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为了研究管壳式换热器流动状态与传热分析,运用了数值模拟的方法对管壳式换热器进行分析。先使用Gambit对管壳式换热器的三维模型进行构建,然后应用FLUENT软件对模型进行求解,得到了因入口速度不同,温度场、速度矢量场等变化的关系。通过改变折流板间距,分析得到了折流板数目与换热量的关系。 相似文献
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螺旋盘管流动特性的实验研究 总被引:1,自引:0,他引:1
在一定流量范围内对流体流经平面和立体螺旋盘管进行了流动性能的实验研究 ,得出了盘管折合沿程阻力系数随雷诺数、盘管几何条件及不同盘绕方式等的变化关系曲线及部分经验公式 ,并与同条件下的直管进行了比较 相似文献
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管壳式换热器是目前应用最广泛和可靠的换热器,其壳程流体通道设计是工艺设计和设备设计的重要内容.文中论述了管壳式换热器壳程流道设计的主要类型、适用场合,对合理地选用和设计壳程结构具有一定的参考价值. 相似文献
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对薄管板换热器进行了电测,绘制了压力为1-5MPa壳程的应力和叠加相应法兰力矩下的综合应力,提出了对于中低压下的贴面式薄管板换热器必须考虑兰力矩的影响,指出了贴面式薄板强度设计的关键是非布管区。 相似文献
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BINGHAM流体环空管流流动及传热规律研究 总被引:1,自引:0,他引:1
结合BINGHAM流体的本构方程、管流运动方程及能量方程 ,推导了BINGHAM流体环空管流速度分布及温度分布。由于BINGHAM流体具有屈服值 ,环空管流流动中会形成流核。流核的宽度与屈服应力成正比 ,与广义压力梯度呈反比。流核中心线偏离环空中心线 ,且偏向环空内侧。环空内外径之比越小 ,相对偏离越远。在其他条件不变的情况下 ,当屈服应力增大时 ,速度分布剖面变得愈扁平。当其他条件不变时 ,流核速度随环空内外径之比减小而增大。流核内温度变化比环空内外侧明显小 ,随屈服应力的增大 ,温度分布剖面愈扁平。 相似文献
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《综合运输》2019,(8)
为分析不同主轴直径、叶片倾角对路面螺旋输送机输运效果的影响,对路面螺旋输送机、焦油沥青颗粒进行实体测量,建立路面螺旋输送机UG模型导入EDEM软件中,并建立合焦油沥青颗粒进进行分析,得知路面螺旋输送机拐角处焦油沥青颗粒速度较小,且其运动方向并非路面螺旋输送机轴与叶片的传输方向。在路面螺旋输送机拐角处以17.1s~18.0s时间段内路面螺旋输送机出口处的焦油沥青颗粒数目为评价指标,分析不同主轴直径、叶片倾角对输运效果的影响。据此,在不同给料率的情况下进行验证,仿真结果显示:路面螺旋输送机入口处每秒生成焦油沥青数目为3000、5000、7000时,均出主轴直径为4400mm左右,叶片倾角为30°左右时路面螺旋输送机出口处的焦油沥青颗粒数目最多。当主轴直径与叶片倾角相同时,随着给料率的增加,路面螺旋输送机出口处的焦油沥青颗粒数目逐渐减小,其最大值出现在入口处数量为3000,主轴直径为440mm与叶片倾角为30°时,其值分别为10992个与10968个。试验与仿真所得结论一致,该结果为其他路面螺旋输送机的研究设计提供理论基础与依据。 相似文献
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采用非标准螺旋形的加旋元件,形成加旋喷头,使喷出的射流在旋转过程中向外扩散,达到内壁清洗和钻孔的目的。加旋喷头分为圆管进液段、流槽加旋段以及锥形收缩段。文中对其流槽加旋段及锥形收缩段内流体的速度函数关系进行了探讨,得出了相应的函数关系表达式。结果表明:液体在流槽加旋段内的运动,可视为一元轴对称螺旋流动,在锥形收缩段内流体的运动可视为二元轴对称螺旋流动。 相似文献
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管道内污水两相流的阻力计算 总被引:3,自引:1,他引:2
目前的污水管道设计是将污水在管道内的流动视为单相均匀流,主要用谢才(Chezy)公式进行水力计算。由于存在管线长、流量大以及区域地形变化幅度较大等因素,建设区域排水系统需要采用新的方法,以便较准确的计算水头损失。文中将污水视为液-固两相流体。对于沿程阻力的计算,将流体分为均质流与非均质流,分别给出沿程阻力系数的计算公式;对于局部阻力,则借用气-固两相流动的局部阻力系数计算公式。最后得出了两相流情况下与单相流情况下的阻力系数区别。结论是沿程阻力系数的区别可不计,局部阻力系数差别较大,在进行设计时必须考虑。 相似文献
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Pedestrians as compared to vehicular traffic enjoy a high degree freedom of movement even in heavily congested areas. Consequently, there are more alternative links available to pedestrians between a given origin‐destination (O‐D) pair. This paper describes a study done by the University of Calgary to evaluate the factors affecting the choice of route on intra‐CBD trips or trips within the Central Business District (CBD). An origin destination survey conducted in downtown Calgary, Alberta enabled the identification of the most significant factors influencing the choice. These factors were analyzed in relation to the physical characteristics of the location, personal characteristics of the trip maker and the type of the trip. It appears that most people chose the shortest link and factors such as the level of congestion, safety or visual attractions were only secondary. This suggests that the length should be made a major consideration when planning and designing pedestrian links. 相似文献
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《Transportation Research Part A: General》1991,25(6):407-418
The main deficiency of most current modeling approaches to transportation can be identified as neglect of the integration of existing geographical knowledge in regard to the ex ante transport/land use modeling approaches, with its focus on territorial dynamics and theory development. This paper addresses this aspect of the problem by introducing a theoretical and methodological framework for the analysis of the interrelationship between land uses. The analysis attempts to determine to what extent the functional land use in a city can be considered an ordered pattern. The order sought does not rely on purely spatial configurations, but on the correlation of transportation and land use. The first section of this paper focuses on theoretical considerations. It stresses the fact that conventional approaches do not apply in the present context. It then suggests an alternative based on areas of influence and measured in terms of level of attractance of land uses. The second describes a procedure based on this alternative following the remarkable contribution of Hanjoul, Beguin and Thill. An application of this procedure to the analysis of Shanghai is then examined. Finally, an evaluation of the strategies for optimizing the interrelationship between land uses is presented. The paper concludes with a possible research agenda. 相似文献
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明确埋地管道防腐保温层的技术评价标准,对埋地钢质管道的安全运行,延长管道使用寿命具有重要意义。为了对埋地管道防腐保温层做出有效评价,从间接检测与开挖检测2个方面,结合现场检测数据,提出了基于防腐保温层的电流衰减率、绝缘电阻率、质量状况与厚度的分级评价标准及基于4种评价指标的综合评判方法。工程实践表明,该评价标准对防腐保温层是否存在失效能做出有效判断。 相似文献
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介绍了城市轨道交通工程中杂散电流不同的监测系统的构成,分析了集中式、分散式和智能型等监测系统的配置和功能,以及智能型实时在线监测系统的重要意义,为轨道交通工程杂散电流监测系统的选择与应用提供参考。 相似文献
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Joseph N. Prashker 《Transportation》1979,8(4):329-346
Reliability of travel modes was found to be the most important characteristic of transportation systems in several attitudinal investigations of individual travel behavior. This paper represents the first part of a research effort aimed at gaining a better understanding of the characteristics of reliability of transportation modes in urban travel. In this research, reliability characteristics are identified; their importance relative to each other is assessed, and an insight into possible structure of an objective reliability index is discussed. The research is based on perceived values of reliability, which were identified through a large attitudinal survey conducted in the Chicago metropolitan area. 相似文献
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