Study On Flow Characteristic And Reliability Of New Type Control Valve

This paper is focus on the problem of flow characteristic and reliability of a new type control valve.Considering the problem that the control valve designed before is not regulated linearly,the improved design is investigated so that the flow of the valve can be controlled linearly and the experimental flows can meet the requirements under cold and thermal conditions,respectively.Furthermore,the improved control valve can fit the demands in the actual work environment.In this paper,the Pro/E software is used to build the model of the flow channel,and then mesh generation of the model is developed by Gambit software.Based on the calculation and analysis of the flow field by the Fluent software,the push rod and the structure of the control valve are modified to regulate the flow linearly.The experiments have been carried out on the strength,the seal performance,basic errors,backlashes,the limit errors of the beginning point and the ending point,leakage tests,the stability of long term operation,movement life,numerical simulation verification,performance under cold and thermal conditions,respectively.The experimental results show that the flow characteristic of the improved control valve is linear and the improved control valve satisfies the performances.On another hand,the reliability evaluation model and analysis method of the new type control valve are addressed in this paper.According to the system composition and the function of each part,the valve is divided into different small system based on important function for the valve,whose fault can cause serious consequences.Then FMECA analysis of the products is done,and it is found that screw bolt has greatest influence on the reliability safety of the valve.Finally,considering the small sample that the test data is not sufficient,reliability and reliable life are calculated by Bayes method,Bootstrap method,T theory and the method based on the theory of incomplete experience respectively.Furthermore,it is better to using Bootstrap method than others when the sample number is more than 20.And reliability assessment is better than others when sample number is 1.