Specifications of the hydraulic flow regime for the ending portion of the pressure tubular spillways with a vertical flow outlet

Introduction. An approach to the study of the hydraulic flow regime behind the end section is presented in order to determine the possibility of ensuring uniform distribution of speeds across the width of the outflow channel and safe coupling of the outgoing flow to the lower pool. The four variants of designs of the ending portion of the pressure tubular spillways with a vertical flow outlet are considered, following constructions: a disk reflector, a flat horizontal sector reflector, a flat slanted sector reflector and a curved sector reflector. Materials and methods. The most common approach to the comparison of structures were made according to the following parameters: the length of the stream’s flight, the width of the jet, the form of flow spreading, the uniformity of the distribution of specific water flow, clash of the jet on the slopes of the channel. The diameter of the conduit on the model is d = 3.4 cm, the cost of Q = 0.67...2.44 l/s, pressure head H = 35...60 cm. For comparison of the chosen design with similar geometric parameters: the relative radiuses of the sectors of the reflector R/d = 3.0 and relative diameter of the disk-reflector D/d = 3.0. Results. The lengths of the jet departure are determined for disk and flat sector in the relative height range of t/d from 0.5 to 1.0, for slanted and curved sectors-from 0 to 1.0. The planned outlines of the jet are determined, the uniformity of the distribution of specific water discharge is estimated, the analysis of the hydraulic regime of the presented end portions is carried out. Conclusions. In of civil engineering the revealed advantages and disadvantages of the considered end portions allow to recommend it for use taking into account the peculiarities of the hydraulic regimes arising at the same time. The greatest length of the jet departure has a curved sector-reflector, and the smallest - a flat horizontal sector-reflector. Lowest unit costs are achieved with a disc reflector, the largest in the flat horizontal sector-reflector.