Study On The Supercavitating High-pressure Water Jet Used For The Cleaning Of Seawater Heat Exchanger Pipes

In seawater heat exchangers,due to long-term work in this environment,a large amount of marine biomass fouling will accumulate on the wall of heat exchanger pipes,which has a great impact on the efficiency and service life of seawater heat exchangers.Traditional cleaning methods,such as chemical cleaning and high pressure water jet cleaning,can not effectively and safely clean the pipe.This paper innovatively puts forward the supercavitating high pressure water jet cleaning technology,which combines the supercavitation technology applied in Naval Weapons with the conventional high pressure water jet technology.The author makes use of the drag reduction principle of supercavitation technology,so that the high-pressure water jet cleaning can have a higher jet velocity and achieve a longer cleaning distance,so as to clean the fouling adhesion of the seawater heat exchanger pipe more efficiently.Firstly,this paper takes supercavitating high-pressure water jet cleaning technology as the research object,and introduces its theoretical basis.At present,supercavitation technology is mainly used in naval warfare weapons to reduce the resistance of navigating body in water.The theory of supercavitation originates from the principle of cavitation.The basis of judging whether cavitation occurs or not is the number of cavitation ?.Meanwhile,the cleaning mechanism of high pressure water jet and the collapse model of cavitation bubble near the pipe wall are also discussed.Secondly,aiming at the experiment of cleaning seawater heat exchanger pipeline by supercavitating high pressure water jet,this paper designs supercavitating high pressure water jet nozzle,and considers the structural parameters of various aspects;later,the whole experimental equipment is designed and constructed.Thirdly,the flow field of supercavitating high-pressure water jet and conventional high-pressure water jet are simulated and analyzed,and the differences between them in jet velocity,pressure and other parameters are obtained.Aiming at the influence of ventilation and jet pressure on cleaning of supercavitating high-pressure water jet,the author also carries out relevant simulation research.Afterwards,the process of single cavitation bubble growing to collapse near the wall of the pipeline is modeled.Similarly,the pressure at each time point in the whole process and the resulting jet velocity are obtained.Fourthly,the author carried out an experimental study on the use of supercavitating high pressure water jet to clean heat exchanger pipes.The cleaning characteristics of supercavitating high pressure water jet on titanium tube of heat exchanger were investigated,and the advantages of supercavitating high pressure water jet cleaning were analyzed by comparing with conventional high pressure water jet cleaning.In addition,the effects of artificial ventilation and jet pressure on the cleaning efficiency of supercavitating high pressure water jet were explored through experiments.Finally,physical and chemical tests were carried out on the cleaning titanium tube and the uncleaned titanium tube used in the experiment to explore whether supercavitating high pressure water jet cleaning caused structural damage to the inner surface of the titanium tube.