Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regu...Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regularity of its surface change, the suitable sectional dimensions of open channel or flood control work can be designed. Commonly, computation of non-uniform flow adopts the traditional methods by hand or by graphic method. The speed and precision of computation are restricted. In this paper, a software to calculate water surface profile is introduced. The software is put forward by using C++ .By means of interpolate method and dialogue between user and computer, we can calculate the water surface profile much more quickly and exactly.展开更多
Elbow-inlet passage is widely used in large drainage pumping stations.Flow uniformity at the exit section directly determines its hydraulic performance.Flow uniformity must be optimized to improve the operational effi...Elbow-inlet passage is widely used in large drainage pumping stations.Flow uniformity at the exit section directly determines its hydraulic performance.Flow uniformity must be optimized to improve the operational efficiency of the large axial-flow pumping station.Modeling and numerical simulation methods were used to investigate the elbow-inlet passage,and the accuracy of the calculation results was verified.The key geometric parameters affecting the uniformity of the flow were optimized by the orthogonal experiment design.The optimal schemes were obtained and compared with the original scheme.The results show that flow uniformity V u after optimization is 95.41%,which is increased by 1.04%.The pumping station efficiency is increased by 1.89%,thereby confirming the applicability and accuracy of the proposed scheme,especially for the optimization of flow uniformity of the exit section of the elbow-inlet passage.展开更多
A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature de...A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.展开更多
天然河流水流会挟带大量泥沙,这种泥沙运动会影响水流结构和河床,因此研究泥沙起动概率问题对于山洪治理、水力发电以及水库淤积等具有重要意义。采用滚动或者滑动的运动模式,结合泥沙颗粒水流推移力、水流上举力和泥沙自身的重力与泥...天然河流水流会挟带大量泥沙,这种泥沙运动会影响水流结构和河床,因此研究泥沙起动概率问题对于山洪治理、水力发电以及水库淤积等具有重要意义。采用滚动或者滑动的运动模式,结合泥沙颗粒水流推移力、水流上举力和泥沙自身的重力与泥沙颗粒水下休止角之间的关系,泥沙颗粒起动时,其水平方向的推移力必须大于阻力,根据受力平衡关系式得到了泥沙颗粒起动概率积分表达式,该表达式充分揭示了泥沙颗粒的受力图景,弥补了以往起动概率公式忽略水流推移力的不足。本文建立的起动概率公式有5个参数需要确定,通过无量纲粒径参数结合试验资料,求出了起动概率公式中的水下休止角正切值变量;利用粗糙床面水流流速和紊动分布试验数据,确定了近床面的时均流速和水流方向的紊动强度;利用均匀沙起动资料结合比例法确定了水流推移力系数和水流上举力系数,以及Luque的7组实测资料和Guy的108组试验资料对本文泥沙颗粒起动概率公式进行了验证,并与爱因斯坦公式、Engelund and Fredsoe公式以及程年生等计算公式进行了比较。结果显示:研究得到的起动概率公式具有最高的计算精度。对于临界状态的泥沙颗粒,本文起动概率倾向于弱动的起动模式,而其他公式则趋向于中动起动模式;与经典的希尔兹起动概率公式比较,本文的起动概率公式可以很好地与希尔兹曲线重合,而其他公式则是一条直线,只能计算大颗粒的泥沙起动问题。展开更多
文摘Most of water flow in open channel or in river belongs to steady non-uniform flow. The surface profiles are caused by changes of channel section. It is very important to analyze its computation. According to the regularity of its surface change, the suitable sectional dimensions of open channel or flood control work can be designed. Commonly, computation of non-uniform flow adopts the traditional methods by hand or by graphic method. The speed and precision of computation are restricted. In this paper, a software to calculate water surface profile is introduced. The software is put forward by using C++ .By means of interpolate method and dialogue between user and computer, we can calculate the water surface profile much more quickly and exactly.
基金Natural Science Foundation of China(51806053)Anhui Provincial Key Research and Development Program(1804a09020012,1804a09020007)
文摘Elbow-inlet passage is widely used in large drainage pumping stations.Flow uniformity at the exit section directly determines its hydraulic performance.Flow uniformity must be optimized to improve the operational efficiency of the large axial-flow pumping station.Modeling and numerical simulation methods were used to investigate the elbow-inlet passage,and the accuracy of the calculation results was verified.The key geometric parameters affecting the uniformity of the flow were optimized by the orthogonal experiment design.The optimal schemes were obtained and compared with the original scheme.The results show that flow uniformity V u after optimization is 95.41%,which is increased by 1.04%.The pumping station efficiency is increased by 1.89%,thereby confirming the applicability and accuracy of the proposed scheme,especially for the optimization of flow uniformity of the exit section of the elbow-inlet passage.
基金Work(NRF-2012H1B8A2026145)supported by the Human Resource Training Program for Regional Innovation through the Ministry of Education and National Research Foundation of KoreaProject(2015K000281)supported by the Functional Districts of the Science Belt Support Program,Ministry of Science,ICT and Future Planning,Korea
文摘A complete control type plant factory has high efficiency in terms of cultivation area by constructing vertical multiple layered cultivation beds.However,it has a problem of irregular crop growth due to temperature deviation at upper and lower beds and increases in energy consumption by a prolonged cultivation period.In this work,air flow rate inside a facility was improved by a hybrid control of air flow devices like air conditioning and air circulation fan with an established wireless sensor network to minimize temperature deviations between upper and lower beds and to promote crop growth.The performance of proposed system was verified with an experimental environment or Case A wherein air conditioning device was operated without a control algorithm and Case B wherein air conditioning and circulation fans were alternatively operated based on the hybrid control algorithm.After planting leafy vegetables under each experimental condition,crops were cultivated for 21 days.As a result,Case B wherein AC(air conditioning) and ACF(air-circulation fan) were alternatively operated based on the hybrid control algorithm showed that fresh mass,number of leaves,and leaf length for the crops grown were increased by 40.6%,41.1%,and 11.1%,respectively,compared to Case A.
文摘天然河流水流会挟带大量泥沙,这种泥沙运动会影响水流结构和河床,因此研究泥沙起动概率问题对于山洪治理、水力发电以及水库淤积等具有重要意义。采用滚动或者滑动的运动模式,结合泥沙颗粒水流推移力、水流上举力和泥沙自身的重力与泥沙颗粒水下休止角之间的关系,泥沙颗粒起动时,其水平方向的推移力必须大于阻力,根据受力平衡关系式得到了泥沙颗粒起动概率积分表达式,该表达式充分揭示了泥沙颗粒的受力图景,弥补了以往起动概率公式忽略水流推移力的不足。本文建立的起动概率公式有5个参数需要确定,通过无量纲粒径参数结合试验资料,求出了起动概率公式中的水下休止角正切值变量;利用粗糙床面水流流速和紊动分布试验数据,确定了近床面的时均流速和水流方向的紊动强度;利用均匀沙起动资料结合比例法确定了水流推移力系数和水流上举力系数,以及Luque的7组实测资料和Guy的108组试验资料对本文泥沙颗粒起动概率公式进行了验证,并与爱因斯坦公式、Engelund and Fredsoe公式以及程年生等计算公式进行了比较。结果显示:研究得到的起动概率公式具有最高的计算精度。对于临界状态的泥沙颗粒,本文起动概率倾向于弱动的起动模式,而其他公式则趋向于中动起动模式;与经典的希尔兹起动概率公式比较,本文的起动概率公式可以很好地与希尔兹曲线重合,而其他公式则是一条直线,只能计算大颗粒的泥沙起动问题。
