Numerical and experimental analysis of a 200 N class GOX-ABS hybrid rocket engine

• Acrylonitrile butadiene styrene (ABS) is a promising fuel for hybrid rocket engines. • A firing test of a 200 N class hybrid rocket burning ABS and gaseous oxygen is performed. • A combined numerical and experimental analysis of ABS regression rate and combustion characteristics is carried out. • A novel approach for ABS combustion allows to successfully rebuild the firing test. Hybrid rocket engines offer a promising alternative to liquid and solid rockets, and the use of 3D-printable fuels enables great flexibility in grain design, allowing engine performance to be tailored to mission requirements. Among such fuels, acrylonitrile butadiene styrene (ABS) stands out as one of the most promising options due to its favorable mechanical properties and combustion performance. In this context, predictive numerical simulations can serve as a key tool during the design phase, allowing for a significant reduction in development time and costs. Accurate prediction of ABS combustion behavior is essential to fully exploit its potential for cost-effective and flexible hybrid rocket design. Nonetheless, significant uncertainties remain in modeling its behavior as a rocket fuel. In this work, a firing test of a 200 N-class hybrid rocket using gaseous oxygen and ABS is conducted, followed by an extensive numerical simulation campaign. A computational approach based on axisymmetric Reynolds-averaged Navier-Stokes (RANS) simulations is employed, incorporating sub-models for turbulence, chemistry, gas-surface interaction, and radiation. A reconstruction of the firing test is carried out, yielding errors of 2 % and 5 % on the average regression rate and chamber pressure, respectively. Considering the uncertainties in fuel properties, parametric simulations are conducted to evaluate the effect of the pyrolysis law and heat of vaporization on the computed regression rate. These analyses highlight the importance of a detailed understanding of the main gas-surface interaction parameters in accurately predicting the fuel burning behavior.