Hydraulic Characteristics and Reduction Measure for Rooster Tails Behind Spillway Piers

Abstract

During flood discharge in a hydraulic project, rooster tails occur downstream of the piers in the spillway and have adverse effects on the operation of the discharge chute. The present paper provides an experimental study of the rooster tail generated by a pier in a chute spillway. Causes of the rooster tail were analyzed, and factors affecting the characteristics of the rooster tail were investigated. The results indicate that rooster tail height is significantly influenced by several parameters, including the spillway slope ratio, pier width and type, and outlet section water depth. A new formula was developed for estimating rooster tail height, and all the experimental data fit well in the selected experimental range. Moreover, a composite sloping-tail pier was designed based on the generation mechanism of the rooster tail. This pier can effectively eliminate rooster tail and has simple construction and lower costs.