Abstract
In this study, the effects of the gate opening, sill placement with different widths under the gate, and the sill position from under the gate on the discharge coefficient were investigated ...experimentally. Sills are placed in positions below, tangentially and upstream of the gate at distances of 7.5 and 17.5 cm from the gate. The results of the present study showed that the discharge coefficient increases with increasing sill width and decreasing total area of the flow passing through the gate. The discharge coefficient increases by installing the sill at certain intervals at increasing distance with respect to the upstream of the sluice gate and has a lower value compared to the non-sill state. At the same opening in non-sill and suppressed sill states, with a sill below and tangential to the gate, the discharge coefficient of the sluice gate with the sill has increased compared to the non-sill state. In addition, the discharge coefficient for a tangential sill has the highest value.
Abstract
This investigation focuses on flow energy, a crucial parameter in the design of water structures such as channels. The research endeavors to explore the relative energy loss (ΔEAB/EA) in a ...constricted flow path of varying widths, employing Support Vector Machine (SVM), Artificial Neural Network (ANN), Gene Expression Programming (GEP), Multiple Adaptive Regression Splines (MARS), M5 and Random Forest (RF) models. Experiments span a Froude number range from 2.85 to 8.85. The experimental findings indicate that the ΔEAB/EA exceeds that observed in a classical hydraulic jump with constriction section. Within the SVM model, the linear kernel emerges as the best predictor of ΔEAB/EA, outperforming polynomial, radial basis function (RBF), and sigmoid kernels. In addition, in the ANN model, the MLP network was more accurate compared to the RBF network. The results indicate that the relationship proposed by the MARS model can play a significant role resulting in high accuracy compared to the non-linear regression relationship in predicting the target parameter. Upon comprehensive evaluation, the ANN method emerges as the most promising among the candidates, yielding superior performance compared to the other models. The testing phase results for the ANN-MLP are noteworthy, with R = 0.997, average RE% = 0.63%, RMSE = 0.0069, BIAS = −0.0004, DR = 0.999, SI = 0.0098 and KGE = 0.995.
This study investigates experimentally and numerically the effects of sills with different geometric specifications at various positions on the hydraulic characteristics of flow through sluice gates. ...The simulation results showed that the RNG turbulence model’s statistical indicators yield high accuracy compared to the k-ε, k-ω, and LES turbulence models. The discharge coefficient (Cd) has an inverse relationship with gate opening. Regarding sill state, the discharge coefficient is higher than no-sill state. In the case of non-suppressed sills, the Cd decreases compared to the smaller openings as the opening of the gate changes. The results showed that the Cd with a sill in the tangent position upstream of the gate is higher than the downstream tangent and below situations. Increasing the sill length leads to an increase in flow shear stress and consequently a decrease in Cd. The Cd of gates with different sill thicknesses is always higher than the no-sill state, but due to the constant ratio of the fluid depth above the sill to the gate opening, the Cd increases to a certain extent and then decreases with increasing sill thickness.
This study investigates the effects of gate openings and different sill widths on the sluice gate’s energy dissipation and discharge coefficient (Cd). The physical model of the sills includes ...rectangular sills of different dimensions. The results show that the gate opening size is inversely related to the Cd for a gate without a sill. In addition, increasing the gate opening size for a given discharge decreases the relative energy dissipation, and increasing the Froude number increases the relative energy dissipation. The results also show that the Cd and relative energy dissipation decrease when the width of the sill is decreased, thus increasing the total area of the flux flowing through the sluice gate and vice versa. According to the experimental results, the relative energy dissipation and the Cd of the sluice gate are larger for all sill widths than without the sill. Finally, non-linear polynomial relationships are presented based on dimensionless parameters for predicting the relative energy dissipation and outflow coefficient.
The use of gate-sill combinations in recent years has been one of the new methods in increasing the hydraulic performance of gates, including the discharge coefficient (Cd). The present research aims ...to investigate the Cd of the gate with a sill in different dimensions in width and various positions relative to the gate using support vector machine (SVM) models, the K nearest neighbor (KNN) algorithm, and the artificial neural network (ANN) method using Statistica software. Out of 345 experimental data, 70% (241) were used for training and 30% (104) for testing. The best results are obtained when all dimensionless parameters (Atotal/B2, H0/B, Z/B, ε/B, and X/B) are used. The results of different kernels showed that RBF kernel has better results in predicting Cd compared to Polynomial, Linear, and Sigmoid kernels. The results of the statistical indexes of R, KGE, RMSE, and Mean RE% for the RBF kernel in the test phase are 0.955, 0.90, 0.0192 and 1.82%, respectively. In the KNN model, Manhattan distance measure has favorable results compared to other Euclidean, Euclidean Squared, and Chebychev criteria. The results showed that the ANN method has the best performance compared to SVM and KNN models with values of 0.984, 0.976, 0.0098, and 1.15%, respectively.
This study numerically investigated the effects of geometric parameters of chimney weirs on the discharge coefficient (C
d
). Here, chimney weirs with apex angles 74°, 84°, 94.4°, 106° and 116° at ...two crest heights were examined. The RNG turbulence model was selected due to its greater accuracy compared to k-ε, k-ω and LES methods for these types of flows. With increasing discharge and crest height, the value of C
d
decreases. The effect of constant C
d
showed an increase in the percentage of discharge deviation from the discharge values obtained from numerical solution. Based on dimensionless variables such as ratio of water head to the crest height, the ratio of crest length to the crest height, the ratio of the vertical distance between weir crest and the first point where the weir slope changes to the crest height, and the vertex angle of the inverted triangle, non-linear polynomial regression relations were obtained.
Highlights
A numerical investigation of the discharge coefficient of Chimney weir with different geometry has been done using FLOW-3D software.
Chimney weirs have high reliability in measuring discharge due to less sensitivity to changes in upstream water depth.
This investigation improves the design of hydraulic control structures.
New equation was developed for calculating the discharge coefficient of Chimney weir.
One of the significant issues in hydraulic engineering is reducing erosion in rivers by using groynes to preserve soil. The purpose of this study is to investigate numerically the groynes' presence ...on the sedimentary flow parameters using FLOW-3D software. For this purpose, groynes were examined at angles 30°, 60°, and 90° under 10 scenarios in various discharge and hydraulic conditions. Here, the mesh block with dimensions of 5 mm was chosen as the optimal mesh block for simulating models. In addition, Large Eddy Simulation (LES) turbulence model was used for simulations. In the scenarios where two blades are used scouring is observed in the first blade, while the sedimentation phenomenon was observed in the groyne after the first groyne in the direction of the flow. In the two blades with a distance of 0.60 m from each other, 48 mm erosion occurred. The highest amount of scour is related to the arched groyne (LLeft-Q285) with 45 mm. Discharges have an increased effect on scouring, so by comparing the scenarios with one groyne (I-Q285, I-Q200, and I-Q350), the lowest amount is with the value of 5.5mm corresponding to I-Q200. The insufficient erosion in the angled groynes corresponds to the smaller angle scenario.
Viable renewable energy sources must be low-cost, easy to install, clean, and reliable if they are to meet the energy demand of urban or rural areas. Water is able to provide efficient sources of ...electrical energy among alternative renewable energy sources. Using modern hydraulic techniques, drinking water can be transported to the areas where it is needed. Studies on obtaining energy from drinking water networks are quite limited. Although not as necessary as water in terms or human health, electrical power is still critically important in many applications (lighting, heating, cooling, etc.). Consequently, many countries are developing energy using various renewable energy sources. In this study, a water distribution network in the Armağan Village of Maçka district of Trabzon province were used to obtain electrical energy. There are 47 pressure breaking valves (PBVs) in this network and the broken energy height is 236.35 m. The same energy loss can be achieved by installing microturbines instead of PBVs, and electricity generation can thus be achieved with a clean energy source. It was found that 84.12kWh of energy was obtained from each PBV, with a total of 3950kWh. The most suitable microturbine was selected according to sound microturbine selection criteria. From this study, it is revealed that electricity can be produced by using a Microturbine instead of Pressure Breaker Valves (PBVs).
Here, the effect of sill application on hydraulic jump parameters has been investigated. The model of sills is made of polyethylene in various dimensions. The sills were investigated in different ...positions relative to the gate in single, double, and triple arrangements. In a certain opening, the sill leads to more energy dissipation. By increasing the ratio of initial depth to sequent depth, the ∆EAB/yA decreases. It occurs due to the convergence of initial and sequent depths. In the under gate suppressed sill state, the ∆EAB/EA is 11.05% more than the upstream tangential position, while it's 14.56% for downstream specific energy. The results showed that the energy dissipation decreases with increasing the opening by at most 34.88%. In the same opening of no-sill and with sill cases, the use of suppressed sill leads to a decrease in the sequent depth compared to the no-sill one. The application of the sill causes an increase in the initial depth and accordingly the initial specific energy decreases; therefore, the sill leads to the reduction of the specific energy in the flow conjugate depths. The regression nonlinear polynomial equations were proposed to estimate the relative energy dissipation. Statistical indicators Relative Error (RE), Root Mean Square Error (RMSE), and Kling Gupta Efficiency (KGE) have been used to check the accuracy of presented equations. The mean RE% and RMSE for presented equation of ∆EAB/EA are 0.78%, and 0.004, respectively. These values are 0.87%, and 0.009 for ∆EAB/EB, respectively. The KGE is in very good range for equations.
Here, the contraction coefficient, discharge coefficient, hydraulic jump length, and relative energy dissipation in which the gate acts as a supercritical flow generator were investigated at ...different openings. The maximum value of the contraction coefficient is related to the gate with the lowest amount of opening. The amount of gate opening is inversely related to the discharge coefficient. At a certain discharge, increasing opening leads to a decrease in relative energy dissipation. Moreover, with increasing Froude number, relative energy dissipation increases. Here, the amplitude of the Froude number changed from 2.2 to 14.2, which has a direct effect on the hydraulic jump length, and with increasing opening, the Froude number and jump length decreased. The amount of opening is inversely related to the upstream water depth and the hydrodynamic force applied to the gate. Regression nonlinear polynomial relationships were presented to predict relative energy dissipation and discharge coefficient with appropriate statistical indicators of root mean square error and Kling Gupta. For the discharge coefficient, mdecreasedore than 78% of the data have an error of less than ±1.5%. In addition, for energy dissipation relative to the upstream and downstream, more than 88% of the data have a relative error of less than ±5 and ±1%, respectively.
