Injection flow regulators with flat diffusers

Abstract

Injection flow controllers are culverts installed on the canals of irrigation systems. A distinctive feature of these hydraulic automatics is the absence of movable elements. For the design of structures and assessment of the possibility of installation on the channel of the injection outlet with a specific form of the flow part, flow characteristics are used. Most injection outlets have a nozzle at the end of the transit portion necessary to increase the velocity of the flow entering the downstream pool, i.e. its injection capacity. The end section is equipped with a sudden expansion or diffuser. The material of the study was the data of physical modeling of the operation of the regulator with a flat diffuser in the absence of a nozzle. The positions of the interface between the streams in the mixing chamber were determined using numerical modeling methods. The flow characteristic of the regulator was built and the acceptability of the existing design relationships for determining the injected and injected flow rates of the water outlet was confirmed. Comparison of flow characteristics showed that, all other things being equal, the absence of a nozzle reduces both the injection coefficient and the relative head of the regulator. For the first time, the formation of a hydraulic jump on the cover of a flat diffuser in the intermediate pool was studied. For the first time, design relationships are given that make it possible to associate the conjugate depths in the intermediate pool with the accuracy of control, as well as recommendations are given for changing the geometric parameters of the intermediate pool based on the conditions for accurate injection of the injected flow rate.