Characterisation of thrust performance of micro-nozzle machined by micro end-milling

Micro thruster is the power plant of mini-spacecraft. It enables the mini-spacecraft to realize orbit adjustment, station keeping and attitude controlling. Micro nozzle is one of key parts of the micro thruster. The surface roughness of its inner surface significantly influences the thrust performance of the thruster. In this paper, a residual surface model is developed for micro-nozzle obtained by micro machining using a ball end mill and a taper end mill. The residual surface model is then used to investigate the relationship between the surface quality and nozzle thrust performance in nozzle flow field. A thrust measuring apparatus is designed and manufactured to inspect the thrust performance of the machined micro nozzles. Both simulation and experiment results indicate that good machined surface quality is obtained with taper end mill. The nozzle machined with the taper end mill has better thrust performance than that with the ball end mill under the same inlet pressure.