The optimization of rough surface supersonic nozzles

In this work, a theoretical optimization study of compressible gases adiabatic flows was conducted for conical nozzles with internal rough surface. A mathematical model was developed for allowing the determination of thrust accounting for nozzle friction and divergence losses. In the first part of the study, it is shown that in rough surface nozzles there are critical values of the nozzle opening half angle, under which, additional increase in gas velocity is not obtained. It is also observed that the minimum nozzle opening half angle value increases as the flow velocity and the nozzle internal surface roughness increase. In the second part of the study, it is shown that there are optimal values of nozzle opening half angle for minimum hydraulic loss across the nozzle, for each combination of the hydraulic resistance caused by the internal surface roughness and the nozzle outlet cross sectional area.