Experimental study of cavitation index in an ogee spillway by considering convergence angle of sidewalls

Abstract

Cavitation is among the most complex and common damages occurring in spillway structures, which is one of the most expensive parts of a dam. The cavitation index, as the one of the most efficient approaches, can be used to analyze this important hydraulic phenomenon. The present study examines the changes in the cavitation index caused by changes in the convergence angle of an ogee spillway's sidewalls with an arc in the plan. To this end, a spillway was constructed on the 1:50 scale. Then, it was tested with four different convergence angles, including 0°, 60°, 90°, and 120°, relative to the spillway's sidewalls and six different flow rates per unit width ranging from 6.74 to 48.42 (l/s)/m. The results indicated that as the flow rate increased, the cavitation index relatively declined at both crest and chute of the spillway while growing at its toe. It was observed that the lowest cavitation index was found to be 1.54 in.X/Hd = 2.42 at an angle of 0° and a flow rate per unit width of 40.52 (L/s)/m.

Numerical Modeling of Flow Pattern with Different Spillway Locations

“…It is different from a low spillway that has considerable approach velocity and can affect the discharge coefficient in addition to the profile of the spillway crest [8]. In contrast to large dams, when the dam height is low compare to the water head on the crest of spillway the high probability of cavitation is considered [9]. The limited hydrologic data means the evaluation of design head on the crest will be risked and expected head may be less or greater than a real head.…”

Experimental Investigation of Energy Dissipation in Ogee Spillway Using New Distributions of Dissipation Blocks

“…The increasing need for water supply, flood control, hydroelectric power generation, and recreation has made dam construction a high priority throughout the world. As water is of critical importance for human life, modern techniques in the design of dams are essential for better management of water resources [1]. All dams are equipped with spillways as a safety measure against overtopping.…”