Nonlinear Dynamics of Pilot-Operated Hydraulic Control Valves for Submersible Based on Improved Newmark- Integration Method

Submersible is an important equipment for the development and utilization of marine resources. The pilot-operated hydraulic control valves have an extremely wide range of applications in the buoyancy adjustment system of submersibles. The existing hydraulic control valves have insufficient flow rate and pressure adjustment ability in a wide range of system pressures. A pilot-operated hydraulic control valve with a wide range of adjustable pressures, a high flow rate control accuracy, and anti-turbulence and cavitation is designed. A joint simulation method combining MATLAB/Simulink and UDF dynamic mesh is developed. The dynamic characteristics of the piping system and pilot-operated hydraulic control valve under different system inlet pressures are investigated by using the metric cellular automata technology and one- and three-dimensional co-simulation platforms. The results of the joint simulation show that: the flow rate of the system stabilizes for a period at a system inlet pressure of 1.6 MPa, and the phenomena such as fluctuations and oscillations will occur after a period. To address this phenomenon, an improved Newmark-
$\beta $
integration method is proposed based on establishing a correct nonlinear model. The established model is solved in a longer time domain to obtain the nonlinear dynamic bifurcation behavior of the model. The stability of the pilot-operated hydraulic control valve is analyzed by displacement dynamic response diagrams, phase space trajectory diagrams, and bifurcation diagrams. A direction is provided for the applied research of nonlinear system bifurcation theory in self-operated valves.