Studies on air removal processes from pipelines of floating docks ballast systems
Authors:   Krylov State Research Centre, St. Petersburg, Russia, Shtoda A.I. 
Published: July 2022

Object and purpose of research. The objective of the study are modern technical solutions for removal of air masses penetrating into the pipelines of ballast systems of floating docks used in shipbuilding. The purpose of the paper is to determine the effectiveness of various design solutions and special devices used in the process of design, construction and operation of floating docks by modeling the separation processes of aerated spatial flows in pumping chambers and collectors of ballast systems in experimental installation. Materials and methods. Official information materials in the field of science and technology in the area of analytical and experimental studies of air removal processes in marine systems. Methodology of fluid mechanics, methods of dimension theory, experimental methods. Main results. Achievements in the field of design, construction and operation of ballast systems for floating docks and floating drilling rigs, as well as in hydraulic structures were considered. To control the processes of separation and removal of air penetrating into suction pipelines, tests of a number of special technical solutions used in ballast systems of floating structures were carried out on an experimental hydraulic installation using modifiable models according to the developed program and methodology. In connection with the well-known continuing problem of prolonging the operation of ballast pumps at the final stages of deballasting of floating dock compartments, an experimental assessment of the ingenuity and progressiveness of a number of layout design solutions used in the water ducts of pumping compartments of floating docks was carried out. In ballast systems, imperfections of internal devices in collecting pipelines-collectors and pumping chambers were manifested, due to the hydromechanical phenomena of the interaction of two-phase flows in an enclosed confined space. The current state of the art is characterized by the insufficient level of knowledge of flows in the conditions under consideration governing the development of the objects under study at the present stage. The main patterns of excessively aerated flows behaviour in conditions of ballast system ducts in pumping compartment with physical parameters set, according to the specifications, for the standard pumping equipment used in the systems, are revealed. The performed studies fill in the missing information about the behaviour and interaction of aerated flows inside collectors and pumping chambers of various structural designs. The characteristic significant reasons hindering the optimization of the ongoing separation processes are identified, promising design directions for improving the applied ballast systems are identified. Conclusion. The achieved results of the development allow us to make rational decisions about the use of a specific type of equipment and outfit in certain operating conditions as part of ballast systems of floating docks and other floating structures of similar purpose. The proposed technical solutions are relevant for the development of a more advanced structural design of collecting pipelines and pumping chambers. Experimental materials are also suitable for the development of requirements in design of ballast systems of floating docks and other floating structures with high-performance pumps. The obtained data on behaviour of aerated spatial fluid flows inside closed chambers with a variable flow section as the medium flows to the pump can also be useful in designing rational water chambers in hydraulic structures with high-performance vane pumps.