Experimental and numerical study on critical submergence for dual lateral rectangular hydraulic intakes

ABSTRACT Critical submergence (Sc) is a cover of water at which air entrainment starts into the intakes. The computation of Sc for rectangular dual intakes in an open channel flow has been investigated experimentally and numerically in this paper. The experiments were performed at the Hydraulics Laboratory, IIT Roorkee, India, using a concrete channel 9.47 m long, 0.5 m wide and 0.6 m deep. A three-dimensional multi-phase steady-state volume of fluid (VOF) model was developed to compute the critical submergence and air-water interaction at the surface interface of in-line positioned dual rectangular intakes in open channel flows. Reynolds-averaged Navier–Stokes (RANS) equation with standard k-ω turbulence model were used to discretize the fluid flow inside the test domain. Air entraining vortex at critical condition was identified using volume fraction studies and free surface streamlines. The effect of intake bottom clearance on the vortex formation at Sc was also analysed. From both experimental and numerical studies, it is found that Sc increases with an increase in intake Froude number (Fri) and decreases with an increase in approach Froude number (Fr) and intake bottom clearances (c). The CFD outcomes were validated with experimental data with reasonably good agreements.