Determination of the required degree of surface perforation of collecting drainage pipelines

The operational characteristics of a collecting pressure pipeline, where the flow enters through holes and slots along its length in a turbulent mode, and a pressure drainage pipeline, where liquid enters through the side walls in a filtration mode, are investigated. Based on a comparison of analytical dependencies used to describe the flow entry laws into the pipelines in each case, relatively simple and practical calculation formulas have been derived to determine the required degree of the side walls perforation of the drainage pipeline. These formulas ensure that the desired water flow rate is achieved in the collector. The degree of perforation S in this work is defined as the ratio of the area of the perforation holes (slots) in the side walls of the drainage pipeline to the total area of its side surface. In the analysis of the pipelines considered, parameter A is used, which comprehensively accounts for both the design and filtration characteristics of the drainage pipelines. Relevant analytical dependencies and a graph for determining this parameter are presented. A series of calculations have been performed using the proposed formulas to determine the degree of perforation for these pipelines. It is shown that, in general, the magnitude of the perforation degree is influenced by both the structural characteristics of the pipeline itself and the filtration properties of the surrounding soil and the surface of the drainage pipes.