Nozzle two-phase flow in H2O2/HTPB hybrid rocket motor was numerically simulated by the stochastic trajectory model.Accuracy of the simulation results was verified by comparison with experimental data.A parametric study of different condensed phase mass fractions and particle mean diameters was performed to investigate the influence of condensed phase parameters on nozzle performance

and the results show that the nozzle efficiency decreases with the increasing of condensed phase mass fraction and particle mean diameter.An orthogonal design of fuel formulation was conducted to investigate the effect of different fuel additives(Al

Mg

AP and B) on the motor performance

and an optimal formulation was obtained.The results indicate that the condensed phase mass fraction increases with the increasing of mass fractions of Al and Mg

and is low dependent on the mass fractions of AP and B;the addition of Al

Mg

AP and B has little effect on the maximum specific impulse

and can enhance the maximum density specific impulse effectively.Moreover

the addition of Al and Mg reduces the nozzle efficiency

the actual specific impulse and the actual density specific impulse

while the addition of AP and B has little effect on the nozzle performance.