Numerical analysis of fuel regression rate distribution characteristics in hybrid rocket motors with different fuel types

This paper presents three-dimensional numerical simulations of the hybrid rocket motor with hydrogen peroxide (HP) and hydroxyl terminated polybutadiene (HTPB) propellant combination and investigates the fuel regression rate distribution characteristics of different fuel types. The numerical models are established to couple the Navier-Stokes equations with turbulence, chemical reactions, solid fuel pyrolysis and solid-gas interfacial boundary conditions. Simulation results including the temperature contours and fuel regression rate distributions are presented for the tube, star and wagon wheel grains. The results demonstrate that the changing trends of the regression rate along the axis are similar for all kinds of fuel types, which decrease sharply near the leading edges of the fuels and then gradually increase with increasing axial locations. The regression rates of the star and wagon wheel grains show apparent three-dimensional characteristics, and they are higher in the regions of fuel surfaces near the central core oxidizer flow. The average regression rates increase as the oxidizer mass fluxes rise for all of the fuel types. However, under same oxidizer mass flux, the average regression rates of the star and wagon wheel grains are much larger than that of the tube grain due to their lower hydraulic diameters.