Control valve is the industrial automation control important link in the system. With the rapid development of the electronic computer, computational fluid dynamics ( CFD ) numerical superiority is more and more obvious, we use the CFD common software FLUENT a three-dimensional numerical simulation of an angle type control valve, flow characteristic curve of the valve was obtained through a series of open flow simulation degree, and to show the different flow state inside the valve flow velocity and pressure distribution and vortex distribution, thus further analysis of the influence of flow to the diagonal flow characteristics of regulating valve.
Structure and meshing angle type control valve
The structure of a certain type of profile angle regulating valve as. It consists of the valve stem, valve cover, valve, valve seat and valve body and other parts. At right angles to the passage of the valve body, it is known as the angle type control valve. It has a large circulation, good self-cleaning advantages, suitable for high viscosity fluid valve and pressure and requirements of rectangular tubing occasions. Angle type used by the control valve nominal diameter 25mm, nominal pressure 1.6MPa, the ideal flow characteristics for linear characteristics, the rated flow coefficient is 15m2, spool stroke 16mm, adjustable ratio R=50.
Engineering, angle valve usually choose open flow type (i.e., the bottom side ) to. The inlet pressure is 1.6MPa, the outlet pressure is 1.5MPa, the pressure contour of the regulating valve fully open on the plane of symmetry and the velocity isoline 5 as shown in Figure 4, figure. As can be seen from the graph, the pressure and velocity inlet are uniform; when the water flows through the throttle position between the valve core and valve seat, the circulation area suddenly decreases, the pressure decreases, the speed increases, the throttling position and close to the outlet side of the speed is greater than the other side, namely reducing growth effect is obvious; the flow of water through the throttling position flow to the outlet pressure and velocity, and tends to be uniform.
Symmetrical surface velocity vector chart valve opening are respectively 100% and 30% open type flow to the 6 and 7. As can be seen from figure two, the side on exports in the valve cavity, had an obvious swirling disaster, which will have a greater energy loss, increase the resistance coefficient. This shows that open flow type is easy to produce vortex in the valve chamber, resulting in energy loss. Application of FLUENT software to carry on the numerical simulation of flow closed to fully open the valve on the flow velocity vector model, get on the plane of symmetry of the figure 8. As you can see from figure 8, the valve cavity is almost no vortex, to illustrate the flow closed flow can greatly avoid vortex generation, reduce energy consumption.
For different channel model for numerical simulation of flow closed type flow, the flow coefficient of open under the see " Table 1 ". As can be seen from the table, the same opening, flow coefficient flow closed than open type flow increased obviously, full opening, flow coefficient increased by 15.3%. This is due to the flow of closed type valve flow without swirl generated, reducing energy consumption, improve the flow coefficient. From the table it can be seen, with the valve opening decreases, the percentage increase of flow coefficient decreases, the 10% opening flow coefficient is no longer raise. This is because, valve opening, flow to the vortex type fluid velocity, kinetic energy, and the energy loss, and the flow of closed type flowing almost no loss of energy generated by the swirling disaster, so the flow coefficient increases significantly. With the valve opening decreases, the fluid velocity decreases, the flow of open type and the energy loss is reduced, so the flow coefficient of 2 kinds of flow tends to be equal.
To open the flow coefficient under different
Opening / %102030405060708090100
Open type flow / m21.734.576.989.3611.2012.2413.1413.9714.6915.30
The flow of closed type / m21.734.687.5610.0812.2413.5015.0515.8416.8117.64
Increase the percentage / % - 2.408.307.709.3010.3014.5013.4014.4015.30
Conclusion
( 1 ) of the valve flow coefficient is simulated through theoretical calculation and numerical calculation, that is consistent with the theoretical simulation results by computational fluid dynamics software. Optimization design which will contribute to the valve, shorten the design period, save a lot of cost. In this paper.
( 2 ) angle valve usually choose open type flow direction will produce vortex in the valve chamber, resulting in energy loss. And the flow of closed type to avoid vortex generation, reduce energy consumption.
( 3 ) angle type control valve selection autistic-type flow could increase the flow coefficient, especially in the valve opening, flow coefficient increases significantly. In engineering practice, if the valve is often large opening in the work, choose to install to the flow of closed type, can better improve the flow coefficient.
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