Design And Optimization Analysis Of High Pressure Water Jet Cleaning System For Marine Organisms Based On ROV

Offshore platform is an important infrastructure for offshore production.Due to the long-term immersion in the complex seawater environment,the hard marine organisms attach seriously at the jacket legs in the seawater immersion area and tidal range area.The accumulation and adhesion of a large number of hard marine organisms will lead to the increase of platform load,the decrease of smoothness and the aggravation of corrosion,which will lead to the decrease of platform bearing capacity and the shortening of service life,which will have a great negative impact on the safety and structural stability of the platform.Therefore,it is of great significance to carry out the cleaning of hard attached marine organisms on a regular basis to ensure the safety of offshore production.The traditional operation mode is mainly underwater cleaning by divers,and the commonly used cleaning devices are single nozzle high-pressure water jet gun and cavitation jet gun.This method has high requirements for operators,great labor intensity,low operation efficiency and limited water depth.The debris splashing and the reaction force produced by water jet in the cleaning process may cause injury to the operators,and the operation safety is relatively poor.Therefore,based on the underwater high-pressure water jet cleaning technology,combined with material mechanics,structural mechanics and fluid mechanics,using the finite element simulation calculation and optimization design method,this paper designs and develops a set of marine organisms cleaning device with rigid attachment based on ROV system.This paper mainly includes the following parts(1)Structural design,parts selection and check of mechanical systemThe mechanical system of the device is mainly composed of spray gun body,flexible clamping mechanism and anti-collision mechanism.The main body of spray gun is mainly composed of rotating spray gun and secondary transmission device;The flexible clamping mechanism is mainly composed of buffer part and clamping part;The anti-collision mechanism is mainly composed of connecting disc,support column and lower support ring.According to the initial parameters when designing the mechanical system,and assuming that the nozzle is completely blocked,the key parts such as motor,gear,connecting thread and bearing are selected and checked in turn.(2)Calculation,analysis and optimization of the influence of various parameters on underwater cleaning effectIn order to achieve the best cleaning effect of the system,the parameters that may affect the underwater cleaning effect are analyzed by fluent simulation,which are nozzle angle,inlet pressure,nozzle diameter and nozzle number.Through a lot of simulation,the results show that the nozzle inclination is 30° The effective range of the water jet and the swept area of the cleaning system can reach a relatively large value;When the inlet pressure increases from 50 MPa to 70 MPa,the effective range of water jet increases significantly,and when the inlet pressure increases from 70 MPa to 90 MPa,the effective range increases slightly;With the increase of nozzle diameter,the slower the velocity and dynamic pressure decay,the farther the effective range is,but the flow rate is also doubled;When the total flow of the pumping station is constant,increasing the number of nozzles will reduce the effective range of the water jet,but will increase the number of sweeps in the same cleaned area.After comprehensive consideration,the parameters determined are:nozzle inclination 30°,The inlet pressure is 70 MPa,the nozzle diameter is 1.8mm,and the number of nozzles is 2.(3)Design and optimization of high pressure water seal structureIn order to improve the efficiency of the system,the cleaning device designed in this paper can spray water jet at the same time ° Therefore,a rotary dynamic seal under high pressure environment is formed at the joint.In this paper,the high pressure rotary dynamic seal structure of cleaning device is designed and simulated,including seal form,seal material and seal clearance.By comparing the advantages and disadvantages of different sealing forms and combining with the actual working conditions of the system,the O-type seal is selected as the sealing form of the cleaning device after some improvement;The O-rings made of natural rubber,hydrogenated NBR and rubber plastic were simulated by ANSYS,and the stress and strain under high pressure were observed.Finally,the O-rings made of rubber plastic were selected,which ensured that the cleaning device was well sealed and smoothly rotated after entering a stable working state;The sealing structure of O-ring with one-sided interference of 0.7mm and 0.9mm was simulated and analyzed by ANSYS.Finally,the sealing gap with one-sided interference of 0.9mm was selected to ensure that the cleaning system has good initial sealing,good sealing and smooth rotation after entering the stable working state.