The Sluice Gate with Freight Carts is the earliest extant scroll in China that depicted a water mill.It was drawn during the early or middle Northern Song dynasty and was possibly a true portrayal of the West Water Mi...The Sluice Gate with Freight Carts is the earliest extant scroll in China that depicted a water mill.It was drawn during the early or middle Northern Song dynasty and was possibly a true portrayal of the West Water Mill Office.The copresence of a banquet scene of the Northern Song dynasty’s scholar-officials and a water mill both suggests a realistic reproduction of a specific scene and indicates the significance of the water mill as a cultural space.The Northern Song dynasty’s government-operated water mills were especially noticeable in the Capital Circuit京畿路,whose center was Dongjing东京.The basic development path of government-operated water mills in the inner and outer city of Dongjing was first from grain processing,which supplied the needs of the imperial palace,to tea processing,in which the governmental commercial capital also participated.Regarding city space and the use of water sources,the development spread from the north of the city to the south.Other prefectures outside Dongjing also had government-operated water mills—some brought income that could be used as official fiscal expenditure,including military expenditure,and were used to satisfy the need of local people’s livelihood,while some were used to serve the monopoly policy of tea and demonstrate the benevolent governance of local officials.In the Northern Song dynasty,the water mill was no longer merely a production site;rather,it was also a cultural space that integrated a natural background and artificial ingenuity.Closely related to the hosting of emperors and the garden making,sightseeing,feasting,and drinking of scholar-officials,along with the festival activities of locals,the water mill in the Northern Song dynasty was of great cultural significance.展开更多
In this study,the main properties of the hydraulic jump in an asymmetric trapezoidal flume are analyzed experimentally,including the so-called sequent depths,characteristic lengths,and efficiency.In particular,an asym...In this study,the main properties of the hydraulic jump in an asymmetric trapezoidal flume are analyzed experimentally,including the so-called sequent depths,characteristic lengths,and efficiency.In particular,an asymmetric trapezoidal flume with a length of 7 m and a width of 0.304 m is considered,with the bottom of the flume transversely inclined at an angle of m=0.296 and vertical lateral sides.The corresponding inflow Froude number is allowed to range in the interval(1.40<F1<6.11).The properties of this jump are compared to those of hydraulic jumps in channels with other types of cross-sections.A relationship for calculating hydraulic jump efficiency is proposed for the considered flume.For F1>5,the hydraulic jump is found to be more effective than that occurring in triangular and symmetric trapezoidal channels.Also,when■mes>8 and■>5,the hydraulic jump in the asymmetrical trapezoidal channel downstream of a parallelogram sluice gate is completely formed as opposed to the situation where a triangular sluice is considered.展开更多
The turbulent flow discharging under a sluice gate is one kind of typical flows with complicated boundaries in hydraulic and hydroelectric engineering, and the characteristics of its flow field and flow evolution are ...The turbulent flow discharging under a sluice gate is one kind of typical flows with complicated boundaries in hydraulic and hydroelectric engineering, and the characteristics of its flow field and flow evolution are important in engineering hydraulics. Although there were many studies in this regard, which mainly focus on the discharge capacity, the local scour and the mean flow field, some issues remain to be further investigated, for example, the variation of the mechanical energy during the scouring process, and the adjustment of the unsteady turbulent flow after the local scour with the downstream steady uniform flow. In this paper, the turbulent flow behind a sluice gate is divided into a rapidly varied flow region and a gradually varied flow region, and the above problems are investigated by theoretical analysis and numerical simulation. The main conclusions are as follows：（1） In the discharging process of the turbulent flow under a sluice gate, the river bed would be scoured continuously and the water–air interface is adjusted accordingly, which leads to a decrease of the mechanical energy of the total flow in the rapidly varied flow region, and the mechanical energy loss would also decrease with the increase of the time, yet the variation of the flow discharge under the sluice gate is very small.（2） In the link between the rapidly varied flow and the uniform flow downstream, the mean wall shear stress and the coefficient for the mechanical energy loss would decrease in the longitudinal direction, the decay of the turbulent kinetic energy near the free surface is much more significant than that near the bed in the longitudinal direction, and the mean turbulent kinetic energy in the section would decrease in the longitudinal direction and the decreasing rate is smaller than that of the mean wall shear stress.展开更多
In the concrete water conservancy construction, the sluice is widely used in various water conservancy projects, which has irreplaceable significance. If there is a certain problem in the sluice, it will inevitably ca...In the concrete water conservancy construction, the sluice is widely used in various water conservancy projects, which has irreplaceable significance. If there is a certain problem in the sluice, it will inevitably cause serious consequences to the whole project, and will also cause some potential safety hazards to the downstream area. More seriously, it will cause the lives and property of the residents to be threatened, thus causing serious economic losses and seriously hindering the development of society. In order to solve this problem, we must do a good job in the reinforcement design of water conservancy projects, carry out a comprehensive design of the reinforcement work of the sluice in strict accordance with various engineering standards, and ensure the smooth progress of water conservancy projects.展开更多
Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) w...Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) weirs. However, the scale effects downstream of these single-type weirs have not been thoroughly investigated. This study examined the scale effects on flows over a combined weir system consisting of an ogee weir and a sharp-crested weir, both upstream and downstream, utilizing physical modeling at a 1:33.33 scale based on Froude similarity and three-dimensional (3D) computational fluid dynamics (CFD) modeling. The sharp-crested weir in this study was represented by two sluice gates that remain closed and submerged during flood events. The experimental data confirmed that the equivalent discharge coefficients of the combined weir system behaved similarly to those of a sharp-crested weir across various H/P (where H is the total head, and P is the weir height) values. However, scale effects on the discharge rating curve due to surface tension and viscosity could only be minimized when H/P > 0.4, Re > 26 959, and We > 240 (where Re and We are the Reynolds and Weber numbers, respectively), provided that the water depth exceeded 0.042 m above the crest. Additionally, Re greater than 4 × 104 was necessary to minimize scale effects caused by viscosity in flows in the spillway channel and stilling basin (with baffle blocks). The limiting criteria aligned closely with existing literature. This study offers valuable insights for practical applications in hydraulic engineering in the future.展开更多
文摘The Sluice Gate with Freight Carts is the earliest extant scroll in China that depicted a water mill.It was drawn during the early or middle Northern Song dynasty and was possibly a true portrayal of the West Water Mill Office.The copresence of a banquet scene of the Northern Song dynasty’s scholar-officials and a water mill both suggests a realistic reproduction of a specific scene and indicates the significance of the water mill as a cultural space.The Northern Song dynasty’s government-operated water mills were especially noticeable in the Capital Circuit京畿路,whose center was Dongjing东京.The basic development path of government-operated water mills in the inner and outer city of Dongjing was first from grain processing,which supplied the needs of the imperial palace,to tea processing,in which the governmental commercial capital also participated.Regarding city space and the use of water sources,the development spread from the north of the city to the south.Other prefectures outside Dongjing also had government-operated water mills—some brought income that could be used as official fiscal expenditure,including military expenditure,and were used to satisfy the need of local people’s livelihood,while some were used to serve the monopoly policy of tea and demonstrate the benevolent governance of local officials.In the Northern Song dynasty,the water mill was no longer merely a production site;rather,it was also a cultural space that integrated a natural background and artificial ingenuity.Closely related to the hosting of emperors and the garden making,sightseeing,feasting,and drinking of scholar-officials,along with the festival activities of locals,the water mill in the Northern Song dynasty was of great cultural significance.
文摘In this study,the main properties of the hydraulic jump in an asymmetric trapezoidal flume are analyzed experimentally,including the so-called sequent depths,characteristic lengths,and efficiency.In particular,an asymmetric trapezoidal flume with a length of 7 m and a width of 0.304 m is considered,with the bottom of the flume transversely inclined at an angle of m=0.296 and vertical lateral sides.The corresponding inflow Froude number is allowed to range in the interval(1.40<F1<6.11).The properties of this jump are compared to those of hydraulic jumps in channels with other types of cross-sections.A relationship for calculating hydraulic jump efficiency is proposed for the considered flume.For F1>5,the hydraulic jump is found to be more effective than that occurring in triangular and symmetric trapezoidal channels.Also,when■mes>8 and■>5,the hydraulic jump in the asymmetrical trapezoidal channel downstream of a parallelogram sluice gate is completely formed as opposed to the situation where a triangular sluice is considered.
基金Project supported by the Governmental Public Industry Research Special Funds for Projects(Grant No.201101005)
文摘The turbulent flow discharging under a sluice gate is one kind of typical flows with complicated boundaries in hydraulic and hydroelectric engineering, and the characteristics of its flow field and flow evolution are important in engineering hydraulics. Although there were many studies in this regard, which mainly focus on the discharge capacity, the local scour and the mean flow field, some issues remain to be further investigated, for example, the variation of the mechanical energy during the scouring process, and the adjustment of the unsteady turbulent flow after the local scour with the downstream steady uniform flow. In this paper, the turbulent flow behind a sluice gate is divided into a rapidly varied flow region and a gradually varied flow region, and the above problems are investigated by theoretical analysis and numerical simulation. The main conclusions are as follows：（1） In the discharging process of the turbulent flow under a sluice gate, the river bed would be scoured continuously and the water–air interface is adjusted accordingly, which leads to a decrease of the mechanical energy of the total flow in the rapidly varied flow region, and the mechanical energy loss would also decrease with the increase of the time, yet the variation of the flow discharge under the sluice gate is very small.（2） In the link between the rapidly varied flow and the uniform flow downstream, the mean wall shear stress and the coefficient for the mechanical energy loss would decrease in the longitudinal direction, the decay of the turbulent kinetic energy near the free surface is much more significant than that near the bed in the longitudinal direction, and the mean turbulent kinetic energy in the section would decrease in the longitudinal direction and the decreasing rate is smaller than that of the mean wall shear stress.
文摘In the concrete water conservancy construction, the sluice is widely used in various water conservancy projects, which has irreplaceable significance. If there is a certain problem in the sluice, it will inevitably cause serious consequences to the whole project, and will also cause some potential safety hazards to the downstream area. More seriously, it will cause the lives and property of the residents to be threatened, thus causing serious economic losses and seriously hindering the development of society. In order to solve this problem, we must do a good job in the reinforcement design of water conservancy projects, carry out a comprehensive design of the reinforcement work of the sluice in strict accordance with various engineering standards, and ensure the smooth progress of water conservancy projects.
基金supported by the Ministry of Public Works and Housing of Indonesia and Parahyangan Catholic University(Grant No.II/PD/2023-07/02-SJ).
文摘Research on scale effects on flows over weirs has been conducted on a limited basis, primarily focusing on flows upstream of a single-type weir, such as ogee, broad-crested, and sharp-crested (linear and non-linear) weirs. However, the scale effects downstream of these single-type weirs have not been thoroughly investigated. This study examined the scale effects on flows over a combined weir system consisting of an ogee weir and a sharp-crested weir, both upstream and downstream, utilizing physical modeling at a 1:33.33 scale based on Froude similarity and three-dimensional (3D) computational fluid dynamics (CFD) modeling. The sharp-crested weir in this study was represented by two sluice gates that remain closed and submerged during flood events. The experimental data confirmed that the equivalent discharge coefficients of the combined weir system behaved similarly to those of a sharp-crested weir across various H/P (where H is the total head, and P is the weir height) values. However, scale effects on the discharge rating curve due to surface tension and viscosity could only be minimized when H/P > 0.4, Re > 26 959, and We > 240 (where Re and We are the Reynolds and Weber numbers, respectively), provided that the water depth exceeded 0.042 m above the crest. Additionally, Re greater than 4 × 104 was necessary to minimize scale effects caused by viscosity in flows in the spillway channel and stilling basin (with baffle blocks). The limiting criteria aligned closely with existing literature. This study offers valuable insights for practical applications in hydraulic engineering in the future.
