Research On In-orbit Ultrasonic Measurement Technology Of Propellant Flow

In order to maximize the use of propellants,increase the payload of satellites and extend the life of satellites,accurate measurement of satellite propellant residuals has been the goal pursued by aerospace researchers.Compared with traditional flowmeters such as turbine flowmeters,the time-difference ultrasonic flowmeter has the advantages of high measurement accuracy,no obstruction flow components,being suitable for small flow measurement under small pipe diameter conditions,and has good development prospects in propellant flow in-orbit measurement.Foreign research on ultrasonic flowmeters has been carried out early,and its preparation process is relatively mature,and has developed high-precision time-difference ultrasonic flowmeters for propellant flow in-orbit measurement.Due to the late start of the research,the ultrasonic flowmeter developed in China has a large gap in accuracy and reliability compared with the advanced level in foreign countries.Based on in-depth study of relevant references at home and abroad,combined with theoretical and simulation analysis,this paper designs and prepares an ultrasonic transducer for propellant flow in-orbit measurement.Combined with ultrasonic testing card and upper computer processing software,based on the basic principle of time-difference ultrasonic flow measurement,a time-difference ultrasonic flowmeter for propellant flow in-orbit measurement is designed.Firstly,the development history of ultrasonic flowmeters at home and abroad,as well as the latest research results in the field of ultrasonic flowmeters at home and abroad in recent years were introduced.Then the measurement principle of the time-difference ultrasonic flowmeter and the main factors affecting its accuracy are introduced from the aspects of the performance of ultrasonic transducer,temperature,fluid velocity distribution in the pipeline and accuracy of time-difference measurement.Based on the measurement principle of time-difference method,this paper designs a new measuring tube of ?-type structure,which effectively eliminates the interference of fluid radial flow.At the same time,combined with theoretical and simulation analysis,PZT-5A piezoelectric ceramics are selected as piezoelectric wafer,metal aluminum and polystyrene are selected as matched layers,epoxy resin E51-618+tungsten powder and epoxy resin GCC2002+tungsten powder are selected as backing layers.In this paper,two kinds of ultrasonic transducers are designed,optimized and prepared,and the transducer performance tests are carried out.The two transducers are studied and analyzed.This paper builds a flow measurement test platform and performs calibration and flow measurement tests on the flowmeter prototype according to the JJG1030-2007 Ultrasonic Flowmeter Calibration Regulations.In this paper,the linear regression and polynomial fitting method are used to analyze and process the test results,and the error results and accuracy of the prototype are analyzed.The test results show that in the flow range of 0~300g/s,the relative error of the flowmeter prototype built with the transducers which are selecting polystyrene as matched layers,epoxy resin GCC2002+tungsten powder as backing layers is within ±0.29%,the accuracy can be up to 0.5.