Experimental and numerical study of sluice gate flow pattern with non- suppressed sill and its effect on discharge coefficient in free-flow conditions

The purpose of this study is to investigate the flow pattern and discharge coefficient of sluice gate with the non-suppressed sill in experimental and numerical conditions. For this purpose, the sill of a rectangular cube in widths of 7.5, 10, 15, and 20 cm was installed under the sluice gate. Experimental results showed that placing a non-suppressed sill under the sluice gate by creating a failure in the flow lines causes a different flow pattern compared to the without sill state. Deviation of streamlines after colliding with the sill causes the formation of V-shaped currents. The discretization of equations for simulations were performed using VOF method. After selecting a cell with a size of 0.07 cm as the optimal cell, the RNG turbulence model was used. The results of the numerical simulation showed an acceptable agreement with the experimental results. Thus, the place of formation of V-shaped currents was transferred downstream of the sluice gate by increasing the width of the sill and the inflow discharge. The results of the study of the discharge coefficient showed that the placement of the sill with a width of 7.5 and 20 cm, increased the discharge coefficient by an average of 5.3% and 15.5% in the experimental model and 4.7% and 16% in the numerical simulation. This relationship is without sill state and with sill state with root mean square error of 0.967 and 0.968, respectively, estimated the discharge coefficient of the sluice gate

Numerical Investigation on Effective Parameters on Hydraulic Flows in a Sluice Gate with Sill on Free-Flow Condition

The presence of a sill under the sluice gate is one of the solutions to control the flow rate. This study was conducted to numerically investigate the discharge coefficient (Cd) of sluice gates with different heights and widths of sills in free flow conditions. The simulations were performed using FLOW-3D software. Results show that Cd increases as the gate opening decreases. Also, results showed that reducing the gate opening from 5 cm to 2 cm increases the Cd in the gate with sill by 9% compared to the non-sill gate. Discharge coefficients with 1 cm and 4 cm sills, compared to the non-sill condition were estimated at 1.5% and 18%, respectively. Examination of sill width changes showed that decreasing the width reduces the discharge coefficient by reducing the amount of velocity and flow pressure along the sill sides. The effects of three parameters of the gate opening, sill height, and sill width were compared. The results showed that increasing the sill width compared to the two mentioned parameters has the maximum increase in the Cd

Experimental Study of Geometric Shape and Size of Sill Effects on the Hydraulic Performance of Sluice Gates

The present research was conducted to investigate the effect of sill geometry and sill width on the discharge coefficient and hydraulic jump characteristics. For this purpose, sills with semi-cylindrical, cylindrical, pyramidal, and rectangular cube geometries with widths of 0.075, 0.10, 0.15, and 0.2 m were installed under a sluice gate. Results showed that increasing the sill width increased the sluice gate discharge coefficient compared to the no-sill mode. The results of placing a sill with different geometric shapes under a sluice gate indicate that using a semi-cylindrical sill increases the discharge coefficient. The ranked order of other sills, from the largest to smallest discharge coefficient, is: cylindrical, pyramidal, and rectangular cubic sills, respectively. The results show that the use of a sill increases the energy dissipation. Examining sills of different widths indicates that with increasing width, the increase in velocity and consequent decrease in the depth of the hydraulic jump causes an increase in energy loss. When employing sills of maximum width (b = 0.20 m) for pyramidal, semi-cylindrical, cylindrical, and rectangular shapes, the energy loss increased by 125, 119, 116, and 125% in section A, respectively. The semi-cylindrical sill is most effective in increasing the discharge coefficient, while the pyramidal sill is most effective for increasing energy dissipation

Determination of flow characteristics over sharp-crested triangular plan form weirs using numerical simulation

ABSTRACTTriangular plan form weirs are one type of long-crested weirs. Therefore, they can pass more discharge capacity than weirs at the given channel width. This study aims to investigate the effects of different number of teeth (3, 4, and 5 teeth), angle of the weir tip (90, 60, 120, and 150 degrees), and the amount of different discharges (0.009–0.0063 m3/s) of sharp-crested triangular plan form weirs on the hydraulic parameters by using the Finite Volume Method (FVM). It was found that, increasing the effective length of the crest, increases the discharge coefficient up to 95% in the case with 5 teeth (L/B = 4.14 and h/W = 0.128), 45% in the case with 4 teeth (L/B = 3.71 and h/W = 0.168) and 39% for 3 teeth (L/B = 3.28 and h/W = 0.188) compared to the simple triangular plan weir (without teeth). Also, Results indicated that the discharge coefficient has an inverse relationship with the h/w ratio. In contrast, the investigations showed that the velocity in the flow jet is affected by the effective length of the triangular plan crest, and the increase in the effective length results in a decrease in the average velocity of the flow jet. So that these disturbances caused the highest dissipation of energy to occur in the triangular plan crest with 5 teeth (27% compared to the upstream section (Section 1) and 37% compared to the downstream section (Section 2))