙潜水渗流或排水通道相连通造成的,阐明承压水与裂隙潜水的连通一般对大坝的安全不会构成威胁的观点。     

泄洪洞中闸室出口侧墙掺气体型研究

为消除中闸室出口侧墙上的掺气盲区并且改善水流流态,该文提出了突扩-渐扩侧掺气体型。采用RNG k-ε紊流模型对此掺气体型进行数值模拟,获得了侧墙上水流流态、压力分布以及水翅强度等水力特性。利用物理模型试验对计算结果进行验证,计算结果具有可靠性。结果表明:出闸水流弗劳德数一定时,侧墙突扩宽度和渐扩长度是影响水翅强度的主要因素,突扩宽度越大或渐扩长度越短,水翅强度越大;侧墙压力中心主要是由出闸水流冲击泄洪洞底板造成的;此掺气体型能形成稳定侧空腔并且侧墙上无负压产生,能够有效避免空化空蚀。