scholarly journals Discharge coefficient of flow over Al-Shalalat stepped weir on Al-Khusr River

2021 ◽  
Vol 11 (2) ◽  
Author(s):  
Azza N. Altalib
Keyword(s):  
Energy Dissipation ◽  
Discharge Coefficient ◽  
Open Channel ◽  
Hydraulic Structures ◽  
Percentage Error ◽  
Hydraulic Characteristics ◽  
Irrigation Channels ◽  
Different Shapes ◽  
Coefficient Of Discharge ◽  
Discharge Measurements

AbstractMany hydraulic structures are constructed in an open channel according to the purposes and the nature of the region. Weir is one of these structures which is used for discharge measurements as well as rising water depth in irrigation channels. According to the crest, there are two different shapes: sharp and broad crested weir. A stepped weir is constructed to reduce scour that happened downstream. There are different studies dealt with discharge coefficient, energy dissipation, and other hydraulic characteristics for flow over the weir. In this study, the coefficient of discharge for the Al-Shalalat stepped weir on the Al-Khusr River has been evaluated. The discharge coefficient equation is predicted, and the result values are compared with previous studies. The percentage error for the predicted discharge equation presented in this study compared with previous studies does not exceed 10%.

EXPERIMENTAL STUDY OF FLOW THROUGH TRAPEZOIDAL WEIR CONTROLLED UNDER A SEMI-CIRCULAR GATE

2021 ◽  
Vol 5 (2) ◽  
pp. 245-154
Author(s):  
Bashir Tanimu ◽  
Bilal Abdullahi Be ◽  
Muhammad Mujihad Muhammad ◽  
Surajo Abubakar Wada
Keyword(s):  
Experimental Study ◽  
Discharge Coefficient ◽  
Percentage Error ◽  
Nonlinear Regression Analysis ◽  
Block Model ◽  
Gate Structure ◽  
Flow Through ◽  
Mathematical Equations ◽  
Coefficient Of Discharge ◽  
Good Agreement

Different parameters of a weir model have a great effect on the discharge coefficient. In this experimental study the effect of varying angle of a trapezoidal weir coupled with a below semi-circular gate is determined. The result showed that the higher the value of  the higher the coefficient of discharge. The respective average discharge coefficient  of the block model and the trapezoidal weir models are; 0.48031,0.48880, 0.49565, 0.49647, 0.49892 and 0.49934. As such the trapezoidal weir with   has the highest value of average discharge coefficient =0.49934. Hence the most efficient. Linear and nonlinear regression analysis were used to generate mathematical equations that can be used to predict the flow rate Q for the combined weir-gate structure and the discharge coefficient  of the most efficient model with  respectively. The discharge coefficient for the most efficient weir model was found to be 3.81% more than that of the block model (with rectangular weir). The predicted coefficient of discharge   for the most efficient model was also found to be in good agreement with the observed discharge coefficient with a percentage error in the range of  0.4%

scholarly journals Machine Learning as a Tool for Estimating Discharge Coefficient for Rectangular Weir with Multiple Slots

2020 ◽  
Vol 9 (4) ◽  
pp. 773-777
Keyword(s):  
Machine Learning ◽  
Regression Models ◽  
Discharge Coefficient ◽  
Support Vector ◽  
Data Set ◽  
Regression Algorithms ◽  
Reasonable Solution ◽  
Irrigation Channels ◽  
Predicted Values ◽  
Coefficient Of Discharge

In terms of higher water demand due to increases of agriculture lands which depend on irrigation channels, there is a need to increase the efficiency of weirs already constructed on those channels. The most reasonable solution is to modify the existing weirs instead of replacing them by new ones to avoid costly solutions. In this study, a potential of using different Machine Learning regression algorithms has been investigated to estimate the coefficient of discharge Cd for rectangular weir with multiple circular slots. Using experimental data set, three Machine Learning regression models; Decision Tree Regressor (DTR), Artificial Neural Networks (ANN) and Support Vector Machine Regressor (SVR) were developed and compared to find most suitable algorithm. Based on the simulation results of the three developed models, it was found that the ANNs algorithm is the superior one which can be used to estimate discharge coefficient Cd for rectangular weirs with multiple circular slots. It gives the highest matching between measured and predicted values with correlation coefficient (R2 ) value of 0.759, minimum MAE with value 0.001 and minimum MSE with value 0.022. Finally, an equation using ANNs is presented to estimate the discharge coefficient.

scholarly journals Effect of the Area Contraction Ratio on the Hydraulic Characteristics of the Toothed Internal Energy Dissipaters

Water ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1406
Author(s):  
Ting Zhang ◽  
Rui-xia Hao ◽  
Xiu-qing Zheng ◽  
Ze Zhang
Keyword(s):  
Energy Dissipation ◽  
Internal Energy ◽  
Dissipation Rate ◽  
Pressure Coefficient ◽  
Energy Dissipation Rate ◽  
Flow Coefficient ◽  
Physical Model Test ◽  
Hydraulic Characteristics ◽  
Body Type ◽  
Contraction Ratio

Toothed internal energy dissipaters (TIED) are a new type of internal energy dissipaters, which combines the internal energy dissipaters of sudden reduction and sudden enlargement forms with the open-flow energy dissipation together. In order to provide a design basis for an optimized body type of the TIED, the effect of the area contraction ratio (ε) on the hydraulic characteristics, including over-current capability, energy dissipation rate, time-averaged pressure, pulsating pressure, time-averaged velocity, and pulsating velocity, were studied using the methods of a physical model test and theoretical analysis. The main results are as follows. The over-current capability mainly depends on ε, and the larger ε is, the larger the flow coefficient is. The energy dissipation rate is proportional to the quadratic of Re and inversely proportional to ε. The changes of the time-averaged pressure coefficients under each flow are similar along the test pipe, and the differences of the time-averaged pressure coefficient between the inlet of the TIED and the outlet of the TIED decrease with the increase of ε. The peaks of the pulsating pressure coefficient appear at 1.3 D after the TIED and are inversely proportional to ε. When the flow is 18 l/s and ε increases from 0.375 to 0.625, the maximum of time-averaged velocity coefficient on the line of Z/D = 0.42 reduces from 2.53 to 1.17, and that on the line of Z/D = 0 decreases from 2.99 to 1.74. The maximum values of pulsating velocity on the line of Z/D = 0.42 appear at 1.57D and those of Z/D = 0 appear at 2.72D, when the flow is 18 l/s. The maximum values of pulsating velocity decrease with the increase of ε. Finally, two empirical expressions, related to the flow coefficient and energy loss coefficient, are separately presented.

Study on Hydraulic Characteristics and Optimization of Siphon Channel with Two Inlets in Drydock

2014 ◽  
Vol 638-640 ◽  
pp. 1285-1292
Author(s):  
Peng Zhao ◽  
Yu Chuan Bai
Keyword(s):  
Energy Dissipation ◽  
Numerical Model ◽  
Kinetic Energy ◽  
Dissipation Rate ◽  
Three Dimensional ◽  
Flow State ◽  
Hydraulic Characteristics ◽  
Channel System ◽  
Guide Wall ◽  
Low Efficiency

Compared with the siphon channel with one inlet, the siphon channel with two inlets has some problems such as low efficiency of flooding. Combining with the model test of siphon channel with two inlets in a drydock, three-dimensional numerical model was built to study the hydraulic characteristics of siphon channel system. The reliability of numerical model was confirmed by comparing the calculated value and measured value of hump pressure and flooding rate. Results of turbulent kinetic energy and dissipation rate indicate that flow kinetic energy is mainly dissipated by the friction and its impacting the wall behind partition and the effect of energy dissipation pillars are not obvious. By comparing flow state in front of energy dissipation section and flooding rate between design scheme and modified scheme, it is suggested that the guide wall should be dismantled to ameliorate flow state.

scholarly journals The regularities of resistance and flow in pipes and wide channels

2018 ◽  
Vol 193 ◽  
pp. 02034
Author(s):  
Ilya Bryansky ◽  
Yuliya Bryanskaya ◽  
Аleksandra Оstyakova
Keyword(s):  
Comparative Analysis ◽  
Velocity Profile ◽  
Hydraulic Resistance ◽  
Cross Section ◽  
Resistance Coefficient ◽  
Hydraulic Structures ◽  
Hydraulic Characteristics ◽  
Hydraulic Resistance Coefficient ◽  
Logarithmic Velocity Profile

The data of hydraulic characteristics of flow are required to be more accurate to increase reliability and accident-free work of water conducting systems and hydraulic structures. One of the problems in hydraulic calculations is the determination of friction loss that is associated with the distribution of velocities over the cross section of the flow. The article presents a comparative analysis of the regularities of velocity distribution based on the logarithmic velocity profile and hydraulic resistance in pipes and open channels. It is revealed that the Karman parameter is associated with the second turbulence constant and depend on the hydraulic resistance coefficient. The research showed that the behavior of the second turbulence constant in the velocity profile is determined mainly by the Karman parameter. The attached illustrations picture the dependence of logarithmic velocity profile parameters based on different values of the hydraulic resistance coefficient. The results of the calculations were compared to the experimental-based Nikuradze formulas for smooth and rough pipes.

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