2013 年 61 巻 2 号 p. 31-37
For hybrid rocket engines, there are some unique relationships between the parameters, such as the fuel regression rate, oxidizer mass flow rate, equivalence ratio and so on, which determine the burning properties. These relationships are strongly related to the engine performance. Our final goal of this study is to establish the optimum design method which considers the engine performance of hybrid rocket engines for practical hybrid rockets varying with time. In this paper, we focused on the time variation of ballistic parameters of the swirling-oxidizer-flow-type hybrid rocket engine. We establish the new simulation method, the Two-Step combustion model, in which at the fuel grain head the fuel regression rate is independent of the oxygen mass flux and in the rear region depends on the flux according to the ordinary hybrid combustion formula. The model succeeded to predict the time variation of the burning properties and ballistics parameters, which coincided with the experimental burning values and time behavior. These results show the possibility that there are two different combustion mechanisms in the burning process of the swirling-oxidizer-flow-type hybrid rocket engine.