Abstract
In order to design hybrid rocket engines, we developed a numerical prediction method to the internal ballistics, such as the characteristic of fuel regression rate. Our model includes quasi-one-dimensional flowfield and one-dimensional thermal conduction into the solid fuel. Besides, the energy-flux balance equation at the solid fuel surface is solved to determine the regression rate. In addition to convective heat transfer, radiative heat transfer is introduced into the energy-flux balance equation in order to improve the estimation accuracy of the regression rate characteristics. The emissivity of combustion gas is estimated by Leckner's empirical correlation. Parameters related to this correlation, such as flame temperature and chemical composition at the flame, are evaluated by the chemical equilibrium calculation in which Gibbs energy minimization is implemented. The calculation results are compared with the experimental data in an open literature. As a result, it is confirmed that the calculations with the radiation model predict the regression rate dependency on oxidizer mass flux more precisely than the calculations without the radiation model. However the estimated regression rates are overestimated compared to the experimental data. It is confirmed that one of the reasons for the overestimation is the use of the wrong value of the velocity ratio in the thermochemical blowing parameter definition.
