| As the most common actuator, the control valve is widely used in petroleum, natural gas, chemical, electric power, metallurgy and other various industrial sectors. It is the essential part in industrial automation system. As modern industry got higher demands on the performance of control valves, not only the pressure, the flow, the temperature and other conditions of the fluid must be met, the flow characteristics of the control valve are paid more attention. Traditionally, engineers mainly choose a right valve by calculating the flow characteristics with the empirical formulas. The distribution and variation of the fluid field variables are not considered. In this paper, with the method of CFD(Computational Fluid Dynamics), an inner fluid simulation model of the control valve is established. The characteristics of the steady flow, the transient flow and the transient flow in the FSI(Fluid-Structure Interaction) situation are comprehensive analyzed.Firstly, an inner fluid region and a control valve geometric model are established with the CAD technology based on PRO/E. In order to reduce the computational scale and fit the numerical analysis, some reasonable simplifications and assumptions are carried to the model. The inside chamfers and outside flange bolt holes are ignored. The control valve, which is assumed a whole-part, is simplified by reducing the symmetry half. Then, the fluid model is meshed with ICEM CFD which is a powerful mesh tool. After the previous wok, the inner fluid mesh model which contains some tetrahedral and hexahedral elements is got.Secondly, the inner steady flow simulation model of the flow field in different opening is established. The models in various opening with 1MPa differential pressure between the inlet and outlet are solved. The visualization analysis has been carried to the computed results. The flowing characteristics can be got from the pressure contours and the velocity streamlines of the symmetry face and the valve wall. The mass flow of the outlet in various opening is also got, which can conclude the flow characteristics of the valve. The results indicate that the circulation area is smaller; the choking effect is more significant. As a result, the pressure will be brought down; simultaneously the flow rate will be increased. At the throttle of the valve, the fluid is easier to develop to turbulent flow and the flow resistance pressure is larger. When the valve core is a flat-bottomed with a balance chamber, the flow characteristic of the valve is a quick-opening type. The flow of the valve will quickly increase during the opening process. The flow percentage can be achieve above 50% when the opening is about 20%, which is consistent with the rapid opening and responding requirements.Finally, the transient flows in non-FSI situation and in FSI situation are analyzed. The transient models with a sinusoidal inlet pressure in 0.1s are solved. The flow field and the structure field results in different time steps are abstracted. The pressure contours and the velocity streamlines in these time steps are got. The transient flowing characteristics are analyzed and the average time-history output pressure curves are observed. In addition, the stresses and deformations of the valve in the FSI situation are analyzed. The control valve got different deformations and stresses under the fluid effects during the 0.1s time. Contrast the results of the non-FSI models and the FSI models, it can be concluded that the FSI effect makes the fluid be prone to turbulent and being fast. The output pressure fluctuations in the FSI situation are much greater than the non-FSI situation.The subject has positive meaning in optimizing the flow properties and stabilizing the outlet pressure, which can improve the design and research level of the domestic control valve.
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