| In winter,central heating is generally used in northern China,and hydraulic imbalance is a common problem in heating network.Self-operated differential pressure valve can adjust the pressure fluctuation of pipe network caused by uncertain factors,maintain the hydraulic balance of pipe network,and play an important role in solving the problem of hydraulic imbalance.The control characteristic data and other basic physical properties of the self-operated differential pressure valve must be obtained to simulate the accurate control of the secondary pipe network through the test-bed.In this paper,the finite element numerical analysis method is used to study the control characteristics and vibration characteristics of the self-supporting differential pressure valve,which has great guiding significance for the optimization and accurate control of the pipe network.1.The three-dimensional model of self operated differential pressure control valve was established by ANSYS.The distribution of pressure field,turbulent flow field and velocity field of the valve under different flow conditions were calculated.Five groups of corresponding relationships between spool displacement and valve pressure drop were obtained.According to the simulation results,the relationship equation was fitted,and the control characteristics of self operated differential pressure control valve were obtained.The pressure variation and pressure drop of the valve under different working conditions were analyzed by pressure nephogram.2.The advantages and disadvantages of the classical control characteristics of the three valves are analyzed,and the linear control characteristics of the self operated differential pressure valve are determined.According to the control equations and the actual control boundary conditions,the model is optimized.The control characteristics of the optimized valve are linear functions,which are consistent with the objective function.The feasibility of the optimization scheme is proved.Compared with the original structure of turbulence,vector,pressure nephogram,the results show that the flow field after optimization is greatly improved compared with that before optimization,reducing the influence of turbulence and vortex on the key parts of the valve core.To verify whether the methods used in the valve optimization process can produce general guiding significance for this type of valve.3.Based on fluent + transient structural + system coupling,the flow induced vibration of different positions of the valve core and the stress of different positions of the valve core are obtained.The force and influence of the valve core are analyzed,and the law of flow induced vibration of the valve core is discussed.The maximum positive principal stress is8.34 × e6 pa,and the maximum negative principal stress is 2.09 × e6 pa.The maximum stress of the valve core is far less than that of the material.The first natural vibration frequency of valve core is 55.88 hz.Under the condition of small flow rate,the vibration frequency of the valve core is close to 100 Hz.With the increase of flow rate,the main frequency and peak value of valve core vibration are different in different parts.Under the maximum flow condition,the main frequency of the vibration at both ends of the valve core is low,which is close to the natural first-order vibration frequency of the valve core.The valve disc area has large amplitude,high vibration frequency and more noise,which coincides with the vortex concentration area. |
