Investigation on the effect of liquefying diaphragmin hybrid rocket motors using paraffin-based fuel

Hybrid rocket propulsion experiments using gaseous oxygen as oxidizer and pure paraffin as fuel with a liquefying combustible diaphragm made from 10 wt% LDPE and 90 wt% paraffin were performed. Results of experiments were compared to those of pure paraffin and to diaphragm grain having different step height. Blended combustible diaphragm fuel is chosen for this study to highlight its combustion characteristics and advantages over the metallic diaphragm fuel. Though the segmented grain configuration of the combustible diaphragm is intricate compared to the classical single grain, the capability of combustible diaphragm showed better combustion characte ristics over the single grain in terms of efficiency and performance. In addition, the exposure type diaphragm showed a further improvement in efficiency and characteristic velocity due to the increased turbulent intensity and mixing past the diaphragm. Results of this study accent on the potential of the combustible diaphragm which may be an efficient mixing device for improving the low combustion efficiency of the paraffin based fuel for hybrid rocket motor.