Assessing the value of the hydraulic friction factor in pipelines working with a flow connection along the path

Abstract

The results of an experimental study of the hydraulic friction factor of perforated pipelines that work with the collection of fluid along the path are reported. Clarification of this issue will make it possible to solve an important engineering task – to devise a reliable procedure for the hydraulic calculation of perforated pipes. The experiments were carried out on an assembled experimental bench. A steel pipeline with a perforated part of 1–3 m was investigated. Perforation holes were taken with a diameter of 3.6 and 9 mm. In the experiments, fluid flow, pressure loss, and average velocity were measured. Based on the data obtained, the values of the coefficient under study were calculated. It has been established that it is significantly larger than its values with uniform movement and is variable in length of the pipeline. Experimental dependences λcol on the value of the ratio of the velocities of the flowing jets of liquid to the average flow velocity in the corresponding section (Uh/V), as well as on the design characteristics of the channel, were obtained. It is shown that the lower value of the degree of pipe perforation corresponds to the higher values of λcol. This result can be explained by the influence of the attached flow rate on the main flow. The confirmation of this conclusion is the resulting shapes of diagrams of the average flow velocity obtained in the experiments, which differ significantly from standard diagrams with uniform motion. Obviously, additional energy is spent on the reformation of the velocities, and this causes additional head losses. Dependences were obtained for calculating the considered coefficient for prefabricated pipelines, including in the presence of transit flow rate. Their use in the calculation of the pipes under consideration will increase the reliability and efficiency of the sewage treatment plant, in which they are important structural elements