In order to build a high energy space engine, the combustion characteristics of a hybrid rocket are explored in the present study.
Oxidizers such as hydrogen peroxide (HP), inhibited red fuming nitric acid
(IRFNA), and nitrogen tetroxide (NTO) have been screened to provide the
rocket a better propulsion performance. An important result found in this
study is that the combustion characteristics as well as the propulsion
performance are strong functions of the oxidizer-to-fuel ratio. But, the
influence of chamber pressure on these two issues is not so significant.
Considerable amount of vapor and oxygen that may cause a severe erosion
of insulator and nozzle throat exist in the flue gas if the system is running in the fuel-lean situation. This effect suggests that it is better to operate a hybrid rocket under the fuel-rich condition. The best vacuum specific impulse of this study is 331 seconds with HP oxidizer and is in the same as that with NTO oxidizer. However, result also shows that the rocket performs the highest density specific impulse of 444 seconds when IRFNA is used as the oxidizer. Hence, IRFNA is the most promising oxidizer to have a small vehicle construction.