Firing tests of hybrid engine with varying oxidizer nature and operating conditions

International audience8 Hybrid combustors are of increasing interest for space and civilian propulsion. A test facility has been settled to 9 investigate the high density polyethylene combustion (propellant of 0.15 m long). A parametric study has been 10 achieved on the oxidiser nature (gaseous oxygen diluted in nitrogen, from 31.4 vol.% to 69.2 vol.% of O 2), on the 11 oxidiser flow rate (from 28.6 g.s-1 to 53.1 g.s-1), on the combustor pressure (from 11.4 bar to 25 bar) and on the 12 nozzle diameter (from 6.4 mm to 12.9 mm). The regression rate has been estimated by weight loss (mean value of 13 0.207 mg.s-1) and by thermocouples (0.198 mg.s-1). Its values are compared to existing data through the Marxman 14 law; this enlarges the range of validity of this law. The conduction heat flux in the solid reducer is estimated around 15 6000 W to 8000 W; which is related to the low regression rate of the solid fuel. The axial thrust has been measured 16 in addition to other parameters (pressures, temperatures, mass flow rates). Solid particles have been gathered at the 17 combustor outlet to conduct additional chemical analyses. These particles were formed at the surface of the reducer 18 and extracted by the oxidizer from the solid surface. 1