Influence of aeration induced by piers on the starting position of the flow aeration and extreme pressures in stepped spillways

Influência da aeração induzida por pilares na posição de aeração do escoamento e nas pressões extremas em vertedouros em degraus

ABSTRACT

The operation of stepped spillways is limited by a range of discharges due to the risk of occurrence of the cavitation phenomenon and erosion on its steps. Since there is a demand for spillways with the possibility of overflow of greater discharges, the designs seek to increase the air concentration of the flow, which can occur through the installation of piers in the spillway in order to protect the structure from the above mentioned damage. The aim of this work is to analyze flow characteristics and extreme minimum and maximum pressures with non-exceedance probability of 0.1% and 99.9% acting next to the step edges of the spillway with aeration induced by piers through an experimental analysis in a physical model. Based on the results obtained, flow behavior was defined and equations for predicting the extreme pressures that occur along the stepped spillway with aeration induced by piers were proposed.

Keywords:
Pre-aeration; Aerators; Physical model; Aerated flow