Drag Characteristics of Two-Dimensional Sills in Forced Hydraulic Jumps

摘要

Sills and other appurtenances are often used to aid the formation of a hydraulic jump in a stilling basin. The drag force acting on a sill in forced hydraulic jump depends on the initial Froude number F_1, the height of the sill S, and its distance x_s, measured from the toe of the jump. The forward flow in the main body of the hydraulic jump behaves like a wall jet. Therefore, based on observed data, simple relationships were developed to predict the maximum velocity U_m and the half-width b of a free hydraulic jump. These are coupled with a dynamic pressure model that expresses the local drag coefficient C_(dδ) of a sill in a plane turbulent wall jet. The drag coefficient for the sill in a forced hydraulic jump C_d was obtained by a simple transformation involving the wall jet parameters.