Design And Optimization Of Thermal Mass Flowmeter

Flow rate is an important parameter in the industrial production process,and the accuracy and stability of its measurement have a greater impact on the production process.Thermal mass flow meters are commonly used equipment for flow measurement,and their performance is directly affected by the flowmeter structure and the development level of the internal flow field.In order to reveal the theoretical mechanism of the flowmeter in depth,based on the comparison of existing research,this article will improve thermal mass flowmeter measurement stability is the goal,and corresponding theoretical analysis and flow field optimization are carried out.Aiming at the problem of flowmeter measurement stability,based on the in-depth analysis of the structural principle of capillary thermal mass flowmeter,a theoretical model of flowmeter measurement was established.Through analysis and calculation,it can be known that:(1)The structure of the laminar flow element directly affects the stability of the flow ratio between the capillary and the main channel:(2)The flow conditioner has a positive effect on the stability of the fluid entering the main channel of the flowmeter.For this reason,in order to improve the measurement stability of the flowmeter,this paper focuses on the influence of the structure of the laminar flow element on the stability of the flow through the capillary of the flowmeter and the stability of the flow after the irregular fluid is rectified by the flow conditioner.In the research of laminar flow element,the analysis of the influence of changing the opening ratio of laminar flow element on the stability of flow ratio under different flow input is carried out,and it is solved that when the opening ratio is 0.49,the laminar flow element can get the conclusion that a stable flow ratio can be obtained.Aiming at the analysis of the flow conditioner,this paper establishes a CFD-based flow conditioner research model and evaluation method to realize the fully developed evaluation of the flow field of the downstream pipeline of the flow conditioner.To evaluate the performance of the etoile conditioner,an improved structure with multiple sets of cored blades staggered distribution conditioner is proposed.This structure cores the etoile conditioner blades whose length is twice the pipe diameter(2D),and divides them into a number of 2D/n lengths.The blade groups of are arranged staggered at a certain angle.In order to obtain the optimal structural parameters,the number of blade groups and the staggered angle of two adjacent blade groups are used as the variable parameters to analyze and evaluate its influence on the stability of the downstream flow field of the conditioner.The analysis results show that the improved structure of the conditioner can effectively improve the downstream flow field stability,and its effect is strengthened with the increase of the number of blade groups.Among them,the four cored blade groups are arranged in a staggered 10° arrangement,and the downstream flow field of the conditioner is stable.Relatively optimal.Subsequently,a simulation analysis of the overall operation process of the flowmeter was carried out,and the analysis results reached the expected goal.On the basis of theoretical analysis,the optimized thermal mass flowmeter system design and physical production were carried out,a flowmeter test bench was built,and accuracy and repeatability tests were carried out on the flowmeter,and the test results met relevant requirements.The test of the influence of the number of conditioner blade groups on the stability of the flowmeter verifies that the increase in the number of blade groups can improve the stability.