Reduction of the erosive effects of effluent jets from spillways by contractions in the flow

Abstract

Flaring Piers and Slit Buckets are structures that can improve the process of energy dissipation and have been implanted in Chinese spillways for at least four decades. These structures basically narrow the passages of the outflow through the spillway, promoting changes in the effluent jets, reducing their erosion potential. However, the literature available on the subject is very limited, and the benefits are disseminated only qualitatively. In order to learn more about how these structures perform, a test program on a hydraulic model was carried out, using a spillway originally designed with a conventional ski jump. The results indicate that there is a correlation between the angle of deflection of the walls that narrow the chute and the depth of the scour hole formed downstream. One of the alternative tests had scour depth 60% smaller than that generated by the spillway without the device, indicating that they can be promising solutions.Keywords: Ski jump; Erosion; Flaring piers; Slit bucket. RESUMOFlaring Piers e Slit Buckets são estruturas que propiciam melhorar o processo de dissipação de energia e que vem sendo implantadas em vertedouros de barragens chinesas há pelo menos quatro décadas. Trata-se basicamente da implantação de estreitamentos na passagem do escoamento pelo vertedouro que promovem alterações no jato efluente, reduzindo seu potencial erosivo. No entanto, a bibliografia disponível sobre o assunto é bastante restrita e os benefícios são divulgados de forma apenas qualitativa. Visando aprofundar o conhecimento sobre o desempenho dessas estruturas, foi realizado um programa de ensaios em modelo reduzido utilizando um vertedouro projetado originalmente com salto de esqui convencional. Os resultados indicam existir uma correlação entre o ângulo de deflexão dos paramentos que estreitam a calha e a profundidade da fossa de erosão formada a jusante. Uma das alternativas ensaiadas teve profundidade máxima de erosão 60% menor do que aquela gerada pelo vertedouro sem o dispositivo, indicando que podem ser soluções promissoras.

Research on the Optimization Design of Abnormal Flip Buckets

“…erefore, the standard k − ε model is only applicable to simulations of the complete turbulence flow process. is model was proposed by Spalding and Launder in 1972 [16,17]. e dissipation rate of turbulence (ε) is defined as follows:…”

Flow Pressure Behavior Downstream of Ski Jumps

“…In Ref. [6], a test program on a hydraulic model was conducted aiming to explore how flaring piers and slit bucket structures perform the process of energy dissipation in order to mitigate the erosive effects of effluent jets from spillways. Results indicate that a correlation exists between the deflection angle and the downstream scour hole.…”