Head Losses at Junction Boxes

Abstract

The explanation of the hydraulics of junction boxes is poor in comparison with the corresponding explanation of the hydraulics of pipes. The results of a detailed experimental hydraulic model study of the hydraulic interactions in two common junction box configurations are presented. For a three‐pipe configuration a recently proposed empirically based model is shown to adequately represent both the lateral and longitudinal loss coefficients in a variety of flow conditions. The results from this configuration also indicate that substantial reductions in head losses at the box are possible through the incorporation of strategically placed deflector plates in the base of the junction box. The two‐pipe configuration results indicate that the benching of the box floor leads to the improved hydraulic efficiency of the box. Circulating mechanisms in the boxes are shown to be strongly related to corresponding head losses at the boxes. Both configurations demonstrate that the influences of Froude number and box submergence are not major, but nevertheless are important in some flow conditions.