Combustion of Bio-derived Fuels With Additives and Research on the Losses of Unburned Fuel in Hybrid Propellant Rocket Engines

Abstract

The paper represents the study of combustion of paraffin and paraffin with aluminum powder in a small-scale Hybrid Propellant Rocket Engine (HPRE). This study is a part of the long-term research of specific features of combustion using non-conventional bio-derived hybrid rocket fuels such as paraffin, beeswax, lard, and bio-derived fuels with additives which are non-toxic and non-explosive along with different oxidizers. Such fuels could replace conventional toxic and explosive fuels, and are planned to be used on the NASA sounding rockets. The goal of the research is to study the combustion of bio-derived fuels, obtain regression rates, compare operational parameters of HPREs and investigate losses of melted unburned bio-derived fuels. A small-scale HPRE, test fixture and instrumentation system have been designed, manufactured, assembled and used for the combustion research and analysis. The results of the research were presented at the 50 and 51 AIAA Meeting and Exhibits, and SciTech, 52 Aerospace Sciences Meeting. The following paper summarizes recent research results on the combustion of paraffin and paraffin with aluminum powder, represents new findings, such as regression rate formulas for the combustion of paraffin wax with 10% of aluminum powder obtained for two different grain port diameters, and discusses novel methodology and results for prediction of losses of unburned fuel based on the combustion products exhaust plume temperature measurements and thermodynamic calculations of the combustion of bio-derived fuels.