Flow Characteristics of Hydraulic Intake Structures in Group: Fid-Bau Portal

Flow Characteristics of Hydraulic Intake Structures in Group

Hashid, Muhammed / Eldho, T. I.

Intake structures are submerged water diversion structures widely used for various purposes like hydropower, irrigation, desalination plants, pump sump intakes, water distribution, etc. Intakes in the group show an enhanced flow withdrawal compared to isolated intakes of the same cross-sectional area. The withdrawal capacity and critical submergence of hydraulic intakes are usually affected by impervious boundaries in the form of bed boundaries, side walls and the intake pipe itself. The air entrainment through surface vortices and secondary vortex generated from interaction between withdrawal flow and approach flow will affect the efficiency and operation of water intakes. The present paper discusses the characteristics of the flow withdrawal for multiple lateral intakes under uniform approach flow with the help of a multiphase CFD model. The present study uses SST k-omega turbulence model to compute the flow pattern at multiple water intakes. The effect of impervious boundary blockage from near-walls and intake pipe was found to be causing significant changes in the flow hydrodynamics at the intake vicinity. The interphase of the multiphase (air and water) at the free surface was modelled with a better accurate estimation of interface curvature and surface tension forces caused by the curvature. The distribution of discharge variables at multiple intakes placed in a row showed that the withdrawal of upstream intake causes a flow reversal at the intermittent space between intakes, and this favours the withdrawal at the other intake in the downstream. The near-wall treatment adopted in the present model helped to properly simulate laminar sublayer flow, especially at the junction of lateral intake and approach flow channel domain.