Effects of the nozzle divergent cone contour on solid rocket motor performance

The effects of the nozzle divergent cone contour on motor performance were studied through calculating the specific impulse losses of nozzle axisymmetric two-phase flow and boundary layer. The results show when the length of nozzle divergent cone is constant, the nozzle expansion ratio has an optimum value and when the nozzle expansion ratio is a constant, nozzle performance increases along with increased length of nozzle divergent cone. It is concluded that for making the combined performance optimum, a ratio 1-1.25 of the nozzle divergent cone length to its exit diameter is reasonable. The conclusion can be referred by nozzle designers.