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You are here : eLibrary : IAHR World Congress Proceedings : 36th Congress - The Hague (2015) ALL CONTENT : Water engineering : Research on effect of contraction angle and ratio of flaring piers on impact pressure in stilling ba...
Research on effect of contraction angle and ratio of flaring piers on impact pressure in stilling basin
The joint energy dissipater of flaring piers and stilling basin has been introduced into wide use in high dam constructions
located in narrow valley areas, which often confront restricted discharge width and large discharge per unit width. At the
end of the flaring piers, the overflow nappe is compelled to contract laterally as well as extend longitudinally and vertically.
As a consequence, the contraction jet can meet the requirements of the discharge and energy dissipation. With
inappropriate contraction ratio or contraction angle, however, the flaring piers may cause a rise in the impact pressure in
the stilling basin. The influence of the contraction angle and ratio of flaring piers on the impact pressure downstream
should thus be a cause of concern. A model of flaring piers with alterable contraction ratios and contraction angles was
established in a circulating water system. The contraction ratios ranged from 0.2 to 0.8 with a gap of 0.2. The contraction
angles were set to be 15, 20, 25 or 30 degrees. Experiments under three different discharge conditions were performed.
The variation of the impact pressure in the stilling basin with different contraction angles and ratios of the flaring piers were
summarized. As the results showed, the largest impact pressure, in most cases, decreased as the contraction angle
increased from 15 to 25 degree. As the contraction angle increased to 30 degrees, the peak value of the impact pressure
altered indistinctly. Meanwhile, the largest impact pressures varied in their sensitivity to the contraction ratio under
different discharge. The contraction ratios of 0.6 and 0.4 were regarded as proper values according to the data analysis.
The results may provide a reference for engineering design.
File Size : 1,885,479 bytes
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Chapter : IAHR World Congress Proceedings
Category : 36th Congress - The Hague (2015) ALL CONTENT
Article : Water engineering
Date Published : 20/08/2015
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