A Simple Model to Predict the Hydraulic Jump Location in a Not Fully Filled Horizontal Pipe Flow

Hydraulic jump is a local nonuniform flow phenomenon which occurs when the supercritical flow decelerates to a subcritical flow. It may be seen from a not fully filled pipe flow equation that when the Froude number of the fluid approaches unity with a value greater than 1, the differential variation of the fluid level in the direction of the flow becomes infinity. The result, then, is a marked discontinuity on the surface, characterized by the steep upward slope of the profile. In this study, a simple concept where the excessive energy of the supercritical flow is set equal to the energy dissipated by the wall friction is suggested to predict the location of the jump in a pipe flow. Then the location of the jump is simply determined by using the Manning formula. The feasibility of this concept is confirmed indirectly through an evaluation of the water level distribution of the reactor coolant during a mid-loop operation in a real reactor plant.