Experimental And Computational Study Of Catalytic Decomposition And High Pressure Combustion Reaction Based On Ammonium Dinitramide(ADN) Liquid Propellant

Ammonium dinitramide(ADN)based liquid propellant is a new type propellant with high performance,non-toxic and storable.It can be represented a new research direction and development trend of the space propulsion.It has shown a significant influence to improve the thruster performance,pre-packaged implementation of satellite propulsion system and the response speed of China's satellite launch.In this study,the catalytic decomposition and combustion reactions of the ADN propellant during the working process in a 1N ADN based liquid thruster were investigated with the experimental and numerical methods.The vacuum ignition test bench for the ADN based thruster,consisting of storage tank and pipeline system,thruster rack system,vacuum chamber system,image acquisition and data measurement system and exhaust post-processing system,was established.An experimental system containing the TDLAS system was established and used to measure the gaseous pressure and temperature in the combustion chamber of the thruster.The signal of the CO species and temperature was analyzed.The sensors in the experimental system was calibrated and tested before measurement.The performance of the catalytic particles was validated by the firing test in the real ADN based thruster.Then the outer.wall temperature on the catalytic chamber and combustion chamber of the thruster,the pressure in the combustion chamber were measured.The gaseous temperature and CO concentration in the combustion chamber were obtained by the TDLAS technique.According to the experimental data,the empirical models of the combustion pressure,temperature and CO molar fraction under different conditions were determined with fitting method.A mathematical model was developed to describe the working process of the ADN based thruster by consideration of the liquid breakup,evaporation,heat and mass transfer in the porous region,catalytic decomposition reactions of ADN and combustion reactions of the methanol.The boundary condition of the liquid jet breakup was obtained by the PDA measurement.A simple 19-step chemical kinetics mechanisms was used in this study.The model of ADN catalytic decomposition and high-pressure combustion was validated by comparing the experimental results which obtained by means of the vacuum ignition test.The numerical study of the working processes of the ADN based thruster was carried out by the model developed in present study.Firstly,the comparison of the numerical results of the gaseous temperature,pressure and CO molar fraction with the experimental data was performed.The performance of the numerical model and the spatial distribution of the key intermediate species were discussed.Then the effect of the operating conditions(i.e.the propellant injection pressure,the preheating temperature of the catalytic chamber)on the working performance of the thruster was carried out,and the results of distributions of the temperature and related species were discussed.The effect of the main structure parameters(i.e.the diameter of the catalytic chamber,the length of the combustion chamber and porosity ratio of the catalytic chamber)on the chemical reactions and specific impulse of the thruster was also investigated and discussed in detail.The results indicated that the numerical gaseous temperature and pressure results showed a good agreement with the experimental data.The calculated CO molar fraction was in the same order of magnitude as the measurement results.The combustion pressure,temperature and specific impulse of the thruster could be significantly increased with the increase of injection pressure and preheating temperature.In addition,the structure parameters(i.e.the diameter of the catalytic chamber,the length of the combustion chamber and porosity ratio of the catalytic chamber)also had a great influence on the performance of the thruster.The decomposed reactions could be affected by influencing the effective specific surface area through changing the porosity ratio and the diameter of the catalytic chamber.The solid mass and resistance of the catalytic chamber led to affect the temperature rise,which would have an influence on the catalytic decompose reactions...