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the inception point of flow aeration on a rough stepped spillway
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نویسنده
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parsaie abbas ,dah mardeh arman ,haghiabi amirhamzeh
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منبع
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هيدروليك - 2024 - دوره : 18 - شماره : 4 - صفحه:27 -33
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چکیده
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Stepped spillways are used in hydraulic engineering projects such as small and large dams. the inception point of aeration on such hydraulic structures is essential in determining the zones of single and two-phase flow. in this study, the effect of the surface roughness of steps on the location of ifpa on a stepped spillway is studied. for this purpose, a laboratory model of ogee-stepped spillway was designed based on the maximum energy dissipation guidelines and its steps were roughened with gravel (with a specific grain size). the experiments were conducted in a channel with a longitudinal slope of 0.001, length of 12m, width of 0.5m, and depth of 0.8m on a stepped spillway with a height of 0.6m that has 9 steps. the flow discharge ranged between 6 (l/s) and 16(l/s). it was concluded that flow aeration starts at a distance of about 12 times the critical depth from the crest and by doubling the critical depth, its distance from the crest increased up to 50 percent. notably, roughing the step surface reduces the length of the non-aeration area by about 15%.
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کلیدواژه
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rough steps ,flow aeration ,effective roughness ,critical depth
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آدرس
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shahid chamran university of ahvaz, faculty of water and environmental engineering, iran, university of sistan and baluchestan, department of civil engineering, iran, lorestan university, water engineering department, iran
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پست الکترونیکی
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haghiabi.a@lu.ac.ir
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the inception point of flow aeration on a rough stepped spillway
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Authors
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Abstract
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stepped spillways are used in hydraulic engineering projects such as small and large dams. the inception point of aeration on such hydraulic structures is essential in determining the zones of single and two-phase flow. in this study, the effect of the surface roughness of steps on the location of ifpa on a stepped spillway is studied. for this purpose, a laboratory model of ogee-stepped spillway was designed based on the maximum energy dissipation guidelines and its steps were roughened with gravel (with a specific grain size). the experiments were conducted in a channel with a longitudinal slope of 0.001, length of 12m, width of 0.5m, and depth of 0.8m on a stepped spillway with a height of 0.6m that has 9 steps. the flow discharge ranged between 6 (l/s) and 16(l/s). it was concluded that flow aeration starts at a distance of about 12 times the critical depth from the crest and by doubling the critical depth, its distance from the crest increased up to 50 percent. notably, roughing the step surface reduces the length of the non-aeration area by about 15%.
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Keywords
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rough steps ,flow aeration ,effective roughness ,critical depth
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