Experimental analysis of the heat fluxes during combustion of a N2O/C2H4 premixed green propellant in a research rocket combustor

Abstract

Across the globe, several green propellants as substitute for the highly toxic hydrazine are under investigation. A possible alternative are so called nitrous oxide fuel blends. This paper presents the results of combustion tests conducted with a premixed monopropellant consisting of N2O and C2H4. In four test series the influence of the mixture ratio, the chamber pressure, the chamber length and the average flow velocity on the combustion efficiency and on the heat flux is analyzed and discussed. Furthermore four empirical Nusselt correlations derived by Bartz, Cinjarew, Dittus–Boelter and Gnielinski are compared to the experimental results and finally modified to improve their accuracy. In an additional test campaign the oxidizer N2O was used as regenerative coolant prior to the mixing with C2H4. However, mixing of the hot N2O with C2H4 resulted in the decomposition of C2H4 and the formation of soot. For this reason in a final test campaign a premixed N2O/C2H6 propellant was used. The N2O/C2H6 mixture was successfully used as regenerative coolant and combustion tests up to 10 min were performed.