The Study of the Effect of the Sill Slope on the Discharge Coefficient of the Labyrinth Weir

This paper proposes a model based on gene expression programming for predicting discharge coefficient of triangular labyrinth weirs. The parameters influencing discharge coefficient prediction were first examined and presented as crest height ratio to the head over the crest of the weir (p/y), crest length of water to channel width (L/W), crest length of water to the head over the crest of the weir (L/y), Froude number (F=V/√(gy)) and vertex angle () dimensionless parameters. Different models were then presented using sensitivity analysis in order to examine each of the dimensionless parameters presented in this study. In addition, an equation was presented through the use of nonlinear regression (NLR) for the purpose of comparison with GEP. The results of the studies conducted by using different statistical indexes indicated that GEP is more capable than NLR. This is to the extent that GEP predicts the discharge coefficient with an average relative error of approximately 2.5% in such a manner that the predicted values have less than 5% relative error in the worst model.

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Using data mining methods to improve discharge coefficient prediction in Piano Key and Labyrinth weirs

Water Science & Technology Water Supply ◽

10.2166/ws.2021.304 ◽

2021 ◽

Author(s):

Mahdi Majedi-Asl ◽

Mehdi Foladipanah ◽

Venkat Arun ◽

Ravi Prakash Tripathi

Keyword(s):

Discharge Coefficient ◽

Gene Expression Programming ◽

Research Work ◽

Coefficient Of Determination ◽

Support Vector ◽

Effective Parameters ◽

Data Set ◽

Labyrinth Weir ◽

Dimensional Parameters ◽

Using Data

Abstract As a remarkable parameter, the discharge coefficient (Cd) plays an important role in determining weirs' passing capacity. In this research work, the support vector machine (SVM) and the gene expression programming (GEP) algorithms were assessed to predict Cd of piano key weir (PKW), rectangular labyrinth weir (RLW), and trapezoidal labyrinth weir (TLW) with gathered experimental data set. Using dimensional analysis, various combinations of hydraulic and geometric non-dimensional parameters were extracted to perform simulation. The superior model for the SVM and the GEP predictor for PKW, RLW, and TLW included , and respectively. The results showed that both algorithms are potential in predicting discharge coefficient, but the coefficient of determination (RMSE, R2, Cd(DDR)max) illustrated the superiority of the GEP performance over the SVM. The results of the sensitivity analysis determined the highest effective parameters for PKW, RLW, and TLW in predicting discharge coefficients are , , and Fr respectively.

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Energy Dissipation and Hydraulics of Flow over Trapezoidal–Triangular Labyrinth Weirs

Water ◽

10.3390/w12071992 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1992 ◽

Cited By ~ 5

Author(s):

Amir Ghaderi ◽

Rasoul Daneshfaraz ◽

Mehdi Dasineh ◽

Silvia Di Francesco

Keyword(s):

Energy Dissipation ◽

Discharge Coefficient ◽

Residual Energy ◽

Free Flow ◽

Flow Conditions ◽

Labyrinth Weir ◽

Sidewall Angle ◽

Weir Height ◽

Downstream Flow ◽

Labyrinth Weirs

In this work experimental and numerical investigations were carried out to study the influence of the geometric parameters of trapezoidal–triangular labyrinth weirs (TTLW) on the discharge coefficient, energy dissipation, and downstream flow regime, considering two different orientations in labyrinth weir position respective to the reservoir discharge channel. To simulate the free flow surface, the volume of fluid (VOF) method, and the Renormalization Group (RNG) k-ε model turbulence were adopted in the FLOW-3D software. The flow over the labyrinth weir (in both orientations) is simulated as a steady-state flow, and the discharge coefficient is validated with experimental data. The results highlighted that the numerical model shows proper coordination with experimental results and also the discharge coefficient decreases by decreasing the sidewall angle due to the collision of the falling jets for the high value of H/P (H: the hydraulic head, P: the weir height). Hydraulics of flow over TTLW has free flow conditions in low discharge and submerged flow conditions in high discharge. TTLW approximately dissipates the maximum amount of energy due to the collision of nappes in the upstream apexes and to the circulating flow in the pool generated behind the nappes; moreover, an increase in sidewall angle and weir height leads to reduced energy. The energy dissipation of TTLW is largest compared to vertical drop and has the least possible value of residual energy as flow increases.

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Prognostication of discharge coefficient of labyrinth weir using outlier robust extreme learning machine

Flow Measurement and Instrumentation ◽

10.1016/j.flowmeasinst.2019.101681 ◽

2020 ◽

Vol 71 ◽

pp. 101681 ◽

Cited By ~ 1

Author(s):

Shahabodin Shafiei ◽

Mohsen Najarchi ◽

Saeid Shabanlou

Keyword(s):

Extreme Learning Machine ◽

Discharge Coefficient ◽

Labyrinth Weir ◽

Learning Machine

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Introducing the T-shaped weir: a new nonlinear weir

Water Science & Technology Water Supply ◽

10.2166/ws.2021.144 ◽

2021 ◽

Author(s):

Behzad Noroozi ◽

Jalal Bazargan ◽

Akbar Safarzadeh

Keyword(s):

Discharge Coefficient ◽

Vertical Wall ◽

Hydraulic Performance ◽

Height Ratio ◽

Maximum Increase ◽

Labyrinth Weir ◽

Numerical Tests ◽

Vertical Walls ◽

Piano Key Weir ◽

3D Software

Abstract In the present study, a new nonlinear weir called the T-Shaped Weir (TSW), which is a combination of the Labyrinth Weir (LW) and the Piano Key Weir (PKW), was introduced, and its hydraulic performance was compared with the PKW. Based on the presence of the vertical walls at the inlet key, outlet key, or both keys, the TSW weirs were classified as type A, B, and C weirs, respectively. The flow pattern of different TSW cases was analyzed, and the discharge coefficient curves were provided. Furthermore, to accurately study the hydrodynamics of the tested weirs, the 3D numerical simulations were performed using the FLOW-3D software. The results showed that inserting a vertical wall at the upstream of the outlet keys (C-TSW type) has a negligible effect on the hydraulic performance of the PKW. A maximum increase of 16% occurred in the discharge coefficient of the B-TSW in comparison to the PKW, and up to a head to height ratio (Ht/p) of 0.45, effect of the vertical wall on increasing the performance of the B-TSW was maintained. Based on the experimental and numerical tests, the optimal height ratio of the vertical wall (Pd/P) in B-TSW with highest discharge capacity was determined equal to 0.4.

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The effects of dentate crest and a row of consecutive orifices along and below the crest edge on labyrinth weir efficiency

Canadian Journal of Civil Engineering ◽

10.1139/cjce-2018-0008 ◽

2019 ◽

Vol 46 (6) ◽

pp. 552-555

Author(s):

Zobeideh Ahmadi ◽

Seyed Asadollah Mohseni Movahed ◽

Javad Mozaffari

Keyword(s):

Discharge Coefficient ◽

Labyrinth Weir ◽

Laboratory Flume ◽

Discharge Efficiency

A labyrinth weir is one of the most effective ways of increasing weir discharge efficiency compared with a linear overflow structure. In this study, two proposed models of labyrinth weir, one with a dentate crest and another with a row of orifices along and below the crest edge were compared with a simple labyrinth weir, measuring their effects on the discharge coefficient. Experiments on nine labyrinth weir models were conducted in the hydraulic laboratory flume. These experiments indicated that creation of both dentate crest edge and row of consecutive orifices led to an increased discharge coefficient of between 11 to 25.3% and 31.6 to 52.9%, respectively, relative to simple labyrinth weir. By increasing the upstream head water, the discharge coefficient for the labyrinth weir model with dentate crest and the model with a row of consecutive orifices are closer together and eventually will converge.

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