The Research Of The Opening And Closing Characteristics Of A New Pilot-operated Globe Valve

The pilot-operated globe valve, utilizing differential pressure to achieve the action of the valve core, is a new kind of valve with a simple structure, prompt opening and closing action and lower driving energy consumption. However, systemic theoretical research, numerical analysis and experimental verification are deficient at present, especially about the opening and closing characteristics. The relationship between opening and closing characteristics directly affects the performance of the valve even affects the stability and security of the entire pipeline system. Thus in this paper, the flow field of the pilot-operated globe valve, the characteristics of the force on valve core and the valve core motion, and the formula for selection of spring were studied via numerical simulation and experiment research. Main contents and results of this research are as follow:1. The feasibility of utilizing differential pressure to control valve opening and closing and the rationality of valve structure were initially verified; the steady flow field under different conditions was researched; the pressure force in steady state was analyzed which would lay the foundation for dynamic simulation.2. The differential equation of the force on valve core and the difference equation of the valve core motion were not only built, but also as a basis for the preparation of the UDF program, which made dynamic simulation of the new pilot-operated globe valve become possible and laid the foundation for it.3. The opening and closing processes and characteristics of the pilot-operated globe valve were studied, which were understood with a more comprehensive view through analyzing the flow field, the force on valve core, and the changes of the displacement and velocity with time. It was researched that how the flow field of the opening and closing characteristics in dynamic state would be influenced under different conditions. It was summed up that how the flow field respectively changes with inlet pressure, spring stiffness and the pilot time during the valve opening and closing process which would guide the application and the design of the pilot-operated globe valve. It is revealed that how the movement characteristics of valve core would be influenced under different conditions including the laws of the movement, the displacement and the opening and closing time of valve core changing with inlet pressure, spring stiffness and the pilot time, which provided the most basic, the most critical and the most valuable conclusions for further optimization of the valve.4. The formula for preliminary selection of spring has been summarized and tested in the experiment. On the one hand, the law was obtained from experimental data to verify the accuracy of qualitative analysis on simulation; on the other hand, comparing the experimental data and simulation data, quantitative analysis on the simulation was proved reasonably. Modified selection formula would improve the design efficiency and reduce the blindness on the design process.All in all, these results have important academic significance and value for the optimization and engineering applications of the new pilot-operated globe valve.