Author(s): Zhou Zhao; Wang Junxing

Linked Author(s):

Keywords: Incompletely flaring gate pier; Energy dissipation; Deep tail water; 3D numerical simulation; Stilling basin

Abstract: Aimed at the common problems in deep tail water project, this paper particularly proposes incompletely flaring gate pier to promote shear turbulence and vertical vortex to enhance energy dissipation through shrinking partial chamber section. Limited by large unit discharge above the overflow weir and deep tail water inside the stilling basin, the incoming flow inside stilling basin is seriously short of enough energy dissipation and outgoing flow still carries much energy with large velocity, bound to form secondary hydraulic jump outside stilling basin and scour upon downstream river bed. Compared to tail water depth, auxiliary energy dissipators are so small in sizes that almost couldn't touch the mainstream or improve flow field inside stilling basin. This paper particularly proposes flat gate pier program and incompletely flaring gate pier (FGP) program to comparatively promote energy dissipation inside stilling basin. Submerged hydraulic jump in each chamber of flat gate pier program refluxes to almost inundate overflow weir crest due to deep tail water inside stilling basin. Shown in figure 1, energy dissipation inside stilling basin is really inadequate with maximum outgoing flow velocity(0+120m) reaching 12m/s and turbulent kinetic energy (TKE) reaching 10m2/s2. But energy dissipation in incompletely FGP program is observably enhanced. There are 4 evident high turbulent areas with maximum TKE reaching 12.5m2/s2 in upstream stilling basin and outgoing flow falling down to 4.44m/s. Water jet from FGP chamber greatly diffuses and offsets toward both sides to form vertical vortex from bottom to surface (shown in figure 2) due to velocity gradients and water level gap between adjacent inflow from each chamber. Comprehensively considering flow pattern, aeration concentration and horizontal flow field inside stilling basin, incompletely FGP can not only intensify shear turbulence and promote vertical vortex from bottom to surface inside upstream stilling basin, but also solve the secondary hydraulic jump due to insufficient energy dissipation.

DOI: https://doi.org/10.3850/978-981-11-2731-1_022-cd

Year: 2018