Abstract

JOUBERT, A.J.  and  DOBSON, R.T.. Theoretical and Experimental Evaluation of a Liquefied Gas Micro Satellite Thruster. R&D j. (Matieland, Online) [online]. 2007, vol.23, pp.12-25. ISSN 2309-8988.

The design, test apparatus, theory and evaluation of a liquefied gas micro satellite thruster is presented in this paper. The thruster system included an accumulator such that copper mesh could be placed in it to improve the heat transfer to the butane vapour. Thermocouples were placed in the accumulator to measure the temperature and two pressure transducers were placed on either side of the mesh in the accumulator to measure the pressure drop across the mesh. A calibrated cantilever beam thrust sensor was used. A theoretical model was developed to model the two-phase flow behaviour and heat transfer of the butane in the accumulator. Idealised gas dynamics were used to model the flow of the butane vapour through the nozzle. An increase of 62% in the total impulse was achieved with the addition of copper mesh to the accumulator with a 13 ml charge of liquid butane. The specific impulse I_sp achieved under atmospheric conditions was 5.3 seconds without mesh in the accumulator and 8.6 seconds with mesh in the accumulator. Under vacuum conditions the I_sp achieved without mesh in the accumulator was 67.5 seconds. An I_sp of 109.5 seconds was estimated under vacuum conditions with mesh in the accumulator. The theoretical results presented show a good correlation between the theoretical results and the experimental results provided that there are no Shockwaves present in the nozzle.