自动喷水灭火系统水力计算方法

为克服目前自动喷水灭火系统水力计算方法存在的缺陷，根据水力学原理分析了自动喷水灭火系统配水支管上各喷头流量之间的比例关系和水压平衡方程，提出了适于管路及喷头“不规则布置”的自动喷水灭火系统的水力计算方法，可精确计算自动喷水灭火系统的设计流量。     

Water hammer in pressurized polyethylene pipes: conceptual model and experimental analysis

This paper analyzes the dynamic effects of pipe wall viscoelasticity on hydraulic transients. These effects have been observed in transient data collected from two polyethylene (PE) pipe systems. The first is a 270 m pipeline, 50 mm diameter, at Imperial College London, and the second is the world's longest experimental PE pipeline, 1.3 km long, 110 mm diameter, buried underground at Thames Water Utilities (London, UK). A mathematical model has been developed to calculate hydraulic transients in polyethylene pipe systems based on the assumption that the viscoelastic behaviour of pipe walls is linear. An additional term has been added to the continuity equation to describe the retarded deformation of the pipe wall and the resulting governing equations are solved by the Method of Characteristics. The numerical results are compared with both the classic elastic solution and with collected transient data. Good agreement between numerical results for the viscoelastic solution and observed data was obtained by fitting the creep function J(t). Unlike classic water hammer analysis, the developed mathematical model is capable of accurately predicting transient pressures in polyethylene pipes and the circumferential strains in the pipe walls.     

沉淀池多斗排泥系统的设计

建立了沉淀池多斗排泥管水力计算简易公式。经分析论证,该水力计算公式是成立的。同时,揭示了多斗排泥的某些规律和特性,在结构上延伸了水力计算公式的内涵,并提出了在排泥工况下排泥管内存在一个水力闭合环及流量逆形成两个观点,可为沉淀池多斗排泥水处理系统的设计及运行管理提供参考。     

基于MIDAS的大体积混凝土桩承台温度场有限元分析

以南昌某高层建筑的大体积混凝土桩承台为例,考虑冷却水管作用,采用MIDAS有限元分析软件对施工期大体积混凝土的水化热温度场进行模拟研究.研究结果表明,桩承台中间布置两排冷却管,水管间距取1.0m,保持1.2m3/h水流量的管冷方案能够保证各控制点内外结构温差不超过25C,有效控制了温度裂缝,使施工质量得到保证.     

异程布置的冷冻水系统管网水力特性计算方法

大型中央空调冷冻水系统管网水力特性精确计算是研究其优化设计和运行的必要条件,简化模型因计算误差大而无法应用于大型管网拓扑结构的水力计算。以异程布置的冷冻水系统为研究对象,在充分考虑末端支路温度调节阀调节特性的基础上,建立了管网水力特性精确数学模型,提出了虚拟流量的计算机逻辑算法。以10个AHU支路的异程式管网为仿真计算对象,计算该管网最小供回水压差以及不同供回水压差条件下的各支路温度调节阀开度和实际流量,计算结果符合异程式管网存在较大压力不平衡的固有特性。该计算方法能够确保计算收敛,实现了利用一个逻辑程序计算管网各种水力特性,为异程式管网水力特性研究提供了参考价值。     

热水地面辐射采暖常用加热管材水力计算

介绍了热水地面辐射采暖常用管材的水力计算方法,得出了6种常用管材的水力计算表并绘制了水力线算图。对塑料管材和金属Cu管材进行水力比较,结果表明相同条件下Cu管材水力较优;在塑料类管材中,PE—X管材水力较优。     

Centrifuge modeling of scale effect on hydraulic gradient of backward erosion piping in uniform aquifer under river levees

The hydraulic gradient that causes backward erosion piping under a river levee is influenced by the scale of the levee, which is a major concern in the physical modeling. In this study, the results of 1 g and centrifuge tests performed on backward erosion piping were analyzed to facilitate a better understanding of the scale effect mechanism. The three-dimensional profile of the pipe and the flow rate of water in the pipe were observed using a transparent model levee. Although the flow in the pipe was determined to be laminar in most tests, it was found to be transient and turbulent in the coarse sand model at high g levels. The hydraulic gradient in the pipe was significantly high in the turbulent flow. Additionally, the scale effect was investigated based on the hydraulic conditions that cause sand transportation in an ideal pipe. The critical Shields number (θ_c), estimated for the model pipes, was consistent with that observed in the Shields diagram. The effects of centrifugal acceleration on the hydraulic gradient of the extending pipes can be explained by the change in θ_c with the particle Reynolds number and the hydraulic gradient in the pipe.     

自动喷水灭火系统中喷头间流量关系及设计流量计算

根据水力学原理分析了自动喷水灭火系统各喷头的流量存在的比例关系,提出了适用于喷头及管路呈不规则布置的自动喷水灭火系统设计流量的确定方法,并结合示例介绍了具体的水力计算步骤.     

单排管冻土帷幕平均温度控制参数敏感性分析

在冻土帷幕平均温度计算中,控制参数的变化直接影响到计算结果。以单排管冻土帷幕温度场的巴霍尔金解析解为基础,使用近似积分和有限元模拟方法计算直线形单排管冻土帷幕的整体平均温度。针对基于巴霍尔金模型的平均温度计算公式中的冻结管外表面温度、冻结管间距及冻土帷幕边界到冻结管中心的距离与冻结管间距的比值3个参数对冻土帷幕整体平均温度影响的敏感性进行分析。得到以下结论:(1)冻土帷幕整体平均温度与冻结管外表面温度成正比;(2)在相同的偏差下,冻结管间距越小,对整体平均温度影响越大;(3)随着冻结发展,冻土帷幕厚度逐渐增大,其误差对整体平均温度计算的影响逐渐降低。     

城市供水管网仿真模拟分析平台的开发与应用

针对人们对城市供水安全性要求日益提高、供水系统的规模不断扩大、复杂性随之提高等问题,对城市供水管网仿真建模与软件开发技术进行了系统研究．首先,对供水管网参数测试分析技术进行研究,较为准确地掌握了整个供水管网的用水量负荷、用户用水模式及变化规律、压力分布规律及主要供水管段的实际过流能力等状况,建立供水管网仿真模拟数据库．在此基础上,以供水管网科学合理运行、保障供水水质等为目标,结合供水管网在线监测技术,以某城市开放式区域供水管网为例,建立了该区域供水管网微观水力模型,并开发了城市供水管网仿真模拟分析平台．该平台具有良好的扩展性及实用性,目前正在某城市进行应用．     

能源锚杆地源热泵冬季工况传热模拟与分析

为得到冬季传热工况下能源锚杆地源热泵系统设计的基础数据,即单位埋管长度换热量受各因素的影响情况,基于有限元分析软件ADINA,建立PE管-锚杆-土壤U型埋管三维非稳态温度场的传热模型,模拟冬季工况下能源锚杆热泵系统运行状况。通过给定条件下埋管周围温度场分布态势图,分析土壤热物性参数、供水温度、埋管流体速度及钻孔填充材料等参数对热泵系统传热效率的影响,得出最佳供水温度、进水速度及热作用半径,以期为相关能源锚杆热泵冬季工况下制热效率的提高和施工设计提供指导。     

建筑给水设计中几种易被忽视的管道设计计算

水箱或水池的泄空管、溢流管以及从市政给水管网直接进水时水箱和水池的进水管管径常常采用经验的方法来确定,有时会出现设计管径不满足实际的情况。故此,特对这几种管道的水力务件进行分析,论述水箱和水池的泄空管、进水管、溢流管的设计计算方法。     

Risk-based asset management: automated structural reliability assessment of geographically distributed pipeline networks for gas and water in the Netherlands

Pipeline networks for gas and water are the lifelines of our society. Most pipelines are buried, which obstructs direct monitoring of the pipes, and introduces the need for other techniques to provide network operators with information on the structural reliability of their network. One of the threats related to pipelines, possibly jeopardising the integrity of the network, is deformation of the subsurface surrounding the pipes, which imposes stress in the pipes. This paper describes the development of a fully computerised and automated model to calculate the probability of failure caused by subsurface deformation of pipes over time in the Netherlands. The objective is to provide failure probability information to network operators assisting the decision-making process regarding preventive measures, such as timely replacement. It will result in a reduction of costs associated with pipe failure, and lead to increased safety (e.g. explosion hazard) and certainty of delivery. The methodology used to develop the model is denoted as the STOOP system-of-systems. First results of the model are presented for a case study and show that different data sources and different models can be combined into a system of systems capable of performing predictive assessments.     

高流速地下水流地层冻结壁形成的研究

利用多孔介质热运移理论及达西模拟建立的考虑地下水流时冻结峰面发展的数学模型 ,采用数值计算法 ,分析了冻结过程中温度场及地下水流场的变化规律 ;获得了冻结孔布置间距极限值与地下水流速、饱和砂原始温度、冻结管外表面温度、冻结管管径及未冻饱和砂导热系数间的定量关系 ;干密度、含水率与比热不影响冻结孔布置间距极限值大小 ,但影响冻结壁发展快慢。     

Sewerage network modelling in Latvia, use of InfoWorks CS and Storm Water Management Model 5 in Liepaja city

The existing partially combined sewerage system in the city of Liepaja, Latvia, is in a poor structural condition and hydraulic overloading causes flooding and pollution. As part of a wider project to upgrade water services in the city, supported by the European Union (EU) cohesion fund (CF), a mathematical model of the system was constructed and verified. In determining appropriate software for use, two key objectives had to be considered: (i) fast model construction to allow upgrading works to be designed and implemented within the timeframe given in the EU Financing Agreement and (ii) provision of an affordable design and assessment tool for future use by the water company. To meet these objectives, InfoWorks CS software was used for model building and verification and the model was subsequently exported to freely available Storm Water Management Model (SWMM) 5. The predictive results of the two models were compared with validate the SWMM5 model.     

供水管网地震漏损蒙特卡洛模拟分析

为研究供水管网在不同地震烈度下的漏损情况和水力特性,基于管道地震破坏评估模型和概率分析方法,对不同地震烈度下管线的破坏概率和渗漏状态进行了计算分析,引入折减系数对管段抗震可靠度分析方法进行改进,并与传统计算方法比较,验证了其合理性。发展了Monte Carlo模拟技术在供水管网流分析方面的应用,并考虑带渗漏和爆管两种出流方式。编制程序对一大型管网进行了模拟分析,给出了震后带漏损情况下管网的漏失率和破坏情况,结果与实际地震灾害情况相符。     

大型输水弯管结构有限元分析

弯管结构是输水管道工程中实现高低管道连接的重要部分,其结构形式和受力都比较特殊。结合一具体工程,对大型弯管结构的计算方法进行了讨论,并建立有限元模型对其应力进行了计算分析,给出了相应的结论和建议以指导设计。     

Prediction models for serviceability deterioration of stormwater pipes

Reducing the number of annual blockages and the consequential flooding events is one of the most important tasks for stormwater pipe infrastructure managers in Australia. Blockages are more likely to occur with pipes experiencing serviceability deterioration, resulting in a reduction of hydraulic capacity. When changing from a problem-based approach to a proactive maintenance and rehabilitation (M&R) approach, the asset managers need predictive information on the serviceability condition of pipes in order to firstly prepare the necessary resources from limited annual budgets and, secondly, to allocate these resources for the maintenance of the deteriorated pipes as precisely as possible. This paper investigates the application of a Markov model and an ordinal regression model for predictions of serviceability deterioration of stormwater pipes. The first model provides the prediction at a network level, which satisfies the first requirement, and the second model predicts serviceability condition for individual pipes, given the attributes of the pipes, in order to satisfy the second requirement. Both models are calibrated using Bayesian inference and Markov Chain Monte Carlo (MCMC) simulation techniques on a dataset supplied from the City of Greater Dandenong, Australia.