Hood Characteristics for Siphon‐Shaft Spillways

Abstract

A shaft spillway is equipped with a hood in order to operate as a siphon. Appropriate hood dimensions and shape are searched by using cylindrical hoods of different dimensions for a standard bellmouthed shaft. The hood, sized and streamlined according to experimental results, showed a good performance concerning the discharge and subatmospheric pressure conditions. Design charts for discharge coefficient as well as critical hood and shaft‐crest pressures are presented for such a siphon‐shaft spillway, and a design example is given.