Research On Dynamic Water Pressure Control In Large Closed Volume

With the continuous development of deep sea technology,the reliability and safety requirements of underwater equipment are also getting higher and higher,the pressure simulation test of the deep-sea environment on land is very important to ensure the normal operation of the underwater equipment.For some large size underwater equipment,it is necessary to test the hydraulic environment by the dynamic water pressure control system in large closed volume.In this paper,the dynamic water pressure pressure control system in large closed volume is studied,the design difficulties are analyzed,and then,it is considered that the maximum parameter that affects the dynamic hydraulic pressure control is the effective volume elastic modulus.This thesis established the model of effective bulk modulus of elasticity,analyzed the influencing parameters and proposed some corresponding solutions.The paper designed the pressure control system with bladder accumulator as the pressure transmission device.The related factors that affect the hydraulic pressure control were simulated,which provided theoretical basis and model basis for system structure design,parameter optimization and control strategy research.In this paper,the two control strategies of PID and fuzzy adaptive PID control are simulated and compared,and the fuzzy adaptive PID control strategy is better than the classical PID control strategy in terms of rapidity and stability.Finally,the design of measurement and control system based on PC+PLC is completed.The main research contents are as follows.The first chapter expounds the significance of research on the dynamic water pressure control system in large closed volume and the research status at home and abroad.The principle of hydraulic control is introduced in detail.The existing problems and difficulties of dynamic pressure control system of large closed chamber are analyzed,and finally introduced the main research content.The second chapter established the closed cavity pressure model.It is pointed out that the parameter affecting the maximum dynamic water pressure control is the effective bulk modulus.A new model of effective bulk modulus of elasticity is established.The influence of pressure,free gas content and temperature on the elastic modulus of liquid is considered.Finally,the influencing factors are analyzed and the solutions are put forward.The third chapter analyzed the advantages and disadvantages of various hydraulic control schemes and applicable conditions,selected the hydraulic control scheme of the pressure transmission device,and designed the structure and parameters of two kinds of pressure transmission devices of accumulator and hydraulic cylinder.Established the mathematical model,and the simulation results showed that the bladder-type accumulator had better dynamic characteristics as a pressure transmission device.The fourth chapter designed the hydraulic system and hydraulic system,established the hydraulic control system simulation model,the influence of the natural frequency of the proportional valve,supply flow and gas content on the water pressure control is analyzed.Designed the hydraulic structure with servo proportional valve control pressure,variable pump and accumulator.Aiming at the influence factors and technical requirements of water pressure control,the control scheme of maintaining oil temperature stability,flow section control and pressure closed-loop control is put forward.A simulation study of PID and fuzzy adaptive PID control strategy is carried out,and the results show that the fuzzy adaptive PID control is better than the classical PID control in terms of the speed and smoothness.The fifth chapter designed the measurement and control system of the hydraulic control system,adopts the master-slave structure of PC + PLC,completed the compilation of PLC program and WinForm software based on C#language.Finally,the dynamic pressure control test to verify the performance of hydraulic control system.The sixth chapter summarized the work content and prospects the future research direction.