共查询到20条相似文献,搜索用时 78 毫秒
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针对三个泉倒虹吸过流量富余的问题,基于工程特点及其水力设计方法,借鉴大口径钢管和预应力钢筒混凝土管(PCCP管)当量粗糙度的取值,根据雷诺数与相对粗糙度,结合莫迪图判别分析了大流量工况下倒虹吸管道水流流态,在此基础上,利用齐恩公式、海曾—威廉公式、谢才公式分别计算了三个泉倒虹吸水头损失值,并与实测资料进行对比分析。结果表明,随着管径增大,管壁光滑程度增加,使得PCCP管内水流处于紊流过渡区而非阻力平方区,因此不应选用谢才公式,而这正是导致三个泉倒虹吸过流能力与设计标准不符的主要原因。此外,发现齐恩公式、海曾—威廉公式适用于大口径有压PCCP管沿程水头损失计算。 相似文献
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为了探究大口径预应力钢筒混凝土管(PCCP管)当量粗糙度取值问题,以新疆三个泉倒虹吸管(DN2 800 mm)及天津新地河泵站PCCP试验管(DN1 600 mm)为例,通过库尔干诺夫式判别大口径PCCP管水流流态,选用齐恩公式、哈兰德公式计算PCCP管9个典型当量粗糙度对应的多组流量工况下的管道水头损失值,并将计算结果与实测资料做了对比分析。结果表明,新疆三个泉倒虹吸PCCP管当量粗糙度取值范围为0.03~0.07 mm;天津新地河泵站PCCP试验管当量粗糙度取值范围为0.05~0.07 mm;建议大口径PCCP管当量粗糙度取0.10 mm。研究成果为下一步研究奠定了基础。 相似文献
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西北某大型倒虹吸工程设计水头高达300m,输水压力管道长度达2 500m,属于大型倒虹吸工程。由于原工程已不能满足安装使用要求,因此需重建倒虹吸。为了保证倒虹吸工程安全可靠的发挥效能,结合当地的地形地质条件和原工程的使用及管理情况,分析了高水头长距离倒虹吸工程的设计特点,研究了倒虹吸工程的管线布置、管材和管径选择、管壁厚度的确定、伸缩节形式的确定以及加劲环和支撑环设计时注意的问题。综合考虑各种因素,并经比较和计算,基本可选用在原管线上重建,设计时可选用管径为800mm、压力分级可为五级、管壁厚度在8~16mm之间,伸缩节可采用套筒式伸缩节,盘根填料采用聚四氟乙烯石棉,支墩间加劲环间距和位移计算宜采用有限元计算来确定。 相似文献
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引调水工程不可避免地存在建筑物交叉跨越的情况,交叉建筑物结构性态关乎工程能否安全运行。依托河南省某输水工程,考虑输引水过程中土体—水体—结构间的耦合作用,建立南水北调中线工程倒虹吸和输水工程中输水管道结构交叉跨越的三维有限元模型,分别考虑结构未修建、完建期和正常运行期,分析各模拟工况下交叉建筑物结构性态影响。结果表明,建筑物交叉跨越会对既存建筑物产生一定影响,尤其是交叉部分结构性态改变较大,倒虹吸结构最大拉应力由0.54 MPa增至0.97 MPa,最大沉降量由-1.38 mm增至-1.90 mm;输水管道拉应力从1.03 MPa增至1.34 MPa,最大沉降量由-3.78 mm增至-4.07 mm,应力值、沉降量可满足工程要求;随着输水管道两道支承埋深增加,倒虹吸所受影响越小。研究结果可为类似工程分析提供参考。 相似文献
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运用流体力学、数值计算方法的相关知识,详细地分析了影响复杂管网水力输送的因素,提出了复杂环状管网水力计算方法。通过严密的数学推导,导出了节点流量修正量的一般表达式,运用VB编程实现了徐州市某小区自来水管网的水力计算,通过联立节点流量连续性方程和管段水力损失平衡方程建立的管网水力平衡计算模型,具有收敛速度快,精度高,克服传统计算方法水力损失与节点流量不平衡的缺陷,是目前大城市复杂环状管网水力计算的有效方法。 相似文献
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复杂环状管网水力计算方法探究 总被引:1,自引:0,他引:1
本文运用流体力学、数值计算方法的相关知识,详细地分析了影响复杂管网水力输送的因素,提出了复杂环状管网水利计算方法。通过严密的数学推导,导出了结点流量修正量的一般表达式,从而能够利用计算机编程解决复杂管网水力计算问题。 相似文献
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Effects of micro heat pipe (MHP) cross-sections and orientations on its thermal performance are experimentally investigated in this study. Tests are conducted using five different cross-sections (circular, semicircular, elliptical, semi-elliptical and rectangular) of micro heat pipes having same hydraulic diameter of 3 rnm placed at three different inclination angles (0°, 45°, 90°), where water is used as the working fluid. Evaporator section of the MHP is heated by an electric heater and the condenser section is cooled by circulation of water in an annular space between condenser section and the water jacket. Temperatures at different locations of the MHP are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the MHP is flattened. Thus among all cross-sections of MHP, circular one exhibits the best thermal performance in terms of heat flux dissipation followed by semi-elliptical, semi-circular, elliptical and rectangular cross-sections. Moreover, its heat transfer capability also decreases with decreasing of its inclination angle. Finally, a correlation is developed which covers all the experimental data within +7%. 相似文献
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针对蒸汽在供热管道流动过程中密度不断发生变化的问题,用连续性方程、动量方程推导出适合于蒸汽供热管网的水力计算公式,实例验证其与文献提供的计算公式对比具有较好的计算精度,水力计算误差平均减少5.6%。 相似文献
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Xiao Liu Hao Sun Simiao Tang Chenglong Wang Wenxi Tian Suizheng Qiu Guanghui Su 《国际能源研究杂志》2019,43(9):4170-4183
Microheat pipe cooled reactor power source (HRP) designed for space or underwater vehicles meets the future demands, such as safer structure, longer operating time, and fewer mechanical moving parts. In this paper, potassium heat pipe cooled reactor power source system which generates 50 kWe electricity is proposed. The reactor core using uranium nitride fuel is cooled by 37 potassium high‐temperature heat pipes. The shields are designed as tungsten and water, and reactor reactivity is controlled by control drums. The thermoelectric generator (TEG) consists of thermoelectric conversion units and seawater cooler. The thermoelectric conversion units convert thermal energy to electric energy through the high‐performance thermoelectric material. A code applied for designing and analyzing the reactor power system is developed. It consists of multichannel reactor core model, heat pipe model using thermal resistance network, thermoelectric conversion, and thermal conductivity model. Then, the sensitivity analysis is performed on two key parameters including the length of the heat pipe condensation section and the cold junction temperature of the TE cell. Meanwhile, the steady‐state calculations are conducted. Results show that the maximum fuel temperature is 938 K located in the center of reactor core and the outlet temperature of coolant reaches 316 K. Both of them are within the limitation. It is concluded that the preliminary design of HPR design is reasonable and reliable. The designed residual heat removal system has sufficient safety margin to release the decay heat of the reactor. This research provides valuable analysis for the application of micronuclear power source. 相似文献
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供热管网系统规模日益扩大,管网结构也更加复杂,具有较强的非线性,为避免供热过程中不出现水力失调以及降低管网建设成本,必须进行管网设计优化。采用图论方法,构建复杂供热管网,建立了管网水力计算数学模型,构造出水力计算的矩阵方程组,并利用MATLAB软件采用迭代法进行求解。针对辽宁某地区热力管网进行分析,计算结果和供热管网实际运行数据进行对比,基于图论的复杂管网水力计算模型精度满足工程要求。 相似文献
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本文提出并研究了管网水力计算的一种求解方法,该方法将管网计算的回路法和节点法两者结合起来,具有编程简单,计算收敛迅速的特点,适用于沿程阻力损失系数分布复杂的管网水力计算。 相似文献