Experimental and Numerical Investigation of the Trajectory of Outlet Jets through the Pressurized Discharge Gates of Reservoir Dams

Document Type : Applied Article

Authors

• A. Taheri Aghdam ¹
• F. Salmasi ²
• A. Hosseinzade Dalir ²
• A. Abbaspour ³

¹ Ph.D. Student, Department of Water Engineering, Tabriz University, Tabriz, Iran

² Professor, Department of Water Engineering, Tabriz University, Tabriz, Iran

³ Associate Professor, Department of Water Engineering, Tabriz University, Tabriz, Iran

10.22067/jwsd.v10i3.2301-1207

Abstract

Accurate knowledge of where jets hit downstream of dams helps designers a lot in locating plunging pools. The purpose of this study is to investigate experimentally and numerically the trajectory of pressurized jets through the gates and to determine their location downstream of the dam. Ansys - Fluent software was used for numerical simulation. The results showed that there is a significant difference between the experimental values and the values extracted from the jet projectile equations for predicting the path of the pressurized jets, and this discrepancy may be due to the effect of air resistance on flow. The existing jet trajectory equations don’t consider air resistance. To minimize this difference, the projectile equation was modified. Also, the effect of changing the diameter of the dam gate and the discharge on the point of impact of the pressurized jet on the ground surface was examined. By increasing the diameter of the dam outlet at a constant discharge, the location of impact of the impinging jet to the ground from the dam toe decreases, and with increasing discharge at a constant diameter of outlet, the place of impact of the pressurized jet to the ground from the toe of the dam increases. In addition, the numerical simulation results showed that the dynamic pressure as well as the velocity at the point of impingement of the jets on the river bed have the maximum value that should be considered in designs. The dynamic pressure as well as the velocity of the jet coming out of the gate hit the ground with an average increase of 145% and 242% relative to the end edge of the gate, respectively. In addition, the breaking length of the pressurized jet was investigated in this study, and it was found that the breaking length of the pressurized jet increases with the increase in the initial velocity of the water jet.

Keywords

• Pressurized Jet
• Plunging Pool
• Gate
• Dynamic Pressure
• Projectile Equation

Main Subjects

• Water Transfer & Hydraulic Structures

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