NUMERICAL STUDY OF LOW-THRUST NOZZLES FOR SATELLITES

Axisymmetric low-thrust nozzles were numerically investigated for thei r performance. Both the Euler and Navier-Stokes solvers were developed for studying the flowfields and the viscous effect of the nozzle flow s. The low-thrust nozzles considered are the conventional conical nozz le and the minimum-length nozzle. These two types of nozzle were analy zed and compared for their performance by varying the values of geomet ric parameters and were designed to produce short nozzles with a requi red thrust for satellite control. Since a minimum-length nozzle may be too long, causing an additional energy loss in the boundary layer and too heavy for economic considerations, a technique of cutting off the supersonic section about 71% at a distance 10 throat radii from the t hroat is suggested, with only a 2% loss in the thrust and specific imp ulse ratios for the viscous model. The losses can be compensated by in creasing the throat area by the same percentage. It was also found tha t the lower the wall temperature, the greater the mass how rate needed to maintain the required thrust. Consequently, a low wall temperature will reduce the nozzle efficiency.