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1
Zhuk, Volodymyr, Ivan Matlai, Ihor Popadiuk, Lesiia Vovk et Vladyslav Rehush. « Discharge coefficient of broad-crested weirs as a function of the relative weir height for different weir lengths ». Theory and Building Practice 2020, no 2 (20 novembre 2020) : 63–68. http://dx.doi.org/10.23939/jtbp2020.02.063.
Texte intégralRésumé :
Broad-crested weirs (BCW) are often used in hydraulic engineering and water management. The most complex factor that affects the discharge capacity of BCW is the discharge coefficient. In Ukrainian engineering practice, the flow rate of BCW is defined as a function of the relative height of the spillway wall, while in the most common European methods – as a function of the relative length of the weir. The experimental dependences of the discharge coefficient of rectangular sharp-edged BCW with vertical inlet and outlet walls with the ratio of the weir length and height d/Р = 2; 4 are obtained. A comparison of the obtained results with the values of the discharge coefficient of the same BCW using the methods of Kumin and Hager indicates that this coefficient depends on both the height of the wall and the length of the weir. The corresponding empirical power law dependences are obtained. At the same values of the relative height of the wall, the discharge coefficient for the weir with the ratio d/Р = 4 is significantly lower comparing the weir with d/Р = 2, that can be explained by the more significant effect of friction resistance for the weir with longer threshold.
2
Bhukya, Raj Kumar, Manish Pandey, Manousos Valyrakis et Panagiotis Michalis. « Discharge Estimation over Piano Key Weirs : A Review of Recent Developments ». Water 14, no 19 (26 septembre 2022) : 3029. http://dx.doi.org/10.3390/w14193029.
Texte intégralRésumé :
The piano key (PK) weir has advanced over the labyrinth weir to increase the discharge capacity. Piano key weirs exhibit nonlinear flow behavior and are easy to place on the existing spillway or newly constructed dam with less base area. Various investigators are given equations to calculate the discharge coefficient for free and submerged flow conditions. The study focuses on reviewing the impacts of the PK weir geometry on the weir flow discharge coefficient, including weir length and height, upstream and downstream key widths, and apex overhangs. In this study, all possible aspects of PK weirs were briefly reviewed. From sensitivity analysis, it is observed that the discharge coefficient of the PK weir is more sensitive for the L/W dimensionless ratio followed by the B/P ratio. L is total length of the weir crest, W is width of the weir, B is total width of PK weir and P is height of the weir. This review paper is intended to serve as an accessible resource for hydraulic structures researchers and hydraulic engineering professionals alike interested in the hydraulics of PK weirs.
3
Emiroglu, M. Emin, et Ahmet Baylar. « Experimental Study of the Influence of Different Weir Types on the Rate of Air Entrainment ». Water Quality Research Journal 38, no 4 (1 novembre 2003) : 769–83. http://dx.doi.org/10.2166/wqrj.2003.048.
Texte intégralRésumé :
Abstract Aeration is used in water treatment to alter the concentration of dissolved gases, to strip volatile organics, and to reduce tastes and odours. This can be obtained by creating turbulence in the water. One method of producing such turbulence is via the overflow jets downstream of weir structures. This paper investigates the effect of varying weir types on the air entrainment rate. Empirical correlations predicting the maximum penetration depth and air entrainment rate were developed for different weir types. It is demonstrated that the air entrainment rate of the broad-crested weirs is generally much better than for the sharp-crested weir and the labyrinth weirs. The air entrainment rate increased as the weir longitudinal slope of the broad-crested weirs and the weir sill slope of the labyrinth weirs became larger.
4
Al Babely, Emad Abdul-Gabbar, Adnan Abdul-Wahab Al Muhammad et Mohammad A. Al Dabbagh. « Overflow Characteristic of Cylindrical Shape Crest Weirs over Horizontal Bed ». Tikrit Journal of Engineering Sciences 18, no 4 (31 décembre 2011) : 29–39. http://dx.doi.org/10.25130/tjes.18.4.04.
Texte intégralRésumé :
The most common types of weirs are the broad-crested weir, the sharp-crested weir, the circular crested weir and the ogee crested weir. Advantages of the cylindrical weir shape include the stable overflow pattern, the ease to pass floating debris, the simplicity of design compared to ogee crest design and the associated lower costs. In present study, it was investigated the overflow characteristics of circular weirs in laboratory for various cylinder radii of three sizes (11.4, 9.0, 6.3 cm), and the models fixed on the channel bed vertically to the direction of flow. The result shows that the increase in the ratio of head to weir radius ratio (Hw/R) value causes an increase in discharge coefficient (Cd) value for the same height of weir. It was observed that the cylinder size (i.e. radius of cylindrical weir (R)) has an effect on the (Cd). The flow magnification factor (qw/qs) increases with an increase in (Hw/R) value and values of (qw/qs) were always higher than one for all values of (Hw/R), this means that weirs of cylindrical shape performed better than those of sharp crest for any value of weir radius tested in this study
5
Vanishree, B. Rao, et R. Manjula. « Analysis of various parameters affecting weir design and fabrication of Weirs : An Overview ». MATEC Web of Conferences 144 (2018) : 01006. http://dx.doi.org/10.1051/matecconf/201814401006.
Texte intégralRésumé :
Several geometric parameters influence weir discharge and it is explained in our present study. The PK weir is more efficient than rectangular labyrinth weir due to reduction in entrance losses of PK weir inlet key geometry. PK weir is a type of labyrinth weir with variation in angle. Therefore, in this paper we also discuss about labyrinth weir. PKW are compatible for constructing on existing or new spillway with lesser space requirement and structural stability. PKW are installed in order to increase the discharge capacity for a given footprint area. PKW is used to increase the overflow capacity of existing dams such as, Hazelmare dam (South Africa), Dartmouth dam (Australia). Trapezoidal piano key weirs have higher discharge efficiency than rectangular weirs and it is due to interference wedge. Cd of TPKW is influenced by L/W but Wi/Wo has least effect.
6
Baylar, Ahmet. « An Investigation on the Use of Venturi Weirs as an Aerator ». Water Quality Research Journal 38, no 4 (1 novembre 2003) : 753–67. http://dx.doi.org/10.2166/wqrj.2003.047.
Texte intégralRésumé :
Abstract The most classic example of a hydraulic structure where gas transfer occurs is a weir. Transfer of gases between the atmosphere and river water can occur in a free overfall jet from a weir. A free overfall jet from a weir plunging into downstream water causes entrainment of air bubbles if the free overfall jet velocity exceeds the critical value where aeration occurs. This paper investigates the free overfall jets from Venturi and rectangular notch weirs and their effect on air entrainment rate. A Venturi weir was placed at the upstream channel end in order to increase the flow velocity of the free overfall jet and, in turn, to increase air entrainment. It was demonstrated that the air entrainment rate of the Venturi weir is significantly better than the rectangular notch weir, and this advantage becomes more pronounced as the throat width of the Venturi weir is decreased. These results demonstrated that Venturi weirs can be used as highly effective aerators in streams, rivers, constructed channels, fish hatcheries, water treatment plants, etc. Moreover, a regression equation was obtained for the Venturi weirs, relating air entrainment rate to unit discharge, weir crest width, drop height and throat width of Venturi weir. There was good agreement between the measured air entrainment rates and the values computed from the predictive equation.
7
Bijankhan, Mohammad, et Vito Ferro. « Dimensional analysis and stage-discharge relationship for weirs : a review ». Journal of Agricultural Engineering 48, no 1 (17 février 2017) : 1–11. http://dx.doi.org/10.4081/jae.2017.575.
Texte intégralRésumé :
Deducing the weir flow stage-discharge relationship is a classical hydraulic problem. In this regard Buckingham’s theorem of dimensional analysis can be used to find simple and accurate formulas to obtain the rating curves of different weir types. At first, in this review paper the rectangular weir that is a very common hydraulic structure is studied. It is indicated that the crest shape, approach channel width, obliquity (angle between the weir crest and the direction normal to the flow motion) and vertical inclination (pivot weir) are the key-parameters affecting the flow over the rectangular weirs. The flow over the triangular, labyrinth, parabolic, circular, elliptical, and W-weirs are also studied using dimensional analysis and incomplete self-similarity concept. For all mentioned weirs the stage-discharge relationships are presented and the application limits are discussed. The results of this paper can be used and implemented by the irrigation and drainage network designers to simplify the procedure of weir design.
8
Namaee, Mohammad Reza, Mohammad Sadegh Jalaledini, Mahdi Habibi, Saeed Reza Sabbagh Yazdi et Mona Ghafouri Azar. « Discharge coefficient of a broad crested side weir in an earthen channel ». Water Supply 13, no 1 (1 février 2013) : 166–77. http://dx.doi.org/10.2166/ws.2012.081.
Texte intégralRésumé :
Side weirs are widely used to divert flows from rivers and channels. However, the hydraulic behavior of this type of weir is complex and difficult to predict accurately. Previous studies on side weirs have generally focused on side weirs in rectangular channels with a smooth bed. However, one of the applications of side weirs is in irrigation systems which have trapezoidal cross sections and significant bed roughness. The present study investigates the hydraulic behavior of a broad crested side weir in an earthen channel with a rough bed under subcritical flow. These investigations showed that the side weir discharge coefficient is influenced by four main parameters which are upstream Froude number, ratio of the main channel width to the upstream flow depth, ratio of the length of the side weir to the main channel width and ratio of side weir height to the upstream flow depth. The results showed that the discharge coefficient of the side weir gives a lower coefficient value compared to other researchers’ equations. Nearly 90 experimental tests were carried out and finally new equations are proposed for prediction of discharge coefficient of a broad crested side weir in an earthen channel under subcritical conditions which can be mainly used in common irrigation systems.
9
Baylar, Ahmet, et M. Emin Emiroglu. « The effect of sharp-crested weir shape on air entrainment ». Canadian Journal of Civil Engineering 29, no 3 (1 juin 2002) : 375–83. http://dx.doi.org/10.1139/l02-017.
Texte intégralRésumé :
Aeration in the waters of rivers and streams is very important to the quality and existence of aquatic life. If the overfall jets downstream of weir structures plunges into a plunge pool, entrained air bubbles will contribute to aeration. This paper investigates sharp-crested weirs having different cross-sectional geometry and their effect on the air entrainment rate. It is demonstrated that the air entrainment rate of a 30° triangular sharp-crested weir is better than that of the other sharp-crested weirs tested. Moreover, variation in the number of V-notches over the width of the weir plate was studied for 30° triangular sharp-crested weirs. The 30° triangular sharp-crested weir with two V-notches was found to have higher values of air entrainment rate.Key words: aeration, air entrainment rate, plunging overfall jet, sharp-crested weir.
10
Rezazadeh, Shiva, Mohammad Manafpour et Hamze Ebrahimnejadian. « Three-Dimensional Simulation of Flow Over Sharp-Crested Weirs Using Volume of Fluid Method ». Journal of Applied Engineering Sciences 10, no 1 (1 mai 2020) : 75–82. http://dx.doi.org/10.2478/jaes-2020-0012.
Texte intégralRésumé :
AbstractIn sharp crested weirs, significant changes occur in the hydraulic characteristics of the flow past the weirs with different geometry. A detailed investigation and better understanding of hydraulic behavior will help practically to choose an appropriate geometry for weir. The purpose of this research is simulate the flow over sharp crested weir and investigate the effect of geometric shapes of sharp crested weirs on hydraulic characteristics of the flow such as pressure, velocity, water level profiles and discharge coefficients. Thus the limitation and usage range of sharp crested weirs are clarified. In this research OpenFOAM open source 3D software with RNG K-ε turbulence model and Volume of Fluid method (VOF) was used to analyze the hydraulic flow passing through sharp crested weir. The correlation coefficient for flow Surface profiles and discharge coefficients among numerical and experimental data is obtained 0.96 for different discharge rates. In the present research, discharge coefficients for rectangular weirs with compression coefficient 0%, trapezoidal and triangular weirs are determined 1.20, 0.68 and 0.51 respectively using discharge rate of 0.05183m3/s. The maximum discharge coefficient is obtained for rectangular sharp crested weir while the triangular sharp crested weir has minimum discharge coefficient.
11
Atashi, Vida, Mahmood Shafai Bejestan et Yeo Howe Lim. « Flow Pattern and Erosion in a 90-Degrees Sharp Bend around a W−Weir ». Water 15, no 1 (21 décembre 2022) : 11. http://dx.doi.org/10.3390/w15010011.
Texte intégralRésumé :
Different flow-altering methods, such as W−Weirs, have been developed to reduce erosion. For this study, we performed two experiments: (1) installing a W−Weir in various positions to determine the best angle for placement, and (2) investigating the variation of flow patterns and bed shear stress distribution in a 90-degree sharp bend by measuring the 3D components of flow velocities, with and without W−Weirs, where the greatest scour depth occurs. The results from the three installation angles indicate that less scour depth and volume of sediment removal occur when the weir is located close to the end of a bend. In addition, the value of the secondary circular power without a weir was higher than the position with a weir; however, this value significantly increased at 70 degrees due to turbulence flow near the W−Weir. This secondary flow power reduction at 45 degrees with a W−Weir increased by 65.8 percent for a Froude number value of 0.17, and by 29.8 percent for a Froude number value of 0.28, compared to values without the W−Weir, respectively.
12
Bettez, J., R. D. Townsend et A. Comeau. « Scale model testing and calibration of City of Ottawa sewer weirs ». Canadian Journal of Civil Engineering 28, no 4 (1 août 2001) : 627–39. http://dx.doi.org/10.1139/l01-024.
Texte intégralRésumé :
This paper reports the results of a laboratory study of the effects of (i) manhole proximity to installation site, (ii) pipe slope (i.e., approach velocity), (iii) upstream head measurement location, and (iv) submergence on the "hydraulics" of two types of sewer weirs used by the City of Ottawa. The City's streamlined form of broad-crested weir and its compound-shaped sharp-crested weir were initially calibrated for a "pipe straight"-arrangement (no upstream manhole is present) for a wide range of flow conditions at 0.2%, 0.4%, and 1.0% pipe slopes. The calibration tests were then repeated with the weirs positioned immediately downstream of a model manhole structure ("manhole"-arrangement). Corresponding data sets were compared to determine the effects of (i) approach velocity and (ii) manhole proximity (for two different shapes of manhole "benching") on the respective weir discharge coefficients.Key words: sewer weirs, broad-crested weir, compound sharp-crested weir, calibration, sewer benching, discharge coefficients.
13
Yousif, Omed S. Q., et Moses Karakouzian. « Effect of Corner Shape on Hydraulic Performance of One-Cycle Rectangular Labyrinth Weirs ». Fluids 5, no 3 (20 juillet 2020) : 117. http://dx.doi.org/10.3390/fluids5030117.
Texte intégralRésumé :
The hydraulic performance of rectangular labyrinth weirs has been investigated by many researchers, however, the effects of the corner shape on the hydraulic performance of rectangular labyrinth weirs have not been addressed in the current literature. Accordingly, this experimental study aims to explore the effect of the corner shape of on discharge efficiency of rectangular labyrinth weirs. Five flat-crested rectangular labyrinth weirs, with five different corner shapes, were made of High-Density Polyethylene Plastic (HDPE) and tested in a rectangular flume. Under different overflow discharges, the discharge coefficients for the rectangular labyrinth weirs were determined. The results showed that the shape of corners for rectangular labyrinth weirs was an effective factor. For example, rounding or beveling the corners can significantly increase the discharge capacity of the rectangular labyrinth weirs. However, the rounded corner shape was slightly better than the beveled corner shape. Among all labyrinth weir models tested in this study, the rectangular labyrinth weir with a semi-circular apex showed the highest hydraulic efficiency, while the one with an acute-angle corner shape showed the lowest hydraulic efficiency. For the rectangular labyrinth weir having a semi-circular shape, although the original effective length reduced by about 14%, the discharge coefficient, CL, increased by 16.7% on average. For the rectangular labyrinth weir that has an acute-angle corner shape, although the effective length (LC) of the weir increased by 23%, its discharge capacity decreased by 35.2% on average. Accordingly, improper folding of the side-walls of the rectangular labyrinth weir led to a significant reduction in the weir’s hydraulic performance.
14
Wibowo, Andri Rachmanto, Mohammad Bisri, Sumiadi et Very Dermawan. « MODEL OF FALLING POINT AT NAPPE TRAJECTORY FOR CREST GATE TYPE OF RUBBER WEIR ». Journal of Southwest Jiaotong University 56, no 6 (24 décembre 2021) : 389–99. http://dx.doi.org/10.35741/issn.0258-2724.56.6.33.
Texte intégralRésumé :
Crest Gate Rubber Weir is a modification of a rubber weir with an installed curved metal plate or crest gate in front of the rubber weir. This crest gate serves as protection for the rubber weir and increases the water level contained by the rubber weir. Although this kind of weir is widely used, the behavior of falling water after passing through or nappe has not been studied adequately. Previous studies of nappe trajectories apply to static weirs with a flat upstream face. The nappe trajectory of this Crest Gate Rubber Weir should be examined differently because it is affected by the curvature of the crest gate and the various angles formed by the weir. This study aims to find the effect of the weir angle with the nappe trajectory by conducting a hydraulic model test of the 18o, 35o, and 53o weir models. The research found that the nappe trajectory of this Crest Gate Rubber Weir is influenced by the design head (Hd) and the weir upstream slope or the ratio of height and length (P/L) of the weir. This finding is applicable for determining which part of the downstream apron is impacted most from nappe and may require special reinforcement.
15
Lee, Hyeonju, Min-Ho Koo, Byong Wook Cho, Yong Hwa Oh, Yongje Kim, Soo Young Cho, Jung-Yun Lee, Yongcheol Kim et Dong-Hun Kim. « Effects of Baekje Weir Operation on the Stream–Aquifer Interaction in the Geum River Basin, South Korea ». Water 12, no 11 (24 octobre 2020) : 2984. http://dx.doi.org/10.3390/w12112984.
Texte intégralRésumé :
Hydraulic structures have a significant impact on riverine environment, leading to changes in stream–aquifer interactions. In South Korea, 16 weirs were constructed in four major rivers, in 2012, to secure sufficient water resources, and some weirs operated periodically for natural ecosystem recovery from 2017. The changed groundwater flow system due to weir operation affected the groundwater level and quality, which also affected groundwater use. In this study, we analyzed the changes in the groundwater flow system near the Geum River during the Baekje weir operation using Visual MODFLOW Classic. Groundwater data from 34 observational wells were evaluated to analyze the impact of weir operation on stream–aquifer interactions. Accordingly, the groundwater discharge rates increased from 0.23 to 0.45 cm/day following the decrease in river levels owing to weir opening, while the hydrological condition changed from gaining to losing streams following weir closure. The variation in groundwater flow affected the groundwater quality during weir operation, changing the groundwater temperature and electrical conductivity (EC). Our results suggest that stream–aquifer interactions are significantly affected by weir operation, consequently, these repeated phenomena could influence the groundwater quality and groundwater use.
16
Zerihun, Yebegaeshet T. « Free Flow and Discharge Characteristics of Trapezoidal-Shaped Weirs ». Fluids 5, no 4 (10 décembre 2020) : 238. http://dx.doi.org/10.3390/fluids5040238.
Texte intégralRésumé :
A number of studies have considered the effects of weir design variations on the free- and submerged-flow characteristics of trapezoidal broad-crested weirs. It appears that the hydraulics of short-crested weir flows have received little attention; thus, the current knowledge is incomplete. By systematically analyzing a large set of experimental data, the present study aims to fill in this knowledge gap and to provide a complete description of the discharge characteristics of trapezoidal-shaped weirs, including the salient features of two-dimensional weir flows. The analysis of the axial free-surface profiles for short-crested weir flows attested that the location of the nearest station for the correct measurement of the overflow depth under free-flow conditions is at η0 from the heel of the weir, where η0 is the upstream free-surface elevation. Additionally, an empirical equation for the free-flow discharge coefficient is proposed as being valid for a trapezoidal-shaped weir with varying upstream- and downstream-face slopes. The results of this investigation reveal that the streamline curvature and the slopes of the upstream and downstream weir faces significantly affect the streamwise flow patterns and, hence, the free-flow discharge.
17
Alizadeh Sanami, Forough, Amir Ghaderi, Fardin Alizadeh Sanami, Parisa Mirkhorli et Silvia Di Francesco. « Laboratory Study of the Hydraulic Performance of the A-Type Triangular Piano Key Weir ». Water 15, no 11 (2 juin 2023) : 2124. http://dx.doi.org/10.3390/w15112124.
Texte intégralRésumé :
A piano key weir (PKW), a new type of weir aiming to increase the discharge capacity of an existing dam, was recently designed. Despite a large body of research in this field, only a few studies were conducted on A-type triangular piano key weirs (TPKW) in straight channels. In this context, this present research sought to study the flow regime, stage–discharge relationship, and discharge coefficient. Experiments were carried out using nine TPKW models and three linear weirs (LW) as the control weirs. The results indicated that the triangular piano key weirs are capable of passing a higher discharge in similar laboratory conditions compared to linear key weirs due to their longer length. For a given h/P ratio (h is the water head over the weir crest, and P is the weir height) and constant length (Le), an increase in the weir height from 0.07 m to 0.15 m decreases the discharge coefficient by approximately 20%. From sensitivity analysis, the most influential parameters for the tested TPKW models are the h/Le dimensionless ratio, followed by the P/Le and Fr. Moreover, the discharge coefficient has a reverse trend when the dimensionless parameters h/P, h/Le, and Froude number are increased. However, with decreasing h/Le, the discharge coefficient of TPKW tends to that of a broad-crested weir because of local submergence. It is expected that the results obtained will be a reference for researchers who work in this field.
18
Hussain, Ruqiya Abed, Sawsan Abdullah Hassan et Asmaa Abdul Jabbar Jamel. « Experimental Study on Flow over Triangular Labyrinth Weirs ». International Journal of Design & ; Nature and Ecodynamics 17, no 2 (27 avril 2022) : 249–55. http://dx.doi.org/10.18280/ijdne.170211.
Texte intégralRésumé :
Recently, many research studies have focused on labyrinth weirs' hydraulic performance, especially as dependent on engineering features. In the current study, the hydraulic properties of flow over labyrinth triangular weirs models (from the upper perspective) with sharp crest have been experimentally studied and compare their efficiency with suppressed rectangular weirs (conventional weirs). Twelve fiberglass models are developed for this reason and tested in a 6m in length, 30cm in width, and 40cm height in laboratory flume, nine models were constructed for triangular labyrinth weirs and three models were constructed for suppressed rectangular weirs, Three alternative heights (p=15, 20, and 25cm) were employed in this research, for each height, the vertex angle (θ) changed three times (60օ, 90օ, 120օ), and for each one of these weirs was used, seven different discharge were approved. The overall tests in this study were 84. The dimensionless parameters on which the discharge coefficient (Cd) is dependent were obtained using dimensional analysis. parameters were plotted. According to this experimental present study, as compared to linear weirs, labyrinth triangular weirs shown to be more hydraulically efficient. Also, the height of the weir (P) has effects on the discharge coefficient, where (Cd) increased with decreasing (P). Also, the vertex angle of triangular labyrinth weirs(θ) has a major influence on discharge coefficient and on weir performance, where the discharge coefficient raises when decreases the value of angle(θ), in another means, when the angle decreases gave an increase in the path of the flow, where it gave the triangular labyrinth weir with an angle of 60o the discharge coefficient reached its greatest value (2.55), followed by the weir with an angle of 90o and 120o respectively. In other words (a small vertex angle gives more length effective (Le) to the weir) and this leads to an increase in flow capacity or performance for the weir.
19
Gunjalli, Gowthami, Aishwarya S, Muthu D, Venkata Subramaniam C et Ramakrishnan K. « Perforated Weir for Effective Operation – A Study ». International Journal of Engineering & ; Technology 7, no 3.12 (20 juillet 2018) : 285. http://dx.doi.org/10.14419/ijet.v7i3.12.16043.
Texte intégralRésumé :
The excess water during monsoon season in the river is retained using low dams and it overflows through weirs. Maintaining the water depth at the required level and increasing the discharge from the weir are the current problems facing now a days. To overcome these problems, a novel sharp crested perforated weir has been developed in this work with different shapes of perforations viz. circle, rectangle, square and triangle having same area of perforation. A total of 24 models were made with single, double, triple opening for each shape, under two different sets of area of openings. The models were examined in a hydraulic tilting flume by keeping the discharge as constant. The variation in head obtained from these perforated weirs for different shapes were compared with a control weir which is a sharp crested rectangular weir. The expected theoretical discharge from these perforated weirs is compared with the actual discharge obtained. The values of coefficient of discharge for different perforated weirs were obtained by minimizing the error and the effective perforated weir is arrived by analyzing the values. This solution can be applied in solving practical problems.
20
Truong, Hien Chi, et Thuan Hieu Tran. « THE CAPACITY OF THE LOW-HEIGHT PIANO KEY WEIR TYPE A IN DRAINAGE CANAL ». Science and Technology Development Journal 12, no 18 (15 décembre 2009) : 18–24. http://dx.doi.org/10.32508/stdj.v12i18.2378.
Texte intégralRésumé :
The capacity of PK piano weir is 4-5 times higher than conventional weir. This paper describes some hydraulic tests on the low-height P.K. weirs Type A, in order to show that it is possible to build in a drainage canal such a weir, which also improves safety and takes less labor to operate the system. The results of the performed tests can be used in practice as a design hydraulic feature for this weir type (the length of weir, the length of jump). In some cases, an adaptation of these tests could be required.
21
Valentine, Elizabeth, Kurt Kronebusch, David Z. Zhu, N. Rajaratnam, Sid Lodewyk, John Cairns, Steven Chan et Fayi Zhou. « Combined sewer overflow over an oblique weir at Rat Creek in Edmonton, Alberta ». Canadian Journal of Civil Engineering 37, no 3 (mars 2010) : 477–88. http://dx.doi.org/10.1139/l09-177.
Texte intégralRésumé :
Oblique weirs are commonly used in urban drainage systems to remove excess flow from a sewer, in particular, a combined sewer system that has limited conveyance capacity. It is important to understand the hydraulics of these weirs to properly monitor the amount of the overflows as well as to design and improve sewer systems. The Rat Creek structure in Edmonton, Alberta, is a combined sewer overflow structure with a weir at an oblique alignment to the centerline of the sewer. A physical model study of the structure was conducted. The results show that both the approach flow conditions and the chamber geometry can significantly affect the hydraulic performance of the weir and invalidate the application of standard weir equations. A unique flow regime with a linear head–discharge rating curve was observed. The effects of modifying the weir and the hanging baffle wall downstream of the weir were also studied and reported. The results of this case study help to improve the understanding of the hydraulics of oblique weirs in sewer systems.
22
Mohammed, Rangeen Shihab, et Shaker Abdulatif Jalil. « Hydraulic Performance of Sharp-Crested Labyrinth Weir ». Academic Journal of Nawroz University 11, no 1 (7 février 2022) : 47–56. http://dx.doi.org/10.25007/ajnu.v11n1a1025.
Texte intégralRésumé :
Weirs are used as a control structure in the waterways. Among the influencing geometrical parameters on the weir performance is the total crest length. Experimental work on 27 geometric models of two-cycle Labyrinth shape crest weir is tested. The tested physical models consist of three weir heights, three apex widths and the sidewall angle is between (4.67°≤ α ≤ 19°), with three models of rectangular labyrinth weirs. The weirs of the wider apex and the same total length perform better and its coefficient of discharge is higher. Labyrinth weirs of longer sidewall length and contents same apex width performance batter. The larger value of sidewall angle and for a constant apex width reduces the value of discharge coefficient. The value of Cd range from (0.34-0.83) for the ratio of upstream head to the weir height (h/P) is ranged (0.08-0.48). The equations to predict the value of the discharge coefficient are suggested within the limitations of the present study.
23
Wibowo, A. R., M. Bisri, Sumiadi et V. Dermawan. « Model of discharge coefficient of crest gate rubber weir at fully closed condition ». IOP Conference Series : Earth and Environmental Science 930, no 1 (1 décembre 2021) : 012026. http://dx.doi.org/10.1088/1755-1315/930/1/012026.
Texte intégralRésumé :
Abstract Crest Gate Rubber Weir is a modification of rubber weir with adding a metal plate or crest gate on the upstream side. The rubber in this weir functioning as a support while the crest gate serves on elevating water. Although many have been implemented, this weir’s discharge coefficient needs be researched considering its unique shape. This study looks for discharge coefficient to determine the discharge that passes through weirs at fully closed conditions. The research was conducted with a hydraulic model resembling part of Tirtonadi Weir in Surakarta with a hydraulic model. The model is made in an angle 53°, which represents the prototype at fully closed condition. Laboratory experiment shows that the discharge coefficient of this weir is greater than the Ogee Weir and Sluice Gate for the same height because of less flow resistance from this weir structural form.
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Balachandar, R., Silvana Sorbo et A. S. Ramamurthy. « A note on circular sharp-crested weirs ». Canadian Journal of Civil Engineering 18, no 5 (1 octobre 1991) : 881–85. http://dx.doi.org/10.1139/l91-106.
Texte intégralRésumé :
A simple approach is proposed to determine the discharge coefficient of sharp-crested, thin plate circular weirs. The model developed incorporates the effects of the width of the approach channel and the height of the weir crest above the channel floor on the weir discharge coefficient. The model is verified using experimental data. For the practical range encountered in the field, a simplified equation is also suggested to determine the weir discharge coefficient. Key words: sharp-crested weir, circular control section, discharge coefficient.
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Seyedjavad, Minasadat, Seyed Taghi Omid Naeeni et Mojtaba Saneie. « Laboratory Investigation on Discharge Coefficient of Trapezoidal Piano Key Side Weirs ». Civil Engineering Journal 5, no 6 (23 juin 2019) : 1327–40. http://dx.doi.org/10.28991/cej-2019-03091335.
Texte intégralRésumé :
A spillway is a hydraulic structure used to provide the controlled release of surplus waters and floods from a dam into a downstream area. A side weir is a multipurpose hydraulic structure which is constructed in water conveyance systems with a height lower than that of the canal wall. When the water surface level goes up, the side weir regulates the discharge and controls the water surface in the main canal. Besides, the side weir controls and diverts floods in dam reservoirs, diverts the flow and protects the structure against the river inundations. In this research, a laboratory investigation is performed with 16 Type-A piano key weirs and three different pier heights of 10, 15 and 20cm. These weirs are studied for two cases of 1 and 2. The results show that the weirs with 15cm and 20cm heights in both cases 1 and 2 have the highest discharge coefficient in dimensionless ratios of 0.2> H/P> 0.4 and H/P>0.5 respectively. Having reviewed previous studies, it could be concluded that the trapezoidal piano key side weir is capable of releasing a flow 1.2 times more than that of the linear trapezoidal labyrinth weir with 12 degrees angle and 1.87 times more than the one with 6 degrees angle, and 1.5 times more than that of the triangular labyrinth weir.
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Lee, Jiwan, Yonggwan Lee, Soyoung Woo, Wonjin Kim et Seongjoon Kim. « Evaluation of Water Quality Interaction by Dam and Weir Operation Using SWAT in the Nakdong River Basin of South Korea ». Sustainability 12, no 17 (23 août 2020) : 6845. http://dx.doi.org/10.3390/su12176845.
Texte intégralRésumé :
The purpose of this study was to evaluate the streamflow and water quality (SS, T-N, and T-P) interaction of the Nakdong river basin (23,609.3 km2) by simulating dam and weir operation scenarios using the Soil and Water Assessment Tool (SWAT). The operation scenarios tested were dam control (Scenario 1), dam control and weir gate control (Scenario 2), dam control and sequential release of the weirs with a one-month interval between each weir (Scenario 3), dam control and weir gate full open (Scenario 4), dam control and weir gate sequential full open (Scenario 5), weir gate control (Scenario 6), weir gate full open (Scenario 7), and weir gate sequential full open (Scenario 8). Before evaluation, the SWAT was calibrated and validated using 13 years (2005–2017) of daily multi-purpose dam inflow data from five locations ((Andong Dam (ADD), Imha Dam (IHD), Hapcheon Dam (HCD), Namkang Dam (NKD), and Milyang Dam (MYD))multi-function weir inflow data from seven locations (Sangju Weir (SJW), Gumi Weir (GMW), Chilgok Weir (CGW), Gangjeong-Goryeong Weir (GJW), Dalseong Weir (DSW), Hapcheon-Changnyeong Weir (HCW), and Changnyeong-Haman Weir (HAW)), and monthly water quality monitoring data from six locations (Andong-4 (AD-4), Sangju (SJ-2), Waegwan (WG), Hapcheon (HC), Namkang-4 (NK-4), and Mulgeum (MG). For the dam inflows and dam storage, the Nash-Sutcliffe efficiency (NSE) was 0.59~0.78, and the coefficient of determination (R2) was 0.71~0.90. For water quality, the R2 values of SS, T-N, and T-P were 0.58~0.83, 0.53~0.68, and 0.56~0.79, respectively. For the eight dam and weir release scenarios suggested by the Ministry of Environment, Scenarios 4 and 8 exhibited water quality improvement effects compared to the observed data.
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Lee, Hae-Jin, Hae-Kyung Park et Se-Uk Cheon. « Effects of Weir Construction on Phytoplankton Assemblages and Water Quality in a Large River System ». International Journal of Environmental Research and Public Health 15, no 11 (24 octobre 2018) : 2348. http://dx.doi.org/10.3390/ijerph15112348.
Texte intégralRésumé :
Flow regulation is one of the most common anthropogenic factors affecting rivers worldwide. In Korea, 16 weirs were constructed along four major rivers from 2009 to 2012. This study aimed to elucidate initial changes in physical, chemical, and biological variables after the construction of consecutive weirs on the Nakdong River, a major large river system. Water quality variables and phytoplankton cell densities were investigated at eight representative sites and compared with the data recorded before the weir construction. There were spatial and temporal changes in the hydraulic retention time (HRT), total phosphorus (TP), and chlorophyll a concentrations among the eight weir sections. HRT increased after the weir construction, while TP and chlorophyll a tended to decrease from the middle to lower section of the Nakdong River. Furthermore, differences were observed in the phytoplankton community composition between 2006–2007 and 2013. There was a marginal decrease in the duration of centric diatom (Stephanodiscus hantzschii) blooms after weir construction. However, Microcystis aeruginosa proliferated more extensively during summer and autumn than it did before the weir construction. Our results suggest that changes in hydrological factors, in response to consecutive weir construction, may contribute to greater physical, chemical, and ecological variability.
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Kulkarni, Ketaki H., et Ganesh A. Hinge. « Comparative study of experimental and CFD analysis for predicting discharge coefficient of compound broad crested weir ». Water Supply 22, no 3 (22 novembre 2021) : 3283–96. http://dx.doi.org/10.2166/ws.2021.403.
Texte intégralRésumé :
Abstract Present study highlights the behavior of the weir crest head and width parameter on the discharge coefficient of a compound broad crested (CBC) weir. Computational fluid dynamics model (CFD) is validated with laboratory experimental investigations. In the discharge analysis through broad crested weirs, the upstream head over the weir crest (h) is crucial, where the result is mainly dependent upon the weir crest length (L) in the transverse direction to flow, water depth from channel bed. Currently, minimal investigations are known for CFD validations on compound broad crested weirs. The hydraulic research for measuring discharge numerically is carried out using FLOW 3D software. The model applies renormalized group (RNG) using the volume of fluid (VOF) method for improved accuracy in free surface simulations. Structured hexagonal meshes of cubic elements define discretized meshing. The comparative analysis of the numerical simulations and experimental observations confirm the performance of the CBC weir for precise measurement of a wide range of discharges. Series of CFD model studies and experimental validation have led to constant range of discharge coefficients for various heads over the weir crest. The correlation coefficient of discharge predictions is 0.999 with mean error of 0.28%.
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R. Eslinger, Kam, et Brian M. Crookston. « Energy Dissipation of Type a Piano Key Weirs ». Water 12, no 5 (28 avril 2020) : 1253. http://dx.doi.org/10.3390/w12051253.
Texte intégralRésumé :
A Piano Key weir (PK weir) is a nonlinear, labyrinth-type weir well suited for rehabilitation projects due to a relatively small footprint and the ability to pass large discharges for lesser upstream-head values when compared with other weir types. A critical component of a hydraulic structure is the energy-dissipative properties. Currently, information and guidance is limited, with previous energy dissipation studies of PK weirs primarily of specific projects. Therefore, to document and quantify energy dissipation, four laboratory-scale Type A PK weir models with different width ratios (Wi/Wo) were studied, with 255 tests comprising this new dataset, along with detailed observations of the flow field. Results were compared to existing published data regarding energy dissipation downstream of trapezoidal and rectangular labyrinth weirs. To support design efforts, two equations, both functions of head-water ratio (H/P) and Wi/Wo, are proposed to predict the relative residual energy downstream of PK weirs. The energy dissipation of PK weirs is largest at low flows and decreases in a logarithmic-like manner as flow increases. PK weirs with increased hydraulic efficiency, caused by an increase in Wi/Wo, resulted in slightly smaller energy dissipation values within the range 0.2 ≤ H/P ≤ 0.8. The energy dissipation of PK weirs was found to be relatively constant, independent of Wi/Wo, and in the ranges 0.07 ≤ H/P ≤ 0.2 and 0.8 ≤ H/P ≤ 0.95.
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Tian, Zhong, Wei Wang, Ruidi Bai et Nan Li. « Effect of Flaring Gate Piers on Discharge Coefficient for Finite Crest-Length Weirs ». Water 10, no 10 (28 septembre 2018) : 1349. http://dx.doi.org/10.3390/w10101349.
Texte intégralRésumé :
The use of flaring gate piers (FGPs) along with finite crest-length weirs changes the shape of plunging jets and increases the efficiency of energy dissipation in some projects; however, the FGPs may affect the discharge capacity. In this study, the flow pattern and discharge coefficient were experimentally investigated under different conditions by varying the weir lengths Lw, contraction ratio β, contraction angle θ, and water heads H. A comparative analysis of the weirs with and without FGPs was performed. For the finite crest-length weirs with FGPs, the water-surface profiles in the flow channel were backwater curves. Moreover, the plunging jets leaving the weir became narrower and then subsequently diffused largely in the transverse and longitudinal directions in air. The discharge coefficients of the weirs with FGPs were approximately equal for various weir lengths. Moreover, following the earlier studies on traditional finite crest-length weirs, a discharge-coefficient equation was developed for the weir with an FGP in this study. The results showed that in the weirs with FGPs, the discharge coefficients clearly increased with the increase in the contraction ratio and water head, but the changes in their values along with the contraction angle were neglected.
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Tacail, François G., Barry Evans et Alan Babb. « Case study of a labyrinth weir spillway ». Canadian Journal of Civil Engineering 17, no 1 (1 février 1990) : 1–7. http://dx.doi.org/10.1139/l90-001.
Texte intégralRésumé :
A labyrinth weir is an effective and economical means of providing increased spillway capacity under some restricted operating conditions. This type of weir is particularly suited to reservoir sites where a low head to high discharge relation is required, the topography restricts the spillway width, and a self-operating structure is highly desirable for emergency operation. Over the past few decades, labyrinth weir spillways have been constructed throughout the world. Definitive guidelines and theoretical procedures pertaining to hydraulic design of this type of weir are not completely established. The designer is confronted with the use of empirical methods for determining spillway configurations which require careful design and verification by use of a hydraulic model. This paper describes the design and hydraulic model study conducted for a labyrinth weir arrangement proposed for the South Heart Dam in northern Alberta. The model study permitted the designers to adopt a more efficient two-cycle weir for the same spillway width as opposed to an initially proposed three-cycle labyrinth weir. Key words: labyrinth weir, spillways, weirs, floods, hydraulic structures, hydraulics.
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Ghadba, Edan I. « Hydraulic Characteristics of Semi- Circular Sharp Crested Weirs ». Tikrit Journal of Engineering Sciences 18, no 1 (31 mars 2011) : 58–68. http://dx.doi.org/10.25130/tjes.18.1.11.
Texte intégralRésumé :
In this research the hydraulic characteristics of sharp crested weirs with semi- circular shape were studied, the study was depended on the dimensional analysis which confirmed by experimental work. The dimensional analysis results demonstrate that the effective parameters on the discharge of flow over this type of weir are the ratio of water height above the weir crest to the radius of this weir (H/R) and the ratio of water height above the weir crest to the height of the crest (H/P). Experimental tests were carried out on (16) models of weirs with Semi-circle shape where the radius of cutting was change four times (R=5, 10, 15, 20 cm) and for any radius the height of the crest was change four times (P= 30, 25, 20, 15 cm). The results show a great influence of the parameter (H/R) on flow parameter (Q2/gH5) while the effect of the parameter (H/P) is limited. Depending on non-dimensional parameters and experimental results, the statistics program (SPSS) were used to create empirical equation for measuring the discharge over the sharp crested weirs with semi-circular shape. The results of the equation show a very good agreement with the experimental result for determine the discharge with knowing the depth of water over the weir (H) , radius of cutting of the weir (R) and height of the crest (P). Also the equation shows a great influence of the radius (R) and limited influence of the height (P) on the discharge over this type of weirs.
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Hamdan, Ruaa Khalid, Aqeel Al-Adili et Thamer Ahmed Mohammed. « Physical Modeling of the Scour Volume Upstream of a Slit Weir Using Uniform and Non-Uniform Mobile Beds ». Water 14, no 20 (17 octobre 2022) : 3273. http://dx.doi.org/10.3390/w14203273.
Texte intégralRésumé :
This study presents new laboratory data on the time-varying scour upstream of a slit weir used for sediment release near hydropower intake. The governing parameters in temporal and spatial scour hole development under steady and unsteady flow conditions were experimentally investigated. This study includes 40 scenarios for steady flow at center and side slit weirs for uniform and non-uniform sediment with median sizes of d50 = 0.24, 0.55 mm and four scenarios of unsteady flow conditions at a center slit weir under different flow intensities. The steel slit weirs were built in a rectangular brick and concrete flume with dimensions of 1.25 m wide, 8.0 m long and 1.0 m deep. The dimensional analysis supports recent studies. This study demonstrates an increment in the resulted scour volume for fine and uniform sands at the center slit weir of about 2 times the value of coarse sand and 1.25 times the value measured with the side slit weir for uniform and non-uniform sands. However, the resulted scour volume for fine non-uniform sand at the center slit weir was recorded as 2.5 times that of coarse sand. There was a dramatic increase in the scour volume of about 4 times at the center slit weir and 3–3.5 at the side slit weir when the flow rate increased by 4 times.
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Kılıç, Zeyneb. « Geometric and Hydraulic Properties of Arced Labyrinth Weirs ». International Journal of Current Engineering and Technology 12, no 02 (2 avril 2022) : 121–26. http://dx.doi.org/10.14741/ijcet/v.12.2.4.
Texte intégralRésumé :
Weirs serve a critical role in dam safety. Numerous reservoirs' flood projections used in hydraulic design have risen in magnitude in recent years. As a result, many current spillways are no longer adequate since they do not fulfill current discharge capacity standards. Labyrinth weirs are frequently used to rehabilitate existing fixed width spillways. Weirs come in a variety of shapes and sizes, including labyrinth, linear, piano key, and more. Labyrinth weirs enhance the weir crest length for a given width, which increases the weir flow capacity. The majority of labyrinth weirs are designed in linear designs. An Arced cycle layout can boost the discharge capacity and hydraulic efficiency of a labyrinth weir. The article cites an arced geometric layout for labyrinth weirs, as well as nomenclature for arcspecific geometric variables. Experimental studies in the literature are presented by discussing and comparing.
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Azizah, Khusnita, Nurwahid Dimas Saputro, Budi Indra Setiawan et Allen Kurniawan. « Estimation Of Disharge Coefficient On Weir Configuration Based On Flow Rate And Velocity ». Applied Research on Civil Engineering and Environment (ARCEE) 4, no 01 (27 février 2023) : 22–28. http://dx.doi.org/10.32722/arcee.v4i01.4874.
Texte intégralRésumé :
The development of water treatment and water resources considers the flow rate adjusted using a weir. Weir is designed with many hydraulic factors, including the coefficient of discharge (Cd). Characteristics of the value of Cd show a decreasing trend on triangular and rectangular weirs. The value of Cd varies based on the flow's characteristics and the channel's geometry. Estimation of the best Cd value in flow discharge engineering and sediment deposition is necessary to know the accuracy of weir geometry. Some plans in water treatment and water resource building sometimes assume a Cd value based on literature. This study aims to estimate the value of Cd based on variations in flow rate and was conducted on a laboratory scale with weir shape limitations in the form of triangles and rectangles. The water sample was discharged by a water pump into an open channel. The angle of the weir opening was determined for the rectangular and triangular weir of 90°. Flow monitoring included flow discharge through the use of a current meter. Water was recycled in each measurement with a total of 60 cycles. The Cd values in a triangular weir were greater than in a rectangular weir. The Cd values for the rectangular weir ranged from 0.068 to 0.089, while the Cd values for the triangular weir ranged from 0.557 to 0.598. This value indicated that the greater the flow rate, the lower the Cd value. Therefore, weir configuration of water discharged using a triangular weir was better than a rectangular weir at low flow rates, less than 0.05 m3/s.
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Ramamurthy, Amruthur S., Ngoc-Diep Vo et R. Balachandar. « A Note on Irrotational Curvilinear Flow Past a Weir ». Journal of Fluids Engineering 116, no 2 (1 juin 1994) : 378–81. http://dx.doi.org/10.1115/1.2910286.
Texte intégralRésumé :
Curvilinear flows are commonly encountered in hydraulic engineering practice. Detailed velocity surveys of the curvilinear flow field over a circular-crested two dimensional weir were obtained using laser doppler velocimetry (LDV). Using these test data, the basic assumptions related to the streamline geometry and irrotational of flow over weirs made in all existing theoretical weir models are verified. The test data yielded the pattern, slope and curvature of the streamlines. Water surface profiles were also obtained to determine the depth of flow over the crest and the radius of curvature of the surface streamline at the crest section. As part of the study, the velocity profile of the flow over the weir crest was integrated to obtain the weir discharge coefficient. The weir coefficient obtained on the basis of this empirical procedure is compared with the weir coefficient based on direct discharge measurement.
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Hussain, Rukaia A., et Sahar A. Mohammed. « Discharge Coefficient for Cylindrical Weirs ». Tikrit Journal of Engineering Sciences 13, no 1 (31 mars 2006) : 82–96. http://dx.doi.org/10.25130/tjes.13.1.05.
Texte intégralRésumé :
The hydraulic characteristics of cylindrical weirs under free flow conditions were studied experimentally in order to investigate the discharge coefficient (Cd) and the influence of some significant factors and performance of weirs for discharge measuring. The experimental tests were carried out on three models of weirs in which the diameter of weir (D) was varied three times as: 8.0, 10.0 and 12.0 cm. For each model, a series of measurements were taken to measure coefficients of discharge. Results showed that the coefficient of discharge (Cd) increase with increasing the ratio of head to weir diameter (h/D),and for the same ratio (h/D), the discharge coefficient (Cd) increases with increasing weir diameter.
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Christianson, L. E., R. D. Christianson, A. E. Lipka, S. Bailey, J. Chandrasoma, C. McCoy, G. Preza Fontes et al. « Calibration of Stainless Steel-edged V-Notch Weir Stop Logs for Water Level Control Structures ». Applied Engineering in Agriculture 35, no 5 (2019) : 745–49. http://dx.doi.org/10.13031/aea.13350.
Texte intégralRésumé :
Abstract. Dependable flow rate measurements are necessary to calculate flow volumes and resulting nutrient loads from subsurface drainage systems and associated conservation practices. The objectives of this study were (1) to develop appropriate weir equations for a new stainless steel-edged 45° V-notch weir developed for AgriDrain inline water level control structures and (2) to determine if the equation was independent of flow depth in the structure. Weirs for 15 cm (6 in.) and 25 cm (10 in.) inline water level control structures were placed at three heights in each structure: at the base, 48 cm from the base, or 97 cm from the base, and the height of the nappe above the weir crest was recorded over a range of flow rates. The resulting data were fitted to equations of the form Q = aHb where Q is the flow rate, H is the height of the nappe above the weir crest, and a and b are fitted parameters. There were no significant differences in the fitted parameters across the two structure sizes or across the three weir placements. The fitted equation for these new stainless steel-edged V-notch weirs was Q = 0.011H2.28 with Q in liters per second and H in centimeters, and Q = 1.44H2.28, with Q in gallons per minute and H in inches. These equations can be used for measuring flow through AgriDrain in-line structures, although in-house weir calibration is highly recommended for specific applications, when possible. Keywords: Drainage, Flow monitoring, Subsurface drainage, V-notch weir, Weir calibration.
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Yousif, Omed S. Q., Kawa Z. Abdulrahman, Wazira Qadir, Ahang S. Ali et Moses Karakouzian. « Characteristics of Flow over Rectangular Labyrinth Weirs with Round Corners ». Hydrology 8, no 4 (18 octobre 2021) : 158. http://dx.doi.org/10.3390/hydrology8040158.
Texte intégralRésumé :
The hydraulic performance of round-cornered rectangular labyrinth weirs with varying weir heights and effective lengths has not been explored in the existing literature to the authors’ knowledge. The purpose of this experimental study was to see how the height and effective length of round-cornered rectangular labyrinth weirs affect their discharge efficiency. Nine flat-crested rectangular labyrinth weirs made of high-density polyethylene (HDPE) were tested in a rectangular flume under various discharges to fulfill the goals of this study. The discharge coefficients for the weirs were then calculated. The hydraulic efficiency of weirs with round corners increases as the weir height (P) increases, according to the findings; however, with effective length of the weir to channel width ratios (LC/B) ≤ 1.78, the effect of the weir height diminishes. For the HT/P ranges used in this study, 0.1 ≤ HT/P ≤ 0.65, the round-cornered rectangular labyrinth weirs with higher LC/B ratios (greater M values) showed improved hydraulic efficiency. Furthermore, the effects of the round-cornered rectangular labyrinth weirs’ headwater inflation can be mitigated by increasing the effective length of the weirs;by increasing M values (LC/B ratios). Using multiple linear regression analysis, a satisfactory correlation equation was found between discharge coefficients of round-cornered rectangular labyrinth weirs, CB, and the other parameters, LC, P, and h.
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Karimi, Sohrab, Hossein Bonakdari et Azadeh Gholami. « Determination Discharge Capacity of Triangular Labyrinth Side Weir Using Multi-Layer Neural Network (ANN-MLP) ». Current World Environment 10, Special-Issue1 (28 juin 2015) : 111–19. http://dx.doi.org/10.12944/cwe.10.special-issue1.16.
Texte intégralRésumé :
statistic indexes have been used to assess the accuracy of the results. The results of the examinations indicate that using MLP model along with simultaneous use of dimensionless parameters for the purposes of estimating discharge coefficient: the ratio of water behind the weir to the channel width (h/b), ratio of weir crest length to weir height (L/W), relative Froude number (F=V/√(2Side weirs are used in open channels to control flood and the flow passing through it. Discharge capacity is one of the crucial hydraulic parameters of side weirs. The aim of this study is to determine the effect of the intended dimensionless parameters on predicting the discharge coefficient of triangular labyrinth side weir. MAPE, RMSE, and Rgy)) and vertex angle (ϴ), offered the best results (MAPE= 0.67, R2= 0.99, RMSE = 0.009) in comparison with other models.
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Setyandito, O., Novandy, Juliastuti, S. Christian et R. T. Lopa. « Flow Characteristics Investigation On Trapezoidal Weir Using FLOW 3D ». IOP Conference Series : Earth and Environmental Science 998, no 1 (1 février 2022) : 012013. http://dx.doi.org/10.1088/1755-1315/998/1/012013.
Texte intégralRésumé :
Abstract Weir is a building that is formed to change the nature of river flow to accommodate irrigation needs. The main purpose of a weir is to raise the river water level, drain the channel through the intake channel, allow water to be tapped, control all flow, etc. If a flow experiences a large shock, it will cause a hydraulic jump resulting in a transition of flow from supercritical to subcritical. The analysis can be performed, it was done using the Computational Fluids Dynamics (CFD) software, FLOW-3D. To model the 3-D weir used in this FLOW-3d, AutoCAD is used and finally, Flow Sight will be used to display visualization results such as graphics and videos. This paper investigates the Froude number and depth-averaged velocity on the trapezoidal weir. Moreover, the numerical modelling of trapezoidal weirs has been compared with the experimental result and numerical modelling of other types of weirs. The results show that the Froude number is proportional to the average velocity of this depth because the Froude number increases with the increase in the average velocity. There is a difference with the flow that flows after the weir, in a trapezoidal weir the Froude number decrease slightly but after that, it increases again downstream.
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Liu, Xiao Ping, Qiong Huang et Da Bin Xu. « Sedimentation Control before the Weir of Dayuandu Navigation and Hydropower Project ». Advanced Materials Research 1030-1032 (septembre 2014) : 598–602. http://dx.doi.org/10.4028/www.scientific.net/amr.1030-1032.598.
Texte intégralRésumé :
Through an underwater camera at the WES Weir of the Dayuandu Project, the heavy sedimentation on the Weir’s floor can be observed. The sediment changes the water flow patterns before the Weir, resulting in Weir surface wear and sluice leakage. Mathematical models and physical had been builded to analyze the effect of the erosion. The results of these observations provide a reasonable and effective scheduling method to solve the siltation problems in front ofthe WES Weir. Once there are sufficient flow intensity, the ternary complex flow patterns will contribute to the incipient motions of sediment, acquireing desirable effect of sedimentation Control.
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A, Abo A. « Performance Against Cavity Index and Discharge Coefficient between Broad and Sharp Crested Weirs ». Polytechnic Journal 12, no 1 (18 août 2022) : 103–7. http://dx.doi.org/10.25156/ptj.v12n1y2022.pp103-107.
Texte intégralRésumé :
The purpose of this research is examining the performance of rectangular broad and sharp crested weirs in terms of cavity index and discharge coefficient. For this purpose, a computational fluid dynamics CFD code FLUENT is applied. Firstly, the code verified by applies on the experiments work of Hagre et al 1994 the results show excellent agreements between CFD and Hager et al 1994. Secondly the code applied on both broad and sharp crested weirs. The results demonstrate that broad crested weirs have a lower discharge coefficient than sharp crested weirs, implying that broad crested weirs have a lower ability to discharge flow than sharp crested weirs. While the cavity index of a broad crested weir is lower than that of a sharp crested weir, the risk of cavitation is lower for a broad crested weir. Finally, designers should use caution when deciding which type of crest to use in their designs.
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Khorida, Ninik, Mamok Suprapto et Syafi’i. « The concept of Lomaya and Pilohayanga weir rehabilitation based on technical and economic aspects ». MATEC Web of Conferences 195 (2018) : 05009. http://dx.doi.org/10.1051/matecconf/201819505009.
Texte intégralRésumé :
Lomaya and Pilohayanga Weirs are located in Limboto-Bone- Bolango River, Bone Bolango District, and Gorontalo Province. Pilohayanga Weir is located at 1,500 meters downstream of Lomaya Weir, it has 1,045 hectares of irrigation services area while also serving as a supplier of raw water requirements. The damage that occurred in Pilohayanga Weir resulted in its decreasing function, and also resulted in unmet irrigation and raw water needs. Meanwhile, Lomaya Weir has 3,148 hectares of irrigation services area. The aim of this research is to find the optimal solution among several alternative design concepts to meet Pilohayanga Weir’s water needs by supplying water from Lomaya Weir, considering both the technical aspects of hydraulic and the cost of implementation which must be within the economical boundary. In conclusion, the exact solution required is by the addition of several designs, these include: a) creating a new intake area on the right side of Pilohayanga Weir; b) creating an additional channel, flushing out sediment from Lomaya Weir; c) creating sand trap; and d) creating a carrier which will be channelled to Pilohayanga Irrigation Area.
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Lindermuth, Adrian, Théo St Pierre Ostrander, Stefan Achleitner, Bernhard Gems et Markus Aufleger. « Discharge Calculation of Side Weirs with Several Weir Fields Considering the Undisturbed Normal Flow Depth in the Channel ». Water 13, no 13 (22 juin 2021) : 1717. http://dx.doi.org/10.3390/w13131717.
Texte intégralRésumé :
Discharge behavior at side weirs is significantly influenced by the water surface profile along the weir crest. In the past century, different approaches were developed to describe this profile and the associated discharge coefficients. However, the application of these methods to practical problems poses a particular challenge, as a complex three-dimensional funnel is formed due to the discharge reduction, leading to significant uncertainties in determining the relevant flow depth. For this reason, a new approach for the determination of the discharge coefficient of side weirs was developed that refers to the undisturbed normal flow depth in the main channel. Based on a comprehensive parametric study utilizing 3D-numerical simulations, the influence of the weir and channel characteristics on the discharge behavior at the side weir was analyzed. A revised formula for estimating the discharge coefficient for side weirs with multiple weir fields was derived using multiple regression analyses. Validation of the numerical simulations was carried out by applying a physical scale model, showing good agreement between the results.
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Říha, Jaromír, et Zbyněk Zachoval. « Flow characteristics at trapezoidal broad-crested side weir ». Journal of Hydrology and Hydromechanics 63, no 2 (1 juin 2015) : 164–71. http://dx.doi.org/10.1515/johh-2015-0026.
Texte intégralRésumé :
Abstract Broad-crested side weirs have been the subject of numerous hydraulic studies; however, the flow field at the weir crest and in front of the weir in the approach channel still has not been fully described. Also, the discharge coefficient of broad-crested side weirs, whether slightly inclined towards the stream or lateral, still has yet to be clearly determined. Experimental research was carried out to describe the flow characteristics at low Froude numbers in the approach flow channel for various combinations of in- and overflow discharges. Three side weir types with different oblique angles were studied. Their flow characteristics and discharge coefficients were analyzed and assessed based on the results obtained from extensive measurements performed on a hydraulic model. The empirical relation between the angle of side weir obliqueness, Froude numbers in the up- and downstream channels, and the coefficient of obliqueness was derived.
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Burtsev, Anton, Nikhil Mishrikoti, Eric Eide et Robert Ricci. « Weir ». ACM SIGOPS Operating Systems Review 48, no 1 (15 mai 2014) : 65–70. http://dx.doi.org/10.1145/2626401.2626415.
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Ayaz, Md, et Talib Mansoor. « Development of ANN model for discharge prediction and optimal design of sharp-crested triangular plan form weir for maximum discharge using linked ANN–optimization model ». Water Supply 21, no 6 (12 mars 2021) : 3027–41. http://dx.doi.org/10.2166/ws.2021.067.
Texte intégralRésumé :
Abstract Triangular plan form weirs are advantageous over a normal weir in two ways. Within the limited channel width, use of such a weir increases the crest length and hence for a given head, increases the discharge and for a given discharge, reduces the head in comparison with a normal weir. In a previous study, researchers proposed an empirical equation to compute the discharge coefficient of a triangular plan form weir. The prediction error on the discharge coefficient was ±7% from the line of agreement. In the present study, an ANN model has been utilized to train randomly selected 70% data, with 15% tested and validation made for the remaining 15% data. The model predicts the discharge coefficient with a prediction error in the range of ±2.5% from the line of agreement, thereby decreasing the prediction error in Cd by 64%. Also, the sensitivity analysis of the developed ANN model has been performed for all the parameters (weir height, skew weir length and flow depth) involved in the study and the weir height was found to be the most sensitive parameter. Furthermore, the linked ANN–optimization model has been developed to find the optimal values of design parameters of a triangular plan form weir for maximum discharge.
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Yuce, Mehmet Ishak, Aemad A. H. Al-Babely et Mohammad A. Al-Dabbagh. « Flow simulation over oblique cylindrical weirs ». Canadian Journal of Civil Engineering 42, no 6 (juin 2015) : 389–407. http://dx.doi.org/10.1139/cjce-2014-0157.
Texte intégralRésumé :
This paper presents a computational fluid dynamics (CFD) simulation to investigate the effects of the obliqueness of cylindrical weirs on the flow velocity distribution, the pressure distribution and the distribution of water depth over the weir crest. Three different cylindrical weirs with diameters of 0.114 m, 0.09 m, and 0.0635 m, with three dissimilar inclination angles of 90°, 135°, and 150° were used. The SSG Reynolds stress turbulence closure model was utilized in the analyses. The results show that the flow patterns are affected by the inclination angle with respect to the flow direction. It was noticed that inclination angle increment increases the velocity of flow at the downstream surface of the weir, thus increases the absolute value of the negative pressure, at the inward-moved end of the weir. The outward-moved end of the weir was observed not to be covered with water and extending with the increase of the inclination angle.
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Zachoval, Zbyněk, Michaela Knéblová, Ladislav Roušar, Ján Rumann et Jan Šulc. « Discharge coefficient of a rectangular sharp-edged broad-crested weir ». Journal of Hydrology and Hydromechanics 62, no 2 (1 juin 2014) : 145–49. http://dx.doi.org/10.2478/johh-2014-0014.
Texte intégralRésumé :
Abstract This paper is concerned with the determination of the relationship for the calculation of the discharge coefficient at free overflow over a rectangular sharp-edged broad-crested weir without lateral contraction. The determination was made on the basis of new measurement in a range of the relative thickness of the weir from 0.12 to 0.30 and newly in a large range of relative height of the weir extremely from 0.24 to 6.8 which greatly expands the application possibilities of low weirs. In addition, the effects of friction and surface tension on the value of the discharge coefficient were evaluated as well as the effect of the relative thickness of the weir. The new equation for discharge coefficient, expressed using the relative height of the weir, was subjected to verification made by an independent laboratory which confirmed its accuracy.