According to the coupling between the solid fuel and gaseous phases

the solid fuel regression rate model was established.Three-dimensional numerical simulation of a star-shaped fuel grain hybrid rocket motor with hydrogen peroxide(H2O2) and hydroxyl-terminated polybutadiene(HTPB) propellants combination was presented.The flow field and the solid fuel grain regression rate distribution were obtained

and the results were compared with that of two-dimensional axial symmetry engine.The results indicate that the flame layer profile is similar with the star-shaped fuel port

while the thickness and the location of the flame makes differences in the root and the slot of the star-shape.With the axial coordinate increasing

the oxidizer consumes continually

and the flame layer shifts toward the centre of the fuel grain port.The solid fuel regression rate relates with the oxidizer mass flux and solid fuel location.It increases with the oxidizer mass flux growing

and is higher in the root of the star-shape than in the slot.The solid fuel regression rate of three-dimensional fuel grain is larger than two-dimensional axial symmetry under the same oxidizer mass flux.