COMBUSTION OF PLAIN AND REINFORCED PARAFFIN WITH NITROUS OXIDE

摘要

Hybrid rockets may present a good propulsion alternative for different missions, particularly for the emerging field of space tourism, mainly due to the safety of the motor both during development and operation. Nevertheless, for certain applications the low regression rate of conventional polymeric fuels implies too low of a thrust. In recent years, paraffin (wax)-based fuels have been investigated because of their much higher regression rate compared to that of polymeric fuels. Paraffin, however, presents relatively poor mechanical properties. The motivation of this research is to acquire data on pure paraffin (wax) and mixed paraffin- polymer (HTPB) fuels and to compare their actual energetic performance (mainly C), regression rate, and certain mechanical properties. Polymethylmethacrylate (PMMA, Plexiglas) fuel was tested as well, as it is the most used hybrid fuel in laboratory experiments and can serve as a reference to other works. A comparison to results from the literature for similar fuels with oxygen as the oxidizer was also done to identify the influencing properties of the specific oxidizer. It was found that the regression rate of paraffin is about 5 times higher than that of PMMA (polymer). A mixed paraffin-polymer (HTPB) fuel gives a lower regression rate than pure paraffin, yet it is higher by about two- or threefold than that of PMMA. C* efficiency obtained was in the range of 80%-100%, with an average of about 90%.