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基于合流分流的多分支管路流量分配及压力损失数值研究 被引量:6
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作者 秦磊 周凡 +2 位作者 杨家幸 吴仁智 陆亮 《华南理工大学学报(自然科学版)》 EI CAS CSCD 北大核心 2021年第9期109-119,共11页
多分支管路合流分流结构能有效降低管路密度,提升空间利用率,但不合理的结构设计容易造成过大的压力损失、过大的流量分配差异。文中提出了一种多分支管路合流分流最优化设计的数值方法,利用参数化分析法研究了雷诺数、出入口面积比、... 多分支管路合流分流结构能有效降低管路密度,提升空间利用率,但不合理的结构设计容易造成过大的压力损失、过大的流量分配差异。文中提出了一种多分支管路合流分流最优化设计的数值方法,利用参数化分析法研究了雷诺数、出入口面积比、公共腔室末端封闭腔长度、分支管间距以及分支管数量等参数对流量分配、压力损失的影响规律。结果表明:合流腔存在压力恢复区,其对各支路的流量分配及压力损失存在影响;雷诺数对流量分配存在影响,增大雷诺数会增加压力损失、增大流量分配差异;公共腔室末端封闭腔长度对流量分配、压力损失的影响可忽略;出入口面积比、分支管间距、分支管数量与流量分配、压力损失存在重要关联,管路结构的优化设计中需综合考虑这些因素。文中结果可用于指导多分支管路合流分流结构的最优化设计。 展开更多
关键词 合流分流 多分支管路 流量分配 压力损失
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离散制造车间件箱物流输送控制系统的研究与应用 被引量:5
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作者 金愔 吴双 +2 位作者 徐健 田博 蔡通通 《制造业自动化》 北大核心 2023年第4期208-212,共5页
在制造业智能化的进程中,自动化物流系统逐渐取代传统的物流方式,成为许多大型制造业企业首选的物流方式。件箱自动化物流输送系统可接收来自不同离散生产线的产品进行集中输送,同时依据要求,将产品送入不同的库区存储。输送效率和过程... 在制造业智能化的进程中,自动化物流系统逐渐取代传统的物流方式,成为许多大型制造业企业首选的物流方式。件箱自动化物流输送系统可接收来自不同离散生产线的产品进行集中输送,同时依据要求,将产品送入不同的库区存储。输送效率和过程稳定性是衡量输送系统的主要性能指标,在输送速度为定量时,控制策略将决定系统的输送效率。对某厨电制造企业的件箱物流输送系统进行了研究分析,借助PLC内部时间脉冲对传统合流与分流控制方法进行改进,设计了基于脉冲的分合流控制策略。该策略有效提升了件箱输送系统整体的输送效率,满足了生产节拍需求,同时显著提高了合流分流的准确性。 展开更多
关键词 件箱输送系统 合流分流 控制策略 脉冲控制
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有关小区排水分流改造的常见问题及解决措施
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作者 李姣妮 《低碳世界》 2014年第09X期17-18,共2页
根据小区内部排水管网和外部市政管网的排水分流合流情况,分为四类,并针对每一类情况提出具体的解决思路。列举了设计过程中遇到的14种典型问题,并提出解决措施。
关键词 雨污水分流 改造 四类分流合流情况 14种典型问题
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养护工程交通流状态下施工行车的安全风险分析
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作者 王海生 《交通世界》 2023年第21期11-13,共3页
结合某国道双向四车道公路养护工程实践,针对养护工程交通流状态下施工行车安全风险进行探究,系统分析了养护施工区域车流跟行、分流运行状况,指出了养护施工区域存在的行车风险,提出了养护分流、合流方案及行车风险控制措施,旨在提升... 结合某国道双向四车道公路养护工程实践,针对养护工程交通流状态下施工行车安全风险进行探究,系统分析了养护施工区域车流跟行、分流运行状况,指出了养护施工区域存在的行车风险,提出了养护分流、合流方案及行车风险控制措施,旨在提升公路养护效率,确保交通通行安全。 展开更多
关键词 公路养护工程 施工区域 交通流状态 合流分流 行车风险
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地下道路出入口设计的相关研究 被引量:10
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作者 秦云 张天然 刘艺 《城市道桥与防洪》 2006年第4期160-161,167,共3页
该文提出了地下道路出入口布置的基本原则和方法,比较了直接式和平行式变速车道、分离式和整合式分流合流布置形式的优缺点和适用条件,分析了不同情况下出入口视距设计保障和过渡段设计要求。
关键词 地下道路 多点进出 出入口设计 分流合流
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事故影响下路径走行时间演变的拟动态模型
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作者 陈玲娟 蒲云 刘海旭 《交通运输系统工程与信息》 EI CSCD 北大核心 2012年第1期111-118,共8页
为描述交通事故影响下路网中走行时间与用户择路概率的相互作用及其演变规律,建立了基于事故路段及非事故路段流量状态及LOGIT原则的拟动态模型.利用分流合流模型及速度—密度函数,分别建立路段容纳车辆数和非事故路段走行时间模型,通... 为描述交通事故影响下路网中走行时间与用户择路概率的相互作用及其演变规律,建立了基于事故路段及非事故路段流量状态及LOGIT原则的拟动态模型.利用分流合流模型及速度—密度函数,分别建立路段容纳车辆数和非事故路段走行时间模型,通过分析事故路段交通流的演化过程,利用交通波理论估计排队长度,建立事故路段走行时间模型.结果表明:事故发生前,经过一定的模拟时段后,路网交通流趋近稳定,各条路径的选择概率趋于平衡;事故持续时段内,排队长度、路径走行时间、路径选择概率相互影响,且均呈现出震荡状态;事故清除后,路径走行时间持续下降;排队完全消散后,经过一定时段稳定后的路径走行时间和路径选择概率达到新的平衡. 展开更多
关键词 交通工程 拟动态模型 合流-分流模型 路网走行时间 速度密度关系
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CFD-supported optimization of flow distribution in quench tank for heat treatment of A357 alloy large complicated components 被引量:2
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作者 杨夏炜 朱景川 李文亚 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第10期3399-3409,共11页
The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics(CFD) software.The flow velocity and the uniformity of flow f... The flow distribution in quench tank for heat treatment of A357 alloy large complicated components was simulated using FLUENT computational fluid dynamics(CFD) software.The flow velocity and the uniformity of flow field in two types of quench tanks(with or without agitation system) were calculated.The results show that the flow field in the quench tank without agitation system has not evident regularity.While as for the quench tank with agitation system,the flow fields in different parameters have certain regularity.The agitation tanks have a distinct advantage over the system without agitation.Proper process parameters were also obtained.Finally,the tank model established in this work was testified by an example from publication.This model with high accuracy is able to optimize the tank structures and can be helpful for industrial production and theoretical investigation in the fields of heat treatment of large complicated components. 展开更多
关键词 A357 alloy flow distribution quench tank computational fluid dynamics(CFD) simulation
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EXPERIMENT ON FLOW CHARACTERISTICS OF SYNTHETIC JET DRIVEN BY PIEZOELECTRIC MEMBRANE
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作者 谭晓茗 张靖周 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2007年第3期199-204,共6页
The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry (PIV) and the hot-wire anem... The characteristics of the flowfields of a synthetic jet actuator are experimentally investigated with the slot-nozzle driven by the piezoelectric membrane. The particle image velocimetry (PIV) and the hot-wire anemometer are utilized to measure the flowfields and the velocity profiles of the actuator with different actuating factors. Analytical results show that pairs of counter-rotating vortices are generated near the nozzle. With the development of the synthetic ject, the synthetic jet rapidly spreads in the slot-width direction; while in the slot-length direction, it contracts firstly and slowly spreads. The centerline velocity distribution has a up-down tendency varying with axial distances, and accelerates to its maximum at z/b= 10. The transverse velocity profile across the slot-width is centro-symmetric and self-similar. However, the velocity profiles across the slot-length are saddle-like near the nozzle. It shows that there are two resonance frequencies for the actuator. If the actuator works with the resonance frequency, the vorticity and the velocity of the synthetic jet are higher than those of other frequencies. Compared with the continuous jet, the synthetic jet shows special flow characteristics. 展开更多
关键词 synthetic jet flow characteristics velocity distribution particle image velocimetry
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New technique for preparing A356 alloy semisolid slurry and its rheo-diecast microstructure and properties 被引量:9
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作者 Ming-fan QI Yong-lin KANG +2 位作者 Yu-zhao XU Jing-yuan LI Ai-sen LIU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第7期1868-1884,共17页
A new technique for preparing semisolid slurry,namely,distributary-confluence runner(DCR),was combined with die-casting(DC)to conduct rheological die-casting(R-DC)of A356 alloy.The mechanism of DCR for semisolid slurr... A new technique for preparing semisolid slurry,namely,distributary-confluence runner(DCR),was combined with die-casting(DC)to conduct rheological die-casting(R-DC)of A356 alloy.The mechanism of DCR for semisolid slurry preparation was determined via numerical simulations and experiments.The microstructure and mechanical properties of A356 alloys prepared via DC and R-DC were studied.High-quality slurry containing numerous primary α-Al(α1-Al)with an average size of 49μm and a shape factor of 0.81 could be prepared via DCR.Simulation results indicated that the unique flow state and physical field changes during slurry preparation were conducive to accelerating the uniformity of melt temperature and composition fields,nucleation exfoliation,and spherical growth.Compared with the alloy prepared via DC,the tensile strength,yield strength,and elongation of A356 alloy prepared via R-DC increased by 19%,15%,and 107%,respectively. 展开更多
关键词 semisolid slurry A356 alloy distributary-confluence runner rheological die-casting microstructure tensile properties
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Effects of different poses and wind speeds on flow field of dish solar concentrator based on virtual wind tunnel experiment with constant wind 被引量:5
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作者 LIU Guan-lin E Jia-qiang +2 位作者 LIU Teng ZUO Wei ZHANG Qing-ling 《Journal of Central South University》 SCIE EI CAS CSCD 2018年第8期1948-1957,共10页
In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel ... In order to improve structure performance of the dish solar concentrator,a three-dimensional model of dish solar concentrator was established based on the high-precision numerical algorithms.And a virtual wind tunnel experiment with constant wind is adopted to investigate the pressure distribution of the reflective surface,velocity distribution of the fluid domain for the dish solar concentrator in different poses and wind speeds distribution.Some results about wind pressure distribution before and after dish solar concentrator surface and wind load velocity distribution in the entire fluid domain had been obtained.In particular,it is necessary to point out that the stiffness at the center of the dish solar concentrator should be relatively raised.The results can provide a theoretical basis for the improvement of solar concentrator dish structure as well as the failure analysis of dish solar concentrator in engineering practice. 展开更多
关键词 CONCENTRATOR fluid–solid interaction pressure distribution velocity distribution virtual wind tunnel experiment
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Fathal pulmonary hypertension after distal splenorenal shunt in schistosomal portal hypertension 被引量:1
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作者 Roberto de Cleva Paulo Herman +3 位作者 Vincenzo Pugliese Bruno Zilberstein William Abro Saad Joaquim JoséGama-Rodrigues 《World Journal of Gastroenterology》 SCIE CAS CSCD 2004年第12期1836-1837,共2页
Mansonic schistosomiasis is the main cause of portal hypertension in Brazil. Hepatosplenic (HS) form is manifested by hepatomegaly mainly on the left hepatic lobe associated with large splenomegaly and bleeding due to... Mansonic schistosomiasis is the main cause of portal hypertension in Brazil. Hepatosplenic (HS) form is manifested by hepatomegaly mainly on the left hepatic lobe associated with large splenomegaly and bleeding due to esophageal varices with high mortality rates. 展开更多
关键词 ADULT Fatal Outcome Female Humans Hypertension Portal Hypertension Pulmonary Male Postoperative Complications Schistosomiasis mansoni Splenorenal Shunt Surgical
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Is Terzaghi's effective stress a stress variable under seepage conditions? 被引量:1
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作者 雷国辉 赵仲辉 吴宏伟 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第6期2316-2321,共6页
From the continuum mechanics perspective, an attempt was made to clarify the role of Terzaghi's effective stress in the theoretical analysis of saturated soil subjected to seepage. The necessity of performing a co... From the continuum mechanics perspective, an attempt was made to clarify the role of Terzaghi's effective stress in the theoretical analysis of saturated soil subjected to seepage. The necessity of performing a coupled hydromechanical analysis to solve the seepage-deformation interaction problem was illustrated by examining the equations of static equilibrium among the effective stress, seepage force, pore-water pressure and total stress. The conceptual definition of stress variable that satisfies the principles of continuum mechanics is applied in the coupled hydromechanical analysis. It is shown that Terzaghi's effective stress is in fact not a stress variable under seepage conditions, and the seepage force acting on the soil skeleton cannot be viewed as a body force. This offers a clue to the underlying cause of a paradox between the real Pascal's hydrostatic state and the hydrostatic state predicted by a class of continuum hydromechanical theories. 展开更多
关键词 seepage-deformation interaction coupled hydromechanical analysis representative elementary volume stress variable stress state variable
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Fluid solid coupling model based on endochronic damage for roller compacted concrete dam 被引量:4
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作者 顾冲时 魏博文 +1 位作者 徐镇凯 刘大文 《Journal of Central South University》 SCIE EI CAS 2013年第11期3247-3255,共9页
According to the characteristics of thin-layer rolling and pouting construction technology and the complicated mechanical behavior of the roller compacted concrete dam (RCCD) construction interface, a constitutive m... According to the characteristics of thin-layer rolling and pouting construction technology and the complicated mechanical behavior of the roller compacted concrete dam (RCCD) construction interface, a constitutive model of endochronic damage was established based on the endochronic theory and damage mechanics. The proposed model abandons the traditional concept of elastic-plastic yield surface and can better reflect the real behavior of rolled control concrete. Basic equations were proposed for the fluid-solid coupling analysis, and the relationships among the corresponding key physical parameters were also put forward. One three-dimensional finite element method (FEM) program was obtained by studying the FEM type of the seepage-stress coupling intersection of the RCCD. The method was applied to an actual project, and the results show that the fluid-solid interaction influences dam deformation and dam abutment stability, which is in accordance with practice. Therefore, this model provides a new method for revealing the mechanical behavior of RCCD under the coupling field. 展开更多
关键词 roller compacted concrete dam endochronic damage fluid-solid coupling analytical model
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Comparison of the Reynolds-averaged Turbulence Models on Single Phase Flow Simulation in Agitated Extraction Columns 被引量:4
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作者 尤学一 H.J.Bart 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2003年第3期362-366,共5页
The flow field of liquid phase (water) of agitated extraction columns is simulated with the help of computational fluid dynamics (CFD). Four kinds of Reynolds-averaged turbulence models, i.e. the standard k-ε model, ... The flow field of liquid phase (water) of agitated extraction columns is simulated with the help of computational fluid dynamics (CFD). Four kinds of Reynolds-averaged turbulence models, i.e. the standard k-ε model, the RNG (renormalization group) k-s model, the realizable k-ε model and the Reynolds stress model, are compared in detail in order to judge which is the best model in terms of the accuracy, less CPU time and memory required. The performance of the realizable k-s model is obviously improved by reducing the model constant from C2 = 1.90 to C2 = 1.61. It is concluded that the improved realizable k-e model is the optimal model. 展开更多
关键词 agitated extraction column turbulence models computational fluid dynamics
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Numerical Study of the Mixing of Density-Stratified Fluid with a Jet
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作者 Shogo Shakouchi Seiji Shimada Tomomi Uchiyama 《Journal of Mechanics Engineering and Automation》 2014年第10期789-798,共10页
Density stratification of LNG (liquefied natural gas) is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is conside... Density stratification of LNG (liquefied natural gas) is produced in a storage tank when one LNG is loaded on top of another LNG in the same tank. Mixing LNG by a jet issued from a nozzle on the tank wall is considered to a promising technique to prevent and eliminate stratification in LNG storage tanks. This study is concerned with the numerical simulation of a jet flow issued into a two-layer density-stratified fluid in a tank and the resultant mixing phenomena. The jet behavior was investigated with the laboratory-based experiment of the authors' previous study. A numerical method proposed by the authors is employed for the simulation. The upper and lower fluids are water and a NaCl-water solution, respectively, and the lower fluid is issued vertically upward from a nozzle on the bottom of the tank. The Reynolds number (Re) defined by the jet velocity and the nozzle diameter ranges from 95 to 2,378, and the mass concentration of the NaCl-water solution Co is set at 0.02 and 0.04. The simulation highlights the jet-induced mixing between the upper and lower fluids. It also clarifies the effects of Re and C0 on the height and horizontal spread of the jet. 展开更多
关键词 MIXING density-stratified fluid JET CFD (computational fluid dynamics) internal density current.
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生活区中排水设计应注意的问题
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作者 张铭 《中国房地产业》 1998年第11期45-45,共1页
在平时的生活和工作中,我们经常发现居住小区排水系统跑、冒、堵等现象,既妨碍了住户的正常使用,又影响了小区的环境,尤其是在炎热的夏季,更是小区居民提出的焦点问题。通过实地观察和多年的工作经验我认为,除住户使用不当外,发生这种... 在平时的生活和工作中,我们经常发现居住小区排水系统跑、冒、堵等现象,既妨碍了住户的正常使用,又影响了小区的环境,尤其是在炎热的夏季,更是小区居民提出的焦点问题。通过实地观察和多年的工作经验我认为,除住户使用不当外,发生这种情况的主要原因有:一是施工单位施工粗糙、质量不过关;二是设计的不合理。现就生活区排水设计提出几点看法。 居住区内的排水主要是雨水和生活污水的排除。排水系统有分流与合流两种。 展开更多
关键词 排水设计 应注意的问题 生活区 排水系统 分流合流 生活污水 排水管道 居住小区 检查井 工作经验
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Numerical Analysis of Emergency River Restoration Scheme for Qingping Mega Debris Flow 被引量:2
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作者 CHEN Ri-dong LIU Xing-nian +1 位作者 HUANG Er GUO Zhi-xue 《Journal of Mountain Science》 SCIE CSCD 2013年第1期130-136,共7页
The mega debris flow occurred on August 13 th 2010 in Qingping town,China(hereafter called '8.13' Debris Flow) have done great damage to the local habitants as well as to the re-construction projects in the qu... The mega debris flow occurred on August 13 th 2010 in Qingping town,China(hereafter called '8.13' Debris Flow) have done great damage to the local habitants as well as to the re-construction projects in the quake-hit areas,and the channel-fill deposit problem caused by the debris flow was the most destructive.Moreover,it is of high possibility that an even severe deposit problem would reappear and result in worse consequences.In order to maximize risk reduction of this problem,relevant departments of the government established a series of emergency river restoration schemes,for which the numerical analysis is an important procedure to evaluate and determine the optimized one.This study presents a numerical analysis by applying a twodimensional debris flow model combined with a relevant water-sediment model to simulate the deposit during the progress of the debris flow,and to calculate and analyze the river flow field under both the present condition and different restoration conditions.The results show that the debris flow model,which takes the confluence of the Wenjia Gully to the main river into account,could simulate the deposit process quite well.In the reproduced debris flow from the simulation of the '8.13' Debris Flow,the original river flow path has switched to a relatively lower place just along the right bank with a high speed of near 7m.s-1 after being blocked by the deposit,which is highly hazardous.To prevent this hazard,a recommended scheme is derived through inter-comparison of different restoration conditions.It shows that the recommended scheme is able to reduce the water level and as well to regulate the flow path.Based on the given conditions of the mainstream and the tributary confluence for the simulated '8.13' Debris Flow,when encountering a debris flow with deposit volume less than 0.5 million m3,the river channel can endure a 20-year return flood;however,when the deposit volume increases to 2 million m3,the flood capacity of the river will be greatly impacted and the scheme becomes invalid.The recommended scheme supported by the present study has been applied to the emergency river restoration after this mega-debris flow. 展开更多
关键词 Flash flood Debris flow River restoration Numerical analysis Finite element method
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Temperature distribution of the incompletely mixed fluid flowing in the tubes and the unmixed fluid crossing over the tubes 被引量:1
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作者 WANG Jun CHEN Liang-cai +2 位作者 HE Wei FENG Xtao-qiang LIU Wei 《Journal of Energy and Power Engineering》 2007年第1期49-56,共8页
A new model is established to describe heat exchanging of the incompletely mixed fluid flowing in the tubes and the unmixed fluid crossing out of the tubes in the heat-exchangers especially in air cooler. In the model... A new model is established to describe heat exchanging of the incompletely mixed fluid flowing in the tubes and the unmixed fluid crossing out of the tubes in the heat-exchangers especially in air cooler. In the model, a new method of analyzing volume is proposed to develop the temperature distribution equations of the two fluids --tw(x) and ta(X,,7"). With tw(x) and ta (x, ,7), the curves of the temperature distribution of the two fluids can be obtained. Also tw(x) and ta(x,n) can be used to calculate parameters of structure of an air cooler and to improve performances of it. 展开更多
关键词 air cooler heat-exchangers temperature distribution analyzing volume
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Study of the Jet-Induced Mixing of Two-Layer Density-Stratified Fluid in a Rectangular Tank
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作者 Shogo Shakouchi Shota Fukue Tomomi Uchiyama 《Journal of Energy and Power Engineering》 2015年第2期117-127,共11页
The mixing phenomena of a two-layer density-stratified fluid induced by a jet in a tank are experimentally investigated. The upper and lower fluids are water and a NaCl-water solution, respectively, with the lower flu... The mixing phenomena of a two-layer density-stratified fluid induced by a jet in a tank are experimentally investigated. The upper and lower fluids are water and a NaCl-water solution, respectively, with the lower fluid issued vertically upward from a nozzle at the bottom of the tank. The jet Reynolds number Re, defined by the jet velocity and the water kinematic viscosity, ranges from 90 to 4,200. The mass concentration of the NaCl-water solution Co is less than 0.08. The flow visualization makes clear the jet behavior relative to the density interface between the upper and lower fluids. The measurement of the concentration distribution of the water paint issued with the jet highlights the effects of Re and Co on the mixing between the jet and the ambient fluid. The measurement of the fluid velocity distribution with a PIV (particle image velocimetry) system successfully elucidates the relationship between the velocity field and the resultant mixing. 展开更多
关键词 JET density-stratified fluid MIXING INTRUSION CONCENTRATION PIV.
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探讨国省干线公路养护项目交通流状态下施工行车的安全风险
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作者 王涛 《交通科技与管理》 2022年第16期174-176,共3页
国省干线公路养护段施工区,易影响其行车环境改变,不利于车辆进出。国省干线公路养护区交通流状态下施工行车,需结合车辆运行状态、环境特殊性,对国省干线公路养护方案合理优化。文章以某双向四车道国省干线公路养护施工案例为基础,对... 国省干线公路养护段施工区,易影响其行车环境改变,不利于车辆进出。国省干线公路养护区交通流状态下施工行车,需结合车辆运行状态、环境特殊性,对国省干线公路养护方案合理优化。文章以某双向四车道国省干线公路养护施工案例为基础,对交通控制区域划分前提下国省干线公路养护区车流跟行、分流运行状况加以分析,指出交通风险因素和车辆避免冲突的约束条件,通过国省干线公路养护分流、合流方案及行车风险控制策略的控制,为国省干线公路养护效率提升奠定基础。 展开更多
关键词 国省干线公路 养护施工区 强制变换车道 合流分流 行车风险
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