Influence Of Medium Flow Direction On The Unbalanced Force And The Flow Velocity Of Regulating Valve

The valve is an important control equipment in all kinds of fluidal devices, and it has been widely applied in various industries. Now, with the exception of a few inlet valves which are from large-scale complete sets of imported equipment still need purchase from foreigners, domestic manufacturer can supply most of the products. But China’s valve industry research institutions are less, scientific research ability is weak, scientific research input is deficiency, most technicists in the manufacturing enterprise are lack of necessary research techniques and they stay in the level of surveying and mapping, digestion, absorption.The change of the flow direction of medium will make the pressure before and after the regulating valve P1、P2switch, at the same time it also will change the routes of fluid flow. It makes the direction or size of unbalanced force Ft, resulting in poor system stability, which may cause the vibration of the body and excess noise.The flow velocity of medium affects the reliability, stability and service life of the regulating valve. When the liquid medium flows through the throttle, the throttling area is shrinking dramatically, so the velocity of the liquid medium increases and the pressure decreases. It is easy to produce blocking flow, resulting in flashing and cavitation. The occurrence of flashing and cavitation have a serious impact and erosion damage on regulating valve trim, which make the trims present similar to the rough surface of coal cinder, and have serious noise at the same time.As a result, it has very important significance to research the influence of the flow direction of medium on the unbalanced force and the effect of the flow velocity of medium on cavitation for improving the stability, reliability and service life.In this paper, the DN200quickly exchanged single-seat regulating valve and the DN200pressure balanced caged regulating valve are studied according to the demand of an enterprise in ningxia. Firstly, the unbalanced force calculation formula and the throttling face velocity calculation formula about the two kinds of regulating valve are derived. Then, the three dimensional entity modeling of the regulating valve is established, meshing by using GAMBIT software, numerical simulation by using CFX software, and the results are to get the internal pressure field, velocity field and the change trend and volatility of unbalanced force under the different opening of the regulating valve. Finally, it is to verify the correctness of the numerical simulation results by testing.In this paper, the research results show that the quickly exchanged single-seat regulating valve should choose the flow direction to open, the pressure balanced caged regulating valve should choose the flow direction to close.