Abstract
A traditional stepped spillway is prone to cavitation risks. To improve its hydraulic behaviors, distorted step faces and pool weirs are devised. By numerical modelling, comparative studies are conducted to look into the flow features. The pressures on step surfaces of the unconventional layouts exhibit 3D distributions. Pool weirs are essential in increasing both the min. and max. pressure loads. Pressures on the downstream bed show a unique pattern for V- and inverted V-shaped models, with the extreme pressures at the sidewalls for the former and at the central plane for the latter. Symmetrical secondary flows are formed in V- and inverted V-shaped cases with different patterns. Distributions of turbulent kinetic energy suggest differences in flow motions in all cases. Furthermore, the relative energy loss of flat setups is ∼5.4% lower than that of the pooled ones with the same step face angle; inverting the face angle does not give rise to noticeable change. The results provide reference for relevant projects.
Highlights
With the advances in roller compacted concrete (RCC) techniques, stepped spillways have gained popularity with a wide range of applications including hydropower [1,2,3]
Inclining steps upwards is effective in lowering the outlet velocity and increasing energy loss [20]. 3D flow motions are produced by changing the step face angle, leading to higher head loss and aeration [21]
Most of the studies of novel designs focused on the energy dissipation and air entrainment; examinations of step configurations are relatively limited. is paper illustrates, through 3D numerical simulations, the flow features of several step layouts. e aim is to reveal the effects of geometrical layouts of steps on pressure loads and flow structures, which would contribute to better understanding of their hydraulic characteristics and to effective engineering measures in design of stepped spillways
Summary
With the advances in roller compacted concrete (RCC) techniques, stepped spillways have gained popularity with a wide range of applications including hydropower [1,2,3]. Novel designs are implemented to increase the hydraulic performances of traditional stepped spillways. Felder [6]; Zare and Doering [17]; and Kokpinar [18] looked into the aeration and flow resistance in stepped spillways with sills and baffles. Experiments by Zare and Doering [19] suggested higher energy dissipation by rounding the step edges. Most of the studies of novel designs focused on the energy dissipation and air entrainment; examinations of step configurations are relatively limited. E aim is to reveal the effects of geometrical layouts of steps on pressure loads and flow structures, which would contribute to better understanding of their hydraulic characteristics and to effective engineering measures in design of stepped spillways Most of the studies of novel designs focused on the energy dissipation and air entrainment; examinations of step configurations are relatively limited. is paper illustrates, through 3D numerical simulations, the flow features of several step layouts. e aim is to reveal the effects of geometrical layouts of steps on pressure loads and flow structures, which would contribute to better understanding of their hydraulic characteristics and to effective engineering measures in design of stepped spillways
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