Modeling of Hybrid Rocket Combustion Using a Variable Wall Temperature Model

Abstract

The combustion characteristics of hybrid rocket motors have been widely studied and many equations for fuel regression rates have been proposed. Among these, the equation devised by Marxman et al. has been used most often. However, while the results obtained from this equation are in good agreement with the experimental data for some fuels, it is inaccurate for many other fuels. This method was derived using a constant wall temperature model that tends to give results inferior to a variable wall temperature model. Thus, the present work employed a variable wall temperature to derive a theoretical mass flux exponent. The resulting exponent was compared with that predicted by the Marxman equation and with an experimental value. As a result, it is smaller than the value reported by Marxman et al. and slightly closer to the experimental value. Therefore, it was found that the fuel regression rate has a larger error than the error that the surface temperature is constant.