Design And Experimental Research Of Air-conditioning Micro-thruster Test System

Cold gas micro-propulsion system is the most mature way to promote small-satellite technology,the development of micro-propulsion technology to promote micro-thrust test technology continues to progress.At present,the test system uses more methods such as wobble,balance and cantilever.The measurement accuracy needs to be improved.Moreover,the structure of the test device is complex and the system stability is poor.In order to solve the above problems,this paper designs a test system of cold gas micro thruster based on vertical force measurement method,and studies the thrust characteristics experimentally.Theoretical research on the thrust characteristics of cold gas micro thrusters provides an important basis for the design of the test system.Firstly,the structure and working principle of micro thrusters are introduced.By analyzing the gas flow in the nozzle,the thrust calculation formula based on the thrust coefficient is obtained,and the thrust performance of the micro thrusters under ground and vacuum conditions is theoretically studied.According to the test system performance indicators and theoretical research results,the test system of cold gas micro thrusters is designed,including micro-thrust test bench system and data acquisition system.By measuring the force directly by the force sensor,an adjustable angle force measuring device and a vertical force measuring device are designed.In order to collect and process the experimental signals,a data acquisition software based on Lab VIEW is designed to collect,save,retrieve,report and filter the experimental data.The thrust characteristics of cold gas micro thrusters are experimentally studied.By changing the inlet pressure and the ambient pressure,the thrust characteristics of cold gas micro thrusters under ground and vacuum conditions are experimentally studied.The ground thrust of N,and NH3 always remains similar,and the absolute vacuum thrust is obtained according to the measurement of thrust coefficient and degree of vacuum.Compared with the thrust on the ground,double the vacuum thrust,NH3 flash jet enhances the thrust of 10%to 15%.The response time is obtained by measuring the current change.The influence of different propellant gases on the response time is not much different.The effect of the series voltage regulator in the protection loop on improving the dynamic characteristics is greater than the resistance.The error of the thrust measurement experiment was analyzed.The total error of the pressure sensor was 0.39%by the calibration.The static index of the thrust measuring device is analyzed.The error caused by the calibration method is 0.48%and the error caused by the static index is 0.25%.The main sources that affect the measurement error are analyzed.The error caused by the thrust measurement device is 0.54%,and the total error of the micro thrust test system is 0.94%,which meets the technical index requirements of the test system.The total error of the micro thrust test system is less than 1%,and the measurement accuracy is greatly improved.