Experimental and numerical studies on orifice spillway aerator of Bunji Dam

Abstract

ABSTRACTIn this study, hydraulic design of the aerators of steep slope orifice spillways (26°–32°) was evaluated using physical and numerical modeling techniques. The Bunji Dam spillway, which is proposed to be constructed on the Indus River in Pakistan, was selected for physical and numerical modeling of the aerators. Extensive experimentation was carried out on a physical model of the Bunji Dam spillway by changing the air vent size and ramp angle of the aerator. Three air vent sizes and five ramp angles were constructed to assess the hydraulic performance of the aerator. The numerical model was formulated using Computational Fluid Dynamics (CFD)—FLOW 3D. The air vent size showed a significant impact on the dimensionless performance indicators of the aerators. Empirical equations were developed based on the outputs of physical and numerical models of the aerator. It is believed that the proposed equations will be useful for the estimation of nondimensional cavity length and air entrainment coefficient of the orifice spillway aerators having a short horizontal stretch leading to a convex curvature with slope varied from 26° to 32°.