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Information Journal Paper

Title

Experimental Investigation of the Wedge-Shaped Deflector Installation Position Effects on the Flip Bucket Spillway Energy Dissipation

Pages

  87-106

Abstract

 Introduction: A spillway is an important hydraulic structure usually used to transport the controlled release of water of a dam or covey river water over its crest to the river bed downstream. Because of high bed slope, the velocity increases throughout the spillways and it reaches its maximum at the downstream which an energy dissipator structure should be designed to reduce the kinetic energy before it transported to the river bed. A flip-bucket and a Ski-jump structure are among the most common energy dissipator which dissipate the extra energy by throwing the incoming jet into the air and as a result, the air interferes with the water and then penetrate in the downstream pool. Energy dissipation control has always been one of the most significant and vital matter and concern of hydraulic scientists and researchers especially in high dams. One of the most common method to dissipate energy is to discharge flow away from the hydraulic structures and downstream by using Flip bucket spill way. During the past decades, many studies are conducted to develop a design criterion to increase the efficiency of the structure or increase of energy dissipation. The length of the projectile or the horizontal distance of the jet which passes to attach the downstream water, also has been important issue which investigators have tried to reduce as long as possible. The use of deflector installed at the edge of the upstream of the jump is among measures which was first studied by Joun and Hager (2006). Many other studies also showed that the deflector can increase the energy dissipation and reduce the projectile length. However, most of these studies focus on the geometry of the deflector. As the effect of the position of deflector have not been studied, this study was conducted. Methodology: To investigate the effects of deflector installation position on energy dissipation and the length of the projectile jet a new experimental study was conducted in the Hydraulic laboratory of Shahid Chamran university of Ahvaz. Three wedged-shape structures with height of 10 cm, length of 6 cm and angle of 47 degree were installed at four different positions upstream of the jump. Total of. 40 experiments were performed using 10 different flow discharges. It is worth mentioning that all experiments including the none-deflector case, were performed at 8 dimensionless parameter Yc/H. At each experiment the flow discharge, the water surface profile, the jet projectile length and the depth of tailwater was recorded. Photographs also was taken which were used to extract necessary data by using image processing software. In the end relative energy dissipation was calculated by measuring the total energy in the upstream and downstream. In addition to the energy dissipation, Jet projectile length (for each experiment) was determined by using Get data software and the photos taken during the study. Results and discussion: In general, data analysis demonstrated that the waged-shape structures resulted in a remarkable increase in the amount of energy dissipation and a major decrease in jet projectile length, due to the increase of water and air mixture compare to the case of no deflectors. Indeed, deflectors divide the incoming jet to two small different jets, therefore the combination of these two small jets leads to the increase in water and air mixture and consequently the increase of relative energy dissipation. Moreover, it has been shown that the energy dissipation increased directly with the linear distance from the bucket. Furthermore, the experimental study on the jet length indicated a remarkable decrease in the jet length by the increasing of the linear distance. In other words, the different installation position of deflector increases the height of jet trajectory. It directly increases the contact surface of jet and air and leads to increase in energy dissipation and consequently decrease of jet length. Conclusion: In general, the increase of horizontal distance of the installed deflector from the edge of the bucket resulted in the increase in energy dissipation and the decrease in jet projectile length. The maximum relative energy dissipation was observed 65. 9% which occurred where the Yc/H = 0. 027 and Lx/L = 7. 3 and the minimum observed relative energy dissipation was 57. 5%, which occurred for the Yc/H = 0. 061 and Lx/L = 4. 3. Furthermore, the maximum observed jet length was105 cm, which occurred in Yc/H = 0. 061 and its minimum was 35 cm, which occurred in Yc/H = 0. 027. Therefore, according to the results of the all experiments using deflector in proper possessions can significantly reduce the jet projectile length and also cause to increasing the energy dissipation. More studies in larger scale model required before the result of this study can be applied in prototype.

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    APA: Copy

    Saki, Niloofar, & SHAFAI BEJESTAN, MAHMOOD. (2022). Experimental Investigation of the Wedge-Shaped Deflector Installation Position Effects on the Flip Bucket Spillway Energy Dissipation. JOURNAL OF HYDRAULICS, 17(2 ), 87-106. SID. https://sid.ir/paper/966234/en

    Vancouver: Copy

    Saki Niloofar, SHAFAI BEJESTAN MAHMOOD. Experimental Investigation of the Wedge-Shaped Deflector Installation Position Effects on the Flip Bucket Spillway Energy Dissipation. JOURNAL OF HYDRAULICS[Internet]. 2022;17(2 ):87-106. Available from: https://sid.ir/paper/966234/en

    IEEE: Copy

    Niloofar Saki, and MAHMOOD SHAFAI BEJESTAN, “Experimental Investigation of the Wedge-Shaped Deflector Installation Position Effects on the Flip Bucket Spillway Energy Dissipation,” JOURNAL OF HYDRAULICS, vol. 17, no. 2 , pp. 87–106, 2022, [Online]. Available: https://sid.ir/paper/966234/en

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