Research On Passive Piston Micro Gas Flow Calibration Device

The passive piston micro gas flow indicator is a calibration device that calibrates the dynamic performance of the gas flow rate of a micro gas flow meter.Since the characteristics of the gas in the piston cylinder are highly susceptible to external temperature and atmospheric pressure,research on the gas dynamic performance calibration device has been a difficult problem.In addition,most of the current knowledge of the detection of micro gas flow dynamic performance is concentrated in theoretical research.There are relatively few calibration devices for accurate calibration of micro gas flow meters,which also limits the evaluation of comprehensive indicators of micro gas flow.Therefore,a passive p iston type micro gas flow calibration device was developed.The specific research contents are as follows:(1)Combine the research status of the micro gas flow calibration device at home and abroad,and formulate the overall scheme design based on the working principle of the calibration device.(2)Using the fluid mechanics calculation method,the internal dynamic characteristics of the piston cylinder are simulated based on the Fluent simulation software,and the feasibility of the device is verified.(3)DSP(Digital signal processor)is used as the controller of the control system;LabVIEW is used to realize real-time monitoring,data display and report generation of the upper computer;combined with experimental research and analysis of device uncertainty,the reliability of the device is verified.The experimental results show that the temperature of the piston cylinder inlet,the pressure change of the gas in the piston cylinder and the timing value of the photoelectric switch are all stable during the operation,and the expansion uncertainty of the device in the flow detection range(50~8245)sccm Better than 0.5%(k=2).