Browsing by Author "Marti, Ali Ihsan"

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Citation - WoS: 7
Citation - Scopus: 9
Determination of Hydraulic Characteristics of Flow Over a Triangular Sectioned Weir by Using Experimental and Numerical Modeling
(Univ Tehran, Danishgah-i Tihran, 2021) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa; 6062
The spillways of hydraulic structures transfer excessive water from dam reservoir to the downstream in a safe and controlled manner. A labyrinth or triangular weir is a flat spillway folded in plain view. The labyrinth weirs provide an increase in crest length for a given channel width and increase the flow capacity for a given weir load. As a result of the increased flow capacity, the labyrinth and triangular weirs require less space in the dam body than the flat weirs. In this study, experiments were carried out on the labyrinth weirs containing triangles of different heights and numbers by using 3 different weir heights (P=20cm, 30cm, and 40 cm) and 4 different weir shapes. Each experiment was repeated for 30 different discharge values. The effects of weir height and weir shape on the total head over the weir (H-T) and discharge (Q) were investigated. In addition, the numerical models of all experimental setups were created by ANSYS-Fluent program using Computational Fluid Dynamics (CFD). By comparing the results obtained from the numerical models with the physical models, the accuracy of the numerical models was tested. According to the results, as the number of the triangles (N) of the weir increases, the discharge coefficient (Ca) decreases. The weir height (P) does not have a major effect on the discharge.
Citation - WoS: 5
Citation - Scopus: 6
The Hydraulic Investigation of Harmonic Plan Weirs
(Elsevier Sci Ltd, 2024) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa
Existing dams and reservoirs need to be revised to meet safety standards. For the existing reservoirs where flood control is important and the maximum water level is limited, the best method to increase reservoir capacity is to build a labyrinth weir on the dam. In labyrinth weirs, the collision of two nappe flows produces nappe inter-ference, and this reduces the weir performance. In this study, the semi-circle weirs are placed in an open channel harmonically to increase the efficiency of the labyrinth weirs to make the areas more efficient and increase the flow capacity because of the nappe interference and to ensure the flow moving perpendicular to the weir as possible. In the experimental study of the asymmetrically placed circular weirs, 3 different weir heights (P = 20 cm, 30 cm and 40 cm) and 3 different labyrinth cycle numbers (N = 2, N = 3 and N = 4) were used. As a result of the experiments, although there was a 13 % decrease in the discharge coefficients (Cd) compared to the linear weirs, it provided a 57 % increase in the net crest length (Lnet). Discharge coefficient (Cd) is decreased 3.4 %, as the number of cycles (N) increases. As the weir height (P) decreases, Cd increases 7.5 % due to the vacuum effect.
Citation - WoS: 3
Citation - Scopus: 3
Numerical and Experimental Modelling of Flow at Tyrolean Weirs
(Elsevier Sci Ltd, 2021) Yildiz, Ali; Marti, Ali Ihsan; Gogus, Mustafa; 6062
In this study, a small-scaled Tyrolean weir model was constructed in the laboratory environment and a series of experiments were conducted on it, for two different rack inclinations (theta(1) = 18 degrees and theta(2) = 25 degrees) and three different bar spacings (e(1) = 3 mm, e(2) = 6 mm and e(3) = 10 mm) for a range of upstream flow discharges. The flow rates passing through the racks and going downstream over the racks were measured. Empirical equations for the discharge coefficient and water capture capacity of the Tyrolean weirs were determined by applying dimensional analysis to the parameters involved in the phenomenon. The related dimensionless parameters were presented with graphs and empirical equations for discharge coefficients were derived, coefficient of determination R-2 of equations for theta(1) = 18 degrees and theta(2) = 25 degrees are found 0.838 and 0.825 respectively. According to results obtained from experimental data, C-d increases as the Froude number ((F-r)(e)) between bars increases and water capture capacity [(q(w))(i)/(q(w))(T)] of the racks decreases with increasing ((F-r)(e)). Also, a numerical model of the Tyrolean weir was generated by using Flow-3D software and it was shown that the results of the numerical analysis were very consistent with the physical model results at large bar spacing such as e = 10 mm. As the bar spacing (e) reduces, the success of the numerical model giving consistent results with physical model is decreasing.