星形フラクタル形状グレインを用いたハイブリッドロケットにおける平均後退速度の評価

抄録

The main drawback of hybrid rocket is low fuel regression rate. One of the solutions is usage of fuel grain with a complicated geometry port made with additive manufacturing technology. It is difficult to evaluate time- and space-averaged regression rate from experimental data in the case of complicated geometry port, compared to the case of circular port. This reason is that the solid fuel surface of complicated geometry port regresses in intricate manner. In this research, the numerical method to evaluate the time- and space-averaged value was hence developed under the assumption that the solid fuel surface regresses with a uniform and constant speed. Combustion experiments were performed and these experimental data were evaluated with this numerical method. As the results, it was suggested that, except for at low oxidizer mass flux region, the time- and space-averaged regression rates of the star fractal port are almost comparable to those of the circular port and that the fuel mass flow rates of the star fractal port are higher than those of the circular port. These implies the advantage of the star fractal port compared to the circular port in terms of thrust generation.