scholarly journals Laboratory Investigation on Discharge Coefficient of Trapezoidal Piano Key Side Weirs

2019 ◽  
Vol 5 (6) ◽  
pp. 1327-1340 ◽  
Author(s):  
Minasadat Seyedjavad ◽  
Seyed Taghi Omid Naeeni ◽  
Mojtaba Saneie
Keyword(s):  
Laboratory Investigation ◽  
Water Surface ◽  
Discharge Coefficient ◽  
Hydraulic Structure ◽  
Side Weir ◽  
Labyrinth Weir ◽  
Dam Reservoirs ◽  
Water Conveyance ◽  
The One ◽  
Side Weirs

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.

scholarly journals Determination Discharge Capacity of Triangular Labyrinth Side Weir Using Multi-Layer Neural Network (ANN-MLP)

2015 ◽  
Vol 10 (Special-Issue1) ◽  
pp. 111-119 ◽  
Author(s):  
Sohrab Karimi ◽  
Hossein Bonakdari ◽  
Azadeh Gholami
Keyword(s):  
Discharge Capacity ◽  
Discharge Coefficient ◽  
Vertex Angle ◽  
Hydraulic Parameters ◽  
Side Weir ◽  
Dimensionless Parameters ◽  
Weir Height ◽  
Crest Length ◽  
Side Weirs ◽  
Mlp Model

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.

scholarly journals Experimental study to estimate the discharge coefficient over inclined side spillway

2020 ◽  
Vol 7 (2) ◽  
pp. 44-54
Author(s):  
Ayat Mehdi kadhim ◽  
Faisal A. Majid
Keyword(s):  
Experimental Study ◽  
Froude Number ◽  
Water Surface ◽  
Discharge Coefficient ◽  
Flow Direction ◽  
Surface Profile ◽  
Side Weir ◽  
Discharge Water ◽  
Water Surface Profile ◽  
Crest Length

Abstract: Weir is usually used in different hydraulic purposes, mainly for head discharge-water relationship in channels. In this research, the flow has been carried out over the side of spillway using three cases of crest inclination by means of increasing one side of the weir a half centimeter each time with constant crest length equal to 15 cm. This means that the angle θ equals to (1.91˚, 3.82˚ and 5.71˚) respectively towards of the flow and is opposite to the flow with decreasing a half centimeter. Also in case of the breadth is horizontal (θ=0), seven cases have been tested. It is known that the greater amount of discharge occurs when the breadth is horizontal (θ=0). In case of the inclination of the weir is inclined opposite to the flow direction, the discharge is greater than that of which the weir inclined towards the flow direction for all cases of inclination. The greater discharge was obtained when decreasing the angle, which is opposite to the flow direction. The amount of discharge over the side of weir decreases by increasing the angle of the slope opposite to the direction of the flow and become more decreasing in case the inclination of side weir towards the flow. In case of increasing the angle of inclination in flow direction, the amount of discharge over side weir will be decreased. The effect of Froude number has also studied with the discharge coefficient and found that, they are proportionally related to each other. Also the water surface profile along the side spillway weir is studied and taken under consideration theoretically and experimentally in this research.

scholarly journals Experimental study and performance comparison on various types of rectangular piano key side weirs at a 120° section of a 180° curved channel

2020 ◽  
Vol 10 (10) ◽  
Author(s):  
Yaser Mehri ◽  
Solmaz Esmaeili ◽  
Jaber Soltani
Keyword(s):  
Experimental Study ◽  
Discharge Coefficient ◽  
Performance Comparison ◽  
Effective Length ◽  
Bend Angle ◽  
Curved Channel ◽  
Curved Channels ◽  
Water Conveyance ◽  
And Performance ◽  
Side Weirs

Abstract Application of side weirs with high effective length is necessary to discharge excessive flows, to control the flow in water conveyance systems, and irrigation and drainage systems. Most of the studies on the side weirs have been conducted on the straight channels and linear weirs. The flow pattern on the outer arc of the curved channels and its suitability for side weir can be used and combined with the piano key weirs. So far, no comparison has been made on rectangular piano key side weirs (RPKSW) at a 120° Section of a 180° Curved Channel. In this study, an experimental study was performed on A-, B-, C-, and D-type RPKSW at a bend angle of 120 degrees. The results showed that the specific energy at two ends of the RPKSWs was the same, with a slight difference of 3.4% for A-Type, 1.3% for B-Type, 1.1% for C-Type, and 1.8% for D-Type weirs. The discharge coefficients of the studied weirs were also investigated, and it was concluded that B-Type weir has better performance than other weirs. On average, the discharge coefficient of B-Type weir was 9.9%, 21.2%, and 24.1% higher than that of A-Type, C-Type, and D-Type weir, respectively. It was shown that the ratio of P/h1 is the main parameter affecting the weir discharge coefficient. Finally, an empirical equation was proposed for each weir. The proposed equation has MAE = 0.028 for A-Type weir, MAE = 0.041 for B-Type weir, MAE = 0.049 for C-Type weir, and MAE = 0.053 for D-Type weir.

Flow Over Side Weirs in Rectangular and Circular Channels

1989 ◽  
Vol 21 (8-9) ◽  
pp. 739-746 ◽  
Author(s):  
A. Uyumaz
Keyword(s):  
Finite Difference ◽  
Finite Difference Method ◽  
Difference Method ◽  
Water Surface ◽  
Numerical Models ◽  
Rectangular Channel ◽  
Side Weir ◽  
Surface Profiles ◽  
Side Weirs ◽  
Energy Principles

Flow over side weirs in rectangular and circular channels is discussed. Numerical models are obtained from energy principles and are solved by a finite difference method. The results are presented in diagrammatic form for practical use. It is shown that rectangular channel side weir procedures cannot be used for obtaining approximate water surface profiles along the side weirs in circular channels.

scholarly journals Discharge Coefficient of a C-Type Piano Key Side Weir at 30° and 120° Sections of a Curved Channel

2018 ◽  
Vol 4 (7) ◽  
pp. 1702 ◽  
Author(s):  
Yaser Mehri ◽  
Jaber Soltani ◽  
Mojtaba Saneie ◽  
Mohhamad Rostami
Keyword(s):  
Flood Control ◽  
Discharge Coefficient ◽  
Empirical Relationship ◽  
Effective Parameters ◽  
Level Control ◽  
Side Weir ◽  
Space Limitation ◽  
The Mean ◽  
Coefficient Of Discharge ◽  
Side Weirs

A piano key side weir (PKSW) is a non-linear weir that discharge exceeds linear weirs by increasing the length in width. PKSW can be used in side weirs with space limitation. As side weirs are extensively used in flood control, water level control in rivers, and water supply channels, it is necessary to use PKSW as side weirs. This research discusses the discharge coefficient of a PKSW by assessing a C-type PKSW at 30° and 120° sections of a channel with a longitudinal curve. Dimensional analysis was used for identifying the parameters effective in the discharge coefficient. The effects of these parameters are examined by analysing the effective parameters. Finally, an empirical relationship has been proposed for determining the discharge coefficient based on the dimensionless parameters for calculating the discharge coefficient with the correlation coefficient of 0.88 and the mean error of 0.091. The influence of the parameter on the PKSW is more than that of the remaining parameters: With an increase in the value of this parameter, considering decreases in the length of the deviation and a lack of submerged inlet keys, the coefficient of discharge increases.

scholarly journals Investigation of trapezoidal sharp-crested side weir discharge coefficients under subcritical flow regimes using CFD

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Amir Ghaderi ◽  
Mehdi Dasineh ◽  
Saeed Abbasi ◽  
John Abraham
Keyword(s):  
Discharge Coefficient ◽  
Effective Parameters ◽  
Side Weir ◽  
Discharge Coefficients ◽  
Weir Height ◽  
Crest Length ◽  
Side Weirs ◽  
Upstream Flow ◽  
Water Elevation ◽  
Correlation Factors

AbstractSide weirs are utilized to regulate water surface and to control discharge and water elevation in rivers and channels. Here, the discharge coefficient for trapezoidal sharp-crested side weirs (TSCSW) and their affecting parameters are numerically investigated. To simulate the hydraulic and geometric characteristics of TSCSWs, three weir crest lengths of 15 cm, 20 cm and 30 cm with lengths of 20 cm, 30 cm and 40 cm and with two different sidewall slopes are utilized. The results show that for constant P/B (P: weir height, B: main channel width), the depth of flow along the channel and weir decreases as the crest length increases. Also, with increasing P/y1 ratio (P: weir height, y1: upstream flow depth), the discharge coefficient decreases for small crest lengths and increases for large crest lengths. The results show that for constant T/L ratio (T: passing flow width, L: side weir crest length), increasing the length, height and sidewall slope of a side weir will increase the discharge coefficient. It is observed that as the upstream Froude number increases for side weirs with longer crest lengths, the intensity of deviating flow and kinetic energy over the TSCSW will increase. Finally, some relations with high correlation factors are proposed for obtaining discharge coefficients using the dimensionless parameters of P/y1, T/L and Fr1. Based on proposed relations and sensitivity analysis, it is shown that T/L and P/y1 are the most effective parameters for reducing the discharge coefficient reduction.

scholarly journals Equivalent Discharge Coefficient of Side Weirs in Circular Channel—A Lazy Machine Learning Approach

Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2406 ◽  
Author(s):  
Granata ◽  
Nunno ◽  
Gargano ◽  
Marinis
Keyword(s):  
Machine Learning ◽  
Discharge Coefficient ◽  
Nearest Neighbor ◽  
Learning Algorithms ◽  
Machine Learning Algorithms ◽  
Circular Channel ◽  
K Nearest Neighbor ◽  
Side Weir ◽  
Input Variables ◽  
Side Weirs

Side weirs have been widely used since ancient times in many hydraulic works. Their operation can be analyzed following different approaches. However, almost all possible analysis approaches require knowledge of the discharge coefficient, which depends on several geometric and hydraulic parameters. An effective methodology for predicting discharge coefficient can be based on machine learning algorithms. In this research, experimental data obtained from tests carried out on a side weir in a circular channel and supercritical flow have been used to build predictive models of the equivalent discharge coefficient, by which the lateral outflow can be estimated by referring only to the flow depth upstream of the side weir. Four models, different in the input variables, have been developed. Each model has been proposed in 5 variants, depending on the applied algorithm. The focus is mainly on two lazy machine learning algorithms: k Nearest Neighbor and K-Star. The 5-input variables Model 1 and the 4-input variables Model 2 noticeably outperform the 3-input variables Model 3 and Model 4, showing that a suitable characterization of the side weir geometry is essential for a good accuracy of the prediction model. In addition, under models 1 and 2, k Nearest Neighbor and K-Star, despite the simpler structure, provide comparable or better performance than more complex algorithms such as Random Forest and Support Vector Regression.

scholarly journals Flow characteristics at trapezoidal broad-crested side weir

2015 ◽  
Vol 63 (2) ◽  
pp. 164-171 ◽  
Author(s):  
Jaromír Říha ◽  
Zbyněk Zachoval
Keyword(s):  
Flow Field ◽  
Experimental Research ◽  
Discharge Coefficient ◽  
Empirical Relation ◽  
Flow Characteristics ◽  
Side Weir ◽  
Discharge Coefficients ◽  
Approach Channel ◽  
The Subject ◽  
Side Weirs

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.

scholarly journals Using a Deflector and Crest Design to Make a Safe Spillway Operation

2021 ◽  
Author(s):  
Sorosh Esmaelizadeh ◽  
Babak Lashkar-Ara
Keyword(s):  
Discharge Coefficient ◽  
Hydraulic Structure ◽  
Reference Model ◽  
Drainage System ◽  
Dam Failure ◽  
Flow Conditions ◽  
Dam Reservoirs ◽  
Reservoir Conditions ◽  
Inlet Geometry ◽  
The Impact

Abstract Floods are an important hazard throughout the world. The origins of some floods are a dam failure, hydraulic structure failure as well as an improper performance of the spillway. Among these, shaft spillways are known as a flood drainage system in dams, which is submerged by increasing the level of the reservoir, so that reduces the spillway efficiency and causes over topping. Investigations show that using deflector and aeration in shaft spillways will cause the flow pattern to improve. In this study, it has been tried to experiment on the impact of a deflector located in the throat and inlet geometry of the crest on the improvement of the hydraulic performance of the shaft spillway, and decrease to some extent the hazard induced by lack of timely drainage of floods in dam reservoirs. In order to investigate the deflector effect, three constriction specimens in shaft throat with constriction area to shaft area ratio (Ad/Ai) of respectively 0.75, 0.5 and 0.25 were considered as scenarios. In each scenario, the conditions of the flow passing through 12 different specimens of spillway with Crown Wheel inlets were tested and the results were compared with the flow conditions in crown wheel spillways without deflector (reference model). The results showed that the use of deflector has an important role in reducing vortex flows and stabilizing changes in the water level of the reservoir, and also increases the discharge coefficient of the flow. The studies on reference models also showed that Crown Wheel inlets (C.W.) improved shaft spillway performance, with C.W. spillways having an average discharge coefficient of 32% higher than shaft spillways. Finally, considering optimal deflector factors and C.W. geometry, an optimal model was proposed for flood reservoir conditions.

scholarly journals Simulation of discharge coefficient of side weirs placed on convergent canals using modern self-adaptive extreme learning machine

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Reza Gharib ◽  
Majeid Heydari ◽  
Saeid Kardar ◽  
Saeid Shabanlou
Keyword(s):  
Artificial Intelligence ◽  
Froude Number ◽  
Extreme Learning Machine ◽  
Discharge Coefficient ◽  
Numerical Models ◽  
Input Parameter ◽  
Side Weir ◽  
Learning Machine ◽  
Side Weirs ◽  
Self Adaptive

AbstractSide weirs are broadly used in irrigation channels, drainage systems and sewage disposal canals for controlling and adjusting the flow in main channels. In this study, a new artificial intelligence model entitled “self-adaptive extreme learning machine” (SAELM) is developed for simulating the discharge coefficient of side weirs located upon rectangular channels. Also, the Monte Carlo simulations are implemented for assessing the abilities of the numerical models. It should be noted that the k-fold cross-validation approach is used for validating the results obtained from the numerical models. Based on the parameters affecting the discharge coefficient, six artificial intelligence models are defined. The examination of the numerical models exhibits that such models simulate the discharge coefficient valued with acceptable accuracy. For instance, mean absolute error and root mean square error for the superior model are computed 0.022 and 0.027, respectively. The best SAELM model predicts the discharge coefficient values in terms of Froude number (Fd), ratio of the side weir height to the downstream depth (w/hd), ratio of the channel width at downstream to the downstream depth (bd/hd) and ratio of the side weir length to the downstream depth (L/hd). Based on the sensitivity analysis results, the Froude number of the side weir downstream is identified as the most influencing input parameter. Lastly, a matrix is presented to estimate the discharge coefficient of side weirs on convergent channels.

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