Scour downstream of rock-lined stilling basins
Scour downstream of rock-lined stilling basins
Local scour downstreams of a stilling basin with hydraulic jump has been investigated experimentally in the laboratory. The studies embraced both a smooth and a rock-lined bed to the stilling basin. Two rock sizes were used (22mm and 13mm median diameter). Three different sizes of sand (0.35mm, 0.5mm and 1.00mm median diameter) were used in the channel downstream.Tests were conducted to establish the hydraulic characteristics of the rock-lined stilling basin and the effect of scour development on the momentum balance of the jump also to determine the effect of rock size on the scour profile.Empirical equations based on the experimental data have been developed. The logarithmic law was found to be valid for velocity distribution, friction factor and Chezy coefficient. Equivalent sand roughness of the rock was found equal to 0.2 times the characteristic size of the rock.The momentum balance describing the formation of the hydraulic jump for a rigid boundary was adapted to define the formation of the hydraulic jump in the presence of the scour development.The characteristic features of the scoured bed in the equilibrium state have been analysed using dimensional analysis. It has been found that the dimensionless shape of the scour hole can be defined by a general equation. The maximum depth of scour and its distance from the downstream end of the stilling basin in terms of supercritical depth of flow have been found to vary with super-critical Froude number and roughness height.The investigation has shown that scour depth is much reduced downstream of rock-lined stilling basin as compared with a smooth lining. The average reduction of scour depth was about 33% and 18% for 22mm and 13mm rock, respectively. Correspondingly, the distance to the maximum scour depth was increased by about 40% and 15%, respectively. (D81693)
University of Southampton
Al-Nassiri, Aktham Mohamed Saleh Hamoudi
1987
Al-Nassiri, Aktham Mohamed Saleh Hamoudi
Al-Nassiri, Aktham Mohamed Saleh Hamoudi
(1987)
Scour downstream of rock-lined stilling basins.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Local scour downstreams of a stilling basin with hydraulic jump has been investigated experimentally in the laboratory. The studies embraced both a smooth and a rock-lined bed to the stilling basin. Two rock sizes were used (22mm and 13mm median diameter). Three different sizes of sand (0.35mm, 0.5mm and 1.00mm median diameter) were used in the channel downstream.Tests were conducted to establish the hydraulic characteristics of the rock-lined stilling basin and the effect of scour development on the momentum balance of the jump also to determine the effect of rock size on the scour profile.Empirical equations based on the experimental data have been developed. The logarithmic law was found to be valid for velocity distribution, friction factor and Chezy coefficient. Equivalent sand roughness of the rock was found equal to 0.2 times the characteristic size of the rock.The momentum balance describing the formation of the hydraulic jump for a rigid boundary was adapted to define the formation of the hydraulic jump in the presence of the scour development.The characteristic features of the scoured bed in the equilibrium state have been analysed using dimensional analysis. It has been found that the dimensionless shape of the scour hole can be defined by a general equation. The maximum depth of scour and its distance from the downstream end of the stilling basin in terms of supercritical depth of flow have been found to vary with super-critical Froude number and roughness height.The investigation has shown that scour depth is much reduced downstream of rock-lined stilling basin as compared with a smooth lining. The average reduction of scour depth was about 33% and 18% for 22mm and 13mm rock, respectively. Correspondingly, the distance to the maximum scour depth was increased by about 40% and 15%, respectively. (D81693)
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Published date: 1987
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Local EPrints ID: 461777
URI: http://eprints.soton.ac.uk/id/eprint/461777
PURE UUID: 05da96b2-ed11-467b-b44b-f6550c44fd9b
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Date deposited: 04 Jul 2022 18:54
Last modified: 04 Jul 2022 18:54
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Author:
Aktham Mohamed Saleh Hamoudi Al-Nassiri
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