Multiphysics Analysis of Hydroxyl-terminated Polibutadiene Regression in Hybrid Rocket Engines

This work presents a multiphysics numerical investigation of a hybrid rocket engine employing gaseous oxygen and hydroxyl-terminated polybutadiene as propellants. The analysis focuses on the influence of turbulence modeling, chemical reaction mechanisms, and gas-phase radiation on the computed regression rate and internal flowfield. Simulations are performed within the Reynolds-Averaged Navier-Stokes framework using two turbulence models (Spalart-Allmaras and k − ω SST), three chemical mechanisms, and one radiative heat transfer model. Results highlight the significant impact of turbulence and chemistry modeling choices, and show that radiation may give a non-negligible contribution to fuel heating and regression.