The Numerical Simulation And Experiment Research On Internal Flow Field Of Safety Valve Based On Nozzle Theory

Spring safety valve is a self-acting valve, mainly used in boilers, pressure vessels and piping, control pressure does not exceed a predetermined value, it plays an important role in protecting personal safety and equipment operation. When the system pressure exceeds the predetermined value, the safety valve opens and the excess media pressure relief, so that the system pressure does not exceed the allowable value, in order to ensure the system does not cause excessive pressure and accidents. The essence of studying the lift force, Internal Flow Field, flow and the recoil force is to study the essential safety of safety valve, which is the key ensure of the devices essential safety. This paper study the internal flow field of safety valve through the numerical simulation and the experiment methods. The research contents are as follows:Firstly, the research of the safety valve inlet section, throat section, open the flow field parameters change based on theory nozzle and aerodynamics, found that the flowing stream form of the traditional throat outlet flow field and laval nozzle has something similarities.Summarized the law of the critical flow outlet section of the traditional throat,and the supersonic flow, subsonic flow, total flow with stable height variation.Secondly, using cloud and path analysis method to analyze the safety valve opening compete in different stable curtain flow passage airflow flow pattern,founded that the curtain surface flow field has large differences with the traditional throat. By using the effective discharge area method and disc flow equation method calculated the curtain surface outlet supersonic flow. Compared with practical supersonic flow, verified the accuracy of the effective discharge area method and disc flow equation method in evaluating the supersonic flow.Thirdly, studied the effects of different bead height of the recoil plate for open performance of the safety valve, and found that the safety valve is easy to cause flutter and frequency hopping when the bead height is small, The recoil force and lift force reaches a maximum when the bead height is 7.5mm, the recoil force and lift force emerged fluctuated, when the bead height is greater than this value.Fourthly, studied the effect of recoil plate models with different structures of the recoil effect, found that the circular surface model can effectively reduce swirl of the front panel recoil plate,and it is able to provide maximum recoil for the safety open.Provided the basis for safety valve structure optimization design.Fifthly, through the safety valve overpressure relief experiment testing, Obtained displacement, lift force, valve pressure, test flange, pressure sensor data during transient open. By detecting flange pressure sensor data obtained flow data during the course of action of the safety valve, got the recoil by lift force and disc pressure data. Verified that the numerical simulation study for the safety valve performance is reliable by comparing experimental data and simulation result data.